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Posted to dev@kafka.apache.org by Guozhang Wang <wa...@gmail.com> on 2017/06/05 01:23:57 UTC
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
With KIP-159, the added "valueMapperWithKey" and "valueTransformerWithKey"
along seem to be just adding a few syntax-sugars? E.g. we can simply
implement:
mapValues(ValueMapperWithKey mapperWithKey)
as
map((k, v) -> (k, mapperWithKey(k, v))
----------------------
I'm not sure how many users would really need such syntax sugars, and even
they do, we can support them easily as the above implementations;
Similarly for "ReducerWithKey", it can be implemented as `Aggregator<K, V,
V>`, and people who needs key access can just use `aggregate` directly.
The function which I think is really of valuable is `ValueJoinerWithKey`,
and that seems to be the original request from users while others are
coming from "API consistency" concerns. Personally I'd prefer only keep the
last one (`InitializerWithKey` might also have some value, but I have not
seen people widely requesting it in their DSL usage yet; if there is a
common request we can keep it in this KIP as well). WDYT?
Guozhang
On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <je...@gmail.com>
wrote:
> Thanks for clarification Matthias, now everything is clear.
>
> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <ma...@confluent.io>
> wrote:
>
> > I don't think we can drop ValueTransformerSupplier. If you don't have an
> > supplier, you only get a single instance of your function. But for a
> > stateful transformation, we need multiple instances (one for each task)
> > of ValueTransformer.
> >
> > We don't need suppliers for functions like "ValueMapper" etc because
> > those are stateless and thus, we can reuse a single instance over
> > multiple tasks -- but we can't do this for ValueTransformer (and
> similar).
> >
> > Btw: This reminds me about KIP-159: with regard to the RichFunction we
> > might need a supplier pattern, too. (I'll comment on the other thread,
> > too.)
> >
> >
> > -Matthias
> >
> > On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> > > Hi,
> > >
> > > I updated KIP.
> > > Just to avoid misunderstanding, I meant deprecating
> > ValueTransformerSupplier
> > > and I am ok with ValueTransformer.
> > > So instead of using ValueTransformerSupplier can't we directly use
> > > ValueTransformer
> > > or ValueTransformerWithKey?
> > >
> > > Btw, in current design all features of ValueTransformer will be
> available
> > > in ValueTransformerWithKey interface.
> > >
> > > Cheers,
> > > Jeyhun
> > >
> > > On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <matthias@confluent.io
> >
> > > wrote:
> > >
> > >> Thanks Jeyhun.
> > >>
> > >> About ValueTransformer: I don't think we can remove it. Note,
> > >> ValueTransformer allows to attach a state and also allows to register
> > >> punctuations. Both those features will not be available via withKey()
> > >> interfaces.
> > >>
> > >> -Matthias
> > >>
> > >>
> > >> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> > >>> Hi Matthias,
> > >>>
> > >>> Thanks for your comments.
> > >>>
> > >>> I tested the deep copy approach. It has significant overhead.
> > Especially
> > >>> for "light" and stateless operators it slows down the topology
> > >>> significantly (> 20% ). I think "warning" users about not-changing
> the
> > >> key
> > >>> is better warning them about possible performance loss.
> > >>>
> > >>> About the interfaces, additionally I considered adding
> > >> InitializerWithKey,
> > >>> AggregatorWithKey and ValueTransformerWithKey. I think they are
> > included
> > >> in
> > >>> PR but not in KIP. I will also include them in KIP, sorry my bad.
> > >>> Including ReducerWithKey definitely makes sense. Thanks.
> > >>>
> > >>> One thing I want to mention is that, maybe we should deprecate
> methods
> > >> with
> > >>> argument type ValueTransformerSupplier (KStream.transformValues(...))
> > and
> > >>> and as a whole the ValueTransformerSupplier interface.
> > >>> We can use ValueTransformer/ValueTransformerWithKey type instead
> > without
> > >>> additional supplier layer.
> > >>>
> > >>>
> > >>> Cheers,
> > >>> Jeyhun
> > >>>
> > >>>
> > >>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> matthias@confluent.io
> > >
> > >>> wrote:
> > >>>
> > >>>> One more question:
> > >>>>
> > >>>> Should we add any of
> > >>>> - InitizialierWithKey
> > >>>> - ReducerWithKey
> > >>>> - ValueTransformerWithKey
> > >>>>
> > >>>> To get consistent/complete API, it might be a good idea. Any
> thoughts?
> > >>>>
> > >>>>
> > >>>> -Matthias
> > >>>>
> > >>>>
> > >>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> > >>>>> Jeyhun,
> > >>>>>
> > >>>>> I was just wondering if you did look into the key-deep-copy idea we
> > >>>>> discussed. I am curious to see what the impact might be.
> > >>>>>
> > >>>>>
> > >>>>> -Matthias
> > >>>>>
> > >>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> > >>>>>> Hi,
> > >>>>>>
> > >>>>>> Thanks for your comments. I rethink about including rich functions
> > >> into
> > >>>>>> this KIP.
> > >>>>>> I think once we include rich functions in this KIP and then fix
> > >>>>>> ProcessorContext in another KIP and incorporate with existing rich
> > >>>>>> functions, the code will not be backwards compatible.
> > >>>>>>
> > >>>>>> I see Damian's and your point more clearly now.
> > >>>>>>
> > >>>>>> Conclusion: we include only withKey interfaces in this KIP (I
> > updated
> > >>>> the
> > >>>>>> KIP), I will try also initiate another KIP for rich functions.
> > >>>>>>
> > >>>>>> Cheers,
> > >>>>>> Jeyhun
> > >>>>>>
> > >>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> > >> matthias@confluent.io
> > >>>>>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>>> With the current KIP, using ValueMapper and ValueMapperWithKey
> > >>>>>>> interfaces, RichFunction seems to be an independent add-on. To
> fix
> > >> the
> > >>>>>>> original issue to allow key access, RichFunctions are not
> required
> > >>>> IMHO.
> > >>>>>>>
> > >>>>>>> I initially put the RichFunction idea on the table, because I was
> > >>>> hoping
> > >>>>>>> to get a uniform API. And I think, is was good to consider them
> --
> > >>>>>>> however, the discussion showed that they are not necessary for
> key
> > >>>>>>> access. Thus, it seems to be better to handle RichFunctions in an
> > own
> > >>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a main
> > >>>>>>> challenge for this. And introducing RichFunctions with
> > parameter-less
> > >>>>>>> init() method, seem not to help too much. We would get an
> > >>>> "intermediate"
> > >>>>>>> API that we want to change anyway later on...
> > >>>>>>>
> > >>>>>>> As you put already much effort into RichFunction, feel free do
> push
> > >>>> this
> > >>>>>>> further and start a new KIP (we can do this even in parallel) --
> we
> > >>>>>>> don't want to slow you down :) But it make the discussion and
> code
> > >>>>>>> review easier, if we separate both IMHO.
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> -Matthias
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> > >>>>>>>> Hi Damian,
> > >>>>>>>>
> > >>>>>>>> Thanks for your comments. I think providing to users *interface*
> > >>>> rather
> > >>>>>>>> than *abstract class* should be preferred (Matthias also raised
> > this
> > >>>>>>> issue
> > >>>>>>>> ), anyway I changed the corresponding parts of KIP.
> > >>>>>>>>
> > >>>>>>>> Regarding with passing additional contextual information, I
> think
> > it
> > >>>> is a
> > >>>>>>>> tradeoff,
> > >>>>>>>> 1) first, we fix the context parameter for *init() *method in
> > >> another
> > >>>> PR
> > >>>>>>>> and solve Rich functions afterwards
> > >>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
> > providing
> > >>>>>>>> (not-complete) Rich functions and integrate the context
> parameters
> > >> to
> > >>>>>>> this
> > >>>>>>>> afterwards (like improvement)
> > >>>>>>>>
> > >>>>>>>> To me, the second approach seems more incremental. However you
> are
> > >>>> right,
> > >>>>>>>> the names might confuse the users.
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> > >>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> > >>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> Cheers,
> > >>>>>>>> Jeyhun
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> damian.guy@gmail.com
> > >
> > >>>>>>> wrote:
> > >>>>>>>>
> > >>>>>>>>> Hi,
> > >>>>>>>>>
> > >>>>>>>>> I see you've removed the `ProcessorContext` from the
> RichFunction
> > >>>> which
> > >>>>>>> is
> > >>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it to
> > pass
> > >>>> some
> > >>>>>>>>> additional contextual information, i.e., the `RecordContext`
> that
> > >>>>>>> contains
> > >>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with it
> not
> > >>>>>>> passing
> > >>>>>>>>> this contextual information, but is the naming incorrect? I'm
> not
> > >>>> sure,
> > >>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until we
> can
> > >> do
> > >>>> it
> > >>>>>>>>> properly with the correct context?
> > >>>>>>>>>
> > >>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
> > >>>>>>> RichValueJoiner,
> > >>>>>>>>> RichInitializer etc. Why can't they not just be interfaces?
> > >>>> Generally we
> > >>>>>>>>> should provide users with Intefaces to code against, not
> classes.
> > >>>>>>>>>
> > >>>>>>>>> Thanks,
> > >>>>>>>>> Damian
> > >>>>>>>>>
> > >>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> > je.karimov@gmail.com>
> > >>>>>>> wrote:
> > >>>>>>>>>
> > >>>>>>>>>> Hi,
> > >>>>>>>>>>
> > >>>>>>>>>> Thanks. I initiated the PR as well, to get a better overview.
> > >>>>>>>>>>
> > >>>>>>>>>> The only reason that I used abstract class instead of
> interface
> > >> for
> > >>>>>>> Rich
> > >>>>>>>>>> functions is that in future if we will have some
> > >>>> AbstractRichFunction
> > >>>>>>>>>> abstract classes,
> > >>>>>>>>>> we can easily extend:
> > >>>>>>>>>>
> > >>>>>>>>>> public abstract class RichValueMapper<K, V, VR> implements
> > >>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> > >>>>>>>>> AbstractRichFunction*{
> > >>>>>>>>>> }
> > >>>>>>>>>> With interfaces we are only limited to interfaces for
> > >> inheritance.
> > >>>>>>>>>>
> > >>>>>>>>>> However, I think we can easily change it (from abstract class
> ->
> > >>>>>>>>> interface)
> > >>>>>>>>>> if you think interface is a better fit.
> > >>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>>>> Cheers,
> > >>>>>>>>>> Jeyhun
> > >>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> > >>>> matthias@confluent.io
> > >>>>>>>>
> > >>>>>>>>>> wrote:
> > >>>>>>>>>>
> > >>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
> > improved
> > >>>> now
> > >>>>>>>>> --
> > >>>>>>>>>>> great job!
> > >>>>>>>>>>>
> > >>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
> classes
> > >> and
> > >>>>>>> not
> > >>>>>>>>>>> interfaces?
> > >>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>> Overall, I like the KIP a lot!
> > >>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>> -Matthias
> > >>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Thanks for your comments.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>> `AbstractRichFunction`
> > >>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> > interfaces
> > >>>>>>>>> AFAIK.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Maybe I misunderstood your comment.
> > >>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So they
> > don't
> > >>>> have
> > >>>>>>>>>>> direct
> > >>>>>>>>>>>> relation with *AbstractRichFunction*.
> > >>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only one
> > >>>> method ,
> > >>>>>>>>> so
> > >>>>>>>>>>> we
> > >>>>>>>>>>>> can use lambdas.
> > >>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play? Inside
> > Rich
> > >>>>>>>>>>> functions.
> > >>>>>>>>>>>> And we use Rich functions in 2 places:
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> 1. User doesn't use rich functions. Just regular *withKey*
> and
> > >> and
> > >>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We get
> > those
> > >>>>>>>>>>> interfaces
> > >>>>>>>>>>>> and wrap into Rich function while building the topology, and
> > >> send
> > >>>> to
> > >>>>>>>>>>>> Processor.
> > >>>>>>>>>>>> 2. User does use rich functions (Rich functions implement
> > >>>> *withKey*
> > >>>>>>>>>>>> interface). As a result no lamdas here by definition. In
> this
> > >>>> case,
> > >>>>>>>>>> while
> > >>>>>>>>>>>> building the topology we do a type check if the object type
> is
> > >>>>>>>>>>>> *withKey* or *RichFunction*.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for Rich
> > >>>> functions
> > >>>>>>>>>> and
> > >>>>>>>>>>>> does not affect using lambdas.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
> to
> > >>>> have a
> > >>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> RichFunction
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> As I said above, currently we support lambdas for *withKey*
> > >>>>>>>>> interfaces
> > >>>>>>>>>> as
> > >>>>>>>>>>>> well. However, I agree with your idea and I will remove the
> > >>>>>>>>>>>> AbstractRichFunction from the design.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
> > >>>> support
> > >>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any "extended
> > >> API".
> > >>>>>>>>> For
> > >>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>> AbstractRichFunction
> > >>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> more
> > >>>>>>>>>> overloaded
> > >>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> > >> because
> > >>>> we
> > >>>>>>>>>> have
> > >>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> value
> > in
> > >>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Just to clarify, with current design we have only one extra
> > >>>>>>>>> overloaded
> > >>>>>>>>>>>> method per *withOnlyValue* interface: which is *withKey*
> > >> version
> > >>>> of
> > >>>>>>>>>>>> particular interface.
> > >>>>>>>>>>>> We don't need extra overload for Rich function as Rich
> > function
> > >>>>>>>>>>> implements
> > >>>>>>>>>>>> *withKey* interface as a result they have same type. We
> > >>>> differentiate
> > >>>>>>>>>>> them
> > >>>>>>>>>>>> while building the topology.
> > >>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
> > comment:
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can we
> have
> > a
> > >>>>>>>>> design
> > >>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
> might
> > >> make
> > >>>>>>>>>> sense
> > >>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> However, I don't think that this complicates the overall
> > design
> > >>>>>>>>>>>> significantly.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Depending on what we want to support, it might make sense to
> > >>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> this
> > >>>> also
> > >>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> before
> > >>>> driving
> > >>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Based on our discussion I think we should keep Rich
> functions
> > >> as I
> > >>>>>>>>>> don't
> > >>>>>>>>>>>> think that they bring extra layer of overhead to library.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Any comments are appreciated.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> > >>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> thanks for the update.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>> `AbstractRichFunction`
> > >>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> > interfaces
> > >>>>>>>>> AFAIK.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
> to
> > >>>> have a
> > >>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> RichFunction
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> For this approach, AbstractRichFunction does not make sense
> > >>>> anymore,
> > >>>>>>>>>> as
> > >>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> > >>>> implementation of
> > >>>>>>>>>>>>> init() and close() -- if you don't want those, you would
> > >>>> implement a
> > >>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
> > >>>> support
> > >>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any "extended
> > >> API".
> > >>>>>>>>> For
> > >>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>> AbstractRichFunction
> > >>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> more
> > >>>>>>>>>> overloaded
> > >>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> > >> because
> > >>>> we
> > >>>>>>>>>> have
> > >>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> value
> > in
> > >>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Depending on what we want to support, it might make sense
> to
> > >>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> this
> > >>>> also
> > >>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> before
> > >>>> driving
> > >>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Thoughts?
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Sorry for super late response. Thanks for your comments.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a little
> > >> bit? I
> > >>>>>>>>>> cannot
> > >>>>>>>>>>>>>>> follow the explanation in the KIP to see what the problem
> > is.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - From [1] says "A functional interface is an interface
> that
> > >> has
> > >>>>>>>>> just
> > >>>>>>>>>>> one
> > >>>>>>>>>>>>>> abstract method, and thus represents a single function
> > >>>> contract".
> > >>>>>>>>>>>>>> So basically once we extend some interface from another
> (in
> > >> our
> > >>>>>>>>> case,
> > >>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use lambdas
> > in
> > >>>> the
> > >>>>>>>>>>>>> extended
> > >>>>>>>>>>>>>> interface.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
> > >> reformat
> > >>>> the
> > >>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would help.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - I will work on the KIP.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> overlaods
> > >>>> added
> > >>>>>>>>>> for
> > >>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
> add
> > >> any
> > >>>> new
> > >>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - Actually there are more than one Processor and public
> APIs
> > >> to
> > >>>> be
> > >>>>>>>>>>>>>> changed (KStream-KTable
> > >>>>>>>>>>>>>> joins is one case). However all of them has similar
> > structure:
> > >>>> we
> > >>>>>>>>>>>>> overload
> > >>>>>>>>>>>>>> the *method* with *methodWithKey*,
> > >>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
> inside
> > >> the
> > >>>>>>>>>>>>> processor
> > >>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
> > >>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the overall
> idea
> > >> with
> > >>>>>>>>> only
> > >>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all changes.
> > >>>>>>>>>>>>>> Anyway I will update the KIP.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)* and*
> > >>>> close()*
> > >>>>>>>>>>>>> methods
> > >>>>>>>>>>>>>> in every Rich function with empty body like:
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>> void init(ProcessorContext context) {}
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>> void close () {}
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> I thought that we can override them once in
> > >>>> *AbstractRichFunction*
> > >>>>>>>>>> and
> > >>>>>>>>>>>>>> extent new Rich functions from *AbstractRichFunction*.
> > >>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease the
> > >>>>>>>>>> maintenance.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> Merger,
> > >>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
> all,
> > >> but
> > >>>> we
> > >>>>>>>>>>> should
> > >>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> (e.g.,
> > >>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Definitely agree. As I said, the same technique applies to
> > all
> > >>>> this
> > >>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
> wanted
> > >> to
> > >>>>>>>>> give
> > >>>>>>>>>>> the
> > >>>>>>>>>>>>>> overall intuition.
> > >>>>>>>>>>>>>> However, I will update the KIP as I said.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` -- `ValueXXWithKey` --
> > >>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>> in general -- but why can't we do all this with
> interfaces
> > >>>> only?
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Sure we can. However the main intuition is we should not
> > force
> > >>>>>>>>> users
> > >>>>>>>>>> to
> > >>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()* functions
> > >> every
> > >>>>>>>>> time
> > >>>>>>>>>>>>> they
> > >>>>>>>>>>>>>> use Rich functions.
> > >>>>>>>>>>>>>> If one needs, she can override the respective methods.
> > >> However,
> > >>>> I
> > >>>>>>>>> am
> > >>>>>>>>>>> open
> > >>>>>>>>>>>>>> for discussion.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
> any
> > >>>>>>>>> further
> > >>>>>>>>>>> than
> > >>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> done
> > >>>> before
> > >>>>>>>>>>> this?
> > >>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
> > >> large.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> That is good point. I wanted to make
> > *init(ProcessorContext)*
> > >>>>>>>>> method
> > >>>>>>>>>>>>>> persistent among the library (which use ProcessorContext
> as
> > an
> > >>>>>>>>>> input),
> > >>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> > >>>>>>>>>>>>>> So the important question is that (as @dguy and @mjsax
> > >>>> mentioned)
> > >>>>>>>>>>> whether
> > >>>>>>>>>>>>>> continue this KIP without providing users an access to
> > >>>>>>>>>>> *ProcessorContext*
> > >>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
> > >>>>>>>>>>>>>> initiate another KIP before this.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>
> > http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> > >>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> > >>>> damian.guy@gmail.com>
> > >>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
> > any
> > >>>>>>>>> further
> > >>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> done
> > >>>> before
> > >>>>>>>>>>> this?
> > >>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
> > >> large.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> > >>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>
> > >>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is too
> > broad
> > >> in
> > >>>>>>>>>>> general
> > >>>>>>>>>>>>>>>> -- this is even true for transform/process, and it's
> also
> > >>>>>>>>> reflected
> > >>>>>>>>>>> in
> > >>>>>>>>>>>>>>>> the API improvement list we want to do.
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
> > >>>>>>>>>>>>>>> Kafka+Streams+Discussions
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> So I am wondering, if you question the `RichFunction`
> > >>>> approach in
> > >>>>>>>>>>>>>>>> general? Or if you suggest to either extend the scope of
> > >> this
> > >>>> KIP
> > >>>>>>>>>> to
> > >>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for it
> and
> > >>>> delay
> > >>>>>>>>>> this
> > >>>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>> until the other one is done?
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> > >>>>>>>>>>>>>>>>> Thanks for the KIP.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach. Do we
> > >>>> really
> > >>>>>>>>>> want
> > >>>>>>>>>>> to
> > >>>>>>>>>>>>>>>> give
> > >>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext` ? It
> > has
> > >> a
> > >>>>>>>>> bunch
> > >>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of the
> > DSL
> > >>>>>>>>>> methods,
> > >>>>>>>>>>>>>>> i.e,
> > >>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule` etc.
> > It
> > >> is
> > >>>>>>>>> far
> > >>>>>>>>>>> too
> > >>>>>>>>>>>>>>>>> broad. I think it would be better to have a narrower
> > >>>> interface
> > >>>>>>>>>> like
> > >>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
> > >>>>>>>>>>> methods/interfaces
> > >>>>>>>>>>>>>>>> later
> > >>>>>>>>>>>>>>>>> than to remove them
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> > >>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> > little
> > >>>> bit?
> > >>>>>>>>> I
> > >>>>>>>>>>>>>>> cannot
> > >>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> > problem
> > >>>> is.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess it's
> up
> > >> to
> > >>>>>>>>> you.
> > >>>>>>>>>>>>>>> Maybe a
> > >>>>>>>>>>>>>>>>>> committer can comment on this?
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
> > >>>> reformat
> > >>>>>>>>>> the
> > >>>>>>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> help.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> > >> overlaods
> > >>>>>>>>>> added
> > >>>>>>>>>>>>> for
> > >>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
> > add
> > >>>> any
> > >>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> > >> Merger,
> > >>>>>>>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
> > all,
> > >>>> but
> > >>>>>>>>> we
> > >>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> > >> (e.g.,
> > >>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> `ValueXXWithKey`
> > --
> > >>>>>>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> > interfaces
> > >>>>>>>>> only?
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot extend
> the
> > >> two
> > >>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>> if
> > >>>>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1]. Maybe I
> > >> should
> > >>>>>>>>>> change
> > >>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP to
> only
> > >>>>>>>>>>> ValueMapper,
> > >>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> > >>>>>>>>>>>>>>>>>>> Please feel free to comment.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
> > >>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
> > >>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
> > >>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper` we
> don't
> > >>>> need
> > >>>>>>>>> the
> > >>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>> overlaod.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this happens
> > >> when
> > >>>>>>>>>>> building
> > >>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> KafkaStream#start()
> > >> we
> > >>>>>>>>> don't
> > >>>>>>>>>>>>> need
> > >>>>>>>>>>>>>>>> any
> > >>>>>>>>>>>>>>>>>>>> check as we will always use `ValueMapperWithKey`)
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> > >>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> > >>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<? super
> > V,
> > >> ?
> > >>>>>>>>>> extends
> > >>>>>>>>>>>>>>> VR>
> > >>>>>>>>>>>>>>>>>>>>> mapper);
> > >>>>>>>>>>>>>>>>>>>>> with
> > >>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> mapValues(ValueMapperWithKey<?
> > >>>> super
> > >>>>>>>>> V,
> > >>>>>>>>>> ?
> > >>>>>>>>>>>>>>>> extends
> > >>>>>>>>>>>>>>>>>>>> VR>
> > >>>>>>>>>>>>>>>>>>>>> mapper);
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still have to
> > >> check
> > >>>> it
> > >>>>>>>>> is
> > >>>>>>>>>>>>>>>>>>>> ValueMapper
> > >>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into the
> > rich
> > >>>>>>>>>> function.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal Borowiecki <
> > >>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> +1 :)
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
> > >>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am wondering,
> > if
> > >> we
> > >>>>>>>>>> should
> > >>>>>>>>>>>>> do
> > >>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>> design a little different.
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a RichFunction
> > and
> > >>>>>>>>>>>>>>>> non-RichFunction
> > >>>>>>>>>>>>>>>>>>>> at
> > >>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions all the
> > >> time.
> > >>>>>>>>>> Thus,
> > >>>>>>>>>>> on
> > >>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>> DSL
> > >>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
> non-RichFunction,
> > >> we
> > >>>>>>>>> wrap
> > >>>>>>>>>> it
> > >>>>>>>>>>>>>>> by a
> > >>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
> Streams.
> > >> This
> > >>>>>>>>>>>>>>>> RichFunction
> > >>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the key:
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
> snippet):
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
> > >>>>>>>>> RichValueMapper()
> > >>>>>>>>>> {
> > >>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper; //
> set
> > by
> > >>>>>>>>>>>>> constructor
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1 value1,
> > >>>> final V2
> > >>>>>>>>>>>>>>> value2)
> > >>>>>>>>>>>>>>>> {
> > >>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
> value2);
> > >>>>>>>>>>>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not sure
> if
> > >> the
> > >>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc would
> have
> > >>>> more
> > >>>>>>>>>>>>> overhead
> > >>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested method
> call
> > >> for
> > >>>>>>>>>>>>>>>>>> non-RichFunction
> > >>>>>>>>>>>>>>>>>>>>>>> which should be more common than RichFunctions).
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or do I
> > miss
> > >>>>>>>>>>>>> something?)
> > >>>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more top
> > level
> > >>>>>>>>>>> interface
> > >>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
> `close()`
> > >> and
> > >>>>>>>>> also
> > >>>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no abstract
> > classes
> > >>>>>>>>>>> required).
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP to
> > >> include
> > >>>>>>>>> rich
> > >>>>>>>>>>>>>>>>>> functions.
> > >>>>>>>>>>>>>>>>>>>> I
> > >>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of deep
> > copying
> > >>>> of
> > >>>>>>>>>> keys.
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu Fenniak <
> > >>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> > >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
> > >>>> immutability of
> > >>>>>>>>>> the
> > >>>>>>>>>>>>>>> key
> > >>>>>>>>>>>>>>>> is
> > >>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than requiring
> > the
> > >>>> key
> > >>>>>>>>> to
> > >>>>>>>>>>> be
> > >>>>>>>>>>>>>>>>>>>>>> serializable
> > >>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
> > >>>> performance
> > >>>>>>>>>> risk.
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable type
> > >>>> constraints
> > >>>>>>>>>> of
> > >>>>>>>>>>>>>>> some
> > >>>>>>>>>>>>>>>>>>>> kind.
> > >>>>>>>>>>>>>>>>>>>>>> :-)
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias J.
> Sax
> > <
> > >>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow this
> > path,
> > >>>> it
> > >>>>>>>>>>> should
> > >>>>>>>>>>>>>>>> cover
> > >>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> About guarding the key -- I am still not sure
> > what
> > >>>> to
> > >>>>>>>>> do
> > >>>>>>>>>>>>> about
> > >>>>>>>>>>>>>>>>>> it...
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Maybe it might be enough to document it (and
> > name
> > >>>> the
> > >>>>>>>>> key
> > >>>>>>>>>>>>>>>>>> parameter
> > >>>>>>>>>>>>>>>>>>>>>> like
> > >>>>>>>>>>>>>>>>>>>>>>>>>> `readOnlyKey` to make is very clear).
> > Ultimately,
> > >> I
> > >>>>>>>>> would
> > >>>>>>>>>>>>>>> prefer
> > >>>>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>>>>>> guard against any modification, but I have no
> > good
> > >>>> idea
> > >>>>>>>>>> how
> > >>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>> do
> > >>>>>>>>>>>>>>>>>>>>>> this.
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Not sure what others think about the risk of
> > >>>> corrupted
> > >>>>>>>>>>>>>>>>>> partitioning
> > >>>>>>>>>>>>>>>>>>>>>>>>>> (what would be a user error and we could say,
> > >> well,
> > >>>> bad
> > >>>>>>>>>>> luck,
> > >>>>>>>>>>>>>>>> you
> > >>>>>>>>>>>>>>>>>>>> got
> > >>>>>>>>>>>>>>>>>>>>>> a
> > >>>>>>>>>>>>>>>>>>>>>>>>>> bug in your code, that's not our fault), vs
> deep
> > >>>> copy
> > >>>>>>>>>> with
> > >>>>>>>>>>> a
> > >>>>>>>>>>>>>>>>>>>> potential
> > >>>>>>>>>>>>>>>>>>>>>>>>>> performance hit (that we can't quantity atm
> > >> without
> > >>>> any
> > >>>>>>>>>>>>>>>>>> performance
> > >>>>>>>>>>>>>>>>>>>>>>>>> test).
> > >>>>>>>>>>>>>>>>>>>>>>>>>> We do have a performance system test. Maybe
> it's
> > >>>> worth
> > >>>>>>>>>> for
> > >>>>>>>>>>>>> you
> > >>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>> apply
> > >>>>>>>>>>>>>>>>>>>>>>>>>> the deep copy strategy and run the test. It's
> > very
> > >>>>>>>>> basic
> > >>>>>>>>>>>>>>>>>> performance
> > >>>>>>>>>>>>>>>>>>>>>>>>>> test only, but might give some insight. If you
> > >> want
> > >>>> to
> > >>>>>>>>> do
> > >>>>>>>>>>>>>>> this,
> > >>>>>>>>>>>>>>>>>> look
> > >>>>>>>>>>>>>>>>>>>>>>>>>> into folder "tests" for general test setup,
> and
> > >> into
> > >>>>>>>>>>>>>>>>>>>>>>>>>> "tests/kafaktests/benchmarks/streams" to find
> > find
> > >>>> the
> > >>>>>>>>>> perf
> > >>>>>>>>>>>>>>>> test.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> On 5/5/17 8:55 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Matthias,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> I think extending KIP to include
> RichFunctions
> > >>>> totally
> > >>>>>>>>>>>>> makes
> > >>>>>>>>>>>>>>>>>>>> sense.
> > >>>>>>>>>>>>>>>>>>>>>>>>> So,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> we don't want to guard the keys because it
> is
> > >>>>>>>>> costly.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> If we introduce RichFunctions I think it
> should
> > >>>> not be
> > >>>>>>>>>>>>>>> limited
> > >>>>>>>>>>>>>>>>>> only
> > >>>>>>>>>>>>>>>>>>>>>>>>> the 3
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces proposed in KIP but to wide range
> of
> > >>>>>>>>>>> interfaces.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 12:04 AM Matthias J.
> > Sax <
> > >>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> One follow up. There was this email on the
> > user
> > >>>> list:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>> http://search-hadoop.com/m/Kafka/uyzND17KhCaBzPSZ1?subj=
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>> Shouldn+t+the+initializer+of+a+stream+aggregate+accept+the+
> > >>>>>>>>>>>>>>> key+
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> It might make sense so include Initializer,
> > >> Adder,
> > >>>>>>>>> and
> > >>>>>>>>>>>>>>>>>> Substractor
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> inferface, too.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> And we should double check if there are
> other
> > >>>>>>>>> interface
> > >>>>>>>>>>> we
> > >>>>>>>>>>>>>>>> might
> > >>>>>>>>>>>>>>>>>>>>>> miss
> > >>>>>>>>>>>>>>>>>>>>>>>>>> atm.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/4/17 1:31 PM, Matthias J. Sax wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for updating the KIP.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Deep copying the key will work for sure,
> but
> > I
> > >> am
> > >>>>>>>>>>> actually
> > >>>>>>>>>>>>>>> a
> > >>>>>>>>>>>>>>>>>>>> little
> > >>>>>>>>>>>>>>>>>>>>>>>>> bit
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> worried about performance impact... We
> might
> > >>>> want to
> > >>>>>>>>>> do
> > >>>>>>>>>>>>>>> some
> > >>>>>>>>>>>>>>>>>> test
> > >>>>>>>>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> quantify this impact.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: this remind me about the idea of
> > >>>> `RichFunction`
> > >>>>>>>>>>>>>>>> interface
> > >>>>>>>>>>>>>>>>>>>> that
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> would allow users to access record metadata
> > >> (like
> > >>>>>>>>>>>>>>> timestamp,
> > >>>>>>>>>>>>>>>>>>>>>> offset,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> partition etc) within DSL. This would be a
> > >>>> similar
> > >>>>>>>>>>>>> concept.
> > >>>>>>>>>>>>>>>>>>>> Thus, I
> > >>>>>>>>>>>>>>>>>>>>>>>>> am
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> wondering, if it would make sense to
> enlarge
> > >> the
> > >>>>>>>>> scope
> > >>>>>>>>>>> of
> > >>>>>>>>>>>>>>>> this
> > >>>>>>>>>>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>>>>>>>> by
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> that? WDYT?
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/3/17 2:08 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Mathieu,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback. I followed similar
> > >> approach
> > >>>>>>>>> and
> > >>>>>>>>>>>>>>> updated
> > >>>>>>>>>>>>>>>>>> PR
> > >>>>>>>>>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accordingly. I tried to guard the key in
> > >>>> Processors
> > >>>>>>>>>>>>>>> sending
> > >>>>>>>>>>>>>>>> a
> > >>>>>>>>>>>>>>>>>>>> copy
> > >>>>>>>>>>>>>>>>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>>>>>>>>>>> an
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> actual key.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because I am doing deep copy of an
> object, I
> > >>>> think
> > >>>>>>>>>>> memory
> > >>>>>>>>>>>>>>>> can
> > >>>>>>>>>>>>>>>>>> be
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> bottleneck
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in some use-cases.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 2, 2017 at 5:10 PM Mathieu
> > >> Fenniak <
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Jeyhun,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach would change ValueMapper
> > >>>> (...etc) to
> > >>>>>>>>>> be
> > >>>>>>>>>>>>>>>>>> classes,
> > >>>>>>>>>>>>>>>>>>>>>>>>> rather
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, which is also a backwards
> > >>>> incompatible
> > >>>>>>>>>>>>>>> change.
> > >>>>>>>>>>>>>>>>>> An
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> alternative
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> approach that would be backwards
> compatible
> > >>>> would
> > >>>>>>>>> be
> > >>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>> define
> > >>>>>>>>>>>>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, and provide overrides where
> > those
> > >>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>> are
> > >>>>>>>>>>>>>>>>>>>>>> used.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Unfortunately, making the key parameter
> as
> > >>>> "final"
> > >>>>>>>>>>>>>>> doesn't
> > >>>>>>>>>>>>>>>>>>>> change
> > >>>>>>>>>>>>>>>>>>>>>>>>>> much
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> about guarding against key change. It
> only
> > >>>>>>>>> prevents
> > >>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>> parameter
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> variable
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> from being reassigned. If the key type
> is
> > a
> > >>>>>>>>> mutable
> > >>>>>>>>>>>>>>> object
> > >>>>>>>>>>>>>>>>>>>> (eg.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> byte[]),
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> it can still be mutated. (eg. key[0] =
> 0).
> > >> But
> > >>>>>>>>> I'm
> > >>>>>>>>>>> not
> > >>>>>>>>>>>>>>>>>> really
> > >>>>>>>>>>>>>>>>>>>>>> sure
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> there's
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much that can be done about that.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 1, 2017 at 5:39 PM, Jeyhun
> > >> Karimov
> > >>>> <
> > >>>>>>>>>>>>>>>>>>>>>>>>> je.karimov@gmail.com
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The concerns makes sense. Although we
> can
> > >>>> guard
> > >>>>>>>>> for
> > >>>>>>>>>>>>>>>>>> immutable
> > >>>>>>>>>>>>>>>>>>>>>> keys
> > >>>>>>>>>>>>>>>>>>>>>>>>>> in
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> current implementation (with few
> > changes), I
> > >>>>>>>>> didn't
> > >>>>>>>>>>>>>>>> consider
> > >>>>>>>>>>>>>>>>>>>>>>>>>> backward
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> compatibility.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In this case 2 solutions come to my
> mind.
> > In
> > >>>> both
> > >>>>>>>>>>>>> cases,
> > >>>>>>>>>>>>>>>>>> user
> > >>>>>>>>>>>>>>>>>>>>>>>>>> accesses
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> key in Object type, as passing extra
> type
> > >>>>>>>>> parameter
> > >>>>>>>>>>>>> will
> > >>>>>>>>>>>>>>>>>> break
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backwards-compatibility. So user has
> to
> > >> cast
> > >>>> to
> > >>>>>>>>>>> actual
> > >>>>>>>>>>>>>>>> key
> > >>>>>>>>>>>>>>>>>>>>>> type.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
>
> --
> -Cheers
>
> Jeyhun
>
--
-- Guozhang
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Jeyhun Karimov <je...@gmail.com>.
Hi Matthias,
Sorry for long delay. Thanks for the comment. Good to know that the
specified issue is not worth to break the backwards-compatibility.
I fixed the KIP.
Cheers,
Jeyhun
On Fri, Jun 30, 2017 at 1:38 AM Matthias J. Sax <ma...@confluent.io>
wrote:
> Hi Jeyhun,
>
> thanks for starting the VOTE thread. I did make one more pass over the
> KIP before casting my vote and I saw that the KIP still contains
> backward incompatible change introducing `ValueTransformerCommon`.
>
> I think, that for this case, it is not worth breaking compatibility. We
> should have two independent interface and duplicate init() and close()
> (note, with KIP-138 that got merged already, we don't need `punctuate()`
> for ValueTransformerWithKey)
>
>
> -Matthias
>
> On 6/14/17 3:03 PM, Matthias J. Sax wrote:
> > I have no strong opinion, but it seems that at least InitializerWithKey
> > with be helpful if you want to have different start values for different
> > keys (even if I cannot come up with a use case example why one wanted to
> > do this...). Otherwise, there is just the "completeness" argument, that
> > is not too strong either.
> >
> >
> > -Matthias
> >
> > On 6/14/17 2:03 PM, Guozhang Wang wrote:
> >> I'm not particularly concerning that we should NEVER break
> compatibility;
> >> in fact if we think that is worthwhile (i.e. small impact with large
> >> benefit) I think we can break compatibility as long as we have not
> removed
> >> the compatibility annotations from Streams. All I was saying is that if
> we
> >> decided to go this way we need to make sure this is mentioned in the
> >> upgrade guidance.
> >>
> >> Regarding the scope I'm still trying to solicit opinions regarding
> >> ReducerWithKey and InitializerWithKey; to me they are not necessarily
> to be
> >> included.
> >>
> >>
> >> Guozhang
> >>
> >>
> >> On Wed, Jun 14, 2017 at 5:22 AM, Jeyhun Karimov <je...@gmail.com>
> >> wrote:
> >>
> >>> Hi,
> >>>
> >>> I introduced ValueTransformerCommon just to combine common methods of
> >>> ValueTransformer and ValueTransformerWithKey and avoid copy-paste.
> >>> I am aware of this issue and I agree that this needs users to compile
> the
> >>> code and therefore is not backwards compatible. When I saw this issue,
> I
> >>> thought the degree of incompatibility is small (the public APIs are the
> >>> same, users just need to recompile their code), so we can trade more
> >>> maintainable code in this case. I have to comments/solutions:
> >>>
> >>> 1. Basically we can remove ValueTransformerCommon class and return
> >>> ValueTransformer to its original form, which means there will be no
> issues
> >>> with backwards-compatibility. We just copy and past the methods inside
> >>> ValueTransformerCommon to ValueTransformerWithKey and maybe in future
> >>> releases, we can introduce ValueTransformerCommon.
> >>>
> >>> 2. I have some doubts about Matthias's proposal.
> >>> If we extent withKey interface from original one as you mentioned in
> >>> previous email, then we have to deal with
> >>> ValueTransformer.transform(V value) method. As a result, inside
> withKey
> >>> interface we will have two transforms. Even if we make it abstract
> class,
> >>> user still have an access to play with both transform() methods. I
> think
> >>> this should not be allowed and seems "hacky" to me. Actually this was
> one
> >>> reason why I created withKey classes independently from original
> >>> interfaces.
> >>>
> >>> Of course, you can correct me if I am wrong.
> >>>
> >>>
> >>> Cheers,
> >>> Jeyhun
> >>>
> >>>
> >>>
> >>> On Tue, Jun 13, 2017 at 7:42 PM Matthias J. Sax <matthias@confluent.io
> >
> >>> wrote:
> >>>
> >>>> I agree with Guozhang's second point. This change does not seem
> backward
> >>>> compatible.
> >>>>
> >>>> As we don't have to support lambdas, it might be the easiest thing to
> >>>> just extend the current interface:
> >>>>
> >>>>> public interface ValueTransformerWithKey<K, V, VR> extends
> >>>> ValueTransformer<VR>
> >>>>
> >>>> When plugging the topology together, we can check if we get the
> >>>> `withKey` variant and use a corresponding runtime class for execution,
> >>>> so we get only a single time check. Thus, for the `withKey` variant,
> the
> >>>> will be a `transfrom(V value)` method, but we will never call it.
> >>>>
> >>>> Maybe we could make `ValueTransformerWithKey` an abstract class with a
> >>>> `final` no-op implemenation of `transform(V value)` ?
> >>>>
> >>>>
> >>>> -Matthias
> >>>>
> >>>>
> >>>> On 6/6/17 4:58 PM, Guozhang Wang wrote:
> >>>>> Jeyhun, Matthias:
> >>>>>
> >>>>> Thanks for the explanation, I overlooked the repartition argument
> >>>>> previously.
> >>>>>
> >>>>> 1) Based on that argument I'm convinced of having ValueMapperWithKey
> /
> >>>>> ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
> >>>>> convinced with ReducerWithKey and InitializerWithKey since for the
> >>> former
> >>>>> it can be covered with `aggregate` completely and with latter I have
> >>> seen
> >>>>> little use cases with it.
> >>>>>
> >>>>> 2) Another comment is on public interface ValueTransformer<V, VR>
> >>> extends
> >>>>> ValueTransformerCommon<VR>:
> >>>>>
> >>>>> I think changing the interface to extend from a new interface is not
> >>>> binary
> >>>>> compatible though source compatible, i.e. users still need to
> recompile
> >>>>> their code though no need to make code changes. We may need to
> mention
> >>>> that
> >>>>> in the upgrade path if we want to keep it that way.
> >>>>>
> >>>>> Guozhang
> >>>>>
> >>>>> On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je.karimov@gmail.com
> >
> >>>> wrote:
> >>>>>
> >>>>>> Hi,
> >>>>>>
> >>>>>>
> >>>>>> Sorry for late reply. Just to make everybody in sync, the current
> >>>> version
> >>>>>> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces
> are
> >>>>>> independent, meaning they do not extend from "withoutKey"
> >>> (ValueMapper)
> >>>>>> interfaces.
> >>>>>>
> >>>>>>
> >>>>>> I agree with Guozhang, and I am personally a bit reluctant to
> increase
> >>>>>> overloaded methods in public APIs but it seems this is only way to
> >>> solve
> >>>>>> all related jira issues.
> >>>>>> However, the most overloaded methods will be with ValueJoiner type,
> >>>> which
> >>>>>> will be with ValueJoinerWithKey with new overloaded methods. Other
> >>>>>> interfaces require mostly 1 extra overload.
> >>>>>>
> >>>>>>
> >>>>>>>> I would suggest not doing it if user pop it up, but rather
> >>> suggesting
> >>>>>> them
> >>>>>>>> to use `map`
> >>>>>>
> >>>>>> I agree with Matthias as the core idea of this KIP was to collect
> all
> >>>>>> related jira issues and propose one-shot solution for all.
> Afterwards,
> >>>> we
> >>>>>> broke its scope into 2 KIPs (149 and 159).
> >>>>>>
> >>>>>> Cheers,
> >>>>>> Jeyhun
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <
> matthias@confluent.io
> >>>>
> >>>>>> wrote:
> >>>>>>
> >>>>>>> I guess I missunderstood you. Your are right that overloading the
> >>>> method
> >>>>>>> would also work. As both interfaces will be independent from each
> >>>> other,
> >>>>>>> there should be no problem.
> >>>>>>>
> >>>>>>> The initial proposal was to use
> >>>>>>>
> >>>>>>>> interface ValueMapperWithKey extends ValueMapper
> >>>>>>>
> >>>>>>> and this would break Lambda. We totally missed, that we don't need
> >>> new
> >>>>>>> methods but only only overlaods. Great you point this out! I was
> not
> >>>>>>> quite happy with the newly added methods.
> >>>>>>>
> >>>>>>>>> I would suggest not doing it if user pop it up, but rather
> >>> suggesting
> >>>>>>> them
> >>>>>>>>> to use `map`
> >>>>>>>
> >>>>>>> But this might introduce unnecessary re-partitioning for downstream
> >>>>>>> operators. I don't thinks that a good suggestion. But if we only
> add
> >>>> new
> >>>>>>> overloads for mapValue(), flatMapValue() etc, I don't see a big
> issue
> >>>>>>> with "overstaffing" the API (what is btw a very valid concern).
> >>>>>>>
> >>>>>>>
> >>>>>>> -Matthias
> >>>>>>>
> >>>>>>>
> >>>>>>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
> >>>>>>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <
> >>>> matthias@confluent.io
> >>>>>>>
> >>>>>>>> wrote:
> >>>>>>>>
> >>>>>>>>> We started with this proposal but it does not allow for Lambdas
> (in
> >>>>>> case
> >>>>>>>>> you want key access). Do you think preserving Lambdas is not
> >>>> important
> >>>>>>>>> enough for this case -- I agree that there is some price to be
> paid
> >>>> to
> >>>>>>>>> keep Lambdas.
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>> Not sure if I understand this comment.. My main point is not on
> >>>>>> changing
> >>>>>>>> the proposal but just reduce it scope to `ValueJoinerWithKey`
> only;
> >>>> and
> >>>>>>>> even if we want to keep them all, I'd suggest we just implement
> the
> >>>>>> added
> >>>>>>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
> >>>>>> which
> >>>>>>>> seems simpler to me. Does that affect lambda expression usage?
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>> About API consistency: I can't remember a concrete user request
> to
> >>>>>> have
> >>>>>>>>> key access in all operators. But I am pretty sure, if we only add
> >>> it
> >>>>>> for
> >>>>>>>>> some, this request will pop up quickly. IMHO, it's better to do
> it
> >>>> all
> >>>>>>>>> in one shot. (But I am not strict about it if most people think
> we
> >>>>>>>>> should limit it to what was requested by users.)
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>> I would suggest not doing it if user pop it up, but rather
> >>> suggesting
> >>>>>>> them
> >>>>>>>> to use `map` etc directly but set the key unchanged rather than
> >>>>>>> providing a
> >>>>>>>> new operator for it. To me some syntax sugars like this seems of
> >>> less
> >>>>>>>> valuable than others (like print / writeAsText / foreach that are
> >>> all
> >>>>>>>> depending on peek), and keeping adding them will just make the DSL
> >>> too
> >>>>>>>> “overstaffed”.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>> -Matthias
> >>>>>>>>>
> >>>>>>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> >>>>>>>>>> With KIP-159, the added "valueMapperWithKey" and
> >>>>>>>>> "valueTransformerWithKey"
> >>>>>>>>>> along seem to be just adding a few syntax-sugars? E.g. we can
> >>> simply
> >>>>>>>>>> implement:
> >>>>>>>>>>
> >>>>>>>>>> mapValues(ValueMapperWithKey mapperWithKey)
> >>>>>>>>>>
> >>>>>>>>>> as
> >>>>>>>>>>
> >>>>>>>>>> map((k, v) -> (k, mapperWithKey(k, v))
> >>>>>>>>>>
> >>>>>>>>>> ----------------------
> >>>>>>>>>>
> >>>>>>>>>> I'm not sure how many users would really need such syntax
> sugars,
> >>>> and
> >>>>>>>>> even
> >>>>>>>>>> they do, we can support them easily as the above
> implementations;
> >>>>>>>>>>
> >>>>>>>>>> Similarly for "ReducerWithKey", it can be implemented as
> >>>>>> `Aggregator<K,
> >>>>>>>>> V,
> >>>>>>>>>> V>`, and people who needs key access can just use `aggregate`
> >>>>>> directly.
> >>>>>>>>>>
> >>>>>>>>>> The function which I think is really of valuable is
> >>>>>>> `ValueJoinerWithKey`,
> >>>>>>>>>> and that seems to be the original request from users while
> others
> >>>> are
> >>>>>>>>>> coming from "API consistency" concerns. Personally I'd prefer
> only
> >>>>>> keep
> >>>>>>>>> the
> >>>>>>>>>> last one (`InitializerWithKey` might also have some value, but I
> >>>> have
> >>>>>>> not
> >>>>>>>>>> seen people widely requesting it in their DSL usage yet; if
> there
> >>> is
> >>>>>> a
> >>>>>>>>>> common request we can keep it in this KIP as well). WDYT?
> >>>>>>>>>>
> >>>>>>>>>> Guozhang
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
> >>>>>> je.karimov@gmail.com
> >>>>>>>>
> >>>>>>>>>> wrote:
> >>>>>>>>>>
> >>>>>>>>>>> Thanks for clarification Matthias, now everything is clear.
> >>>>>>>>>>>
> >>>>>>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
> >>>>>>> matthias@confluent.io>
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> I don't think we can drop ValueTransformerSupplier. If you
> don't
> >>>>>> have
> >>>>>>>>> an
> >>>>>>>>>>>> supplier, you only get a single instance of your function. But
> >>> for
> >>>>>> a
> >>>>>>>>>>>> stateful transformation, we need multiple instances (one for
> >>> each
> >>>>>>> task)
> >>>>>>>>>>>> of ValueTransformer.
> >>>>>>>>>>>>
> >>>>>>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
> >>>>>> because
> >>>>>>>>>>>> those are stateless and thus, we can reuse a single instance
> >>> over
> >>>>>>>>>>>> multiple tasks -- but we can't do this for ValueTransformer
> (and
> >>>>>>>>>>> similar).
> >>>>>>>>>>>>
> >>>>>>>>>>>> Btw: This reminds me about KIP-159: with regard to the
> >>>> RichFunction
> >>>>>>> we
> >>>>>>>>>>>> might need a supplier pattern, too. (I'll comment on the other
> >>>>>>> thread,
> >>>>>>>>>>>> too.)
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>
> >>>>>>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I updated KIP.
> >>>>>>>>>>>>> Just to avoid misunderstanding, I meant deprecating
> >>>>>>>>>>>> ValueTransformerSupplier
> >>>>>>>>>>>>> and I am ok with ValueTransformer.
> >>>>>>>>>>>>> So instead of using ValueTransformerSupplier can't we
> directly
> >>>> use
> >>>>>>>>>>>>> ValueTransformer
> >>>>>>>>>>>>> or ValueTransformerWithKey?
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Btw, in current design all features of ValueTransformer will
> be
> >>>>>>>>>>> available
> >>>>>>>>>>>>> in ValueTransformerWithKey interface.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> >>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>
> >>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> Thanks Jeyhun.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> About ValueTransformer: I don't think we can remove it.
> Note,
> >>>>>>>>>>>>>> ValueTransformer allows to attach a state and also allows to
> >>>>>>> register
> >>>>>>>>>>>>>> punctuations. Both those features will not be available via
> >>>>>>> withKey()
> >>>>>>>>>>>>>> interfaces.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>> Hi Matthias,
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> I tested the deep copy approach. It has significant
> overhead.
> >>>>>>>>>>>> Especially
> >>>>>>>>>>>>>>> for "light" and stateless operators it slows down the
> >>> topology
> >>>>>>>>>>>>>>> significantly (> 20% ). I think "warning" users about
> >>>>>>> not-changing
> >>>>>>>>>>> the
> >>>>>>>>>>>>>> key
> >>>>>>>>>>>>>>> is better warning them about possible performance loss.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> About the interfaces, additionally I considered adding
> >>>>>>>>>>>>>> InitializerWithKey,
> >>>>>>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they
> >>> are
> >>>>>>>>>>>> included
> >>>>>>>>>>>>>> in
> >>>>>>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry
> my
> >>>>>> bad.
> >>>>>>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> One thing I want to mention is that, maybe we should
> >>> deprecate
> >>>>>>>>>>> methods
> >>>>>>>>>>>>>> with
> >>>>>>>>>>>>>>> argument type ValueTransformerSupplier
> >>>>>>>>> (KStream.transformValues(...))
> >>>>>>>>>>>> and
> >>>>>>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
> >>>>>>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
> >>>>>> instead
> >>>>>>>>>>>> without
> >>>>>>>>>>>>>>> additional supplier layer.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> >>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> One more question:
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Should we add any of
> >>>>>>>>>>>>>>>> - InitizialierWithKey
> >>>>>>>>>>>>>>>> - ReducerWithKey
> >>>>>>>>>>>>>>>> - ValueTransformerWithKey
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> To get consistent/complete API, it might be a good idea.
> Any
> >>>>>>>>>>> thoughts?
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> >>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I was just wondering if you did look into the
> key-deep-copy
> >>>>>> idea
> >>>>>>>>> we
> >>>>>>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
> >>>>>>>>> functions
> >>>>>>>>>>>>>> into
> >>>>>>>>>>>>>>>>>> this KIP.
> >>>>>>>>>>>>>>>>>> I think once we include rich functions in this KIP and
> >>> then
> >>>>>> fix
> >>>>>>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with
> >>>> existing
> >>>>>>>>> rich
> >>>>>>>>>>>>>>>>>> functions, the code will not be backwards compatible.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> I see Damian's and your point more clearly now.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this
> KIP
> >>>> (I
> >>>>>>>>>>>> updated
> >>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
> >>>>>> functions.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> >>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
> >>>>>> ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent
> >>> add-on.
> >>>>>> To
> >>>>>>>>>>> fix
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are
> not
> >>>>>>>>>>> required
> >>>>>>>>>>>>>>>> IMHO.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> I initially put the RichFunction idea on the table,
> >>> because
> >>>>>> I
> >>>>>>>>> was
> >>>>>>>>>>>>>>>> hoping
> >>>>>>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to
> >>> consider
> >>>>>>> them
> >>>>>>>>>>> --
> >>>>>>>>>>>>>>>>>>> however, the discussion showed that they are not
> >>> necessary
> >>>>>> for
> >>>>>>>>>>> key
> >>>>>>>>>>>>>>>>>>> access. Thus, it seems to be better to handle
> >>> RichFunctions
> >>>>>> in
> >>>>>>>>> an
> >>>>>>>>>>>> own
> >>>>>>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to
> >>> be
> >>>> a
> >>>>>>>>> main
> >>>>>>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
> >>>>>>>>>>>> parameter-less
> >>>>>>>>>>>>>>>>>>> init() method, seem not to help too much. We would get
> an
> >>>>>>>>>>>>>>>> "intermediate"
> >>>>>>>>>>>>>>>>>>> API that we want to change anyway later on...
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel
> >>> free
> >>>>>> do
> >>>>>>>>>>> push
> >>>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
> >>>>>> parallel)
> >>>>>>> --
> >>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>> don't want to slow you down :) But it make the
> discussion
> >>>>>> and
> >>>>>>>>>>> code
> >>>>>>>>>>>>>>>>>>> review easier, if we separate both IMHO.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>> Hi Damian,
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
> >>>>>>>>> *interface*
> >>>>>>>>>>>>>>>> rather
> >>>>>>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias
> also
> >>>>>>> raised
> >>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>> issue
> >>>>>>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Regarding with passing additional contextual
> >>> information,
> >>>> I
> >>>>>>>>>>> think
> >>>>>>>>>>>> it
> >>>>>>>>>>>>>>>> is a
> >>>>>>>>>>>>>>>>>>>> tradeoff,
> >>>>>>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init()
> >>> *method
> >>>>>> in
> >>>>>>>>>>>>>> another
> >>>>>>>>>>>>>>>> PR
> >>>>>>>>>>>>>>>>>>>> and solve Rich functions afterwards
> >>>>>>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3])
> >>> with
> >>>>>>>>>>>> providing
> >>>>>>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the
> context
> >>>>>>>>>>> parameters
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>>> afterwards (like improvement)
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> To me, the second approach seems more incremental.
> >>> However
> >>>>>>> you
> >>>>>>>>>>> are
> >>>>>>>>>>>>>>>> right,
> >>>>>>>>>>>>>>>>>>>> the names might confuse the users.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> >>>>>>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> >>>>>>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> >>>>>>>>>>> damian.guy@gmail.com
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> >>>>>>>>>>> RichFunction
> >>>>>>>>>>>>>>>> which
> >>>>>>>>>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have
> expected
> >>>> it
> >>>>>>> to
> >>>>>>>>>>>> pass
> >>>>>>>>>>>>>>>> some
> >>>>>>>>>>>>>>>>>>>>> additional contextual information, i.e., the
> >>>>>> `RecordContext`
> >>>>>>>>>>> that
> >>>>>>>>>>>>>>>>>>> contains
> >>>>>>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok
> >>>> with
> >>>>>>> it
> >>>>>>>>>>> not
> >>>>>>>>>>>>>>>>>>> passing
> >>>>>>>>>>>>>>>>>>>>> this contextual information, but is the naming
> >>> incorrect?
> >>>>>>> I'm
> >>>>>>>>>>> not
> >>>>>>>>>>>>>>>> sure,
> >>>>>>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions`
> >>>> until
> >>>>>>> we
> >>>>>>>>>>> can
> >>>>>>>>>>>>>> do
> >>>>>>>>>>>>>>>> it
> >>>>>>>>>>>>>>>>>>>>> properly with the correct context?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Also, i don't like the abstract classes:
> >>> RichValueMapper,
> >>>>>>>>>>>>>>>>>>> RichValueJoiner,
> >>>>>>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
> >>>>>> interfaces?
> >>>>>>>>>>>>>>>> Generally we
> >>>>>>>>>>>>>>>>>>>>> should provide users with Intefaces to code against,
> >>> not
> >>>>>>>>>>> classes.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Thanks,
> >>>>>>>>>>>>>>>>>>>>> Damian
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> >>>>>>>>>>>> je.karimov@gmail.com>
> >>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
> >>>>>>> overview.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead
> of
> >>>>>>>>>>> interface
> >>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>> Rich
> >>>>>>>>>>>>>>>>>>>>>> functions is that in future if we will have some
> >>>>>>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>>>>>> abstract classes,
> >>>>>>>>>>>>>>>>>>>>>> we can easily extend:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
> >>>>>> implements
> >>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> >>>>>>>>>>>>>>>>>>>>> AbstractRichFunction*{
> >>>>>>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces
> for
> >>>>>>>>>>>>>> inheritance.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> However, I think we can easily change it (from
> >>> abstract
> >>>>>>> class
> >>>>>>>>>>> ->
> >>>>>>>>>>>>>>>>>>>>> interface)
> >>>>>>>>>>>>>>>>>>>>>> if you think interface is a better fit.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> >>>>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is
> >>>> quite
> >>>>>>>>>>>> improved
> >>>>>>>>>>>>>>>> now
> >>>>>>>>>>>>>>>>>>>>> --
> >>>>>>>>>>>>>>>>>>>>>>> great job!
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc
> >>> abstract
> >>>>>>>>>>> classes
> >>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>> not
> >>>>>>>>>>>>>>>>>>>>>>> interfaces?
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
> >>> for
> >>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> >>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces.
> So
> >>>>>> they
> >>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>>>>>> direct
> >>>>>>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have
> >>> only
> >>>>>>> one
> >>>>>>>>>>>>>>>> method ,
> >>>>>>>>>>>>>>>>>>>>> so
> >>>>>>>>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>>> can use lambdas.
> >>>>>>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to
> play?
> >>>>>>> Inside
> >>>>>>>>>>>> Rich
> >>>>>>>>>>>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
> >>>>>>> *withKey*
> >>>>>>>>>>> and
> >>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) .
> >>> We
> >>>>>> get
> >>>>>>>>>>>> those
> >>>>>>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
> >>>>>> topology,
> >>>>>>>>> and
> >>>>>>>>>>>>>> send
> >>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>> Processor.
> >>>>>>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
> >>>>>> implement
> >>>>>>>>>>>>>>>> *withKey*
> >>>>>>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by
> >>> definition.
> >>>>>> In
> >>>>>>>>>>> this
> >>>>>>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>>>>>>> while
> >>>>>>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the
> >>> object
> >>>>>>> type
> >>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar
> >>> for
> >>>>>>> Rich
> >>>>>>>>>>>>>>>> functions
> >>>>>>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
> >>> we
> >>>>>>> need
> >>>>>>>>>>> to
> >>>>>>>>>>>>>>>> have a
> >>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and
> close()
> >>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>>>>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
> >>>>>>> *withKey*
> >>>>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
> >>>>>> remove
> >>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> >>>>>> sufficient
> >>>>>>> to
> >>>>>>>>>>>>>>>> support
> >>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >>>>>>>>> "extended
> >>>>>>>>>>>>>> API".
> >>>>>>>>>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
> >>> idea
> >>>>>> of
> >>>>>>>>>>> more
> >>>>>>>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces
> too
> >>>>>> much
> >>>>>>>>>>>>>> because
> >>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I
> do
> >>>> see
> >>>>>>>>>>> value
> >>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only
> >>> one
> >>>>>>> extra
> >>>>>>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
> >>>>>> *withKey*
> >>>>>>>>>>>>>> version
> >>>>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>>>>>> particular interface.
> >>>>>>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as
> >>> Rich
> >>>>>>>>>>>> function
> >>>>>>>>>>>>>>>>>>>>>>> implements
> >>>>>>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same
> type.
> >>>> We
> >>>>>>>>>>>>>>>> differentiate
> >>>>>>>>>>>>>>>>>>>>>>> them
> >>>>>>>>>>>>>>>>>>>>>>>> while building the topology.
> >>>>>>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of
> >>> the
> >>>>>>>>>>>> comment:
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but
> >>> can
> >>>>>> we
> >>>>>>>>>>> have
> >>>>>>>>>>>> a
> >>>>>>>>>>>>>>>>>>>>> design
> >>>>>>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to
> lambdas,
> >>>> it
> >>>>>>>>>>> might
> >>>>>>>>>>>>>> make
> >>>>>>>>>>>>>>>>>>>>>> sense
> >>>>>>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) ->
> newV`
> >>> ?
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
> >>>>>> overall
> >>>>>>>>>>>> design
> >>>>>>>>>>>>>>>>>>>>>>>> significantly.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might
> make
> >>>>>> sense
> >>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP --
> and
> >>>>>> thus,
> >>>>>>>>>>> this
> >>>>>>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
> >>> KIP"
> >>>>>>>>>>> before
> >>>>>>>>>>>>>>>> driving
> >>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep
> Rich
> >>>>>>>>>>> functions
> >>>>>>>>>>>>>> as I
> >>>>>>>>>>>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
> >>>>>> library.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> >>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> thanks for the update.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
> >>> for
> >>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for
> `withKey`,
> >>> we
> >>>>>>> need
> >>>>>>>>>>> to
> >>>>>>>>>>>>>>>> have a
> >>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and
> close()
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>>>>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not
> >>> make
> >>>>>>>>> sense
> >>>>>>>>>>>>>>>> anymore,
> >>>>>>>>>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow
> the
> >>>>>>>>>>>>>>>> implementation of
> >>>>>>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those,
> you
> >>>>>> would
> >>>>>>>>>>>>>>>> implement a
> >>>>>>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> >>>>>> sufficient
> >>>>>>>>> to
> >>>>>>>>>>>>>>>> support
> >>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >>>>>>>>> "extended
> >>>>>>>>>>>>>> API".
> >>>>>>>>>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
> >>> idea
> >>>>>> of
> >>>>>>>>>>> more
> >>>>>>>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces
> too
> >>>>>> much
> >>>>>>>>>>>>>> because
> >>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I
> do
> >>>> see
> >>>>>>>>>>> value
> >>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might
> make
> >>>>>>> sense
> >>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP --
> and
> >>>>>> thus,
> >>>>>>>>>>> this
> >>>>>>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
> >>> KIP"
> >>>>>>>>>>> before
> >>>>>>>>>>>>>>>> driving
> >>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> Thoughts?
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
> >>>>>>> comments.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you
> elaborate a
> >>>>>>> little
> >>>>>>>>>>>>>> bit? I
> >>>>>>>>>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what
> the
> >>>>>>>>> problem
> >>>>>>>>>>>> is.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
> >>>>>> interface
> >>>>>>>>>>> that
> >>>>>>>>>>>>>> has
> >>>>>>>>>>>>>>>>>>>>> just
> >>>>>>>>>>>>>>>>>>>>>>> one
> >>>>>>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
> >>>>>> function
> >>>>>>>>>>>>>>>> contract".
> >>>>>>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
> >>>>>> another
> >>>>>>>>>>> (in
> >>>>>>>>>>>>>> our
> >>>>>>>>>>>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot
> use
> >>>>>>>>> lambdas
> >>>>>>>>>>>> in
> >>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> extended
> >>>>>>>>>>>>>>>>>>>>>>>>>> interface.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> >>>>>> maybe
> >>>>>>>>>>>>>> reformat
> >>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
> >>> would
> >>>>>>> help.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
> have
> >>>>>>>>>>> overlaods
> >>>>>>>>>>>>>>>> added
> >>>>>>>>>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
> >>> need
> >>>>>> to
> >>>>>>>>>>> add
> >>>>>>>>>>>>>> any
> >>>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
> >>>>>> public
> >>>>>>>>>>> APIs
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
> >>>>>>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has
> >>> similar
> >>>>>>>>>>>> structure:
> >>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>>>> overload
> >>>>>>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> >>>>>>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to
> processor
> >>>> and
> >>>>>>>>>>> inside
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> processor
> >>>>>>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich
> >>>> function.
> >>>>>>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
> >>>>>> overall
> >>>>>>>>>>> idea
> >>>>>>>>>>>>>> with
> >>>>>>>>>>>>>>>>>>>>> only
> >>>>>>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
> >>>>>>> changes.
> >>>>>>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext
> >>> p)*
> >>>>>>> and*
> >>>>>>>>>>>>>>>> close()*
> >>>>>>>>>>>>>>>>>>>>>>>>> methods
> >>>>>>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>>>>>>>>> void close () {}
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
> >>>>>>>>>>>>>>>> *AbstractRichFunction*
> >>>>>>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
> >>>>>> *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and
> >>>> ease
> >>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>> maintenance.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> >>> ForeachAction,
> >>>>>>>>>>> Merger,
> >>>>>>>>>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
> >>> add
> >>>>>> to
> >>>>>>>>>>> all,
> >>>>>>>>>>>>>> but
> >>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> >>>> sense
> >>>>>>>>>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
> >>>>>> applies
> >>>>>>>>> to
> >>>>>>>>>>>> all
> >>>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP,
> >>>> just
> >>>>>>>>>>> wanted
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>> overall intuition.
> >>>>>>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> >>>>>> `ValueXXWithKey`
> >>>>>>>>> --
> >>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we
> >>> should
> >>>>>>> not
> >>>>>>>>>>>> force
> >>>>>>>>>>>>>>>>>>>>> users
> >>>>>>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> >>>>>>>>> functions
> >>>>>>>>>>>>>> every
> >>>>>>>>>>>>>>>>>>>>> time
> >>>>>>>>>>>>>>>>>>>>>>>>> they
> >>>>>>>>>>>>>>>>>>>>>>>>>> use Rich functions.
> >>>>>>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
> >>>>>> methods.
> >>>>>>>>>>>>>> However,
> >>>>>>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>>>>> am
> >>>>>>>>>>>>>>>>>>>>>>> open
> >>>>>>>>>>>>>>>>>>>>>>>>>> for discussion.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of
> `ProcessorContext`
> >>>>>>> spread
> >>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
> >>> that
> >>>>>> is
> >>>>>>>>>>> done
> >>>>>>>>>>>>>>>> before
> >>>>>>>>>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
> >>> becoming
> >>>>>>> too
> >>>>>>>>>>>>>> large.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
> >>>>>>>>>>>> *init(ProcessorContext)*
> >>>>>>>>>>>>>>>>>>>>> method
> >>>>>>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
> >>>>>>> ProcessorContext
> >>>>>>>>>>> as
> >>>>>>>>>>>> an
> >>>>>>>>>>>>>>>>>>>>>> input),
> >>>>>>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> >>>>>>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
> >>>>>> @mjsax
> >>>>>>>>>>>>>>>> mentioned)
> >>>>>>>>>>>>>>>>>>>>>>> whether
> >>>>>>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an
> >>> access
> >>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>> *ProcessorContext*
> >>>>>>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* )
> >>> or
> >>>>>>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> >>>>>>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> >>>>>>>>>>>>>>>> damian.guy@gmail.com>
> >>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of
> `ProcessorContext`
> >>>>>>> spread
> >>>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
> >>> that
> >>>>>> is
> >>>>>>>>>>> done
> >>>>>>>>>>>>>>>> before
> >>>>>>>>>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
> >>> becoming
> >>>>>>> too
> >>>>>>>>>>>>>> large.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> >>>>>>>>>>>>>>>>>
--
-Cheers
Jeyhun
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by "Matthias J. Sax" <ma...@confluent.io>.
Hi Jeyhun,
thanks for starting the VOTE thread. I did make one more pass over the
KIP before casting my vote and I saw that the KIP still contains
backward incompatible change introducing `ValueTransformerCommon`.
I think, that for this case, it is not worth breaking compatibility. We
should have two independent interface and duplicate init() and close()
(note, with KIP-138 that got merged already, we don't need `punctuate()`
for ValueTransformerWithKey)
-Matthias
On 6/14/17 3:03 PM, Matthias J. Sax wrote:
> I have no strong opinion, but it seems that at least InitializerWithKey
> with be helpful if you want to have different start values for different
> keys (even if I cannot come up with a use case example why one wanted to
> do this...). Otherwise, there is just the "completeness" argument, that
> is not too strong either.
>
>
> -Matthias
>
> On 6/14/17 2:03 PM, Guozhang Wang wrote:
>> I'm not particularly concerning that we should NEVER break compatibility;
>> in fact if we think that is worthwhile (i.e. small impact with large
>> benefit) I think we can break compatibility as long as we have not removed
>> the compatibility annotations from Streams. All I was saying is that if we
>> decided to go this way we need to make sure this is mentioned in the
>> upgrade guidance.
>>
>> Regarding the scope I'm still trying to solicit opinions regarding
>> ReducerWithKey and InitializerWithKey; to me they are not necessarily to be
>> included.
>>
>>
>> Guozhang
>>
>>
>> On Wed, Jun 14, 2017 at 5:22 AM, Jeyhun Karimov <je...@gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> I introduced ValueTransformerCommon just to combine common methods of
>>> ValueTransformer and ValueTransformerWithKey and avoid copy-paste.
>>> I am aware of this issue and I agree that this needs users to compile the
>>> code and therefore is not backwards compatible. When I saw this issue, I
>>> thought the degree of incompatibility is small (the public APIs are the
>>> same, users just need to recompile their code), so we can trade more
>>> maintainable code in this case. I have to comments/solutions:
>>>
>>> 1. Basically we can remove ValueTransformerCommon class and return
>>> ValueTransformer to its original form, which means there will be no issues
>>> with backwards-compatibility. We just copy and past the methods inside
>>> ValueTransformerCommon to ValueTransformerWithKey and maybe in future
>>> releases, we can introduce ValueTransformerCommon.
>>>
>>> 2. I have some doubts about Matthias's proposal.
>>> If we extent withKey interface from original one as you mentioned in
>>> previous email, then we have to deal with
>>> ValueTransformer.transform(V value) method. As a result, inside withKey
>>> interface we will have two transforms. Even if we make it abstract class,
>>> user still have an access to play with both transform() methods. I think
>>> this should not be allowed and seems "hacky" to me. Actually this was one
>>> reason why I created withKey classes independently from original
>>> interfaces.
>>>
>>> Of course, you can correct me if I am wrong.
>>>
>>>
>>> Cheers,
>>> Jeyhun
>>>
>>>
>>>
>>> On Tue, Jun 13, 2017 at 7:42 PM Matthias J. Sax <ma...@confluent.io>
>>> wrote:
>>>
>>>> I agree with Guozhang's second point. This change does not seem backward
>>>> compatible.
>>>>
>>>> As we don't have to support lambdas, it might be the easiest thing to
>>>> just extend the current interface:
>>>>
>>>>> public interface ValueTransformerWithKey<K, V, VR> extends
>>>> ValueTransformer<VR>
>>>>
>>>> When plugging the topology together, we can check if we get the
>>>> `withKey` variant and use a corresponding runtime class for execution,
>>>> so we get only a single time check. Thus, for the `withKey` variant, the
>>>> will be a `transfrom(V value)` method, but we will never call it.
>>>>
>>>> Maybe we could make `ValueTransformerWithKey` an abstract class with a
>>>> `final` no-op implemenation of `transform(V value)` ?
>>>>
>>>>
>>>> -Matthias
>>>>
>>>>
>>>> On 6/6/17 4:58 PM, Guozhang Wang wrote:
>>>>> Jeyhun, Matthias:
>>>>>
>>>>> Thanks for the explanation, I overlooked the repartition argument
>>>>> previously.
>>>>>
>>>>> 1) Based on that argument I'm convinced of having ValueMapperWithKey /
>>>>> ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
>>>>> convinced with ReducerWithKey and InitializerWithKey since for the
>>> former
>>>>> it can be covered with `aggregate` completely and with latter I have
>>> seen
>>>>> little use cases with it.
>>>>>
>>>>> 2) Another comment is on public interface ValueTransformer<V, VR>
>>> extends
>>>>> ValueTransformerCommon<VR>:
>>>>>
>>>>> I think changing the interface to extend from a new interface is not
>>>> binary
>>>>> compatible though source compatible, i.e. users still need to recompile
>>>>> their code though no need to make code changes. We may need to mention
>>>> that
>>>>> in the upgrade path if we want to keep it that way.
>>>>>
>>>>> Guozhang
>>>>>
>>>>> On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com>
>>>> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>
>>>>>> Sorry for late reply. Just to make everybody in sync, the current
>>>> version
>>>>>> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
>>>>>> independent, meaning they do not extend from "withoutKey"
>>> (ValueMapper)
>>>>>> interfaces.
>>>>>>
>>>>>>
>>>>>> I agree with Guozhang, and I am personally a bit reluctant to increase
>>>>>> overloaded methods in public APIs but it seems this is only way to
>>> solve
>>>>>> all related jira issues.
>>>>>> However, the most overloaded methods will be with ValueJoiner type,
>>>> which
>>>>>> will be with ValueJoinerWithKey with new overloaded methods. Other
>>>>>> interfaces require mostly 1 extra overload.
>>>>>>
>>>>>>
>>>>>>>> I would suggest not doing it if user pop it up, but rather
>>> suggesting
>>>>>> them
>>>>>>>> to use `map`
>>>>>>
>>>>>> I agree with Matthias as the core idea of this KIP was to collect all
>>>>>> related jira issues and propose one-shot solution for all. Afterwards,
>>>> we
>>>>>> broke its scope into 2 KIPs (149 and 159).
>>>>>>
>>>>>> Cheers,
>>>>>> Jeyhun
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <matthias@confluent.io
>>>>
>>>>>> wrote:
>>>>>>
>>>>>>> I guess I missunderstood you. Your are right that overloading the
>>>> method
>>>>>>> would also work. As both interfaces will be independent from each
>>>> other,
>>>>>>> there should be no problem.
>>>>>>>
>>>>>>> The initial proposal was to use
>>>>>>>
>>>>>>>> interface ValueMapperWithKey extends ValueMapper
>>>>>>>
>>>>>>> and this would break Lambda. We totally missed, that we don't need
>>> new
>>>>>>> methods but only only overlaods. Great you point this out! I was not
>>>>>>> quite happy with the newly added methods.
>>>>>>>
>>>>>>>>> I would suggest not doing it if user pop it up, but rather
>>> suggesting
>>>>>>> them
>>>>>>>>> to use `map`
>>>>>>>
>>>>>>> But this might introduce unnecessary re-partitioning for downstream
>>>>>>> operators. I don't thinks that a good suggestion. But if we only add
>>>> new
>>>>>>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
>>>>>>> with "overstaffing" the API (what is btw a very valid concern).
>>>>>>>
>>>>>>>
>>>>>>> -Matthias
>>>>>>>
>>>>>>>
>>>>>>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
>>>>>>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <
>>>> matthias@confluent.io
>>>>>>>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> We started with this proposal but it does not allow for Lambdas (in
>>>>>> case
>>>>>>>>> you want key access). Do you think preserving Lambdas is not
>>>> important
>>>>>>>>> enough for this case -- I agree that there is some price to be paid
>>>> to
>>>>>>>>> keep Lambdas.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Not sure if I understand this comment.. My main point is not on
>>>>>> changing
>>>>>>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only;
>>>> and
>>>>>>>> even if we want to keep them all, I'd suggest we just implement the
>>>>>> added
>>>>>>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
>>>>>> which
>>>>>>>> seems simpler to me. Does that affect lambda expression usage?
>>>>>>>>
>>>>>>>>>
>>>>>>>>> About API consistency: I can't remember a concrete user request to
>>>>>> have
>>>>>>>>> key access in all operators. But I am pretty sure, if we only add
>>> it
>>>>>> for
>>>>>>>>> some, this request will pop up quickly. IMHO, it's better to do it
>>>> all
>>>>>>>>> in one shot. (But I am not strict about it if most people think we
>>>>>>>>> should limit it to what was requested by users.)
>>>>>>>>>
>>>>>>>>>
>>>>>>>> I would suggest not doing it if user pop it up, but rather
>>> suggesting
>>>>>>> them
>>>>>>>> to use `map` etc directly but set the key unchanged rather than
>>>>>>> providing a
>>>>>>>> new operator for it. To me some syntax sugars like this seems of
>>> less
>>>>>>>> valuable than others (like print / writeAsText / foreach that are
>>> all
>>>>>>>> depending on peek), and keeping adding them will just make the DSL
>>> too
>>>>>>>> “overstaffed”.
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> -Matthias
>>>>>>>>>
>>>>>>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
>>>>>>>>>> With KIP-159, the added "valueMapperWithKey" and
>>>>>>>>> "valueTransformerWithKey"
>>>>>>>>>> along seem to be just adding a few syntax-sugars? E.g. we can
>>> simply
>>>>>>>>>> implement:
>>>>>>>>>>
>>>>>>>>>> mapValues(ValueMapperWithKey mapperWithKey)
>>>>>>>>>>
>>>>>>>>>> as
>>>>>>>>>>
>>>>>>>>>> map((k, v) -> (k, mapperWithKey(k, v))
>>>>>>>>>>
>>>>>>>>>> ----------------------
>>>>>>>>>>
>>>>>>>>>> I'm not sure how many users would really need such syntax sugars,
>>>> and
>>>>>>>>> even
>>>>>>>>>> they do, we can support them easily as the above implementations;
>>>>>>>>>>
>>>>>>>>>> Similarly for "ReducerWithKey", it can be implemented as
>>>>>> `Aggregator<K,
>>>>>>>>> V,
>>>>>>>>>> V>`, and people who needs key access can just use `aggregate`
>>>>>> directly.
>>>>>>>>>>
>>>>>>>>>> The function which I think is really of valuable is
>>>>>>> `ValueJoinerWithKey`,
>>>>>>>>>> and that seems to be the original request from users while others
>>>> are
>>>>>>>>>> coming from "API consistency" concerns. Personally I'd prefer only
>>>>>> keep
>>>>>>>>> the
>>>>>>>>>> last one (`InitializerWithKey` might also have some value, but I
>>>> have
>>>>>>> not
>>>>>>>>>> seen people widely requesting it in their DSL usage yet; if there
>>> is
>>>>>> a
>>>>>>>>>> common request we can keep it in this KIP as well). WDYT?
>>>>>>>>>>
>>>>>>>>>> Guozhang
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
>>>>>> je.karimov@gmail.com
>>>>>>>>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> Thanks for clarification Matthias, now everything is clear.
>>>>>>>>>>>
>>>>>>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
>>>>>>> matthias@confluent.io>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
>>>>>> have
>>>>>>>>> an
>>>>>>>>>>>> supplier, you only get a single instance of your function. But
>>> for
>>>>>> a
>>>>>>>>>>>> stateful transformation, we need multiple instances (one for
>>> each
>>>>>>> task)
>>>>>>>>>>>> of ValueTransformer.
>>>>>>>>>>>>
>>>>>>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
>>>>>> because
>>>>>>>>>>>> those are stateless and thus, we can reuse a single instance
>>> over
>>>>>>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
>>>>>>>>>>> similar).
>>>>>>>>>>>>
>>>>>>>>>>>> Btw: This reminds me about KIP-159: with regard to the
>>>> RichFunction
>>>>>>> we
>>>>>>>>>>>> might need a supplier pattern, too. (I'll comment on the other
>>>>>>> thread,
>>>>>>>>>>>> too.)
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>
>>>>>>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>
>>>>>>>>>>>>> I updated KIP.
>>>>>>>>>>>>> Just to avoid misunderstanding, I meant deprecating
>>>>>>>>>>>> ValueTransformerSupplier
>>>>>>>>>>>>> and I am ok with ValueTransformer.
>>>>>>>>>>>>> So instead of using ValueTransformerSupplier can't we directly
>>>> use
>>>>>>>>>>>>> ValueTransformer
>>>>>>>>>>>>> or ValueTransformerWithKey?
>>>>>>>>>>>>>
>>>>>>>>>>>>> Btw, in current design all features of ValueTransformer will be
>>>>>>>>>>> available
>>>>>>>>>>>>> in ValueTransformerWithKey interface.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>
>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks Jeyhun.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>>>>>>>>>>> ValueTransformer allows to attach a state and also allows to
>>>>>>> register
>>>>>>>>>>>>>> punctuations. Both those features will not be available via
>>>>>>> withKey()
>>>>>>>>>>>>>> interfaces.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
>>>>>>>>>>>> Especially
>>>>>>>>>>>>>>> for "light" and stateless operators it slows down the
>>> topology
>>>>>>>>>>>>>>> significantly (> 20% ). I think "warning" users about
>>>>>>> not-changing
>>>>>>>>>>> the
>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>> is better warning them about possible performance loss.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> About the interfaces, additionally I considered adding
>>>>>>>>>>>>>> InitializerWithKey,
>>>>>>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they
>>> are
>>>>>>>>>>>> included
>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
>>>>>> bad.
>>>>>>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> One thing I want to mention is that, maybe we should
>>> deprecate
>>>>>>>>>>> methods
>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>> argument type ValueTransformerSupplier
>>>>>>>>> (KStream.transformValues(...))
>>>>>>>>>>>> and
>>>>>>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
>>>>>> instead
>>>>>>>>>>>> without
>>>>>>>>>>>>>>> additional supplier layer.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> One more question:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Should we add any of
>>>>>>>>>>>>>>>> - InitizialierWithKey
>>>>>>>>>>>>>>>> - ReducerWithKey
>>>>>>>>>>>>>>>> - ValueTransformerWithKey
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
>>>>>>>>>>> thoughts?
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
>>>>>> idea
>>>>>>>>> we
>>>>>>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
>>>>>>>>> functions
>>>>>>>>>>>>>> into
>>>>>>>>>>>>>>>>>> this KIP.
>>>>>>>>>>>>>>>>>> I think once we include rich functions in this KIP and
>>> then
>>>>>> fix
>>>>>>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with
>>>> existing
>>>>>>>>> rich
>>>>>>>>>>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP
>>>> (I
>>>>>>>>>>>> updated
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
>>>>>> functions.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
>>>>>> ValueMapperWithKey
>>>>>>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent
>>> add-on.
>>>>>> To
>>>>>>>>>>> fix
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
>>>>>>>>>>> required
>>>>>>>>>>>>>>>> IMHO.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I initially put the RichFunction idea on the table,
>>> because
>>>>>> I
>>>>>>>>> was
>>>>>>>>>>>>>>>> hoping
>>>>>>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to
>>> consider
>>>>>>> them
>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>> however, the discussion showed that they are not
>>> necessary
>>>>>> for
>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>> access. Thus, it seems to be better to handle
>>> RichFunctions
>>>>>> in
>>>>>>>>> an
>>>>>>>>>>>> own
>>>>>>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to
>>> be
>>>> a
>>>>>>>>> main
>>>>>>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>>>>>>>>>>> parameter-less
>>>>>>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>>>>>>>>>>> "intermediate"
>>>>>>>>>>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel
>>> free
>>>>>> do
>>>>>>>>>>> push
>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
>>>>>> parallel)
>>>>>>> --
>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
>>>>>> and
>>>>>>>>>>> code
>>>>>>>>>>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
>>>>>>>>> *interface*
>>>>>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
>>>>>>> raised
>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>> issue
>>>>>>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Regarding with passing additional contextual
>>> information,
>>>> I
>>>>>>>>>>> think
>>>>>>>>>>>> it
>>>>>>>>>>>>>>>> is a
>>>>>>>>>>>>>>>>>>>> tradeoff,
>>>>>>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init()
>>> *method
>>>>>> in
>>>>>>>>>>>>>> another
>>>>>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3])
>>> with
>>>>>>>>>>>> providing
>>>>>>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>>>>>>>>>>> parameters
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> To me, the second approach seems more incremental.
>>> However
>>>>>>> you
>>>>>>>>>>> are
>>>>>>>>>>>>>>>> right,
>>>>>>>>>>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>>>>>>>>>>> damian.guy@gmail.com
>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>> which
>>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected
>>>> it
>>>>>>> to
>>>>>>>>>>>> pass
>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>> additional contextual information, i.e., the
>>>>>> `RecordContext`
>>>>>>>>>>> that
>>>>>>>>>>>>>>>>>>> contains
>>>>>>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok
>>>> with
>>>>>>> it
>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>> passing
>>>>>>>>>>>>>>>>>>>>> this contextual information, but is the naming
>>> incorrect?
>>>>>>> I'm
>>>>>>>>>>> not
>>>>>>>>>>>>>>>> sure,
>>>>>>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions`
>>>> until
>>>>>>> we
>>>>>>>>>>> can
>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Also, i don't like the abstract classes:
>>> RichValueMapper,
>>>>>>>>>>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
>>>>>> interfaces?
>>>>>>>>>>>>>>>> Generally we
>>>>>>>>>>>>>>>>>>>>> should provide users with Intefaces to code against,
>>> not
>>>>>>>>>>> classes.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>>>>>> Damian
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>>>>>>>>>>> je.karimov@gmail.com>
>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
>>>>>>> overview.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
>>>>>>>>>>> interface
>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
>>>>>> implements
>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>>>>>>>>>>> inheritance.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> However, I think we can easily change it (from
>>> abstract
>>>>>>> class
>>>>>>>>>>> ->
>>>>>>>>>>>>>>>>>>>>> interface)
>>>>>>>>>>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is
>>>> quite
>>>>>>>>>>>> improved
>>>>>>>>>>>>>>>> now
>>>>>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc
>>> abstract
>>>>>>>>>>> classes
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
>>> for
>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
>>>>>> they
>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have
>>> only
>>>>>>> one
>>>>>>>>>>>>>>>> method ,
>>>>>>>>>>>>>>>>>>>>> so
>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
>>>>>>> Inside
>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
>>>>>>> *withKey*
>>>>>>>>>>> and
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) .
>>> We
>>>>>> get
>>>>>>>>>>>> those
>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
>>>>>> topology,
>>>>>>>>> and
>>>>>>>>>>>>>> send
>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
>>>>>> implement
>>>>>>>>>>>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by
>>> definition.
>>>>>> In
>>>>>>>>>>> this
>>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>>> while
>>>>>>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the
>>> object
>>>>>>> type
>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar
>>> for
>>>>>>> Rich
>>>>>>>>>>>>>>>> functions
>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
>>> we
>>>>>>> need
>>>>>>>>>>> to
>>>>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
>>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
>>>>>> remove
>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>>>>> sufficient
>>>>>>> to
>>>>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>>>>> "extended
>>>>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
>>> idea
>>>>>> of
>>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>>>>> much
>>>>>>>>>>>>>> because
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
>>>> see
>>>>>>>>>>> value
>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only
>>> one
>>>>>>> extra
>>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
>>>>>> *withKey*
>>>>>>>>>>>>>> version
>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as
>>> Rich
>>>>>>>>>>>> function
>>>>>>>>>>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type.
>>>> We
>>>>>>>>>>>>>>>> differentiate
>>>>>>>>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of
>>> the
>>>>>>>>>>>> comment:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but
>>> can
>>>>>> we
>>>>>>>>>>> have
>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas,
>>>> it
>>>>>>>>>>> might
>>>>>>>>>>>>>> make
>>>>>>>>>>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV`
>>> ?
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
>>>>>> overall
>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>>>>> sense
>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>>>>> thus,
>>>>>>>>>>> this
>>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
>>> KIP"
>>>>>>>>>>> before
>>>>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>>>>>>>>>>> functions
>>>>>>>>>>>>>> as I
>>>>>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
>>>>>> library.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
>>> for
>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
>>> we
>>>>>>> need
>>>>>>>>>>> to
>>>>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not
>>> make
>>>>>>>>> sense
>>>>>>>>>>>>>>>> anymore,
>>>>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>>>>>>>>>>> implementation of
>>>>>>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
>>>>>> would
>>>>>>>>>>>>>>>> implement a
>>>>>>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>>>>> sufficient
>>>>>>>>> to
>>>>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>>>>> "extended
>>>>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
>>> idea
>>>>>> of
>>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>>>>> much
>>>>>>>>>>>>>> because
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
>>>> see
>>>>>>>>>>> value
>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>>>>>> sense
>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>>>>> thus,
>>>>>>>>>>> this
>>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
>>> KIP"
>>>>>>>>>>> before
>>>>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
>>>>>>> comments.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>>>>>> little
>>>>>>>>>>>>>> bit? I
>>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>>>>>> problem
>>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
>>>>>> interface
>>>>>>>>>>> that
>>>>>>>>>>>>>> has
>>>>>>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
>>>>>> function
>>>>>>>>>>>>>>>> contract".
>>>>>>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
>>>>>> another
>>>>>>>>>>> (in
>>>>>>>>>>>>>> our
>>>>>>>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
>>>>>>>>> lambdas
>>>>>>>>>>>> in
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>>>>>> maybe
>>>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>>> would
>>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>>>>>>>> overlaods
>>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>>> need
>>>>>> to
>>>>>>>>>>> add
>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
>>>>>> public
>>>>>>>>>>> APIs
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has
>>> similar
>>>>>>>>>>>> structure:
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor
>>>> and
>>>>>>>>>>> inside
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich
>>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
>>>>>> overall
>>>>>>>>>>> idea
>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
>>>>>>> changes.
>>>>>>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext
>>> p)*
>>>>>>> and*
>>>>>>>>>>>>>>>> close()*
>>>>>>>>>>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>>>>>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
>>>>>> *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and
>>>> ease
>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>>> ForeachAction,
>>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>>> add
>>>>>> to
>>>>>>>>>>> all,
>>>>>>>>>>>>>> but
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>>> sense
>>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
>>>>>> applies
>>>>>>>>> to
>>>>>>>>>>>> all
>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP,
>>>> just
>>>>>>>>>>> wanted
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>>> `ValueXXWithKey`
>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we
>>> should
>>>>>>> not
>>>>>>>>>>>> force
>>>>>>>>>>>>>>>>>>>>> users
>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
>>>>>>>>> functions
>>>>>>>>>>>>>> every
>>>>>>>>>>>>>>>>>>>>> time
>>>>>>>>>>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
>>>>>> methods.
>>>>>>>>>>>>>> However,
>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>>>>> spread
>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
>>> that
>>>>>> is
>>>>>>>>>>> done
>>>>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
>>> becoming
>>>>>>> too
>>>>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>>>>>>>>>>> *init(ProcessorContext)*
>>>>>>>>>>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
>>>>>>> ProcessorContext
>>>>>>>>>>> as
>>>>>>>>>>>> an
>>>>>>>>>>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
>>>>>> @mjsax
>>>>>>>>>>>>>>>> mentioned)
>>>>>>>>>>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an
>>> access
>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* )
>>> or
>>>>>>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>>>>>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>>>>> spread
>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
>>> that
>>>>>> is
>>>>>>>>>>> done
>>>>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
>>> becoming
>>>>>>> too
>>>>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface
>>> is
>>>>>> too
>>>>>>>>>>>> broad
>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
>>>>>> it's
>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>> reflected
>>>>>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>>> confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
>>>>>> `RichFunction`
>>>>>>>>>>>>>>>> approach in
>>>>>>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
>>>>>> scope
>>>>>>>>> of
>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP
>>> for
>>>>>> it
>>>>>>>>>>> and
>>>>>>>>>>>>>>>> delay
>>>>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction`
>>> approach.
>>>>>> Do
>>>>>>>>> we
>>>>>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>>>>>> want
>>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the
>>> `ProcessorContext`
>>>>>> ?
>>>>>>> It
>>>>>>>>>>>> has
>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>> bunch
>>>>>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some
>>>> of
>>>>>>> the
>>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`,
>>>> `schedule`
>>>>>>>>> etc.
>>>>>>>>>>>> It
>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>> far
>>>>>>>>>>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
>>>>>> narrower
>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to
>>>> add
>>>>>>>>>>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you
>>> elaborate
>>>>>> a
>>>>>>>>>>>> little
>>>>>>>>>>>>>>>> bit?
>>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what
>>>> the
>>>>>>>>>>>> problem
>>>>>>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know --
>>> guess
>>>>>>> it's
>>>>>>>>>>> up
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can
>>> you
>>>>>>> maybe
>>>>>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>>>>>> would
>>>>>>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
>>>>>> have
>>>>>>>>>>>>>> overlaods
>>>>>>>>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>>>>>> need
>>>>>>>>> to
>>>>>>>>>>>> add
>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>>>>>>> ForeachAction,
>>>>>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>>>>>> add
>>>>>>> to
>>>>>>>>>>>> all,
>>>>>>>>>>>>>>>> but
>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>>>>>> sense
>>>>>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>>>>>>>> `ValueXXWithKey`
>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this
>>> with
>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
>>>>>> extend
>>>>>>>>>>> the
>>>>>>>>>>>>>> two
>>>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
>>>>>>> Maybe I
>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the
>>> KIP
>>>>>> to
>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>>>>>> confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+
>>> ValueTransformer%2C+
>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J.
>>> Sax
>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends
>>> `ValueMapper`
>>>>>> we
>>>>>>>>>>> don't
>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
>>>>>>>>> happens
>>>>>>>>>>>>>> when
>>>>>>>>>>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>>>>>>>>>>> KafkaStream#start()
>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
>>>>>> `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>> mapValues(ValueMapper<?
>>>>>>>>> super
>>>>>>>>>>>> V,
>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>>>>>>>>>> mapValues(ValueMapperWithKey<?
>>>>>>>>>>>>>>>> super
>>>>>>>>>>>>>>>>>>>>> V,
>>>>>>>>>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>
>>>
>>
>>
>>
>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by "Matthias J. Sax" <ma...@confluent.io>.
I have no strong opinion, but it seems that at least InitializerWithKey
with be helpful if you want to have different start values for different
keys (even if I cannot come up with a use case example why one wanted to
do this...). Otherwise, there is just the "completeness" argument, that
is not too strong either.
-Matthias
On 6/14/17 2:03 PM, Guozhang Wang wrote:
> I'm not particularly concerning that we should NEVER break compatibility;
> in fact if we think that is worthwhile (i.e. small impact with large
> benefit) I think we can break compatibility as long as we have not removed
> the compatibility annotations from Streams. All I was saying is that if we
> decided to go this way we need to make sure this is mentioned in the
> upgrade guidance.
>
> Regarding the scope I'm still trying to solicit opinions regarding
> ReducerWithKey and InitializerWithKey; to me they are not necessarily to be
> included.
>
>
> Guozhang
>
>
> On Wed, Jun 14, 2017 at 5:22 AM, Jeyhun Karimov <je...@gmail.com>
> wrote:
>
>> Hi,
>>
>> I introduced ValueTransformerCommon just to combine common methods of
>> ValueTransformer and ValueTransformerWithKey and avoid copy-paste.
>> I am aware of this issue and I agree that this needs users to compile the
>> code and therefore is not backwards compatible. When I saw this issue, I
>> thought the degree of incompatibility is small (the public APIs are the
>> same, users just need to recompile their code), so we can trade more
>> maintainable code in this case. I have to comments/solutions:
>>
>> 1. Basically we can remove ValueTransformerCommon class and return
>> ValueTransformer to its original form, which means there will be no issues
>> with backwards-compatibility. We just copy and past the methods inside
>> ValueTransformerCommon to ValueTransformerWithKey and maybe in future
>> releases, we can introduce ValueTransformerCommon.
>>
>> 2. I have some doubts about Matthias's proposal.
>> If we extent withKey interface from original one as you mentioned in
>> previous email, then we have to deal with
>> ValueTransformer.transform(V value) method. As a result, inside withKey
>> interface we will have two transforms. Even if we make it abstract class,
>> user still have an access to play with both transform() methods. I think
>> this should not be allowed and seems "hacky" to me. Actually this was one
>> reason why I created withKey classes independently from original
>> interfaces.
>>
>> Of course, you can correct me if I am wrong.
>>
>>
>> Cheers,
>> Jeyhun
>>
>>
>>
>> On Tue, Jun 13, 2017 at 7:42 PM Matthias J. Sax <ma...@confluent.io>
>> wrote:
>>
>>> I agree with Guozhang's second point. This change does not seem backward
>>> compatible.
>>>
>>> As we don't have to support lambdas, it might be the easiest thing to
>>> just extend the current interface:
>>>
>>>> public interface ValueTransformerWithKey<K, V, VR> extends
>>> ValueTransformer<VR>
>>>
>>> When plugging the topology together, we can check if we get the
>>> `withKey` variant and use a corresponding runtime class for execution,
>>> so we get only a single time check. Thus, for the `withKey` variant, the
>>> will be a `transfrom(V value)` method, but we will never call it.
>>>
>>> Maybe we could make `ValueTransformerWithKey` an abstract class with a
>>> `final` no-op implemenation of `transform(V value)` ?
>>>
>>>
>>> -Matthias
>>>
>>>
>>> On 6/6/17 4:58 PM, Guozhang Wang wrote:
>>>> Jeyhun, Matthias:
>>>>
>>>> Thanks for the explanation, I overlooked the repartition argument
>>>> previously.
>>>>
>>>> 1) Based on that argument I'm convinced of having ValueMapperWithKey /
>>>> ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
>>>> convinced with ReducerWithKey and InitializerWithKey since for the
>> former
>>>> it can be covered with `aggregate` completely and with latter I have
>> seen
>>>> little use cases with it.
>>>>
>>>> 2) Another comment is on public interface ValueTransformer<V, VR>
>> extends
>>>> ValueTransformerCommon<VR>:
>>>>
>>>> I think changing the interface to extend from a new interface is not
>>> binary
>>>> compatible though source compatible, i.e. users still need to recompile
>>>> their code though no need to make code changes. We may need to mention
>>> that
>>>> in the upgrade path if we want to keep it that way.
>>>>
>>>> Guozhang
>>>>
>>>> On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com>
>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>>
>>>>> Sorry for late reply. Just to make everybody in sync, the current
>>> version
>>>>> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
>>>>> independent, meaning they do not extend from "withoutKey"
>> (ValueMapper)
>>>>> interfaces.
>>>>>
>>>>>
>>>>> I agree with Guozhang, and I am personally a bit reluctant to increase
>>>>> overloaded methods in public APIs but it seems this is only way to
>> solve
>>>>> all related jira issues.
>>>>> However, the most overloaded methods will be with ValueJoiner type,
>>> which
>>>>> will be with ValueJoinerWithKey with new overloaded methods. Other
>>>>> interfaces require mostly 1 extra overload.
>>>>>
>>>>>
>>>>>>> I would suggest not doing it if user pop it up, but rather
>> suggesting
>>>>> them
>>>>>>> to use `map`
>>>>>
>>>>> I agree with Matthias as the core idea of this KIP was to collect all
>>>>> related jira issues and propose one-shot solution for all. Afterwards,
>>> we
>>>>> broke its scope into 2 KIPs (149 and 159).
>>>>>
>>>>> Cheers,
>>>>> Jeyhun
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <matthias@confluent.io
>>>
>>>>> wrote:
>>>>>
>>>>>> I guess I missunderstood you. Your are right that overloading the
>>> method
>>>>>> would also work. As both interfaces will be independent from each
>>> other,
>>>>>> there should be no problem.
>>>>>>
>>>>>> The initial proposal was to use
>>>>>>
>>>>>>> interface ValueMapperWithKey extends ValueMapper
>>>>>>
>>>>>> and this would break Lambda. We totally missed, that we don't need
>> new
>>>>>> methods but only only overlaods. Great you point this out! I was not
>>>>>> quite happy with the newly added methods.
>>>>>>
>>>>>>>> I would suggest not doing it if user pop it up, but rather
>> suggesting
>>>>>> them
>>>>>>>> to use `map`
>>>>>>
>>>>>> But this might introduce unnecessary re-partitioning for downstream
>>>>>> operators. I don't thinks that a good suggestion. But if we only add
>>> new
>>>>>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
>>>>>> with "overstaffing" the API (what is btw a very valid concern).
>>>>>>
>>>>>>
>>>>>> -Matthias
>>>>>>
>>>>>>
>>>>>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
>>>>>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <
>>> matthias@confluent.io
>>>>>>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> We started with this proposal but it does not allow for Lambdas (in
>>>>> case
>>>>>>>> you want key access). Do you think preserving Lambdas is not
>>> important
>>>>>>>> enough for this case -- I agree that there is some price to be paid
>>> to
>>>>>>>> keep Lambdas.
>>>>>>>>
>>>>>>>
>>>>>>> Not sure if I understand this comment.. My main point is not on
>>>>> changing
>>>>>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only;
>>> and
>>>>>>> even if we want to keep them all, I'd suggest we just implement the
>>>>> added
>>>>>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
>>>>> which
>>>>>>> seems simpler to me. Does that affect lambda expression usage?
>>>>>>>
>>>>>>>>
>>>>>>>> About API consistency: I can't remember a concrete user request to
>>>>> have
>>>>>>>> key access in all operators. But I am pretty sure, if we only add
>> it
>>>>> for
>>>>>>>> some, this request will pop up quickly. IMHO, it's better to do it
>>> all
>>>>>>>> in one shot. (But I am not strict about it if most people think we
>>>>>>>> should limit it to what was requested by users.)
>>>>>>>>
>>>>>>>>
>>>>>>> I would suggest not doing it if user pop it up, but rather
>> suggesting
>>>>>> them
>>>>>>> to use `map` etc directly but set the key unchanged rather than
>>>>>> providing a
>>>>>>> new operator for it. To me some syntax sugars like this seems of
>> less
>>>>>>> valuable than others (like print / writeAsText / foreach that are
>> all
>>>>>>> depending on peek), and keeping adding them will just make the DSL
>> too
>>>>>>> “overstaffed”.
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> -Matthias
>>>>>>>>
>>>>>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
>>>>>>>>> With KIP-159, the added "valueMapperWithKey" and
>>>>>>>> "valueTransformerWithKey"
>>>>>>>>> along seem to be just adding a few syntax-sugars? E.g. we can
>> simply
>>>>>>>>> implement:
>>>>>>>>>
>>>>>>>>> mapValues(ValueMapperWithKey mapperWithKey)
>>>>>>>>>
>>>>>>>>> as
>>>>>>>>>
>>>>>>>>> map((k, v) -> (k, mapperWithKey(k, v))
>>>>>>>>>
>>>>>>>>> ----------------------
>>>>>>>>>
>>>>>>>>> I'm not sure how many users would really need such syntax sugars,
>>> and
>>>>>>>> even
>>>>>>>>> they do, we can support them easily as the above implementations;
>>>>>>>>>
>>>>>>>>> Similarly for "ReducerWithKey", it can be implemented as
>>>>> `Aggregator<K,
>>>>>>>> V,
>>>>>>>>> V>`, and people who needs key access can just use `aggregate`
>>>>> directly.
>>>>>>>>>
>>>>>>>>> The function which I think is really of valuable is
>>>>>> `ValueJoinerWithKey`,
>>>>>>>>> and that seems to be the original request from users while others
>>> are
>>>>>>>>> coming from "API consistency" concerns. Personally I'd prefer only
>>>>> keep
>>>>>>>> the
>>>>>>>>> last one (`InitializerWithKey` might also have some value, but I
>>> have
>>>>>> not
>>>>>>>>> seen people widely requesting it in their DSL usage yet; if there
>> is
>>>>> a
>>>>>>>>> common request we can keep it in this KIP as well). WDYT?
>>>>>>>>>
>>>>>>>>> Guozhang
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
>>>>> je.karimov@gmail.com
>>>>>>>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Thanks for clarification Matthias, now everything is clear.
>>>>>>>>>>
>>>>>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
>>>>>> matthias@confluent.io>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
>>>>> have
>>>>>>>> an
>>>>>>>>>>> supplier, you only get a single instance of your function. But
>> for
>>>>> a
>>>>>>>>>>> stateful transformation, we need multiple instances (one for
>> each
>>>>>> task)
>>>>>>>>>>> of ValueTransformer.
>>>>>>>>>>>
>>>>>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
>>>>> because
>>>>>>>>>>> those are stateless and thus, we can reuse a single instance
>> over
>>>>>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
>>>>>>>>>> similar).
>>>>>>>>>>>
>>>>>>>>>>> Btw: This reminds me about KIP-159: with regard to the
>>> RichFunction
>>>>>> we
>>>>>>>>>>> might need a supplier pattern, too. (I'll comment on the other
>>>>>> thread,
>>>>>>>>>>> too.)
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> -Matthias
>>>>>>>>>>>
>>>>>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> I updated KIP.
>>>>>>>>>>>> Just to avoid misunderstanding, I meant deprecating
>>>>>>>>>>> ValueTransformerSupplier
>>>>>>>>>>>> and I am ok with ValueTransformer.
>>>>>>>>>>>> So instead of using ValueTransformerSupplier can't we directly
>>> use
>>>>>>>>>>>> ValueTransformer
>>>>>>>>>>>> or ValueTransformerWithKey?
>>>>>>>>>>>>
>>>>>>>>>>>> Btw, in current design all features of ValueTransformer will be
>>>>>>>>>> available
>>>>>>>>>>>> in ValueTransformerWithKey interface.
>>>>>>>>>>>>
>>>>>>>>>>>> Cheers,
>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>
>>>>>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
>>>>>>>> matthias@confluent.io
>>>>>>>>>>>
>>>>>>>>>>>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks Jeyhun.
>>>>>>>>>>>>>
>>>>>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>>>>>>>>>> ValueTransformer allows to attach a state and also allows to
>>>>>> register
>>>>>>>>>>>>> punctuations. Both those features will not be available via
>>>>>> withKey()
>>>>>>>>>>>>> interfaces.
>>>>>>>>>>>>>
>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
>>>>>>>>>>> Especially
>>>>>>>>>>>>>> for "light" and stateless operators it slows down the
>> topology
>>>>>>>>>>>>>> significantly (> 20% ). I think "warning" users about
>>>>>> not-changing
>>>>>>>>>> the
>>>>>>>>>>>>> key
>>>>>>>>>>>>>> is better warning them about possible performance loss.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> About the interfaces, additionally I considered adding
>>>>>>>>>>>>> InitializerWithKey,
>>>>>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they
>> are
>>>>>>>>>>> included
>>>>>>>>>>>>> in
>>>>>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
>>>>> bad.
>>>>>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> One thing I want to mention is that, maybe we should
>> deprecate
>>>>>>>>>> methods
>>>>>>>>>>>>> with
>>>>>>>>>>>>>> argument type ValueTransformerSupplier
>>>>>>>> (KStream.transformValues(...))
>>>>>>>>>>> and
>>>>>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
>>>>> instead
>>>>>>>>>>> without
>>>>>>>>>>>>>> additional supplier layer.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>
>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> One more question:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Should we add any of
>>>>>>>>>>>>>>> - InitizialierWithKey
>>>>>>>>>>>>>>> - ReducerWithKey
>>>>>>>>>>>>>>> - ValueTransformerWithKey
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
>>>>>>>>>> thoughts?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
>>>>> idea
>>>>>>>> we
>>>>>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
>>>>>>>> functions
>>>>>>>>>>>>> into
>>>>>>>>>>>>>>>>> this KIP.
>>>>>>>>>>>>>>>>> I think once we include rich functions in this KIP and
>> then
>>>>> fix
>>>>>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with
>>> existing
>>>>>>>> rich
>>>>>>>>>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP
>>> (I
>>>>>>>>>>> updated
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
>>>>> functions.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
>>>>> ValueMapperWithKey
>>>>>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent
>> add-on.
>>>>> To
>>>>>>>>>> fix
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
>>>>>>>>>> required
>>>>>>>>>>>>>>> IMHO.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> I initially put the RichFunction idea on the table,
>> because
>>>>> I
>>>>>>>> was
>>>>>>>>>>>>>>> hoping
>>>>>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to
>> consider
>>>>>> them
>>>>>>>>>> --
>>>>>>>>>>>>>>>>>> however, the discussion showed that they are not
>> necessary
>>>>> for
>>>>>>>>>> key
>>>>>>>>>>>>>>>>>> access. Thus, it seems to be better to handle
>> RichFunctions
>>>>> in
>>>>>>>> an
>>>>>>>>>>> own
>>>>>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to
>> be
>>> a
>>>>>>>> main
>>>>>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>>>>>>>>>> parameter-less
>>>>>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>>>>>>>>>> "intermediate"
>>>>>>>>>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel
>> free
>>>>> do
>>>>>>>>>> push
>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
>>>>> parallel)
>>>>>> --
>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
>>>>> and
>>>>>>>>>> code
>>>>>>>>>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
>>>>>>>> *interface*
>>>>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
>>>>>> raised
>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>> issue
>>>>>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Regarding with passing additional contextual
>> information,
>>> I
>>>>>>>>>> think
>>>>>>>>>>> it
>>>>>>>>>>>>>>> is a
>>>>>>>>>>>>>>>>>>> tradeoff,
>>>>>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init()
>> *method
>>>>> in
>>>>>>>>>>>>> another
>>>>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3])
>> with
>>>>>>>>>>> providing
>>>>>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>>>>>>>>>> parameters
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> To me, the second approach seems more incremental.
>> However
>>>>>> you
>>>>>>>>>> are
>>>>>>>>>>>>>>> right,
>>>>>>>>>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>>>>>>>>>> damian.guy@gmail.com
>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>> which
>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected
>>> it
>>>>>> to
>>>>>>>>>>> pass
>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>> additional contextual information, i.e., the
>>>>> `RecordContext`
>>>>>>>>>> that
>>>>>>>>>>>>>>>>>> contains
>>>>>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok
>>> with
>>>>>> it
>>>>>>>>>> not
>>>>>>>>>>>>>>>>>> passing
>>>>>>>>>>>>>>>>>>>> this contextual information, but is the naming
>> incorrect?
>>>>>> I'm
>>>>>>>>>> not
>>>>>>>>>>>>>>> sure,
>>>>>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions`
>>> until
>>>>>> we
>>>>>>>>>> can
>>>>>>>>>>>>> do
>>>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Also, i don't like the abstract classes:
>> RichValueMapper,
>>>>>>>>>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
>>>>> interfaces?
>>>>>>>>>>>>>>> Generally we
>>>>>>>>>>>>>>>>>>>> should provide users with Intefaces to code against,
>> not
>>>>>>>>>> classes.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>>>>> Damian
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>>>>>>>>>> je.karimov@gmail.com>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
>>>>>> overview.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
>>>>>>>>>> interface
>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
>>>>> implements
>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>>>>>>>>>> inheritance.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> However, I think we can easily change it (from
>> abstract
>>>>>> class
>>>>>>>>>> ->
>>>>>>>>>>>>>>>>>>>> interface)
>>>>>>>>>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is
>>> quite
>>>>>>>>>>> improved
>>>>>>>>>>>>>>> now
>>>>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc
>> abstract
>>>>>>>>>> classes
>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
>> for
>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
>>>>> they
>>>>>>>>>>> don't
>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have
>> only
>>>>>> one
>>>>>>>>>>>>>>> method ,
>>>>>>>>>>>>>>>>>>>> so
>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
>>>>>> Inside
>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
>>>>>> *withKey*
>>>>>>>>>> and
>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) .
>> We
>>>>> get
>>>>>>>>>>> those
>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
>>>>> topology,
>>>>>>>> and
>>>>>>>>>>>>> send
>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
>>>>> implement
>>>>>>>>>>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by
>> definition.
>>>>> In
>>>>>>>>>> this
>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>> while
>>>>>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the
>> object
>>>>>> type
>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar
>> for
>>>>>> Rich
>>>>>>>>>>>>>>> functions
>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
>> we
>>>>>> need
>>>>>>>>>> to
>>>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
>>>>> remove
>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>>>> sufficient
>>>>>> to
>>>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>>>> "extended
>>>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
>> idea
>>>>> of
>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>>>> much
>>>>>>>>>>>>> because
>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
>>> see
>>>>>>>>>> value
>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only
>> one
>>>>>> extra
>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
>>>>> *withKey*
>>>>>>>>>>>>> version
>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as
>> Rich
>>>>>>>>>>> function
>>>>>>>>>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type.
>>> We
>>>>>>>>>>>>>>> differentiate
>>>>>>>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of
>> the
>>>>>>>>>>> comment:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but
>> can
>>>>> we
>>>>>>>>>> have
>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas,
>>> it
>>>>>>>>>> might
>>>>>>>>>>>>> make
>>>>>>>>>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV`
>> ?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
>>>>> overall
>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>>>> sense
>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>>>> thus,
>>>>>>>>>> this
>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
>> KIP"
>>>>>>>>>> before
>>>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>>>>>>>>>> functions
>>>>>>>>>>>>> as I
>>>>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
>>>>> library.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
>> for
>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
>> we
>>>>>> need
>>>>>>>>>> to
>>>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not
>> make
>>>>>>>> sense
>>>>>>>>>>>>>>> anymore,
>>>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>>>>>>>>>> implementation of
>>>>>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
>>>>> would
>>>>>>>>>>>>>>> implement a
>>>>>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>>>> sufficient
>>>>>>>> to
>>>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>>>> "extended
>>>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
>> idea
>>>>> of
>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>>>> much
>>>>>>>>>>>>> because
>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
>>> see
>>>>>>>>>> value
>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>>>>> sense
>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>>>> thus,
>>>>>>>>>> this
>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
>> KIP"
>>>>>>>>>> before
>>>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
>>>>>> comments.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>>>>> little
>>>>>>>>>>>>> bit? I
>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>>>>> problem
>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
>>>>> interface
>>>>>>>>>> that
>>>>>>>>>>>>> has
>>>>>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
>>>>> function
>>>>>>>>>>>>>>> contract".
>>>>>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
>>>>> another
>>>>>>>>>> (in
>>>>>>>>>>>>> our
>>>>>>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
>>>>>>>> lambdas
>>>>>>>>>>> in
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>>>>> maybe
>>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>> would
>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>>>>>>> overlaods
>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>> need
>>>>> to
>>>>>>>>>> add
>>>>>>>>>>>>> any
>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
>>>>> public
>>>>>>>>>> APIs
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has
>> similar
>>>>>>>>>>> structure:
>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor
>>> and
>>>>>>>>>> inside
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich
>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
>>>>> overall
>>>>>>>>>> idea
>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
>>>>>> changes.
>>>>>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext
>> p)*
>>>>>> and*
>>>>>>>>>>>>>>> close()*
>>>>>>>>>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>>>>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
>>>>> *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and
>>> ease
>>>>>> the
>>>>>>>>>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>> ForeachAction,
>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>> add
>>>>> to
>>>>>>>>>> all,
>>>>>>>>>>>>> but
>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>> sense
>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
>>>>> applies
>>>>>>>> to
>>>>>>>>>>> all
>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP,
>>> just
>>>>>>>>>> wanted
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>> `ValueXXWithKey`
>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>>>>> interfaces
>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we
>> should
>>>>>> not
>>>>>>>>>>> force
>>>>>>>>>>>>>>>>>>>> users
>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
>>>>>>>> functions
>>>>>>>>>>>>> every
>>>>>>>>>>>>>>>>>>>> time
>>>>>>>>>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
>>>>> methods.
>>>>>>>>>>>>> However,
>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>>>> spread
>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
>> that
>>>>> is
>>>>>>>>>> done
>>>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
>> becoming
>>>>>> too
>>>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>>>>>>>>>> *init(ProcessorContext)*
>>>>>>>>>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
>>>>>> ProcessorContext
>>>>>>>>>> as
>>>>>>>>>>> an
>>>>>>>>>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
>>>>> @mjsax
>>>>>>>>>>>>>>> mentioned)
>>>>>>>>>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an
>> access
>>>>> to
>>>>>>>>>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* )
>> or
>>>>>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>>>>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>>>> spread
>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
>> that
>>>>> is
>>>>>>>>>> done
>>>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
>> becoming
>>>>>> too
>>>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface
>> is
>>>>> too
>>>>>>>>>>> broad
>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
>>>>> it's
>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>> reflected
>>>>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>> confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
>>>>> `RichFunction`
>>>>>>>>>>>>>>> approach in
>>>>>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
>>>>> scope
>>>>>>>> of
>>>>>>>>>>>>> this
>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP
>> for
>>>>> it
>>>>>>>>>> and
>>>>>>>>>>>>>>> delay
>>>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction`
>> approach.
>>>>> Do
>>>>>>>> we
>>>>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>>>>> want
>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the
>> `ProcessorContext`
>>>>> ?
>>>>>> It
>>>>>>>>>>> has
>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>> bunch
>>>>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some
>>> of
>>>>>> the
>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`,
>>> `schedule`
>>>>>>>> etc.
>>>>>>>>>>> It
>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>> far
>>>>>>>>>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
>>>>> narrower
>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to
>>> add
>>>>>>>>>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you
>> elaborate
>>>>> a
>>>>>>>>>>> little
>>>>>>>>>>>>>>> bit?
>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what
>>> the
>>>>>>>>>>> problem
>>>>>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know --
>> guess
>>>>>> it's
>>>>>>>>>> up
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can
>> you
>>>>>> maybe
>>>>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>>>>> would
>>>>>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
>>>>> have
>>>>>>>>>>>>> overlaods
>>>>>>>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>>>>> need
>>>>>>>> to
>>>>>>>>>>> add
>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>>>>>> ForeachAction,
>>>>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>>>>> add
>>>>>> to
>>>>>>>>>>> all,
>>>>>>>>>>>>>>> but
>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>>>>> sense
>>>>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>>>>>>> `ValueXXWithKey`
>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this
>> with
>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
>>>>> extend
>>>>>>>>>> the
>>>>>>>>>>>>> two
>>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
>>>>>> Maybe I
>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the
>> KIP
>>>>> to
>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>>>>> confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+
>> ValueTransformer%2C+
>>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J.
>> Sax
>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends
>> `ValueMapper`
>>>>> we
>>>>>>>>>> don't
>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
>>>>>>>> happens
>>>>>>>>>>>>> when
>>>>>>>>>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>>>>>>>>>> KafkaStream#start()
>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
>>>>> `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>> mapValues(ValueMapper<?
>>>>>>>> super
>>>>>>>>>>> V,
>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>>>>>>>>> mapValues(ValueMapperWithKey<?
>>>>>>>>>>>>>>> super
>>>>>>>>>>>>>>>>>>>> V,
>>>>>>>>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>
>>
>
>
>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Michal Borowiecki <mi...@openbet.com>.
If java 7 support is dropped by the time this is released, we could make
transform(V value) a default no-op method and keep
ValueTransformerWithKey as a functional interface, therefore supporting
lambdas, otherwise...
Changing an abstract class into an interface is not backward compatible,
so may be better to keep it an interface, sacrificing lambda support for
now but once java 7 support is dropped, make transform(V value) a
default method with no-op implementation to make it a functional
interface allowing lambdas.
Cheers,
Michał
On 13/06/17 18:42, Matthias J. Sax wrote:
> I agree with Guozhang's second point. This change does not seem backward
> compatible.
>
> As we don't have to support lambdas, it might be the easiest thing to
> just extend the current interface:
>
>> public interface ValueTransformerWithKey<K, V, VR> extends ValueTransformer<VR>
> When plugging the topology together, we can check if we get the
> `withKey` variant and use a corresponding runtime class for execution,
> so we get only a single time check. Thus, for the `withKey` variant, the
> will be a `transfrom(V value)` method, but we will never call it.
>
> Maybe we could make `ValueTransformerWithKey` an abstract class with a
> `final` no-op implemenation of `transform(V value)` ?
>
>
> -Matthias
>
>
> On 6/6/17 4:58 PM, Guozhang Wang wrote:
>> Jeyhun, Matthias:
>>
>> Thanks for the explanation, I overlooked the repartition argument
>> previously.
>>
>> 1) Based on that argument I'm convinced of having ValueMapperWithKey /
>> ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
>> convinced with ReducerWithKey and InitializerWithKey since for the former
>> it can be covered with `aggregate` completely and with latter I have seen
>> little use cases with it.
>>
>> 2) Another comment is on public interface ValueTransformer<V, VR> extends
>> ValueTransformerCommon<VR>:
>>
>> I think changing the interface to extend from a new interface is not binary
>> compatible though source compatible, i.e. users still need to recompile
>> their code though no need to make code changes. We may need to mention that
>> in the upgrade path if we want to keep it that way.
>>
>> Guozhang
>>
>> On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com> wrote:
>>
>>> Hi,
>>>
>>>
>>> Sorry for late reply. Just to make everybody in sync, the current version
>>> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
>>> independent, meaning they do not extend from "withoutKey" (ValueMapper)
>>> interfaces.
>>>
>>>
>>> I agree with Guozhang, and I am personally a bit reluctant to increase
>>> overloaded methods in public APIs but it seems this is only way to solve
>>> all related jira issues.
>>> However, the most overloaded methods will be with ValueJoiner type, which
>>> will be with ValueJoinerWithKey with new overloaded methods. Other
>>> interfaces require mostly 1 extra overload.
>>>
>>>
>>>>> I would suggest not doing it if user pop it up, but rather suggesting
>>> them
>>>>> to use `map`
>>> I agree with Matthias as the core idea of this KIP was to collect all
>>> related jira issues and propose one-shot solution for all. Afterwards, we
>>> broke its scope into 2 KIPs (149 and 159).
>>>
>>> Cheers,
>>> Jeyhun
>>>
>>>
>>>
>>> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <ma...@confluent.io>
>>> wrote:
>>>
>>>> I guess I missunderstood you. Your are right that overloading the method
>>>> would also work. As both interfaces will be independent from each other,
>>>> there should be no problem.
>>>>
>>>> The initial proposal was to use
>>>>
>>>>> interface ValueMapperWithKey extends ValueMapper
>>>> and this would break Lambda. We totally missed, that we don't need new
>>>> methods but only only overlaods. Great you point this out! I was not
>>>> quite happy with the newly added methods.
>>>>
>>>>>> I would suggest not doing it if user pop it up, but rather suggesting
>>>> them
>>>>>> to use `map`
>>>> But this might introduce unnecessary re-partitioning for downstream
>>>> operators. I don't thinks that a good suggestion. But if we only add new
>>>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
>>>> with "overstaffing" the API (what is btw a very valid concern).
>>>>
>>>>
>>>> -Matthias
>>>>
>>>>
>>>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
>>>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <matthias@confluent.io
>>>>> wrote:
>>>>>
>>>>>> We started with this proposal but it does not allow for Lambdas (in
>>> case
>>>>>> you want key access). Do you think preserving Lambdas is not important
>>>>>> enough for this case -- I agree that there is some price to be paid to
>>>>>> keep Lambdas.
>>>>>>
>>>>> Not sure if I understand this comment.. My main point is not on
>>> changing
>>>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
>>>>> even if we want to keep them all, I'd suggest we just implement the
>>> added
>>>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
>>> which
>>>>> seems simpler to me. Does that affect lambda expression usage?
>>>>>
>>>>>> About API consistency: I can't remember a concrete user request to
>>> have
>>>>>> key access in all operators. But I am pretty sure, if we only add it
>>> for
>>>>>> some, this request will pop up quickly. IMHO, it's better to do it all
>>>>>> in one shot. (But I am not strict about it if most people think we
>>>>>> should limit it to what was requested by users.)
>>>>>>
>>>>>>
>>>>> I would suggest not doing it if user pop it up, but rather suggesting
>>>> them
>>>>> to use `map` etc directly but set the key unchanged rather than
>>>> providing a
>>>>> new operator for it. To me some syntax sugars like this seems of less
>>>>> valuable than others (like print / writeAsText / foreach that are all
>>>>> depending on peek), and keeping adding them will just make the DSL too
>>>>> “overstaffed”.
>>>>>
>>>>>
>>>>>> -Matthias
>>>>>>
>>>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
>>>>>>> With KIP-159, the added "valueMapperWithKey" and
>>>>>> "valueTransformerWithKey"
>>>>>>> along seem to be just adding a few syntax-sugars? E.g. we can simply
>>>>>>> implement:
>>>>>>>
>>>>>>> mapValues(ValueMapperWithKey mapperWithKey)
>>>>>>>
>>>>>>> as
>>>>>>>
>>>>>>> map((k, v) -> (k, mapperWithKey(k, v))
>>>>>>>
>>>>>>> ----------------------
>>>>>>>
>>>>>>> I'm not sure how many users would really need such syntax sugars, and
>>>>>> even
>>>>>>> they do, we can support them easily as the above implementations;
>>>>>>>
>>>>>>> Similarly for "ReducerWithKey", it can be implemented as
>>> `Aggregator<K,
>>>>>> V,
>>>>>>> V>`, and people who needs key access can just use `aggregate`
>>> directly.
>>>>>>> The function which I think is really of valuable is
>>>> `ValueJoinerWithKey`,
>>>>>>> and that seems to be the original request from users while others are
>>>>>>> coming from "API consistency" concerns. Personally I'd prefer only
>>> keep
>>>>>> the
>>>>>>> last one (`InitializerWithKey` might also have some value, but I have
>>>> not
>>>>>>> seen people widely requesting it in their DSL usage yet; if there is
>>> a
>>>>>>> common request we can keep it in this KIP as well). WDYT?
>>>>>>>
>>>>>>> Guozhang
>>>>>>>
>>>>>>>
>>>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
>>> je.karimov@gmail.com
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Thanks for clarification Matthias, now everything is clear.
>>>>>>>>
>>>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
>>>> matthias@confluent.io>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
>>> have
>>>>>> an
>>>>>>>>> supplier, you only get a single instance of your function. But for
>>> a
>>>>>>>>> stateful transformation, we need multiple instances (one for each
>>>> task)
>>>>>>>>> of ValueTransformer.
>>>>>>>>>
>>>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
>>> because
>>>>>>>>> those are stateless and thus, we can reuse a single instance over
>>>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
>>>>>>>> similar).
>>>>>>>>> Btw: This reminds me about KIP-159: with regard to the RichFunction
>>>> we
>>>>>>>>> might need a supplier pattern, too. (I'll comment on the other
>>>> thread,
>>>>>>>>> too.)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -Matthias
>>>>>>>>>
>>>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> I updated KIP.
>>>>>>>>>> Just to avoid misunderstanding, I meant deprecating
>>>>>>>>> ValueTransformerSupplier
>>>>>>>>>> and I am ok with ValueTransformer.
>>>>>>>>>> So instead of using ValueTransformerSupplier can't we directly use
>>>>>>>>>> ValueTransformer
>>>>>>>>>> or ValueTransformerWithKey?
>>>>>>>>>>
>>>>>>>>>> Btw, in current design all features of ValueTransformer will be
>>>>>>>> available
>>>>>>>>>> in ValueTransformerWithKey interface.
>>>>>>>>>>
>>>>>>>>>> Cheers,
>>>>>>>>>> Jeyhun
>>>>>>>>>>
>>>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
>>>>>> matthias@confluent.io
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> Thanks Jeyhun.
>>>>>>>>>>>
>>>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>>>>>>>> ValueTransformer allows to attach a state and also allows to
>>>> register
>>>>>>>>>>> punctuations. Both those features will not be available via
>>>> withKey()
>>>>>>>>>>> interfaces.
>>>>>>>>>>>
>>>>>>>>>>> -Matthias
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>
>>>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
>>>>>>>>> Especially
>>>>>>>>>>>> for "light" and stateless operators it slows down the topology
>>>>>>>>>>>> significantly (> 20% ). I think "warning" users about
>>>> not-changing
>>>>>>>> the
>>>>>>>>>>> key
>>>>>>>>>>>> is better warning them about possible performance loss.
>>>>>>>>>>>>
>>>>>>>>>>>> About the interfaces, additionally I considered adding
>>>>>>>>>>> InitializerWithKey,
>>>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
>>>>>>>>> included
>>>>>>>>>>> in
>>>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
>>> bad.
>>>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>>>>>>>
>>>>>>>>>>>> One thing I want to mention is that, maybe we should deprecate
>>>>>>>> methods
>>>>>>>>>>> with
>>>>>>>>>>>> argument type ValueTransformerSupplier
>>>>>> (KStream.transformValues(...))
>>>>>>>>> and
>>>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
>>> instead
>>>>>>>>> without
>>>>>>>>>>>> additional supplier layer.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Cheers,
>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>>>>>>>> matthias@confluent.io
>>>>>>>>>>>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> One more question:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Should we add any of
>>>>>>>>>>>>> - InitizialierWithKey
>>>>>>>>>>>>> - ReducerWithKey
>>>>>>>>>>>>> - ValueTransformerWithKey
>>>>>>>>>>>>>
>>>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
>>>>>>>> thoughts?
>>>>>>>>>>>>>
>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
>>> idea
>>>>>> we
>>>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
>>>>>> functions
>>>>>>>>>>> into
>>>>>>>>>>>>>>> this KIP.
>>>>>>>>>>>>>>> I think once we include rich functions in this KIP and then
>>> fix
>>>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with existing
>>>>>> rich
>>>>>>>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
>>>>>>>>> updated
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
>>> functions.
>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
>>> ValueMapperWithKey
>>>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on.
>>> To
>>>>>>>> fix
>>>>>>>>>>> the
>>>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
>>>>>>>> required
>>>>>>>>>>>>> IMHO.
>>>>>>>>>>>>>>>> I initially put the RichFunction idea on the table, because
>>> I
>>>>>> was
>>>>>>>>>>>>> hoping
>>>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to consider
>>>> them
>>>>>>>> --
>>>>>>>>>>>>>>>> however, the discussion showed that they are not necessary
>>> for
>>>>>>>> key
>>>>>>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions
>>> in
>>>>>> an
>>>>>>>>> own
>>>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
>>>>>> main
>>>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>>>>>>>> parameter-less
>>>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>>>>>>>> "intermediate"
>>>>>>>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel free
>>> do
>>>>>>>> push
>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
>>> parallel)
>>>> --
>>>>>>>> we
>>>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
>>> and
>>>>>>>> code
>>>>>>>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
>>>>>> *interface*
>>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
>>>> raised
>>>>>>>>> this
>>>>>>>>>>>>>>>> issue
>>>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Regarding with passing additional contextual information, I
>>>>>>>> think
>>>>>>>>> it
>>>>>>>>>>>>> is a
>>>>>>>>>>>>>>>>> tradeoff,
>>>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method
>>> in
>>>>>>>>>>> another
>>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
>>>>>>>>> providing
>>>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>>>>>>>> parameters
>>>>>>>>>>> to
>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> To me, the second approach seems more incremental. However
>>>> you
>>>>>>>> are
>>>>>>>>>>>>> right,
>>>>>>>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>>>>>>>> damian.guy@gmail.com
>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>>>>>>>> RichFunction
>>>>>>>>>>>>> which
>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it
>>>> to
>>>>>>>>> pass
>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>> additional contextual information, i.e., the
>>> `RecordContext`
>>>>>>>> that
>>>>>>>>>>>>>>>> contains
>>>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with
>>>> it
>>>>>>>> not
>>>>>>>>>>>>>>>> passing
>>>>>>>>>>>>>>>>>> this contextual information, but is the naming incorrect?
>>>> I'm
>>>>>>>> not
>>>>>>>>>>>>> sure,
>>>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until
>>>> we
>>>>>>>> can
>>>>>>>>>>> do
>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
>>>>>>>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
>>> interfaces?
>>>>>>>>>>>>> Generally we
>>>>>>>>>>>>>>>>>> should provide users with Intefaces to code against, not
>>>>>>>> classes.
>>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>>> Damian
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>>>>>>>> je.karimov@gmail.com>
>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
>>>> overview.
>>>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
>>>>>>>> interface
>>>>>>>>>>> for
>>>>>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
>>> implements
>>>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>>>>>>>> inheritance.
>>>>>>>>>>>>>>>>>>> However, I think we can easily change it (from abstract
>>>> class
>>>>>>>> ->
>>>>>>>>>>>>>>>>>> interface)
>>>>>>>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
>>>>>>>>> improved
>>>>>>>>>>>>> now
>>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
>>>>>>>> classes
>>>>>>>>>>> and
>>>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
>>> they
>>>>>>>>> don't
>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only
>>>> one
>>>>>>>>>>>>> method ,
>>>>>>>>>>>>>>>>>> so
>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
>>>> Inside
>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
>>>> *withKey*
>>>>>>>> and
>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We
>>> get
>>>>>>>>> those
>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
>>> topology,
>>>>>> and
>>>>>>>>>>> send
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
>>> implement
>>>>>>>>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition.
>>> In
>>>>>>>> this
>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>> while
>>>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the object
>>>> type
>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for
>>>> Rich
>>>>>>>>>>>>> functions
>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
>>>> need
>>>>>>>> to
>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
>>>> *withKey*
>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
>>> remove
>>>>>> the
>>>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>> sufficient
>>>> to
>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>> "extended
>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
>>> of
>>>>>>>> more
>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>> much
>>>>>>>>>>> because
>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>>>>>> value
>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one
>>>> extra
>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
>>> *withKey*
>>>>>>>>>>> version
>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
>>>>>>>>> function
>>>>>>>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
>>>>>>>>>>>>> differentiate
>>>>>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
>>>>>>>>> comment:
>>>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can
>>> we
>>>>>>>> have
>>>>>>>>> a
>>>>>>>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
>>>>>>>> might
>>>>>>>>>>> make
>>>>>>>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
>>> overall
>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>> sense
>>>>>> to
>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>> thus,
>>>>>>>> this
>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>>>>>> before
>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>>>>>>>> functions
>>>>>>>>>>> as I
>>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
>>> library.
>>>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
>>>> need
>>>>>>>> to
>>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
>>>>>> sense
>>>>>>>>>>>>> anymore,
>>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>>>>>>>> implementation of
>>>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
>>> would
>>>>>>>>>>>>> implement a
>>>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>>> sufficient
>>>>>> to
>>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>>> "extended
>>>>>>>>>>> API".
>>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
>>> of
>>>>>>>> more
>>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>>> much
>>>>>>>>>>> because
>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>>>>>> value
>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>>> sense
>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>>> thus,
>>>>>>>> this
>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>>>>>> before
>>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
>>>> comments.
>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>>> little
>>>>>>>>>>> bit? I
>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>>> problem
>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
>>> interface
>>>>>>>> that
>>>>>>>>>>> has
>>>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
>>> function
>>>>>>>>>>>>> contract".
>>>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
>>> another
>>>>>>>> (in
>>>>>>>>>>> our
>>>>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
>>>>>> lambdas
>>>>>>>>> in
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>>> maybe
>>>>>>>>>>> reformat
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>>>>> overlaods
>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
>>> to
>>>>>>>> add
>>>>>>>>>>> any
>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
>>> public
>>>>>>>> APIs
>>>>>>>>>>> to
>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
>>>>>>>>> structure:
>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
>>>>>>>> inside
>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
>>>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
>>> overall
>>>>>>>> idea
>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
>>>> changes.
>>>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)*
>>>> and*
>>>>>>>>>>>>> close()*
>>>>>>>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
>>> *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease
>>>> the
>>>>>>>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add
>>> to
>>>>>>>> all,
>>>>>>>>>>> but
>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
>>> applies
>>>>>> to
>>>>>>>>> all
>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
>>>>>>>> wanted
>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>> `ValueXXWithKey`
>>>>>> --
>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>>> interfaces
>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should
>>>> not
>>>>>>>>> force
>>>>>>>>>>>>>>>>>> users
>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
>>>>>> functions
>>>>>>>>>>> every
>>>>>>>>>>>>>>>>>> time
>>>>>>>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
>>> methods.
>>>>>>>>>>> However,
>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>> spread
>>>>>>>> any
>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
>>> is
>>>>>>>> done
>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
>>>> too
>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>>>>>>>> *init(ProcessorContext)*
>>>>>>>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
>>>> ProcessorContext
>>>>>>>> as
>>>>>>>>> an
>>>>>>>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
>>> @mjsax
>>>>>>>>>>>>> mentioned)
>>>>>>>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access
>>> to
>>>>>>>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
>>>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>>> spread
>>>>>>>>> any
>>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
>>> is
>>>>>>>> done
>>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
>>>> too
>>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is
>>> too
>>>>>>>>> broad
>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
>>> it's
>>>>>>>> also
>>>>>>>>>>>>>>>>>> reflected
>>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
>>> `RichFunction`
>>>>>>>>>>>>> approach in
>>>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
>>> scope
>>>>>> of
>>>>>>>>>>> this
>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for
>>> it
>>>>>>>> and
>>>>>>>>>>>>> delay
>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach.
>>> Do
>>>>>> we
>>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>>> want
>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext`
>>> ?
>>>> It
>>>>>>>>> has
>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>> bunch
>>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of
>>>> the
>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
>>>>>> etc.
>>>>>>>>> It
>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>> far
>>>>>>>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
>>> narrower
>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
>>>>>>>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate
>>> a
>>>>>>>>> little
>>>>>>>>>>>>> bit?
>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>>>>>> problem
>>>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess
>>>> it's
>>>>>>>> up
>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>>>> maybe
>>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>>> would
>>>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
>>> have
>>>>>>>>>>> overlaods
>>>>>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>>> need
>>>>>> to
>>>>>>>>> add
>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>>>> ForeachAction,
>>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>>> add
>>>> to
>>>>>>>>> all,
>>>>>>>>>>>>> but
>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>>> sense
>>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>>>>> `ValueXXWithKey`
>>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
>>> extend
>>>>>>>> the
>>>>>>>>>>> two
>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
>>>> Maybe I
>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP
>>> to
>>>>>>>> only
>>>>>>>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>>> confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper`
>>> we
>>>>>>>> don't
>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
>>>>>> happens
>>>>>>>>>>> when
>>>>>>>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>>>>>>>> KafkaStream#start()
>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
>>> `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
>>>>>> super
>>>>>>>>> V,
>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>>>>>>> mapValues(ValueMapperWithKey<?
>>>>>>>>>>>>> super
>>>>>>>>>>>>>>>>>> V,
>>>>>>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still
>>> have
>>>> to
>>>>>>>>>>> check
>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into
>>>> the
>>>>>>>>> rich
>>>>>>>>>>>>>>>>>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal
>>>> Borowiecki
>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
>>>>>> wondering,
>>>>>>>>> if
>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a
>>>> RichFunction
>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> at
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions
>>> all
>>>>>> the
>>>>>>>>>>> time.
>>>>>>>>>>>>>>>>>>> Thus,
>>>>>>>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
>>>>>>>> non-RichFunction,
>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> wrap
>>>>>>>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>>>>>> by a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
>>>>>>>> Streams.
>>>>>>>>>>> This
>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the
>>> key:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
>>>>>>>> snippet):
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
>>>>>>>>>>>>>>>>>> RichValueMapper()
>>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper;
>>> //
>>>>>>>> set
>>>>>>>>> by
>>>>>>>>>>>>>>>>>>>>>> constructor
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
>>>>>> value1,
>>>>>>>>>>>>> final V2
>>>>>>>>>>>>>>>>>>>>>>>> value2)
>>>>>>>>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
>>>>>>>> value2);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not
>>>> sure
>>>>>>>> if
>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc
>>> would
>>>>>>>> have
>>>>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>>> overhead
>>>>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested
>>> method
>>>>>>>> call
>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than
>>>> RichFunctions).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or
>>>> do I
>>>>>>>>> miss
>>>>>>>>>>>>>>>>>>>>>> something?)
>>>>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more
>>>> top
>>>>>>>>> level
>>>>>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
>>>>>>>> `close()`
>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no
>>> abstract
>>>>>>>>> classes
>>>>>>>>>>>>>>>>>>>> required).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP
>>> to
>>>>>>>>>>> include
>>>>>>>>>>>>>>>>>> rich
>>>>>>>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of
>>> deep
>>>>>>>>> copying
>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>> keys.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu
>>>> Fenniak
>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
>>>>>>>>>>>>> immutability of
>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
>>>>>> requiring
>>>>>>>>> the
>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> serializable
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
>>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>>> risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable
>>> type
>>>>>>>>>>>>> constraints
>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> kind.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> :-)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias
>>> J.
>>>>>>>> Sax
>>>>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow
>>>> this
>>>>>>>>> path,
>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>> cover
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
>>
>>
--
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Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Guozhang Wang <wa...@gmail.com>.
I'm not particularly concerning that we should NEVER break compatibility;
in fact if we think that is worthwhile (i.e. small impact with large
benefit) I think we can break compatibility as long as we have not removed
the compatibility annotations from Streams. All I was saying is that if we
decided to go this way we need to make sure this is mentioned in the
upgrade guidance.
Regarding the scope I'm still trying to solicit opinions regarding
ReducerWithKey and InitializerWithKey; to me they are not necessarily to be
included.
Guozhang
On Wed, Jun 14, 2017 at 5:22 AM, Jeyhun Karimov <je...@gmail.com>
wrote:
> Hi,
>
> I introduced ValueTransformerCommon just to combine common methods of
> ValueTransformer and ValueTransformerWithKey and avoid copy-paste.
> I am aware of this issue and I agree that this needs users to compile the
> code and therefore is not backwards compatible. When I saw this issue, I
> thought the degree of incompatibility is small (the public APIs are the
> same, users just need to recompile their code), so we can trade more
> maintainable code in this case. I have to comments/solutions:
>
> 1. Basically we can remove ValueTransformerCommon class and return
> ValueTransformer to its original form, which means there will be no issues
> with backwards-compatibility. We just copy and past the methods inside
> ValueTransformerCommon to ValueTransformerWithKey and maybe in future
> releases, we can introduce ValueTransformerCommon.
>
> 2. I have some doubts about Matthias's proposal.
> If we extent withKey interface from original one as you mentioned in
> previous email, then we have to deal with
> ValueTransformer.transform(V value) method. As a result, inside withKey
> interface we will have two transforms. Even if we make it abstract class,
> user still have an access to play with both transform() methods. I think
> this should not be allowed and seems "hacky" to me. Actually this was one
> reason why I created withKey classes independently from original
> interfaces.
>
> Of course, you can correct me if I am wrong.
>
>
> Cheers,
> Jeyhun
>
>
>
> On Tue, Jun 13, 2017 at 7:42 PM Matthias J. Sax <ma...@confluent.io>
> wrote:
>
> > I agree with Guozhang's second point. This change does not seem backward
> > compatible.
> >
> > As we don't have to support lambdas, it might be the easiest thing to
> > just extend the current interface:
> >
> > > public interface ValueTransformerWithKey<K, V, VR> extends
> > ValueTransformer<VR>
> >
> > When plugging the topology together, we can check if we get the
> > `withKey` variant and use a corresponding runtime class for execution,
> > so we get only a single time check. Thus, for the `withKey` variant, the
> > will be a `transfrom(V value)` method, but we will never call it.
> >
> > Maybe we could make `ValueTransformerWithKey` an abstract class with a
> > `final` no-op implemenation of `transform(V value)` ?
> >
> >
> > -Matthias
> >
> >
> > On 6/6/17 4:58 PM, Guozhang Wang wrote:
> > > Jeyhun, Matthias:
> > >
> > > Thanks for the explanation, I overlooked the repartition argument
> > > previously.
> > >
> > > 1) Based on that argument I'm convinced of having ValueMapperWithKey /
> > > ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
> > > convinced with ReducerWithKey and InitializerWithKey since for the
> former
> > > it can be covered with `aggregate` completely and with latter I have
> seen
> > > little use cases with it.
> > >
> > > 2) Another comment is on public interface ValueTransformer<V, VR>
> extends
> > > ValueTransformerCommon<VR>:
> > >
> > > I think changing the interface to extend from a new interface is not
> > binary
> > > compatible though source compatible, i.e. users still need to recompile
> > > their code though no need to make code changes. We may need to mention
> > that
> > > in the upgrade path if we want to keep it that way.
> > >
> > > Guozhang
> > >
> > > On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com>
> > wrote:
> > >
> > >> Hi,
> > >>
> > >>
> > >> Sorry for late reply. Just to make everybody in sync, the current
> > version
> > >> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
> > >> independent, meaning they do not extend from "withoutKey"
> (ValueMapper)
> > >> interfaces.
> > >>
> > >>
> > >> I agree with Guozhang, and I am personally a bit reluctant to increase
> > >> overloaded methods in public APIs but it seems this is only way to
> solve
> > >> all related jira issues.
> > >> However, the most overloaded methods will be with ValueJoiner type,
> > which
> > >> will be with ValueJoinerWithKey with new overloaded methods. Other
> > >> interfaces require mostly 1 extra overload.
> > >>
> > >>
> > >>>> I would suggest not doing it if user pop it up, but rather
> suggesting
> > >> them
> > >>>> to use `map`
> > >>
> > >> I agree with Matthias as the core idea of this KIP was to collect all
> > >> related jira issues and propose one-shot solution for all. Afterwards,
> > we
> > >> broke its scope into 2 KIPs (149 and 159).
> > >>
> > >> Cheers,
> > >> Jeyhun
> > >>
> > >>
> > >>
> > >> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <matthias@confluent.io
> >
> > >> wrote:
> > >>
> > >>> I guess I missunderstood you. Your are right that overloading the
> > method
> > >>> would also work. As both interfaces will be independent from each
> > other,
> > >>> there should be no problem.
> > >>>
> > >>> The initial proposal was to use
> > >>>
> > >>>> interface ValueMapperWithKey extends ValueMapper
> > >>>
> > >>> and this would break Lambda. We totally missed, that we don't need
> new
> > >>> methods but only only overlaods. Great you point this out! I was not
> > >>> quite happy with the newly added methods.
> > >>>
> > >>>>> I would suggest not doing it if user pop it up, but rather
> suggesting
> > >>> them
> > >>>>> to use `map`
> > >>>
> > >>> But this might introduce unnecessary re-partitioning for downstream
> > >>> operators. I don't thinks that a good suggestion. But if we only add
> > new
> > >>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
> > >>> with "overstaffing" the API (what is btw a very valid concern).
> > >>>
> > >>>
> > >>> -Matthias
> > >>>
> > >>>
> > >>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
> > >>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <
> > matthias@confluent.io
> > >>>
> > >>>> wrote:
> > >>>>
> > >>>>> We started with this proposal but it does not allow for Lambdas (in
> > >> case
> > >>>>> you want key access). Do you think preserving Lambdas is not
> > important
> > >>>>> enough for this case -- I agree that there is some price to be paid
> > to
> > >>>>> keep Lambdas.
> > >>>>>
> > >>>>
> > >>>> Not sure if I understand this comment.. My main point is not on
> > >> changing
> > >>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only;
> > and
> > >>>> even if we want to keep them all, I'd suggest we just implement the
> > >> added
> > >>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
> > >> which
> > >>>> seems simpler to me. Does that affect lambda expression usage?
> > >>>>
> > >>>>>
> > >>>>> About API consistency: I can't remember a concrete user request to
> > >> have
> > >>>>> key access in all operators. But I am pretty sure, if we only add
> it
> > >> for
> > >>>>> some, this request will pop up quickly. IMHO, it's better to do it
> > all
> > >>>>> in one shot. (But I am not strict about it if most people think we
> > >>>>> should limit it to what was requested by users.)
> > >>>>>
> > >>>>>
> > >>>> I would suggest not doing it if user pop it up, but rather
> suggesting
> > >>> them
> > >>>> to use `map` etc directly but set the key unchanged rather than
> > >>> providing a
> > >>>> new operator for it. To me some syntax sugars like this seems of
> less
> > >>>> valuable than others (like print / writeAsText / foreach that are
> all
> > >>>> depending on peek), and keeping adding them will just make the DSL
> too
> > >>>> “overstaffed”.
> > >>>>
> > >>>>
> > >>>>>
> > >>>>> -Matthias
> > >>>>>
> > >>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> > >>>>>> With KIP-159, the added "valueMapperWithKey" and
> > >>>>> "valueTransformerWithKey"
> > >>>>>> along seem to be just adding a few syntax-sugars? E.g. we can
> simply
> > >>>>>> implement:
> > >>>>>>
> > >>>>>> mapValues(ValueMapperWithKey mapperWithKey)
> > >>>>>>
> > >>>>>> as
> > >>>>>>
> > >>>>>> map((k, v) -> (k, mapperWithKey(k, v))
> > >>>>>>
> > >>>>>> ----------------------
> > >>>>>>
> > >>>>>> I'm not sure how many users would really need such syntax sugars,
> > and
> > >>>>> even
> > >>>>>> they do, we can support them easily as the above implementations;
> > >>>>>>
> > >>>>>> Similarly for "ReducerWithKey", it can be implemented as
> > >> `Aggregator<K,
> > >>>>> V,
> > >>>>>> V>`, and people who needs key access can just use `aggregate`
> > >> directly.
> > >>>>>>
> > >>>>>> The function which I think is really of valuable is
> > >>> `ValueJoinerWithKey`,
> > >>>>>> and that seems to be the original request from users while others
> > are
> > >>>>>> coming from "API consistency" concerns. Personally I'd prefer only
> > >> keep
> > >>>>> the
> > >>>>>> last one (`InitializerWithKey` might also have some value, but I
> > have
> > >>> not
> > >>>>>> seen people widely requesting it in their DSL usage yet; if there
> is
> > >> a
> > >>>>>> common request we can keep it in this KIP as well). WDYT?
> > >>>>>>
> > >>>>>> Guozhang
> > >>>>>>
> > >>>>>>
> > >>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
> > >> je.karimov@gmail.com
> > >>>>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>>> Thanks for clarification Matthias, now everything is clear.
> > >>>>>>>
> > >>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
> > >>> matthias@confluent.io>
> > >>>>>>> wrote:
> > >>>>>>>
> > >>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
> > >> have
> > >>>>> an
> > >>>>>>>> supplier, you only get a single instance of your function. But
> for
> > >> a
> > >>>>>>>> stateful transformation, we need multiple instances (one for
> each
> > >>> task)
> > >>>>>>>> of ValueTransformer.
> > >>>>>>>>
> > >>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
> > >> because
> > >>>>>>>> those are stateless and thus, we can reuse a single instance
> over
> > >>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
> > >>>>>>> similar).
> > >>>>>>>>
> > >>>>>>>> Btw: This reminds me about KIP-159: with regard to the
> > RichFunction
> > >>> we
> > >>>>>>>> might need a supplier pattern, too. (I'll comment on the other
> > >>> thread,
> > >>>>>>>> too.)
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> -Matthias
> > >>>>>>>>
> > >>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> > >>>>>>>>> Hi,
> > >>>>>>>>>
> > >>>>>>>>> I updated KIP.
> > >>>>>>>>> Just to avoid misunderstanding, I meant deprecating
> > >>>>>>>> ValueTransformerSupplier
> > >>>>>>>>> and I am ok with ValueTransformer.
> > >>>>>>>>> So instead of using ValueTransformerSupplier can't we directly
> > use
> > >>>>>>>>> ValueTransformer
> > >>>>>>>>> or ValueTransformerWithKey?
> > >>>>>>>>>
> > >>>>>>>>> Btw, in current design all features of ValueTransformer will be
> > >>>>>>> available
> > >>>>>>>>> in ValueTransformerWithKey interface.
> > >>>>>>>>>
> > >>>>>>>>> Cheers,
> > >>>>>>>>> Jeyhun
> > >>>>>>>>>
> > >>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> > >>>>> matthias@confluent.io
> > >>>>>>>>
> > >>>>>>>>> wrote:
> > >>>>>>>>>
> > >>>>>>>>>> Thanks Jeyhun.
> > >>>>>>>>>>
> > >>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
> > >>>>>>>>>> ValueTransformer allows to attach a state and also allows to
> > >>> register
> > >>>>>>>>>> punctuations. Both those features will not be available via
> > >>> withKey()
> > >>>>>>>>>> interfaces.
> > >>>>>>>>>>
> > >>>>>>>>>> -Matthias
> > >>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> > >>>>>>>>>>> Hi Matthias,
> > >>>>>>>>>>>
> > >>>>>>>>>>> Thanks for your comments.
> > >>>>>>>>>>>
> > >>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
> > >>>>>>>> Especially
> > >>>>>>>>>>> for "light" and stateless operators it slows down the
> topology
> > >>>>>>>>>>> significantly (> 20% ). I think "warning" users about
> > >>> not-changing
> > >>>>>>> the
> > >>>>>>>>>> key
> > >>>>>>>>>>> is better warning them about possible performance loss.
> > >>>>>>>>>>>
> > >>>>>>>>>>> About the interfaces, additionally I considered adding
> > >>>>>>>>>> InitializerWithKey,
> > >>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they
> are
> > >>>>>>>> included
> > >>>>>>>>>> in
> > >>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
> > >> bad.
> > >>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> > >>>>>>>>>>>
> > >>>>>>>>>>> One thing I want to mention is that, maybe we should
> deprecate
> > >>>>>>> methods
> > >>>>>>>>>> with
> > >>>>>>>>>>> argument type ValueTransformerSupplier
> > >>>>> (KStream.transformValues(...))
> > >>>>>>>> and
> > >>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
> > >>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
> > >> instead
> > >>>>>>>> without
> > >>>>>>>>>>> additional supplier layer.
> > >>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>> Cheers,
> > >>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> > >>>>>>> matthias@confluent.io
> > >>>>>>>>>
> > >>>>>>>>>>> wrote:
> > >>>>>>>>>>>
> > >>>>>>>>>>>> One more question:
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Should we add any of
> > >>>>>>>>>>>> - InitizialierWithKey
> > >>>>>>>>>>>> - ReducerWithKey
> > >>>>>>>>>>>> - ValueTransformerWithKey
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
> > >>>>>>> thoughts?
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> > >>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
> > >> idea
> > >>>>> we
> > >>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
> > >>>>> functions
> > >>>>>>>>>> into
> > >>>>>>>>>>>>>> this KIP.
> > >>>>>>>>>>>>>> I think once we include rich functions in this KIP and
> then
> > >> fix
> > >>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with
> > existing
> > >>>>> rich
> > >>>>>>>>>>>>>> functions, the code will not be backwards compatible.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> I see Damian's and your point more clearly now.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP
> > (I
> > >>>>>>>> updated
> > >>>>>>>>>>>> the
> > >>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
> > >> functions.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> > >>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
> > >> ValueMapperWithKey
> > >>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent
> add-on.
> > >> To
> > >>>>>>> fix
> > >>>>>>>>>> the
> > >>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
> > >>>>>>> required
> > >>>>>>>>>>>> IMHO.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> I initially put the RichFunction idea on the table,
> because
> > >> I
> > >>>>> was
> > >>>>>>>>>>>> hoping
> > >>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to
> consider
> > >>> them
> > >>>>>>> --
> > >>>>>>>>>>>>>>> however, the discussion showed that they are not
> necessary
> > >> for
> > >>>>>>> key
> > >>>>>>>>>>>>>>> access. Thus, it seems to be better to handle
> RichFunctions
> > >> in
> > >>>>> an
> > >>>>>>>> own
> > >>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to
> be
> > a
> > >>>>> main
> > >>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
> > >>>>>>>> parameter-less
> > >>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
> > >>>>>>>>>>>> "intermediate"
> > >>>>>>>>>>>>>>> API that we want to change anyway later on...
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel
> free
> > >> do
> > >>>>>>> push
> > >>>>>>>>>>>> this
> > >>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
> > >> parallel)
> > >>> --
> > >>>>>>> we
> > >>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
> > >> and
> > >>>>>>> code
> > >>>>>>>>>>>>>>> review easier, if we separate both IMHO.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>> Hi Damian,
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
> > >>>>> *interface*
> > >>>>>>>>>>>> rather
> > >>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
> > >>> raised
> > >>>>>>>> this
> > >>>>>>>>>>>>>>> issue
> > >>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> Regarding with passing additional contextual
> information,
> > I
> > >>>>>>> think
> > >>>>>>>> it
> > >>>>>>>>>>>> is a
> > >>>>>>>>>>>>>>>> tradeoff,
> > >>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init()
> *method
> > >> in
> > >>>>>>>>>> another
> > >>>>>>>>>>>> PR
> > >>>>>>>>>>>>>>>> and solve Rich functions afterwards
> > >>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3])
> with
> > >>>>>>>> providing
> > >>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
> > >>>>>>> parameters
> > >>>>>>>>>> to
> > >>>>>>>>>>>>>>> this
> > >>>>>>>>>>>>>>>> afterwards (like improvement)
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> To me, the second approach seems more incremental.
> However
> > >>> you
> > >>>>>>> are
> > >>>>>>>>>>>> right,
> > >>>>>>>>>>>>>>>> the names might confuse the users.
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> > >>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> > >>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> > >>>>>>> damian.guy@gmail.com
> > >>>>>>>>>
> > >>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> > >>>>>>> RichFunction
> > >>>>>>>>>>>> which
> > >>>>>>>>>>>>>>> is
> > >>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected
> > it
> > >>> to
> > >>>>>>>> pass
> > >>>>>>>>>>>> some
> > >>>>>>>>>>>>>>>>> additional contextual information, i.e., the
> > >> `RecordContext`
> > >>>>>>> that
> > >>>>>>>>>>>>>>> contains
> > >>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok
> > with
> > >>> it
> > >>>>>>> not
> > >>>>>>>>>>>>>>> passing
> > >>>>>>>>>>>>>>>>> this contextual information, but is the naming
> incorrect?
> > >>> I'm
> > >>>>>>> not
> > >>>>>>>>>>>> sure,
> > >>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions`
> > until
> > >>> we
> > >>>>>>> can
> > >>>>>>>>>> do
> > >>>>>>>>>>>> it
> > >>>>>>>>>>>>>>>>> properly with the correct context?
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Also, i don't like the abstract classes:
> RichValueMapper,
> > >>>>>>>>>>>>>>> RichValueJoiner,
> > >>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
> > >> interfaces?
> > >>>>>>>>>>>> Generally we
> > >>>>>>>>>>>>>>>>> should provide users with Intefaces to code against,
> not
> > >>>>>>> classes.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Thanks,
> > >>>>>>>>>>>>>>>>> Damian
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> > >>>>>>>> je.karimov@gmail.com>
> > >>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
> > >>> overview.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
> > >>>>>>> interface
> > >>>>>>>>>> for
> > >>>>>>>>>>>>>>> Rich
> > >>>>>>>>>>>>>>>>>> functions is that in future if we will have some
> > >>>>>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>>>>> abstract classes,
> > >>>>>>>>>>>>>>>>>> we can easily extend:
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
> > >> implements
> > >>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> > >>>>>>>>>>>>>>>>> AbstractRichFunction*{
> > >>>>>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
> > >>>>>>>>>> inheritance.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> However, I think we can easily change it (from
> abstract
> > >>> class
> > >>>>>>> ->
> > >>>>>>>>>>>>>>>>> interface)
> > >>>>>>>>>>>>>>>>>> if you think interface is a better fit.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> > >>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is
> > quite
> > >>>>>>>> improved
> > >>>>>>>>>>>> now
> > >>>>>>>>>>>>>>>>> --
> > >>>>>>>>>>>>>>>>>>> great job!
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc
> abstract
> > >>>>>>> classes
> > >>>>>>>>>> and
> > >>>>>>>>>>>>>>> not
> > >>>>>>>>>>>>>>>>>>> interfaces?
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Thanks for your comments.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>>>>>>>>>> `AbstractRichFunction`
> > >>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
> for
> > >>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>> AFAIK.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> > >>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
> > >> they
> > >>>>>>>> don't
> > >>>>>>>>>>>> have
> > >>>>>>>>>>>>>>>>>>> direct
> > >>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> > >>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have
> only
> > >>> one
> > >>>>>>>>>>>> method ,
> > >>>>>>>>>>>>>>>>> so
> > >>>>>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>> can use lambdas.
> > >>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
> > >>> Inside
> > >>>>>>>> Rich
> > >>>>>>>>>>>>>>>>>>> functions.
> > >>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
> > >>> *withKey*
> > >>>>>>> and
> > >>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) .
> We
> > >> get
> > >>>>>>>> those
> > >>>>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
> > >> topology,
> > >>>>> and
> > >>>>>>>>>> send
> > >>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>> Processor.
> > >>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
> > >> implement
> > >>>>>>>>>>>> *withKey*
> > >>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by
> definition.
> > >> In
> > >>>>>>> this
> > >>>>>>>>>>>> case,
> > >>>>>>>>>>>>>>>>>> while
> > >>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the
> object
> > >>> type
> > >>>>>>> is
> > >>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar
> for
> > >>> Rich
> > >>>>>>>>>>>> functions
> > >>>>>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
> we
> > >>> need
> > >>>>>>> to
> > >>>>>>>>>>>> have a
> > >>>>>>>>>>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> > >>>>>>> RichFunction
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
> > >>> *withKey*
> > >>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>> as
> > >>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
> > >> remove
> > >>>>> the
> > >>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> > >> sufficient
> > >>> to
> > >>>>>>>>>>>> support
> > >>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> > >>>>> "extended
> > >>>>>>>>>> API".
> > >>>>>>>>>>>>>>>>> For
> > >>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>>>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
> idea
> > >> of
> > >>>>>>> more
> > >>>>>>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> > >> much
> > >>>>>>>>>> because
> > >>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>> have
> > >>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
> > see
> > >>>>>>> value
> > >>>>>>>> in
> > >>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only
> one
> > >>> extra
> > >>>>>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
> > >> *withKey*
> > >>>>>>>>>> version
> > >>>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>>>>> particular interface.
> > >>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as
> Rich
> > >>>>>>>> function
> > >>>>>>>>>>>>>>>>>>> implements
> > >>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type.
> > We
> > >>>>>>>>>>>> differentiate
> > >>>>>>>>>>>>>>>>>>> them
> > >>>>>>>>>>>>>>>>>>>> while building the topology.
> > >>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of
> the
> > >>>>>>>> comment:
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but
> can
> > >> we
> > >>>>>>> have
> > >>>>>>>> a
> > >>>>>>>>>>>>>>>>> design
> > >>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas,
> > it
> > >>>>>>> might
> > >>>>>>>>>> make
> > >>>>>>>>>>>>>>>>>> sense
> > >>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV`
> ?
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
> > >> overall
> > >>>>>>>> design
> > >>>>>>>>>>>>>>>>>>>> significantly.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> > >> sense
> > >>>>> to
> > >>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> > >> thus,
> > >>>>>>> this
> > >>>>>>>>>>>> also
> > >>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
> KIP"
> > >>>>>>> before
> > >>>>>>>>>>>> driving
> > >>>>>>>>>>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
> > >>>>>>> functions
> > >>>>>>>>>> as I
> > >>>>>>>>>>>>>>>>>> don't
> > >>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
> > >> library.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> > >>>>>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> thanks for the update.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>>>>>>>>>> `AbstractRichFunction`
> > >>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported
> for
> > >>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>> AFAIK.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`,
> we
> > >>> need
> > >>>>>>> to
> > >>>>>>>>>>>> have a
> > >>>>>>>>>>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> > >>>>>>> RichFunction
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not
> make
> > >>>>> sense
> > >>>>>>>>>>>> anymore,
> > >>>>>>>>>>>>>>>>>> as
> > >>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> > >>>>>>>>>>>> implementation of
> > >>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
> > >> would
> > >>>>>>>>>>>> implement a
> > >>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> > >> sufficient
> > >>>>> to
> > >>>>>>>>>>>> support
> > >>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> > >>>>> "extended
> > >>>>>>>>>> API".
> > >>>>>>>>>>>>>>>>> For
> > >>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>>>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the
> idea
> > >> of
> > >>>>>>> more
> > >>>>>>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> > >> much
> > >>>>>>>>>> because
> > >>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>> have
> > >>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
> > see
> > >>>>>>> value
> > >>>>>>>> in
> > >>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> > >>> sense
> > >>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> > >> thus,
> > >>>>>>> this
> > >>>>>>>>>>>> also
> > >>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext
> KIP"
> > >>>>>>> before
> > >>>>>>>>>>>> driving
> > >>>>>>>>>>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> Thoughts?
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
> > >>> comments.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> > >>> little
> > >>>>>>>>>> bit? I
> > >>>>>>>>>>>>>>>>>> cannot
> > >>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> > >>>>> problem
> > >>>>>>>> is.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
> > >> interface
> > >>>>>>> that
> > >>>>>>>>>> has
> > >>>>>>>>>>>>>>>>> just
> > >>>>>>>>>>>>>>>>>>> one
> > >>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
> > >> function
> > >>>>>>>>>>>> contract".
> > >>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
> > >> another
> > >>>>>>> (in
> > >>>>>>>>>> our
> > >>>>>>>>>>>>>>>>> case,
> > >>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
> > >>>>> lambdas
> > >>>>>>>> in
> > >>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>> extended
> > >>>>>>>>>>>>>>>>>>>>>> interface.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> > >> maybe
> > >>>>>>>>>> reformat
> > >>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
> would
> > >>> help.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> > >>>>>>> overlaods
> > >>>>>>>>>>>> added
> > >>>>>>>>>>>>>>>>>> for
> > >>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
> need
> > >> to
> > >>>>>>> add
> > >>>>>>>>>> any
> > >>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
> > >> public
> > >>>>>>> APIs
> > >>>>>>>>>> to
> > >>>>>>>>>>>> be
> > >>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
> > >>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has
> similar
> > >>>>>>>> structure:
> > >>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>>> overload
> > >>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> > >>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor
> > and
> > >>>>>>> inside
> > >>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>> processor
> > >>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich
> > function.
> > >>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
> > >> overall
> > >>>>>>> idea
> > >>>>>>>>>> with
> > >>>>>>>>>>>>>>>>> only
> > >>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
> > >>> changes.
> > >>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext
> p)*
> > >>> and*
> > >>>>>>>>>>>> close()*
> > >>>>>>>>>>>>>>>>>>>>> methods
> > >>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>>>>>>>>>> void close () {}
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
> > >>>>>>>>>>>> *AbstractRichFunction*
> > >>>>>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
> > >> *AbstractRichFunction*.
> > >>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and
> > ease
> > >>> the
> > >>>>>>>>>>>>>>>>>> maintenance.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> ForeachAction,
> > >>>>>>> Merger,
> > >>>>>>>>>>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
> add
> > >> to
> > >>>>>>> all,
> > >>>>>>>>>> but
> > >>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> > sense
> > >>>>>>> (e.g.,
> > >>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
> > >> applies
> > >>>>> to
> > >>>>>>>> all
> > >>>>>>>>>>>> this
> > >>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP,
> > just
> > >>>>>>> wanted
> > >>>>>>>>>> to
> > >>>>>>>>>>>>>>>>> give
> > >>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>> overall intuition.
> > >>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> > >> `ValueXXWithKey`
> > >>>>> --
> > >>>>>>>>>>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> > >>>>>>> interfaces
> > >>>>>>>>>>>> only?
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we
> should
> > >>> not
> > >>>>>>>> force
> > >>>>>>>>>>>>>>>>> users
> > >>>>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> > >>>>> functions
> > >>>>>>>>>> every
> > >>>>>>>>>>>>>>>>> time
> > >>>>>>>>>>>>>>>>>>>>> they
> > >>>>>>>>>>>>>>>>>>>>>> use Rich functions.
> > >>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
> > >> methods.
> > >>>>>>>>>> However,
> > >>>>>>>>>>>> I
> > >>>>>>>>>>>>>>>>> am
> > >>>>>>>>>>>>>>>>>>> open
> > >>>>>>>>>>>>>>>>>>>>>> for discussion.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> > >>> spread
> > >>>>>>> any
> > >>>>>>>>>>>>>>>>> further
> > >>>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
> that
> > >> is
> > >>>>>>> done
> > >>>>>>>>>>>> before
> > >>>>>>>>>>>>>>>>>>> this?
> > >>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
> becoming
> > >>> too
> > >>>>>>>>>> large.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
> > >>>>>>>> *init(ProcessorContext)*
> > >>>>>>>>>>>>>>>>> method
> > >>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
> > >>> ProcessorContext
> > >>>>>>> as
> > >>>>>>>> an
> > >>>>>>>>>>>>>>>>>> input),
> > >>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> > >>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
> > >> @mjsax
> > >>>>>>>>>>>> mentioned)
> > >>>>>>>>>>>>>>>>>>> whether
> > >>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an
> access
> > >> to
> > >>>>>>>>>>>>>>>>>>> *ProcessorContext*
> > >>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* )
> or
> > >>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> > >>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> > >>>>>>>>>>>> damian.guy@gmail.com>
> > >>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> > >>> spread
> > >>>>>>>> any
> > >>>>>>>>>>>>>>>>> further
> > >>>>>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP
> that
> > >> is
> > >>>>>>> done
> > >>>>>>>>>>>> before
> > >>>>>>>>>>>>>>>>>>> this?
> > >>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is
> becoming
> > >>> too
> > >>>>>>>>>> large.
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> > >>>>>>>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface
> is
> > >> too
> > >>>>>>>> broad
> > >>>>>>>>>> in
> > >>>>>>>>>>>>>>>>>>> general
> > >>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
> > >> it's
> > >>>>>>> also
> > >>>>>>>>>>>>>>>>> reflected
> > >>>>>>>>>>>>>>>>>>> in
> > >>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> > confluence/display/KAFKA/
> > >>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
> > >> `RichFunction`
> > >>>>>>>>>>>> approach in
> > >>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
> > >> scope
> > >>>>> of
> > >>>>>>>>>> this
> > >>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP
> for
> > >> it
> > >>>>>>> and
> > >>>>>>>>>>>> delay
> > >>>>>>>>>>>>>>>>>> this
> > >>>>>>>>>>>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction`
> approach.
> > >> Do
> > >>>>> we
> > >>>>>>>>>>>> really
> > >>>>>>>>>>>>>>>>>> want
> > >>>>>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>>>>> give
> > >>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the
> `ProcessorContext`
> > >> ?
> > >>> It
> > >>>>>>>> has
> > >>>>>>>>>> a
> > >>>>>>>>>>>>>>>>> bunch
> > >>>>>>>>>>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some
> > of
> > >>> the
> > >>>>>>>> DSL
> > >>>>>>>>>>>>>>>>>> methods,
> > >>>>>>>>>>>>>>>>>>>>>>> i.e,
> > >>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`,
> > `schedule`
> > >>>>> etc.
> > >>>>>>>> It
> > >>>>>>>>>> is
> > >>>>>>>>>>>>>>>>> far
> > >>>>>>>>>>>>>>>>>>> too
> > >>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
> > >> narrower
> > >>>>>>>>>>>> interface
> > >>>>>>>>>>>>>>>>>> like
> > >>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to
> > add
> > >>>>>>>>>>>>>>>>>>> methods/interfaces
> > >>>>>>>>>>>>>>>>>>>>>>>> later
> > >>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> > >>>>>>>>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you
> elaborate
> > >> a
> > >>>>>>>> little
> > >>>>>>>>>>>> bit?
> > >>>>>>>>>>>>>>>>> I
> > >>>>>>>>>>>>>>>>>>>>>>> cannot
> > >>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what
> > the
> > >>>>>>>> problem
> > >>>>>>>>>>>> is.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know --
> guess
> > >>> it's
> > >>>>>>> up
> > >>>>>>>>>> to
> > >>>>>>>>>>>>>>>>> you.
> > >>>>>>>>>>>>>>>>>>>>>>> Maybe a
> > >>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can
> you
> > >>> maybe
> > >>>>>>>>>>>> reformat
> > >>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
> > >> would
> > >>>>>>> help.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
> > >> have
> > >>>>>>>>>> overlaods
> > >>>>>>>>>>>>>>>>>> added
> > >>>>>>>>>>>>>>>>>>>>> for
> > >>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
> > >> need
> > >>>>> to
> > >>>>>>>> add
> > >>>>>>>>>>>> any
> > >>>>>>>>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> > >>> ForeachAction,
> > >>>>>>>>>> Merger,
> > >>>>>>>>>>>>>>>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
> > >> add
> > >>> to
> > >>>>>>>> all,
> > >>>>>>>>>>>> but
> > >>>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> > >>> sense
> > >>>>>>>>>> (e.g.,
> > >>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> > >>>>>>> `ValueXXWithKey`
> > >>>>>>>> --
> > >>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this
> with
> > >>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>> only?
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
> > >> extend
> > >>>>>>> the
> > >>>>>>>>>> two
> > >>>>>>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>>>>>>>> if
> > >>>>>>>>>>>>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
> > >>> Maybe I
> > >>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>> change
> > >>>>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the
> KIP
> > >> to
> > >>>>>>> only
> > >>>>>>>>>>>>>>>>>>> ValueMapper,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> > >>> confluence/display/KAFKA/KIP-
> > >>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+
> ValueTransformer%2C+
> > >>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J.
> Sax
> > <
> > >>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends
> `ValueMapper`
> > >> we
> > >>>>>>> don't
> > >>>>>>>>>>>> need
> > >>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
> > >>>>> happens
> > >>>>>>>>>> when
> > >>>>>>>>>>>>>>>>>>> building
> > >>>>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> > >>>>>>> KafkaStream#start()
> > >>>>>>>>>> we
> > >>>>>>>>>>>>>>>>> don't
> > >>>>>>>>>>>>>>>>>>>>> need
> > >>>>>>>>>>>>>>>>>>>>>>>> any
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
> > >> `ValueMapperWithKey`)
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> mapValues(ValueMapper<?
> > >>>>> super
> > >>>>>>>> V,
> > >>>>>>>>>> ?
> > >>>>>>>>>>>>>>>>>> extends
> > >>>>>>>>>>>>>>>>>>>>>>> VR>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> > >>>>>>> mapValues(ValueMapperWithKey<?
> > >>>>>>>>>>>> super
> > >>>>>>>>>>>>>>>>> V,
> > >>>>>>>>>>>>>>>>>> ?
> > >>>>>>>>>>>>>>>>>>>>>>>> extends
> > >>>>>>>>>>>>>>>
>
--
-- Guozhang
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Jeyhun Karimov <je...@gmail.com>.
Hi,
I introduced ValueTransformerCommon just to combine common methods of
ValueTransformer and ValueTransformerWithKey and avoid copy-paste.
I am aware of this issue and I agree that this needs users to compile the
code and therefore is not backwards compatible. When I saw this issue, I
thought the degree of incompatibility is small (the public APIs are the
same, users just need to recompile their code), so we can trade more
maintainable code in this case. I have to comments/solutions:
1. Basically we can remove ValueTransformerCommon class and return
ValueTransformer to its original form, which means there will be no issues
with backwards-compatibility. We just copy and past the methods inside
ValueTransformerCommon to ValueTransformerWithKey and maybe in future
releases, we can introduce ValueTransformerCommon.
2. I have some doubts about Matthias's proposal.
If we extent withKey interface from original one as you mentioned in
previous email, then we have to deal with
ValueTransformer.transform(V value) method. As a result, inside withKey
interface we will have two transforms. Even if we make it abstract class,
user still have an access to play with both transform() methods. I think
this should not be allowed and seems "hacky" to me. Actually this was one
reason why I created withKey classes independently from original
interfaces.
Of course, you can correct me if I am wrong.
Cheers,
Jeyhun
On Tue, Jun 13, 2017 at 7:42 PM Matthias J. Sax <ma...@confluent.io>
wrote:
> I agree with Guozhang's second point. This change does not seem backward
> compatible.
>
> As we don't have to support lambdas, it might be the easiest thing to
> just extend the current interface:
>
> > public interface ValueTransformerWithKey<K, V, VR> extends
> ValueTransformer<VR>
>
> When plugging the topology together, we can check if we get the
> `withKey` variant and use a corresponding runtime class for execution,
> so we get only a single time check. Thus, for the `withKey` variant, the
> will be a `transfrom(V value)` method, but we will never call it.
>
> Maybe we could make `ValueTransformerWithKey` an abstract class with a
> `final` no-op implemenation of `transform(V value)` ?
>
>
> -Matthias
>
>
> On 6/6/17 4:58 PM, Guozhang Wang wrote:
> > Jeyhun, Matthias:
> >
> > Thanks for the explanation, I overlooked the repartition argument
> > previously.
> >
> > 1) Based on that argument I'm convinced of having ValueMapperWithKey /
> > ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
> > convinced with ReducerWithKey and InitializerWithKey since for the former
> > it can be covered with `aggregate` completely and with latter I have seen
> > little use cases with it.
> >
> > 2) Another comment is on public interface ValueTransformer<V, VR> extends
> > ValueTransformerCommon<VR>:
> >
> > I think changing the interface to extend from a new interface is not
> binary
> > compatible though source compatible, i.e. users still need to recompile
> > their code though no need to make code changes. We may need to mention
> that
> > in the upgrade path if we want to keep it that way.
> >
> > Guozhang
> >
> > On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com>
> wrote:
> >
> >> Hi,
> >>
> >>
> >> Sorry for late reply. Just to make everybody in sync, the current
> version
> >> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
> >> independent, meaning they do not extend from "withoutKey" (ValueMapper)
> >> interfaces.
> >>
> >>
> >> I agree with Guozhang, and I am personally a bit reluctant to increase
> >> overloaded methods in public APIs but it seems this is only way to solve
> >> all related jira issues.
> >> However, the most overloaded methods will be with ValueJoiner type,
> which
> >> will be with ValueJoinerWithKey with new overloaded methods. Other
> >> interfaces require mostly 1 extra overload.
> >>
> >>
> >>>> I would suggest not doing it if user pop it up, but rather suggesting
> >> them
> >>>> to use `map`
> >>
> >> I agree with Matthias as the core idea of this KIP was to collect all
> >> related jira issues and propose one-shot solution for all. Afterwards,
> we
> >> broke its scope into 2 KIPs (149 and 159).
> >>
> >> Cheers,
> >> Jeyhun
> >>
> >>
> >>
> >> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <ma...@confluent.io>
> >> wrote:
> >>
> >>> I guess I missunderstood you. Your are right that overloading the
> method
> >>> would also work. As both interfaces will be independent from each
> other,
> >>> there should be no problem.
> >>>
> >>> The initial proposal was to use
> >>>
> >>>> interface ValueMapperWithKey extends ValueMapper
> >>>
> >>> and this would break Lambda. We totally missed, that we don't need new
> >>> methods but only only overlaods. Great you point this out! I was not
> >>> quite happy with the newly added methods.
> >>>
> >>>>> I would suggest not doing it if user pop it up, but rather suggesting
> >>> them
> >>>>> to use `map`
> >>>
> >>> But this might introduce unnecessary re-partitioning for downstream
> >>> operators. I don't thinks that a good suggestion. But if we only add
> new
> >>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
> >>> with "overstaffing" the API (what is btw a very valid concern).
> >>>
> >>>
> >>> -Matthias
> >>>
> >>>
> >>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
> >>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <
> matthias@confluent.io
> >>>
> >>>> wrote:
> >>>>
> >>>>> We started with this proposal but it does not allow for Lambdas (in
> >> case
> >>>>> you want key access). Do you think preserving Lambdas is not
> important
> >>>>> enough for this case -- I agree that there is some price to be paid
> to
> >>>>> keep Lambdas.
> >>>>>
> >>>>
> >>>> Not sure if I understand this comment.. My main point is not on
> >> changing
> >>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only;
> and
> >>>> even if we want to keep them all, I'd suggest we just implement the
> >> added
> >>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
> >> which
> >>>> seems simpler to me. Does that affect lambda expression usage?
> >>>>
> >>>>>
> >>>>> About API consistency: I can't remember a concrete user request to
> >> have
> >>>>> key access in all operators. But I am pretty sure, if we only add it
> >> for
> >>>>> some, this request will pop up quickly. IMHO, it's better to do it
> all
> >>>>> in one shot. (But I am not strict about it if most people think we
> >>>>> should limit it to what was requested by users.)
> >>>>>
> >>>>>
> >>>> I would suggest not doing it if user pop it up, but rather suggesting
> >>> them
> >>>> to use `map` etc directly but set the key unchanged rather than
> >>> providing a
> >>>> new operator for it. To me some syntax sugars like this seems of less
> >>>> valuable than others (like print / writeAsText / foreach that are all
> >>>> depending on peek), and keeping adding them will just make the DSL too
> >>>> “overstaffed”.
> >>>>
> >>>>
> >>>>>
> >>>>> -Matthias
> >>>>>
> >>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> >>>>>> With KIP-159, the added "valueMapperWithKey" and
> >>>>> "valueTransformerWithKey"
> >>>>>> along seem to be just adding a few syntax-sugars? E.g. we can simply
> >>>>>> implement:
> >>>>>>
> >>>>>> mapValues(ValueMapperWithKey mapperWithKey)
> >>>>>>
> >>>>>> as
> >>>>>>
> >>>>>> map((k, v) -> (k, mapperWithKey(k, v))
> >>>>>>
> >>>>>> ----------------------
> >>>>>>
> >>>>>> I'm not sure how many users would really need such syntax sugars,
> and
> >>>>> even
> >>>>>> they do, we can support them easily as the above implementations;
> >>>>>>
> >>>>>> Similarly for "ReducerWithKey", it can be implemented as
> >> `Aggregator<K,
> >>>>> V,
> >>>>>> V>`, and people who needs key access can just use `aggregate`
> >> directly.
> >>>>>>
> >>>>>> The function which I think is really of valuable is
> >>> `ValueJoinerWithKey`,
> >>>>>> and that seems to be the original request from users while others
> are
> >>>>>> coming from "API consistency" concerns. Personally I'd prefer only
> >> keep
> >>>>> the
> >>>>>> last one (`InitializerWithKey` might also have some value, but I
> have
> >>> not
> >>>>>> seen people widely requesting it in their DSL usage yet; if there is
> >> a
> >>>>>> common request we can keep it in this KIP as well). WDYT?
> >>>>>>
> >>>>>> Guozhang
> >>>>>>
> >>>>>>
> >>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
> >> je.karimov@gmail.com
> >>>>
> >>>>>> wrote:
> >>>>>>
> >>>>>>> Thanks for clarification Matthias, now everything is clear.
> >>>>>>>
> >>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
> >>> matthias@confluent.io>
> >>>>>>> wrote:
> >>>>>>>
> >>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
> >> have
> >>>>> an
> >>>>>>>> supplier, you only get a single instance of your function. But for
> >> a
> >>>>>>>> stateful transformation, we need multiple instances (one for each
> >>> task)
> >>>>>>>> of ValueTransformer.
> >>>>>>>>
> >>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
> >> because
> >>>>>>>> those are stateless and thus, we can reuse a single instance over
> >>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
> >>>>>>> similar).
> >>>>>>>>
> >>>>>>>> Btw: This reminds me about KIP-159: with regard to the
> RichFunction
> >>> we
> >>>>>>>> might need a supplier pattern, too. (I'll comment on the other
> >>> thread,
> >>>>>>>> too.)
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> -Matthias
> >>>>>>>>
> >>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> >>>>>>>>> Hi,
> >>>>>>>>>
> >>>>>>>>> I updated KIP.
> >>>>>>>>> Just to avoid misunderstanding, I meant deprecating
> >>>>>>>> ValueTransformerSupplier
> >>>>>>>>> and I am ok with ValueTransformer.
> >>>>>>>>> So instead of using ValueTransformerSupplier can't we directly
> use
> >>>>>>>>> ValueTransformer
> >>>>>>>>> or ValueTransformerWithKey?
> >>>>>>>>>
> >>>>>>>>> Btw, in current design all features of ValueTransformer will be
> >>>>>>> available
> >>>>>>>>> in ValueTransformerWithKey interface.
> >>>>>>>>>
> >>>>>>>>> Cheers,
> >>>>>>>>> Jeyhun
> >>>>>>>>>
> >>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> >>>>> matthias@confluent.io
> >>>>>>>>
> >>>>>>>>> wrote:
> >>>>>>>>>
> >>>>>>>>>> Thanks Jeyhun.
> >>>>>>>>>>
> >>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
> >>>>>>>>>> ValueTransformer allows to attach a state and also allows to
> >>> register
> >>>>>>>>>> punctuations. Both those features will not be available via
> >>> withKey()
> >>>>>>>>>> interfaces.
> >>>>>>>>>>
> >>>>>>>>>> -Matthias
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> >>>>>>>>>>> Hi Matthias,
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>
> >>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
> >>>>>>>> Especially
> >>>>>>>>>>> for "light" and stateless operators it slows down the topology
> >>>>>>>>>>> significantly (> 20% ). I think "warning" users about
> >>> not-changing
> >>>>>>> the
> >>>>>>>>>> key
> >>>>>>>>>>> is better warning them about possible performance loss.
> >>>>>>>>>>>
> >>>>>>>>>>> About the interfaces, additionally I considered adding
> >>>>>>>>>> InitializerWithKey,
> >>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
> >>>>>>>> included
> >>>>>>>>>> in
> >>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
> >> bad.
> >>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> >>>>>>>>>>>
> >>>>>>>>>>> One thing I want to mention is that, maybe we should deprecate
> >>>>>>> methods
> >>>>>>>>>> with
> >>>>>>>>>>> argument type ValueTransformerSupplier
> >>>>> (KStream.transformValues(...))
> >>>>>>>> and
> >>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
> >>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
> >> instead
> >>>>>>>> without
> >>>>>>>>>>> additional supplier layer.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> Cheers,
> >>>>>>>>>>> Jeyhun
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> >>>>>>> matthias@confluent.io
> >>>>>>>>>
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> One more question:
> >>>>>>>>>>>>
> >>>>>>>>>>>> Should we add any of
> >>>>>>>>>>>> - InitizialierWithKey
> >>>>>>>>>>>> - ReducerWithKey
> >>>>>>>>>>>> - ValueTransformerWithKey
> >>>>>>>>>>>>
> >>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
> >>>>>>> thoughts?
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> >>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
> >> idea
> >>>>> we
> >>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
> >>>>> functions
> >>>>>>>>>> into
> >>>>>>>>>>>>>> this KIP.
> >>>>>>>>>>>>>> I think once we include rich functions in this KIP and then
> >> fix
> >>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with
> existing
> >>>>> rich
> >>>>>>>>>>>>>> functions, the code will not be backwards compatible.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> I see Damian's and your point more clearly now.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP
> (I
> >>>>>>>> updated
> >>>>>>>>>>>> the
> >>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
> >> functions.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> >>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
> >> ValueMapperWithKey
> >>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on.
> >> To
> >>>>>>> fix
> >>>>>>>>>> the
> >>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
> >>>>>>> required
> >>>>>>>>>>>> IMHO.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> I initially put the RichFunction idea on the table, because
> >> I
> >>>>> was
> >>>>>>>>>>>> hoping
> >>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to consider
> >>> them
> >>>>>>> --
> >>>>>>>>>>>>>>> however, the discussion showed that they are not necessary
> >> for
> >>>>>>> key
> >>>>>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions
> >> in
> >>>>> an
> >>>>>>>> own
> >>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be
> a
> >>>>> main
> >>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
> >>>>>>>> parameter-less
> >>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
> >>>>>>>>>>>> "intermediate"
> >>>>>>>>>>>>>>> API that we want to change anyway later on...
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel free
> >> do
> >>>>>>> push
> >>>>>>>>>>>> this
> >>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
> >> parallel)
> >>> --
> >>>>>>> we
> >>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
> >> and
> >>>>>>> code
> >>>>>>>>>>>>>>> review easier, if we separate both IMHO.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>> Hi Damian,
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
> >>>>> *interface*
> >>>>>>>>>>>> rather
> >>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
> >>> raised
> >>>>>>>> this
> >>>>>>>>>>>>>>> issue
> >>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Regarding with passing additional contextual information,
> I
> >>>>>>> think
> >>>>>>>> it
> >>>>>>>>>>>> is a
> >>>>>>>>>>>>>>>> tradeoff,
> >>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method
> >> in
> >>>>>>>>>> another
> >>>>>>>>>>>> PR
> >>>>>>>>>>>>>>>> and solve Rich functions afterwards
> >>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
> >>>>>>>> providing
> >>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
> >>>>>>> parameters
> >>>>>>>>>> to
> >>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>> afterwards (like improvement)
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> To me, the second approach seems more incremental. However
> >>> you
> >>>>>>> are
> >>>>>>>>>>>> right,
> >>>>>>>>>>>>>>>> the names might confuse the users.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> >>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> >>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> >>>>>>> damian.guy@gmail.com
> >>>>>>>>>
> >>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> >>>>>>> RichFunction
> >>>>>>>>>>>> which
> >>>>>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected
> it
> >>> to
> >>>>>>>> pass
> >>>>>>>>>>>> some
> >>>>>>>>>>>>>>>>> additional contextual information, i.e., the
> >> `RecordContext`
> >>>>>>> that
> >>>>>>>>>>>>>>> contains
> >>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok
> with
> >>> it
> >>>>>>> not
> >>>>>>>>>>>>>>> passing
> >>>>>>>>>>>>>>>>> this contextual information, but is the naming incorrect?
> >>> I'm
> >>>>>>> not
> >>>>>>>>>>>> sure,
> >>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions`
> until
> >>> we
> >>>>>>> can
> >>>>>>>>>> do
> >>>>>>>>>>>> it
> >>>>>>>>>>>>>>>>> properly with the correct context?
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
> >>>>>>>>>>>>>>> RichValueJoiner,
> >>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
> >> interfaces?
> >>>>>>>>>>>> Generally we
> >>>>>>>>>>>>>>>>> should provide users with Intefaces to code against, not
> >>>>>>> classes.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Thanks,
> >>>>>>>>>>>>>>>>> Damian
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> >>>>>>>> je.karimov@gmail.com>
> >>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
> >>> overview.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
> >>>>>>> interface
> >>>>>>>>>> for
> >>>>>>>>>>>>>>> Rich
> >>>>>>>>>>>>>>>>>> functions is that in future if we will have some
> >>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>> abstract classes,
> >>>>>>>>>>>>>>>>>> we can easily extend:
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
> >> implements
> >>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> >>>>>>>>>>>>>>>>> AbstractRichFunction*{
> >>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
> >>>>>>>>>> inheritance.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> However, I think we can easily change it (from abstract
> >>> class
> >>>>>>> ->
> >>>>>>>>>>>>>>>>> interface)
> >>>>>>>>>>>>>>>>>> if you think interface is a better fit.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> >>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is
> quite
> >>>>>>>> improved
> >>>>>>>>>>>> now
> >>>>>>>>>>>>>>>>> --
> >>>>>>>>>>>>>>>>>>> great job!
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
> >>>>>>> classes
> >>>>>>>>>> and
> >>>>>>>>>>>>>>> not
> >>>>>>>>>>>>>>>>>>> interfaces?
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>>>>>>> interfaces
> >>>>>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> >>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
> >> they
> >>>>>>>> don't
> >>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>> direct
> >>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only
> >>> one
> >>>>>>>>>>>> method ,
> >>>>>>>>>>>>>>>>> so
> >>>>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>> can use lambdas.
> >>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
> >>> Inside
> >>>>>>>> Rich
> >>>>>>>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
> >>> *withKey*
> >>>>>>> and
> >>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We
> >> get
> >>>>>>>> those
> >>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
> >> topology,
> >>>>> and
> >>>>>>>>>> send
> >>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>> Processor.
> >>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
> >> implement
> >>>>>>>>>>>> *withKey*
> >>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition.
> >> In
> >>>>>>> this
> >>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>>> while
> >>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the object
> >>> type
> >>>>>>> is
> >>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for
> >>> Rich
> >>>>>>>>>>>> functions
> >>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> >>> need
> >>>>>>> to
> >>>>>>>>>>>> have a
> >>>>>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
> >>> *withKey*
> >>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
> >> remove
> >>>>> the
> >>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> >> sufficient
> >>> to
> >>>>>>>>>>>> support
> >>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >>>>> "extended
> >>>>>>>>>> API".
> >>>>>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
> >> of
> >>>>>>> more
> >>>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> >> much
> >>>>>>>>>> because
> >>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
> see
> >>>>>>> value
> >>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one
> >>> extra
> >>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
> >> *withKey*
> >>>>>>>>>> version
> >>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>> particular interface.
> >>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
> >>>>>>>> function
> >>>>>>>>>>>>>>>>>>> implements
> >>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type.
> We
> >>>>>>>>>>>> differentiate
> >>>>>>>>>>>>>>>>>>> them
> >>>>>>>>>>>>>>>>>>>> while building the topology.
> >>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
> >>>>>>>> comment:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can
> >> we
> >>>>>>> have
> >>>>>>>> a
> >>>>>>>>>>>>>>>>> design
> >>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas,
> it
> >>>>>>> might
> >>>>>>>>>> make
> >>>>>>>>>>>>>>>>>> sense
> >>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
> >> overall
> >>>>>>>> design
> >>>>>>>>>>>>>>>>>>>> significantly.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> >> sense
> >>>>> to
> >>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> >> thus,
> >>>>>>> this
> >>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >>>>>>> before
> >>>>>>>>>>>> driving
> >>>>>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
> >>>>>>> functions
> >>>>>>>>>> as I
> >>>>>>>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
> >> library.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> >>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> thanks for the update.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>>>>>>> interfaces
> >>>>>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> >>> need
> >>>>>>> to
> >>>>>>>>>>>> have a
> >>>>>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
> >>>>> sense
> >>>>>>>>>>>> anymore,
> >>>>>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> >>>>>>>>>>>> implementation of
> >>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
> >> would
> >>>>>>>>>>>> implement a
> >>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> >> sufficient
> >>>>> to
> >>>>>>>>>>>> support
> >>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >>>>> "extended
> >>>>>>>>>> API".
> >>>>>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
> >> of
> >>>>>>> more
> >>>>>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> >> much
> >>>>>>>>>> because
> >>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do
> see
> >>>>>>> value
> >>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> >>> sense
> >>>>>>> to
> >>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> >> thus,
> >>>>>>> this
> >>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >>>>>>> before
> >>>>>>>>>>>> driving
> >>>>>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Thoughts?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
> >>> comments.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> >>> little
> >>>>>>>>>> bit? I
> >>>>>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> >>>>> problem
> >>>>>>>> is.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
> >> interface
> >>>>>>> that
> >>>>>>>>>> has
> >>>>>>>>>>>>>>>>> just
> >>>>>>>>>>>>>>>>>>> one
> >>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
> >> function
> >>>>>>>>>>>> contract".
> >>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
> >> another
> >>>>>>> (in
> >>>>>>>>>> our
> >>>>>>>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
> >>>>> lambdas
> >>>>>>>> in
> >>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>> extended
> >>>>>>>>>>>>>>>>>>>>>> interface.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> >> maybe
> >>>>>>>>>> reformat
> >>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> >>> help.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> >>>>>>> overlaods
> >>>>>>>>>>>> added
> >>>>>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
> >> to
> >>>>>>> add
> >>>>>>>>>> any
> >>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
> >> public
> >>>>>>> APIs
> >>>>>>>>>> to
> >>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
> >>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
> >>>>>>>> structure:
> >>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>> overload
> >>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> >>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor
> and
> >>>>>>> inside
> >>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>> processor
> >>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich
> function.
> >>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
> >> overall
> >>>>>>> idea
> >>>>>>>>>> with
> >>>>>>>>>>>>>>>>> only
> >>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
> >>> changes.
> >>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)*
> >>> and*
> >>>>>>>>>>>> close()*
> >>>>>>>>>>>>>>>>>>>>> methods
> >>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>>>>> void close () {}
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
> >>>>>>>>>>>> *AbstractRichFunction*
> >>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
> >> *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and
> ease
> >>> the
> >>>>>>>>>>>>>>>>>> maintenance.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> >>>>>>> Merger,
> >>>>>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add
> >> to
> >>>>>>> all,
> >>>>>>>>>> but
> >>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> sense
> >>>>>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
> >> applies
> >>>>> to
> >>>>>>>> all
> >>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP,
> just
> >>>>>>> wanted
> >>>>>>>>>> to
> >>>>>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>> overall intuition.
> >>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> >> `ValueXXWithKey`
> >>>>> --
> >>>>>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>>>>>> interfaces
> >>>>>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should
> >>> not
> >>>>>>>> force
> >>>>>>>>>>>>>>>>> users
> >>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> >>>>> functions
> >>>>>>>>>> every
> >>>>>>>>>>>>>>>>> time
> >>>>>>>>>>>>>>>>>>>>> they
> >>>>>>>>>>>>>>>>>>>>>> use Rich functions.
> >>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
> >> methods.
> >>>>>>>>>> However,
> >>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>> am
> >>>>>>>>>>>>>>>>>>> open
> >>>>>>>>>>>>>>>>>>>>>> for discussion.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> >>> spread
> >>>>>>> any
> >>>>>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
> >> is
> >>>>>>> done
> >>>>>>>>>>>> before
> >>>>>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> >>> too
> >>>>>>>>>> large.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
> >>>>>>>> *init(ProcessorContext)*
> >>>>>>>>>>>>>>>>> method
> >>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
> >>> ProcessorContext
> >>>>>>> as
> >>>>>>>> an
> >>>>>>>>>>>>>>>>>> input),
> >>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> >>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
> >> @mjsax
> >>>>>>>>>>>> mentioned)
> >>>>>>>>>>>>>>>>>>> whether
> >>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access
> >> to
> >>>>>>>>>>>>>>>>>>> *ProcessorContext*
> >>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
> >>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> >>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> >>>>>>>>>>>> damian.guy@gmail.com>
> >>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> >>> spread
> >>>>>>>> any
> >>>>>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
> >> is
> >>>>>>> done
> >>>>>>>>>>>> before
> >>>>>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> >>> too
> >>>>>>>>>> large.
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> >>>>>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is
> >> too
> >>>>>>>> broad
> >>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>> general
> >>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
> >> it's
> >>>>>>> also
> >>>>>>>>>>>>>>>>> reflected
> >>>>>>>>>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> confluence/display/KAFKA/
> >>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
> >> `RichFunction`
> >>>>>>>>>>>> approach in
> >>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
> >> scope
> >>>>> of
> >>>>>>>>>> this
> >>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for
> >> it
> >>>>>>> and
> >>>>>>>>>>>> delay
> >>>>>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach.
> >> Do
> >>>>> we
> >>>>>>>>>>>> really
> >>>>>>>>>>>>>>>>>> want
> >>>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext`
> >> ?
> >>> It
> >>>>>>>> has
> >>>>>>>>>> a
> >>>>>>>>>>>>>>>>> bunch
> >>>>>>>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some
> of
> >>> the
> >>>>>>>> DSL
> >>>>>>>>>>>>>>>>>> methods,
> >>>>>>>>>>>>>>>>>>>>>>> i.e,
> >>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`,
> `schedule`
> >>>>> etc.
> >>>>>>>> It
> >>>>>>>>>> is
> >>>>>>>>>>>>>>>>> far
> >>>>>>>>>>>>>>>>>>> too
> >>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
> >> narrower
> >>>>>>>>>>>> interface
> >>>>>>>>>>>>>>>>>> like
> >>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to
> add
> >>>>>>>>>>>>>>>>>>> methods/interfaces
> >>>>>>>>>>>>>>>>>>>>>>>> later
> >>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> >>>>>>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate
> >> a
> >>>>>>>> little
> >>>>>>>>>>>> bit?
> >>>>>>>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what
> the
> >>>>>>>> problem
> >>>>>>>>>>>> is.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess
> >>> it's
> >>>>>>> up
> >>>>>>>>>> to
> >>>>>>>>>>>>>>>>> you.
> >>>>>>>>>>>>>>>>>>>>>>> Maybe a
> >>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> >>> maybe
> >>>>>>>>>>>> reformat
> >>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
> >> would
> >>>>>>> help.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
> >> have
> >>>>>>>>>> overlaods
> >>>>>>>>>>>>>>>>>> added
> >>>>>>>>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
> >> need
> >>>>> to
> >>>>>>>> add
> >>>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> >>> ForeachAction,
> >>>>>>>>>> Merger,
> >>>>>>>>>>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
> >> add
> >>> to
> >>>>>>>> all,
> >>>>>>>>>>>> but
> >>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> >>> sense
> >>>>>>>>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> >>>>>>> `ValueXXWithKey`
> >>>>>>>> --
> >>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>>>>>>> interfaces
> >>>>>>>>>>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
> >> extend
> >>>>>>> the
> >>>>>>>>>> two
> >>>>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>>>>> if
> >>>>>>>>>>>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
> >>> Maybe I
> >>>>>>>>>> should
> >>>>>>>>>>>>>>>>>> change
> >>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP
> >> to
> >>>>>>> only
> >>>>>>>>>>>>>>>>>>> ValueMapper,
> >>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> >>> confluence/display/KAFKA/KIP-
> >>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
> >>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax
> <
> >>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper`
> >> we
> >>>>>>> don't
> >>>>>>>>>>>> need
> >>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
> >>>>> happens
> >>>>>>>>>> when
> >>>>>>>>>>>>>>>>>>> building
> >>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> >>>>>>> KafkaStream#start()
> >>>>>>>>>> we
> >>>>>>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>>>>>>> need
> >>>>>>>>>>>>>>>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
> >> `ValueMapperWithKey`)
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
> >>>>> super
> >>>>>>>> V,
> >>>>>>>>>> ?
> >>>>>>>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>>>>>>>>> VR>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> >>>>>>> mapValues(ValueMapperWithKey<?
> >>>>>>>>>>>> super
> >>>>>>>>>>>>>>>>> V,
> >>>>>>>>>>>>>>>>>> ?
> >>>>>>>>>>>>>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by "Matthias J. Sax" <ma...@confluent.io>.
I agree with Guozhang's second point. This change does not seem backward
compatible.
As we don't have to support lambdas, it might be the easiest thing to
just extend the current interface:
> public interface ValueTransformerWithKey<K, V, VR> extends ValueTransformer<VR>
When plugging the topology together, we can check if we get the
`withKey` variant and use a corresponding runtime class for execution,
so we get only a single time check. Thus, for the `withKey` variant, the
will be a `transfrom(V value)` method, but we will never call it.
Maybe we could make `ValueTransformerWithKey` an abstract class with a
`final` no-op implemenation of `transform(V value)` ?
-Matthias
On 6/6/17 4:58 PM, Guozhang Wang wrote:
> Jeyhun, Matthias:
>
> Thanks for the explanation, I overlooked the repartition argument
> previously.
>
> 1) Based on that argument I'm convinced of having ValueMapperWithKey /
> ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
> convinced with ReducerWithKey and InitializerWithKey since for the former
> it can be covered with `aggregate` completely and with latter I have seen
> little use cases with it.
>
> 2) Another comment is on public interface ValueTransformer<V, VR> extends
> ValueTransformerCommon<VR>:
>
> I think changing the interface to extend from a new interface is not binary
> compatible though source compatible, i.e. users still need to recompile
> their code though no need to make code changes. We may need to mention that
> in the upgrade path if we want to keep it that way.
>
> Guozhang
>
> On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com> wrote:
>
>> Hi,
>>
>>
>> Sorry for late reply. Just to make everybody in sync, the current version
>> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
>> independent, meaning they do not extend from "withoutKey" (ValueMapper)
>> interfaces.
>>
>>
>> I agree with Guozhang, and I am personally a bit reluctant to increase
>> overloaded methods in public APIs but it seems this is only way to solve
>> all related jira issues.
>> However, the most overloaded methods will be with ValueJoiner type, which
>> will be with ValueJoinerWithKey with new overloaded methods. Other
>> interfaces require mostly 1 extra overload.
>>
>>
>>>> I would suggest not doing it if user pop it up, but rather suggesting
>> them
>>>> to use `map`
>>
>> I agree with Matthias as the core idea of this KIP was to collect all
>> related jira issues and propose one-shot solution for all. Afterwards, we
>> broke its scope into 2 KIPs (149 and 159).
>>
>> Cheers,
>> Jeyhun
>>
>>
>>
>> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <ma...@confluent.io>
>> wrote:
>>
>>> I guess I missunderstood you. Your are right that overloading the method
>>> would also work. As both interfaces will be independent from each other,
>>> there should be no problem.
>>>
>>> The initial proposal was to use
>>>
>>>> interface ValueMapperWithKey extends ValueMapper
>>>
>>> and this would break Lambda. We totally missed, that we don't need new
>>> methods but only only overlaods. Great you point this out! I was not
>>> quite happy with the newly added methods.
>>>
>>>>> I would suggest not doing it if user pop it up, but rather suggesting
>>> them
>>>>> to use `map`
>>>
>>> But this might introduce unnecessary re-partitioning for downstream
>>> operators. I don't thinks that a good suggestion. But if we only add new
>>> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
>>> with "overstaffing" the API (what is btw a very valid concern).
>>>
>>>
>>> -Matthias
>>>
>>>
>>> On 6/4/17 10:37 PM, Guozhang Wang wrote:
>>>> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <matthias@confluent.io
>>>
>>>> wrote:
>>>>
>>>>> We started with this proposal but it does not allow for Lambdas (in
>> case
>>>>> you want key access). Do you think preserving Lambdas is not important
>>>>> enough for this case -- I agree that there is some price to be paid to
>>>>> keep Lambdas.
>>>>>
>>>>
>>>> Not sure if I understand this comment.. My main point is not on
>> changing
>>>> the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
>>>> even if we want to keep them all, I'd suggest we just implement the
>> added
>>>> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
>> which
>>>> seems simpler to me. Does that affect lambda expression usage?
>>>>
>>>>>
>>>>> About API consistency: I can't remember a concrete user request to
>> have
>>>>> key access in all operators. But I am pretty sure, if we only add it
>> for
>>>>> some, this request will pop up quickly. IMHO, it's better to do it all
>>>>> in one shot. (But I am not strict about it if most people think we
>>>>> should limit it to what was requested by users.)
>>>>>
>>>>>
>>>> I would suggest not doing it if user pop it up, but rather suggesting
>>> them
>>>> to use `map` etc directly but set the key unchanged rather than
>>> providing a
>>>> new operator for it. To me some syntax sugars like this seems of less
>>>> valuable than others (like print / writeAsText / foreach that are all
>>>> depending on peek), and keeping adding them will just make the DSL too
>>>> “overstaffed”.
>>>>
>>>>
>>>>>
>>>>> -Matthias
>>>>>
>>>>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
>>>>>> With KIP-159, the added "valueMapperWithKey" and
>>>>> "valueTransformerWithKey"
>>>>>> along seem to be just adding a few syntax-sugars? E.g. we can simply
>>>>>> implement:
>>>>>>
>>>>>> mapValues(ValueMapperWithKey mapperWithKey)
>>>>>>
>>>>>> as
>>>>>>
>>>>>> map((k, v) -> (k, mapperWithKey(k, v))
>>>>>>
>>>>>> ----------------------
>>>>>>
>>>>>> I'm not sure how many users would really need such syntax sugars, and
>>>>> even
>>>>>> they do, we can support them easily as the above implementations;
>>>>>>
>>>>>> Similarly for "ReducerWithKey", it can be implemented as
>> `Aggregator<K,
>>>>> V,
>>>>>> V>`, and people who needs key access can just use `aggregate`
>> directly.
>>>>>>
>>>>>> The function which I think is really of valuable is
>>> `ValueJoinerWithKey`,
>>>>>> and that seems to be the original request from users while others are
>>>>>> coming from "API consistency" concerns. Personally I'd prefer only
>> keep
>>>>> the
>>>>>> last one (`InitializerWithKey` might also have some value, but I have
>>> not
>>>>>> seen people widely requesting it in their DSL usage yet; if there is
>> a
>>>>>> common request we can keep it in this KIP as well). WDYT?
>>>>>>
>>>>>> Guozhang
>>>>>>
>>>>>>
>>>>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
>> je.karimov@gmail.com
>>>>
>>>>>> wrote:
>>>>>>
>>>>>>> Thanks for clarification Matthias, now everything is clear.
>>>>>>>
>>>>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
>>> matthias@confluent.io>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> I don't think we can drop ValueTransformerSupplier. If you don't
>> have
>>>>> an
>>>>>>>> supplier, you only get a single instance of your function. But for
>> a
>>>>>>>> stateful transformation, we need multiple instances (one for each
>>> task)
>>>>>>>> of ValueTransformer.
>>>>>>>>
>>>>>>>> We don't need suppliers for functions like "ValueMapper" etc
>> because
>>>>>>>> those are stateless and thus, we can reuse a single instance over
>>>>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
>>>>>>> similar).
>>>>>>>>
>>>>>>>> Btw: This reminds me about KIP-159: with regard to the RichFunction
>>> we
>>>>>>>> might need a supplier pattern, too. (I'll comment on the other
>>> thread,
>>>>>>>> too.)
>>>>>>>>
>>>>>>>>
>>>>>>>> -Matthias
>>>>>>>>
>>>>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I updated KIP.
>>>>>>>>> Just to avoid misunderstanding, I meant deprecating
>>>>>>>> ValueTransformerSupplier
>>>>>>>>> and I am ok with ValueTransformer.
>>>>>>>>> So instead of using ValueTransformerSupplier can't we directly use
>>>>>>>>> ValueTransformer
>>>>>>>>> or ValueTransformerWithKey?
>>>>>>>>>
>>>>>>>>> Btw, in current design all features of ValueTransformer will be
>>>>>>> available
>>>>>>>>> in ValueTransformerWithKey interface.
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>> Jeyhun
>>>>>>>>>
>>>>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
>>>>> matthias@confluent.io
>>>>>>>>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Thanks Jeyhun.
>>>>>>>>>>
>>>>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>>>>>>> ValueTransformer allows to attach a state and also allows to
>>> register
>>>>>>>>>> punctuations. Both those features will not be available via
>>> withKey()
>>>>>>>>>> interfaces.
>>>>>>>>>>
>>>>>>>>>> -Matthias
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>
>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>
>>>>>>>>>>> I tested the deep copy approach. It has significant overhead.
>>>>>>>> Especially
>>>>>>>>>>> for "light" and stateless operators it slows down the topology
>>>>>>>>>>> significantly (> 20% ). I think "warning" users about
>>> not-changing
>>>>>>> the
>>>>>>>>>> key
>>>>>>>>>>> is better warning them about possible performance loss.
>>>>>>>>>>>
>>>>>>>>>>> About the interfaces, additionally I considered adding
>>>>>>>>>> InitializerWithKey,
>>>>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
>>>>>>>> included
>>>>>>>>>> in
>>>>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
>> bad.
>>>>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>>>>>>
>>>>>>>>>>> One thing I want to mention is that, maybe we should deprecate
>>>>>>> methods
>>>>>>>>>> with
>>>>>>>>>>> argument type ValueTransformerSupplier
>>>>> (KStream.transformValues(...))
>>>>>>>> and
>>>>>>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
>> instead
>>>>>>>> without
>>>>>>>>>>> additional supplier layer.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Cheers,
>>>>>>>>>>> Jeyhun
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>>>>>>> matthias@confluent.io
>>>>>>>>>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> One more question:
>>>>>>>>>>>>
>>>>>>>>>>>> Should we add any of
>>>>>>>>>>>> - InitizialierWithKey
>>>>>>>>>>>> - ReducerWithKey
>>>>>>>>>>>> - ValueTransformerWithKey
>>>>>>>>>>>>
>>>>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
>>>>>>> thoughts?
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>
>>>>>>>>>>>>> I was just wondering if you did look into the key-deep-copy
>> idea
>>>>> we
>>>>>>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks for your comments. I rethink about including rich
>>>>> functions
>>>>>>>>>> into
>>>>>>>>>>>>>> this KIP.
>>>>>>>>>>>>>> I think once we include rich functions in this KIP and then
>> fix
>>>>>>>>>>>>>> ProcessorContext in another KIP and incorporate with existing
>>>>> rich
>>>>>>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
>>>>>>>> updated
>>>>>>>>>>>> the
>>>>>>>>>>>>>> KIP), I will try also initiate another KIP for rich
>> functions.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>
>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> With the current KIP, using ValueMapper and
>> ValueMapperWithKey
>>>>>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on.
>> To
>>>>>>> fix
>>>>>>>>>> the
>>>>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
>>>>>>> required
>>>>>>>>>>>> IMHO.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I initially put the RichFunction idea on the table, because
>> I
>>>>> was
>>>>>>>>>>>> hoping
>>>>>>>>>>>>>>> to get a uniform API. And I think, is was good to consider
>>> them
>>>>>>> --
>>>>>>>>>>>>>>> however, the discussion showed that they are not necessary
>> for
>>>>>>> key
>>>>>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions
>> in
>>>>> an
>>>>>>>> own
>>>>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
>>>>> main
>>>>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>>>>>>> parameter-less
>>>>>>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>>>>>>> "intermediate"
>>>>>>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> As you put already much effort into RichFunction, feel free
>> do
>>>>>>> push
>>>>>>>>>>>> this
>>>>>>>>>>>>>>> further and start a new KIP (we can do this even in
>> parallel)
>>> --
>>>>>>> we
>>>>>>>>>>>>>>> don't want to slow you down :) But it make the discussion
>> and
>>>>>>> code
>>>>>>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thanks for your comments. I think providing to users
>>>>> *interface*
>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
>>> raised
>>>>>>>> this
>>>>>>>>>>>>>>> issue
>>>>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Regarding with passing additional contextual information, I
>>>>>>> think
>>>>>>>> it
>>>>>>>>>>>> is a
>>>>>>>>>>>>>>>> tradeoff,
>>>>>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method
>> in
>>>>>>>>>> another
>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
>>>>>>>> providing
>>>>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>>>>>>> parameters
>>>>>>>>>> to
>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> To me, the second approach seems more incremental. However
>>> you
>>>>>>> are
>>>>>>>>>>>> right,
>>>>>>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>>>>>>> damian.guy@gmail.com
>>>>>>>>>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>>>>>>> RichFunction
>>>>>>>>>>>> which
>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it
>>> to
>>>>>>>> pass
>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>> additional contextual information, i.e., the
>> `RecordContext`
>>>>>>> that
>>>>>>>>>>>>>>> contains
>>>>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with
>>> it
>>>>>>> not
>>>>>>>>>>>>>>> passing
>>>>>>>>>>>>>>>>> this contextual information, but is the naming incorrect?
>>> I'm
>>>>>>> not
>>>>>>>>>>>> sure,
>>>>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until
>>> we
>>>>>>> can
>>>>>>>>>> do
>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
>>>>>>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
>> interfaces?
>>>>>>>>>>>> Generally we
>>>>>>>>>>>>>>>>> should provide users with Intefaces to code against, not
>>>>>>> classes.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>> Damian
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>>>>>>> je.karimov@gmail.com>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
>>> overview.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
>>>>>>> interface
>>>>>>>>>> for
>>>>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
>> implements
>>>>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>>>>>>> inheritance.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> However, I think we can easily change it (from abstract
>>> class
>>>>>>> ->
>>>>>>>>>>>>>>>>> interface)
>>>>>>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
>>>>>>>> improved
>>>>>>>>>>>> now
>>>>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
>>>>>>> classes
>>>>>>>>>> and
>>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>>>>> interfaces
>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
>> they
>>>>>>>> don't
>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only
>>> one
>>>>>>>>>>>> method ,
>>>>>>>>>>>>>>>>> so
>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
>>> Inside
>>>>>>>> Rich
>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
>>> *withKey*
>>>>>>> and
>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We
>> get
>>>>>>>> those
>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>> and wrap into Rich function while building the
>> topology,
>>>>> and
>>>>>>>>>> send
>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
>> implement
>>>>>>>>>>>> *withKey*
>>>>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition.
>> In
>>>>>>> this
>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>> while
>>>>>>>>>>>>>>>>>>>> building the topology we do a type check if the object
>>> type
>>>>>>> is
>>>>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for
>>> Rich
>>>>>>>>>>>> functions
>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
>>> need
>>>>>>> to
>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
>>> *withKey*
>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
>> remove
>>>>> the
>>>>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>> sufficient
>>> to
>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>> "extended
>>>>>>>>>> API".
>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
>> of
>>>>>>> more
>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>> much
>>>>>>>>>> because
>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>>>>> value
>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one
>>> extra
>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
>> *withKey*
>>>>>>>>>> version
>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
>>>>>>>> function
>>>>>>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
>>>>>>>>>>>> differentiate
>>>>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
>>>>>>>> comment:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can
>> we
>>>>>>> have
>>>>>>>> a
>>>>>>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
>>>>>>> might
>>>>>>>>>> make
>>>>>>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> However, I don't think that this complicates the
>> overall
>>>>>>>> design
>>>>>>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>> sense
>>>>> to
>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>> thus,
>>>>>>> this
>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>>>>> before
>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>>>>>>> functions
>>>>>>>>>> as I
>>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
>> library.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>>>>> interfaces
>>>>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
>>> need
>>>>>>> to
>>>>>>>>>>>> have a
>>>>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
>>>>> sense
>>>>>>>>>>>> anymore,
>>>>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>>>>>>> implementation of
>>>>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
>> would
>>>>>>>>>>>> implement a
>>>>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
>> sufficient
>>>>> to
>>>>>>>>>>>> support
>>>>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>>>>> "extended
>>>>>>>>>> API".
>>>>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
>> of
>>>>>>> more
>>>>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
>> much
>>>>>>>>>> because
>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>>>>> value
>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
>>> sense
>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
>> thus,
>>>>>>> this
>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>>>>> before
>>>>>>>>>>>> driving
>>>>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
>>> comments.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>> little
>>>>>>>>>> bit? I
>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>> problem
>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
>> interface
>>>>>>> that
>>>>>>>>>> has
>>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
>> function
>>>>>>>>>>>> contract".
>>>>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
>> another
>>>>>>> (in
>>>>>>>>>> our
>>>>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
>>>>> lambdas
>>>>>>>> in
>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>> maybe
>>>>>>>>>> reformat
>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
>>> help.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>>>> overlaods
>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
>> to
>>>>>>> add
>>>>>>>>>> any
>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
>> public
>>>>>>> APIs
>>>>>>>>>> to
>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
>>>>>>>> structure:
>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
>>>>>>> inside
>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
>>>>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
>> overall
>>>>>>> idea
>>>>>>>>>> with
>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
>>> changes.
>>>>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)*
>>> and*
>>>>>>>>>>>> close()*
>>>>>>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>> extent new Rich functions from
>> *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease
>>> the
>>>>>>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>>>>>>> Merger,
>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add
>> to
>>>>>>> all,
>>>>>>>>>> but
>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
>> applies
>>>>> to
>>>>>>>> all
>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
>>>>>>> wanted
>>>>>>>>>> to
>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>> `ValueXXWithKey`
>>>>> --
>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>> interfaces
>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should
>>> not
>>>>>>>> force
>>>>>>>>>>>>>>>>> users
>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
>>>>> functions
>>>>>>>>>> every
>>>>>>>>>>>>>>>>> time
>>>>>>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
>> methods.
>>>>>>>>>> However,
>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>> spread
>>>>>>> any
>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
>> is
>>>>>>> done
>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
>>> too
>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>>>>>>> *init(ProcessorContext)*
>>>>>>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>>>>>>> persistent among the library (which use
>>> ProcessorContext
>>>>>>> as
>>>>>>>> an
>>>>>>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
>> @mjsax
>>>>>>>>>>>> mentioned)
>>>>>>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access
>> to
>>>>>>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
>>>>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
>>> spread
>>>>>>>> any
>>>>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
>> is
>>>>>>> done
>>>>>>>>>>>> before
>>>>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
>>> too
>>>>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is
>> too
>>>>>>>> broad
>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
>> it's
>>>>>>> also
>>>>>>>>>>>>>>>>> reflected
>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
>> `RichFunction`
>>>>>>>>>>>> approach in
>>>>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
>> scope
>>>>> of
>>>>>>>>>> this
>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for
>> it
>>>>>>> and
>>>>>>>>>>>> delay
>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach.
>> Do
>>>>> we
>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>> want
>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext`
>> ?
>>> It
>>>>>>>> has
>>>>>>>>>> a
>>>>>>>>>>>>>>>>> bunch
>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of
>>> the
>>>>>>>> DSL
>>>>>>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
>>>>> etc.
>>>>>>>> It
>>>>>>>>>> is
>>>>>>>>>>>>>>>>> far
>>>>>>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
>> narrower
>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
>>>>>>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate
>> a
>>>>>>>> little
>>>>>>>>>>>> bit?
>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>>>>> problem
>>>>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess
>>> it's
>>>>>>> up
>>>>>>>>>> to
>>>>>>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
>>> maybe
>>>>>>>>>>>> reformat
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
>> would
>>>>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
>> have
>>>>>>>>>> overlaods
>>>>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
>> need
>>>>> to
>>>>>>>> add
>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
>>> ForeachAction,
>>>>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
>> add
>>> to
>>>>>>>> all,
>>>>>>>>>>>> but
>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
>>> sense
>>>>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>>>>> `ValueXXWithKey`
>>>>>>>> --
>>>>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>>>>> interfaces
>>>>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
>> extend
>>>>>>> the
>>>>>>>>>> two
>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
>>> Maybe I
>>>>>>>>>> should
>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP
>> to
>>>>>>> only
>>>>>>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
>>> confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
>>>>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper`
>> we
>>>>>>> don't
>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
>>>>> happens
>>>>>>>>>> when
>>>>>>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>>>>>>> KafkaStream#start()
>>>>>>>>>> we
>>>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
>> `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
>>>>> super
>>>>>>>> V,
>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>>>>>> mapValues(ValueMapperWithKey<?
>>>>>>>>>>>> super
>>>>>>>>>>>>>>>>> V,
>>>>>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still
>> have
>>> to
>>>>>>>>>> check
>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into
>>> the
>>>>>>>> rich
>>>>>>>>>>>>>>>>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal
>>> Borowiecki
>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
>>>>> wondering,
>>>>>>>> if
>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a
>>> RichFunction
>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>> at
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions
>> all
>>>>> the
>>>>>>>>>> time.
>>>>>>>>>>>>>>>>>> Thus,
>>>>>>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
>>>>>>> non-RichFunction,
>>>>>>>>>> we
>>>>>>>>>>>>>>>>> wrap
>>>>>>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>>>>> by a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
>>>>>>> Streams.
>>>>>>>>>> This
>>>>>>>>>>>>>>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the
>> key:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
>>>>>>> snippet):
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
>>>>>>>>>>>>>>>>> RichValueMapper()
>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper;
>> //
>>>>>>> set
>>>>>>>> by
>>>>>>>>>>>>>>>>>>>>> constructor
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
>>>>> value1,
>>>>>>>>>>>> final V2
>>>>>>>>>>>>>>>>>>>>>>> value2)
>>>>>>>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
>>>>>>> value2);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not
>>> sure
>>>>>>> if
>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc
>> would
>>>>>>> have
>>>>>>>>>>>> more
>>>>>>>>>>>>>>>>>>>>> overhead
>>>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested
>> method
>>>>>>> call
>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than
>>> RichFunctions).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or
>>> do I
>>>>>>>> miss
>>>>>>>>>>>>>>>>>>>>> something?)
>>>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more
>>> top
>>>>>>>> level
>>>>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
>>>>>>> `close()`
>>>>>>>>>> and
>>>>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no
>> abstract
>>>>>>>> classes
>>>>>>>>>>>>>>>>>>> required).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP
>> to
>>>>>>>>>> include
>>>>>>>>>>>>>>>>> rich
>>>>>>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of
>> deep
>>>>>>>> copying
>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>> keys.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu
>>> Fenniak
>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
>>>>>>>>>>>> immutability of
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
>>>>> requiring
>>>>>>>> the
>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> serializable
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>> risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable
>> type
>>>>>>>>>>>> constraints
>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>>>>>>>>> kind.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> :-)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias
>> J.
>>>>>>> Sax
>>>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow
>>> this
>>>>>>>> path,
>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>>> cover
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>
>
>
>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Guozhang Wang <wa...@gmail.com>.
Jeyhun, Matthias:
Thanks for the explanation, I overlooked the repartition argument
previously.
1) Based on that argument I'm convinced of having ValueMapperWithKey /
ValueJoinerWithKey / ValueTransformerWithKey; though I'm still not
convinced with ReducerWithKey and InitializerWithKey since for the former
it can be covered with `aggregate` completely and with latter I have seen
little use cases with it.
2) Another comment is on public interface ValueTransformer<V, VR> extends
ValueTransformerCommon<VR>:
I think changing the interface to extend from a new interface is not binary
compatible though source compatible, i.e. users still need to recompile
their code though no need to make code changes. We may need to mention that
in the upgrade path if we want to keep it that way.
Guozhang
On Mon, Jun 5, 2017 at 2:28 PM, Jeyhun Karimov <je...@gmail.com> wrote:
> Hi,
>
>
> Sorry for late reply. Just to make everybody in sync, the current version
> of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
> independent, meaning they do not extend from "withoutKey" (ValueMapper)
> interfaces.
>
>
> I agree with Guozhang, and I am personally a bit reluctant to increase
> overloaded methods in public APIs but it seems this is only way to solve
> all related jira issues.
> However, the most overloaded methods will be with ValueJoiner type, which
> will be with ValueJoinerWithKey with new overloaded methods. Other
> interfaces require mostly 1 extra overload.
>
>
> >> I would suggest not doing it if user pop it up, but rather suggesting
> them
> >> to use `map`
>
> I agree with Matthias as the core idea of this KIP was to collect all
> related jira issues and propose one-shot solution for all. Afterwards, we
> broke its scope into 2 KIPs (149 and 159).
>
> Cheers,
> Jeyhun
>
>
>
> On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <ma...@confluent.io>
> wrote:
>
> > I guess I missunderstood you. Your are right that overloading the method
> > would also work. As both interfaces will be independent from each other,
> > there should be no problem.
> >
> > The initial proposal was to use
> >
> > > interface ValueMapperWithKey extends ValueMapper
> >
> > and this would break Lambda. We totally missed, that we don't need new
> > methods but only only overlaods. Great you point this out! I was not
> > quite happy with the newly added methods.
> >
> > >> I would suggest not doing it if user pop it up, but rather suggesting
> > them
> > >> to use `map`
> >
> > But this might introduce unnecessary re-partitioning for downstream
> > operators. I don't thinks that a good suggestion. But if we only add new
> > overloads for mapValue(), flatMapValue() etc, I don't see a big issue
> > with "overstaffing" the API (what is btw a very valid concern).
> >
> >
> > -Matthias
> >
> >
> > On 6/4/17 10:37 PM, Guozhang Wang wrote:
> > > On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <matthias@confluent.io
> >
> > > wrote:
> > >
> > >> We started with this proposal but it does not allow for Lambdas (in
> case
> > >> you want key access). Do you think preserving Lambdas is not important
> > >> enough for this case -- I agree that there is some price to be paid to
> > >> keep Lambdas.
> > >>
> > >
> > > Not sure if I understand this comment.. My main point is not on
> changing
> > > the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
> > > even if we want to keep them all, I'd suggest we just implement the
> added
> > > APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc,
> which
> > > seems simpler to me. Does that affect lambda expression usage?
> > >
> > >>
> > >> About API consistency: I can't remember a concrete user request to
> have
> > >> key access in all operators. But I am pretty sure, if we only add it
> for
> > >> some, this request will pop up quickly. IMHO, it's better to do it all
> > >> in one shot. (But I am not strict about it if most people think we
> > >> should limit it to what was requested by users.)
> > >>
> > >>
> > > I would suggest not doing it if user pop it up, but rather suggesting
> > them
> > > to use `map` etc directly but set the key unchanged rather than
> > providing a
> > > new operator for it. To me some syntax sugars like this seems of less
> > > valuable than others (like print / writeAsText / foreach that are all
> > > depending on peek), and keeping adding them will just make the DSL too
> > > “overstaffed”.
> > >
> > >
> > >>
> > >> -Matthias
> > >>
> > >> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> > >>> With KIP-159, the added "valueMapperWithKey" and
> > >> "valueTransformerWithKey"
> > >>> along seem to be just adding a few syntax-sugars? E.g. we can simply
> > >>> implement:
> > >>>
> > >>> mapValues(ValueMapperWithKey mapperWithKey)
> > >>>
> > >>> as
> > >>>
> > >>> map((k, v) -> (k, mapperWithKey(k, v))
> > >>>
> > >>> ----------------------
> > >>>
> > >>> I'm not sure how many users would really need such syntax sugars, and
> > >> even
> > >>> they do, we can support them easily as the above implementations;
> > >>>
> > >>> Similarly for "ReducerWithKey", it can be implemented as
> `Aggregator<K,
> > >> V,
> > >>> V>`, and people who needs key access can just use `aggregate`
> directly.
> > >>>
> > >>> The function which I think is really of valuable is
> > `ValueJoinerWithKey`,
> > >>> and that seems to be the original request from users while others are
> > >>> coming from "API consistency" concerns. Personally I'd prefer only
> keep
> > >> the
> > >>> last one (`InitializerWithKey` might also have some value, but I have
> > not
> > >>> seen people widely requesting it in their DSL usage yet; if there is
> a
> > >>> common request we can keep it in this KIP as well). WDYT?
> > >>>
> > >>> Guozhang
> > >>>
> > >>>
> > >>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <
> je.karimov@gmail.com
> > >
> > >>> wrote:
> > >>>
> > >>>> Thanks for clarification Matthias, now everything is clear.
> > >>>>
> > >>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
> > matthias@confluent.io>
> > >>>> wrote:
> > >>>>
> > >>>>> I don't think we can drop ValueTransformerSupplier. If you don't
> have
> > >> an
> > >>>>> supplier, you only get a single instance of your function. But for
> a
> > >>>>> stateful transformation, we need multiple instances (one for each
> > task)
> > >>>>> of ValueTransformer.
> > >>>>>
> > >>>>> We don't need suppliers for functions like "ValueMapper" etc
> because
> > >>>>> those are stateless and thus, we can reuse a single instance over
> > >>>>> multiple tasks -- but we can't do this for ValueTransformer (and
> > >>>> similar).
> > >>>>>
> > >>>>> Btw: This reminds me about KIP-159: with regard to the RichFunction
> > we
> > >>>>> might need a supplier pattern, too. (I'll comment on the other
> > thread,
> > >>>>> too.)
> > >>>>>
> > >>>>>
> > >>>>> -Matthias
> > >>>>>
> > >>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> > >>>>>> Hi,
> > >>>>>>
> > >>>>>> I updated KIP.
> > >>>>>> Just to avoid misunderstanding, I meant deprecating
> > >>>>> ValueTransformerSupplier
> > >>>>>> and I am ok with ValueTransformer.
> > >>>>>> So instead of using ValueTransformerSupplier can't we directly use
> > >>>>>> ValueTransformer
> > >>>>>> or ValueTransformerWithKey?
> > >>>>>>
> > >>>>>> Btw, in current design all features of ValueTransformer will be
> > >>>> available
> > >>>>>> in ValueTransformerWithKey interface.
> > >>>>>>
> > >>>>>> Cheers,
> > >>>>>> Jeyhun
> > >>>>>>
> > >>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> > >> matthias@confluent.io
> > >>>>>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>>> Thanks Jeyhun.
> > >>>>>>>
> > >>>>>>> About ValueTransformer: I don't think we can remove it. Note,
> > >>>>>>> ValueTransformer allows to attach a state and also allows to
> > register
> > >>>>>>> punctuations. Both those features will not be available via
> > withKey()
> > >>>>>>> interfaces.
> > >>>>>>>
> > >>>>>>> -Matthias
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> > >>>>>>>> Hi Matthias,
> > >>>>>>>>
> > >>>>>>>> Thanks for your comments.
> > >>>>>>>>
> > >>>>>>>> I tested the deep copy approach. It has significant overhead.
> > >>>>> Especially
> > >>>>>>>> for "light" and stateless operators it slows down the topology
> > >>>>>>>> significantly (> 20% ). I think "warning" users about
> > not-changing
> > >>>> the
> > >>>>>>> key
> > >>>>>>>> is better warning them about possible performance loss.
> > >>>>>>>>
> > >>>>>>>> About the interfaces, additionally I considered adding
> > >>>>>>> InitializerWithKey,
> > >>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
> > >>>>> included
> > >>>>>>> in
> > >>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my
> bad.
> > >>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> > >>>>>>>>
> > >>>>>>>> One thing I want to mention is that, maybe we should deprecate
> > >>>> methods
> > >>>>>>> with
> > >>>>>>>> argument type ValueTransformerSupplier
> > >> (KStream.transformValues(...))
> > >>>>> and
> > >>>>>>>> and as a whole the ValueTransformerSupplier interface.
> > >>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type
> instead
> > >>>>> without
> > >>>>>>>> additional supplier layer.
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> Cheers,
> > >>>>>>>> Jeyhun
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> > >>>> matthias@confluent.io
> > >>>>>>
> > >>>>>>>> wrote:
> > >>>>>>>>
> > >>>>>>>>> One more question:
> > >>>>>>>>>
> > >>>>>>>>> Should we add any of
> > >>>>>>>>> - InitizialierWithKey
> > >>>>>>>>> - ReducerWithKey
> > >>>>>>>>> - ValueTransformerWithKey
> > >>>>>>>>>
> > >>>>>>>>> To get consistent/complete API, it might be a good idea. Any
> > >>>> thoughts?
> > >>>>>>>>>
> > >>>>>>>>>
> > >>>>>>>>> -Matthias
> > >>>>>>>>>
> > >>>>>>>>>
> > >>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> > >>>>>>>>>> Jeyhun,
> > >>>>>>>>>>
> > >>>>>>>>>> I was just wondering if you did look into the key-deep-copy
> idea
> > >> we
> > >>>>>>>>>> discussed. I am curious to see what the impact might be.
> > >>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>>>> -Matthias
> > >>>>>>>>>>
> > >>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>> Hi,
> > >>>>>>>>>>>
> > >>>>>>>>>>> Thanks for your comments. I rethink about including rich
> > >> functions
> > >>>>>>> into
> > >>>>>>>>>>> this KIP.
> > >>>>>>>>>>> I think once we include rich functions in this KIP and then
> fix
> > >>>>>>>>>>> ProcessorContext in another KIP and incorporate with existing
> > >> rich
> > >>>>>>>>>>> functions, the code will not be backwards compatible.
> > >>>>>>>>>>>
> > >>>>>>>>>>> I see Damian's and your point more clearly now.
> > >>>>>>>>>>>
> > >>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
> > >>>>> updated
> > >>>>>>>>> the
> > >>>>>>>>>>> KIP), I will try also initiate another KIP for rich
> functions.
> > >>>>>>>>>>>
> > >>>>>>>>>>> Cheers,
> > >>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>
> > >>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> > >>>>>>> matthias@confluent.io
> > >>>>>>>>>>
> > >>>>>>>>>>> wrote:
> > >>>>>>>>>>>
> > >>>>>>>>>>>> With the current KIP, using ValueMapper and
> ValueMapperWithKey
> > >>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on.
> To
> > >>>> fix
> > >>>>>>> the
> > >>>>>>>>>>>> original issue to allow key access, RichFunctions are not
> > >>>> required
> > >>>>>>>>> IMHO.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> I initially put the RichFunction idea on the table, because
> I
> > >> was
> > >>>>>>>>> hoping
> > >>>>>>>>>>>> to get a uniform API. And I think, is was good to consider
> > them
> > >>>> --
> > >>>>>>>>>>>> however, the discussion showed that they are not necessary
> for
> > >>>> key
> > >>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions
> in
> > >> an
> > >>>>> own
> > >>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
> > >> main
> > >>>>>>>>>>>> challenge for this. And introducing RichFunctions with
> > >>>>> parameter-less
> > >>>>>>>>>>>> init() method, seem not to help too much. We would get an
> > >>>>>>>>> "intermediate"
> > >>>>>>>>>>>> API that we want to change anyway later on...
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> As you put already much effort into RichFunction, feel free
> do
> > >>>> push
> > >>>>>>>>> this
> > >>>>>>>>>>>> further and start a new KIP (we can do this even in
> parallel)
> > --
> > >>>> we
> > >>>>>>>>>>>> don't want to slow you down :) But it make the discussion
> and
> > >>>> code
> > >>>>>>>>>>>> review easier, if we separate both IMHO.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>> Hi Damian,
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Thanks for your comments. I think providing to users
> > >> *interface*
> > >>>>>>>>> rather
> > >>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
> > raised
> > >>>>> this
> > >>>>>>>>>>>> issue
> > >>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Regarding with passing additional contextual information, I
> > >>>> think
> > >>>>> it
> > >>>>>>>>> is a
> > >>>>>>>>>>>>> tradeoff,
> > >>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method
> in
> > >>>>>>> another
> > >>>>>>>>> PR
> > >>>>>>>>>>>>> and solve Rich functions afterwards
> > >>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
> > >>>>> providing
> > >>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
> > >>>> parameters
> > >>>>>>> to
> > >>>>>>>>>>>> this
> > >>>>>>>>>>>>> afterwards (like improvement)
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> To me, the second approach seems more incremental. However
> > you
> > >>>> are
> > >>>>>>>>> right,
> > >>>>>>>>>>>>> the names might confuse the users.
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> > >>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> > >>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> > >>>> damian.guy@gmail.com
> > >>>>>>
> > >>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> > >>>> RichFunction
> > >>>>>>>>> which
> > >>>>>>>>>>>> is
> > >>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it
> > to
> > >>>>> pass
> > >>>>>>>>> some
> > >>>>>>>>>>>>>> additional contextual information, i.e., the
> `RecordContext`
> > >>>> that
> > >>>>>>>>>>>> contains
> > >>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with
> > it
> > >>>> not
> > >>>>>>>>>>>> passing
> > >>>>>>>>>>>>>> this contextual information, but is the naming incorrect?
> > I'm
> > >>>> not
> > >>>>>>>>> sure,
> > >>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until
> > we
> > >>>> can
> > >>>>>>> do
> > >>>>>>>>> it
> > >>>>>>>>>>>>>> properly with the correct context?
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
> > >>>>>>>>>>>> RichValueJoiner,
> > >>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be
> interfaces?
> > >>>>>>>>> Generally we
> > >>>>>>>>>>>>>> should provide users with Intefaces to code against, not
> > >>>> classes.
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> Thanks,
> > >>>>>>>>>>>>>> Damian
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> > >>>>> je.karimov@gmail.com>
> > >>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
> > overview.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> The only reason that I used abstract class instead of
> > >>>> interface
> > >>>>>>> for
> > >>>>>>>>>>>> Rich
> > >>>>>>>>>>>>>>> functions is that in future if we will have some
> > >>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>> abstract classes,
> > >>>>>>>>>>>>>>> we can easily extend:
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR>
> implements
> > >>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> > >>>>>>>>>>>>>> AbstractRichFunction*{
> > >>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
> > >>>>>>> inheritance.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> However, I think we can easily change it (from abstract
> > class
> > >>>> ->
> > >>>>>>>>>>>>>> interface)
> > >>>>>>>>>>>>>>> if you think interface is a better fit.
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> > >>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
> > >>>>> improved
> > >>>>>>>>> now
> > >>>>>>>>>>>>>> --
> > >>>>>>>>>>>>>>>> great job!
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
> > >>>> classes
> > >>>>>>> and
> > >>>>>>>>>>>> not
> > >>>>>>>>>>>>>>>> interfaces?
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Thanks for your comments.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>>>>>>> `AbstractRichFunction`
> > >>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> > >>>>> interfaces
> > >>>>>>>>>>>>>> AFAIK.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> > >>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So
> they
> > >>>>> don't
> > >>>>>>>>> have
> > >>>>>>>>>>>>>>>> direct
> > >>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> > >>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only
> > one
> > >>>>>>>>> method ,
> > >>>>>>>>>>>>>> so
> > >>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>> can use lambdas.
> > >>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
> > Inside
> > >>>>> Rich
> > >>>>>>>>>>>>>>>> functions.
> > >>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
> > *withKey*
> > >>>> and
> > >>>>>>> and
> > >>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We
> get
> > >>>>> those
> > >>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>> and wrap into Rich function while building the
> topology,
> > >> and
> > >>>>>>> send
> > >>>>>>>>> to
> > >>>>>>>>>>>>>>>>> Processor.
> > >>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions
> implement
> > >>>>>>>>> *withKey*
> > >>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition.
> In
> > >>>> this
> > >>>>>>>>> case,
> > >>>>>>>>>>>>>>> while
> > >>>>>>>>>>>>>>>>> building the topology we do a type check if the object
> > type
> > >>>> is
> > >>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for
> > Rich
> > >>>>>>>>> functions
> > >>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>> does not affect using lambdas.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> > need
> > >>>> to
> > >>>>>>>>> have a
> > >>>>>>>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> > >>>> RichFunction
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
> > *withKey*
> > >>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>> as
> > >>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will
> remove
> > >> the
> > >>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> sufficient
> > to
> > >>>>>>>>> support
> > >>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> > >> "extended
> > >>>>>>> API".
> > >>>>>>>>>>>>>> For
> > >>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
> of
> > >>>> more
> > >>>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> much
> > >>>>>>> because
> > >>>>>>>>> we
> > >>>>>>>>>>>>>>> have
> > >>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> > >>>> value
> > >>>>> in
> > >>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one
> > extra
> > >>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is
> *withKey*
> > >>>>>>> version
> > >>>>>>>>> of
> > >>>>>>>>>>>>>>>>> particular interface.
> > >>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
> > >>>>> function
> > >>>>>>>>>>>>>>>> implements
> > >>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
> > >>>>>>>>> differentiate
> > >>>>>>>>>>>>>>>> them
> > >>>>>>>>>>>>>>>>> while building the topology.
> > >>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
> > >>>>> comment:
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can
> we
> > >>>> have
> > >>>>> a
> > >>>>>>>>>>>>>> design
> > >>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
> > >>>> might
> > >>>>>>> make
> > >>>>>>>>>>>>>>> sense
> > >>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> However, I don't think that this complicates the
> overall
> > >>>>> design
> > >>>>>>>>>>>>>>>>> significantly.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> sense
> > >> to
> > >>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> thus,
> > >>>> this
> > >>>>>>>>> also
> > >>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> > >>>> before
> > >>>>>>>>> driving
> > >>>>>>>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
> > >>>> functions
> > >>>>>>> as I
> > >>>>>>>>>>>>>>> don't
> > >>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to
> library.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Any comments are appreciated.
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> > >>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> thanks for the update.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> > >>>>>>>>> `AbstractRichFunction`
> > >>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> > >>>>> interfaces
> > >>>>>>>>>>>>>> AFAIK.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> > need
> > >>>> to
> > >>>>>>>>> have a
> > >>>>>>>>>>>>>>>>>> interface approach like this
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - ValueMapper
> > >>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> > >>>> RichFunction
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
> > >> sense
> > >>>>>>>>> anymore,
> > >>>>>>>>>>>>>>> as
> > >>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> > >>>>>>>>> implementation of
> > >>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you
> would
> > >>>>>>>>> implement a
> > >>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is
> sufficient
> > >> to
> > >>>>>>>>> support
> > >>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> > >> "extended
> > >>>>>>> API".
> > >>>>>>>>>>>>>> For
> > >>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> > >>>>>>>>> AbstractRichFunction
> > >>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea
> of
> > >>>> more
> > >>>>>>>>>>>>>>> overloaded
> > >>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too
> much
> > >>>>>>> because
> > >>>>>>>>> we
> > >>>>>>>>>>>>>>> have
> > >>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> > >>>> value
> > >>>>> in
> > >>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> > sense
> > >>>> to
> > >>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and
> thus,
> > >>>> this
> > >>>>>>>>> also
> > >>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> > >>>> before
> > >>>>>>>>> driving
> > >>>>>>>>>>>>>>>>>> this KIP further.
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> Thoughts?
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
> > comments.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> > little
> > >>>>>>> bit? I
> > >>>>>>>>>>>>>>> cannot
> > >>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> > >> problem
> > >>>>> is.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an
> interface
> > >>>> that
> > >>>>>>> has
> > >>>>>>>>>>>>>> just
> > >>>>>>>>>>>>>>>> one
> > >>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single
> function
> > >>>>>>>>> contract".
> > >>>>>>>>>>>>>>>>>>> So basically once we extend some interface from
> another
> > >>>> (in
> > >>>>>>> our
> > >>>>>>>>>>>>>> case,
> > >>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
> > >> lambdas
> > >>>>> in
> > >>>>>>>>> the
> > >>>>>>>>>>>>>>>>>> extended
> > >>>>>>>>>>>>>>>>>>> interface.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> maybe
> > >>>>>>> reformat
> > >>>>>>>>> the
> > >>>>>>>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> > help.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - I will work on the KIP.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> > >>>> overlaods
> > >>>>>>>>> added
> > >>>>>>>>>>>>>>> for
> > >>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
> to
> > >>>> add
> > >>>>>>> any
> > >>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and
> public
> > >>>> APIs
> > >>>>>>> to
> > >>>>>>>>> be
> > >>>>>>>>>>>>>>>>>>> changed (KStream-KTable
> > >>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
> > >>>>> structure:
> > >>>>>>>>> we
> > >>>>>>>>>>>>>>>>>> overload
> > >>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> > >>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
> > >>>> inside
> > >>>>>>> the
> > >>>>>>>>>>>>>>>>>> processor
> > >>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
> > >>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the
> overall
> > >>>> idea
> > >>>>>>> with
> > >>>>>>>>>>>>>> only
> > >>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
> > changes.
> > >>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)*
> > and*
> > >>>>>>>>> close()*
> > >>>>>>>>>>>>>>>>>> methods
> > >>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> @Override
> > >>>>>>>>>>>>>>>>>>> void close () {}
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> I thought that we can override them once in
> > >>>>>>>>> *AbstractRichFunction*
> > >>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>> extent new Rich functions from
> *AbstractRichFunction*.
> > >>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease
> > the
> > >>>>>>>>>>>>>>> maintenance.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> > >>>> Merger,
> > >>>>>>>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add
> to
> > >>>> all,
> > >>>>>>> but
> > >>>>>>>>> we
> > >>>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> > >>>> (e.g.,
> > >>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique
> applies
> > >> to
> > >>>>> all
> > >>>>>>>>> this
> > >>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
> > >>>> wanted
> > >>>>>>> to
> > >>>>>>>>>>>>>> give
> > >>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>> overall intuition.
> > >>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> `ValueXXWithKey`
> > >> --
> > >>>>>>>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> > >>>> interfaces
> > >>>>>>>>> only?
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should
> > not
> > >>>>> force
> > >>>>>>>>>>>>>> users
> > >>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> > >> functions
> > >>>>>>> every
> > >>>>>>>>>>>>>> time
> > >>>>>>>>>>>>>>>>>> they
> > >>>>>>>>>>>>>>>>>>> use Rich functions.
> > >>>>>>>>>>>>>>>>>>> If one needs, she can override the respective
> methods.
> > >>>>>>> However,
> > >>>>>>>>> I
> > >>>>>>>>>>>>>> am
> > >>>>>>>>>>>>>>>> open
> > >>>>>>>>>>>>>>>>>>> for discussion.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> > spread
> > >>>> any
> > >>>>>>>>>>>>>> further
> > >>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
> is
> > >>>> done
> > >>>>>>>>> before
> > >>>>>>>>>>>>>>>> this?
> > >>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> > too
> > >>>>>>> large.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
> > >>>>> *init(ProcessorContext)*
> > >>>>>>>>>>>>>> method
> > >>>>>>>>>>>>>>>>>>> persistent among the library (which use
> > ProcessorContext
> > >>>> as
> > >>>>> an
> > >>>>>>>>>>>>>>> input),
> > >>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> > >>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and
> @mjsax
> > >>>>>>>>> mentioned)
> > >>>>>>>>>>>>>>>> whether
> > >>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access
> to
> > >>>>>>>>>>>>>>>> *ProcessorContext*
> > >>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
> > >>>>>>>>>>>>>>>>>>> initiate another KIP before this.
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>>>>>>
> > >>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> > >>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> > >>>>>>>>> damian.guy@gmail.com>
> > >>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> > spread
> > >>>>> any
> > >>>>>>>>>>>>>> further
> > >>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that
> is
> > >>>> done
> > >>>>>>>>> before
> > >>>>>>>>>>>>>>>> this?
> > >>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> > too
> > >>>>>>> large.
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> > >>>>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is
> too
> > >>>>> broad
> > >>>>>>> in
> > >>>>>>>>>>>>>>>> general
> > >>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and
> it's
> > >>>> also
> > >>>>>>>>>>>>>> reflected
> > >>>>>>>>>>>>>>>> in
> > >>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
> > >>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the
> `RichFunction`
> > >>>>>>>>> approach in
> > >>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the
> scope
> > >> of
> > >>>>>>> this
> > >>>>>>>>> KIP
> > >>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for
> it
> > >>>> and
> > >>>>>>>>> delay
> > >>>>>>>>>>>>>>> this
> > >>>>>>>>>>>>>>>>>> KIP
> > >>>>>>>>>>>>>>>>>>>>> until the other one is done?
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> > >>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach.
> Do
> > >> we
> > >>>>>>>>> really
> > >>>>>>>>>>>>>>> want
> > >>>>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>>>>>>> give
> > >>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext`
> ?
> > It
> > >>>>> has
> > >>>>>>> a
> > >>>>>>>>>>>>>> bunch
> > >>>>>>>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of
> > the
> > >>>>> DSL
> > >>>>>>>>>>>>>>> methods,
> > >>>>>>>>>>>>>>>>>>>> i.e,
> > >>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
> > >> etc.
> > >>>>> It
> > >>>>>>> is
> > >>>>>>>>>>>>>> far
> > >>>>>>>>>>>>>>>> too
> > >>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a
> narrower
> > >>>>>>>>> interface
> > >>>>>>>>>>>>>>> like
> > >>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
> > >>>>>>>>>>>>>>>> methods/interfaces
> > >>>>>>>>>>>>>>>>>>>>> later
> > >>>>>>>>>>>>>>>>>>>>>> than to remove them
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> > >>>>>>>>>>>>>>> matthias@confluent.io
> > >>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate
> a
> > >>>>> little
> > >>>>>>>>> bit?
> > >>>>>>>>>>>>>> I
> > >>>>>>>>>>>>>>>>>>>> cannot
> > >>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> > >>>>> problem
> > >>>>>>>>> is.
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess
> > it's
> > >>>> up
> > >>>>>>> to
> > >>>>>>>>>>>>>> you.
> > >>>>>>>>>>>>>>>>>>>> Maybe a
> > >>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Further comments:
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> > maybe
> > >>>>>>>>> reformat
> > >>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>> wiki
> > >>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock`
> would
> > >>>> help.
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't
> have
> > >>>>>>> overlaods
> > >>>>>>>>>>>>>>> added
> > >>>>>>>>>>>>>>>>>> for
> > >>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't
> need
> > >> to
> > >>>>> add
> > >>>>>>>>> any
> > >>>>>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>> overloads)
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> > ForeachAction,
> > >>>>>>> Merger,
> > >>>>>>>>>>>>>>>>>>>> Predicate,
> > >>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to
> add
> > to
> > >>>>> all,
> > >>>>>>>>> but
> > >>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> > sense
> > >>>>>>> (e.g.,
> > >>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> > >>>> `ValueXXWithKey`
> > >>>>> --
> > >>>>>>>>>>>>>>>>>>>> `RichValueXX`
> > >>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> > >>>>> interfaces
> > >>>>>>>>>>>>>> only?
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot
> extend
> > >>>> the
> > >>>>>>> two
> > >>>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>>>>> if
> > >>>>>>>>>>>>>>>>>>>>>>> we
> > >>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
> > Maybe I
> > >>>>>>> should
> > >>>>>>>>>>>>>>> change
> > >>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP
> to
> > >>>> only
> > >>>>>>>>>>>>>>>> ValueMapper,
> > >>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> > >>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> [1]
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> > confluence/display/KAFKA/KIP-
> > >>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
> > >>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
> > >>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper`
> we
> > >>>> don't
> > >>>>>>>>> need
> > >>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>> new
> > >>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
> > >> happens
> > >>>>>>> when
> > >>>>>>>>>>>>>>>> building
> > >>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> > >>>> KafkaStream#start()
> > >>>>>>> we
> > >>>>>>>>>>>>>> don't
> > >>>>>>>>>>>>>>>>>> need
> > >>>>>>>>>>>>>>>>>>>>> any
> > >>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use
> `ValueMapperWithKey`)
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> > >>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
> > >> super
> > >>>>> V,
> > >>>>>>> ?
> > >>>>>>>>>>>>>>> extends
> > >>>>>>>>>>>>>>>>>>>> VR>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> > >>>>>>>>>>>>>>>>>>>>>>>>>> with
> > >>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> > >>>> mapValues(ValueMapperWithKey<?
> > >>>>>>>>> super
> > >>>>>>>>>>>>>> V,
> > >>>>>>>>>>>>>>> ?
> > >>>>>>>>>>>>>>>>>>>>> extends
> > >>>>>>>>>>>>>>>>>>>>>>>>> VR>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still
> have
> > to
> > >>>>>>> check
> > >>>>>>>>> it
> > >>>>>>>>>>>>>> is
> > >>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
> > >>>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into
> > the
> > >>>>> rich
> > >>>>>>>>>>>>>>> function.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal
> > Borowiecki
> > >> <
> > >>>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
> > >> wondering,
> > >>>>> if
> > >>>>>>> we
> > >>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>> do
> > >>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a
> > RichFunction
> > >>>>> and
> > >>>>>>>>>>>>>>>>>>>>> non-RichFunction
> > >>>>>>>>>>>>>>>>>>>>>>>>> at
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions
> all
> > >> the
> > >>>>>>> time.
> > >>>>>>>>>>>>>>> Thus,
> > >>>>>>>>>>>>>>>> on
> > >>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>> DSL
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
> > >>>> non-RichFunction,
> > >>>>>>> we
> > >>>>>>>>>>>>>> wrap
> > >>>>>>>>>>>>>>> it
> > >>>>>>>>>>>>>>>>>>>> by a
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
> > >>>> Streams.
> > >>>>>>> This
> > >>>>>>>>>>>>>>>>>>>>> RichFunction
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the
> key:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
> > >>>> snippet):
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
> > >>>>>>>>>>>>>> RichValueMapper()
> > >>>>>>>>>>>>>>> {
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper;
> //
> > >>>> set
> > >>>>> by
> > >>>>>>>>>>>>>>>>>> constructor
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
> > >> value1,
> > >>>>>>>>> final V2
> > >>>>>>>>>>>>>>>>>>>> value2)
> > >>>>>>>>>>>>>>>>>>>>> {
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
> > >>>> value2);
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not
> > sure
> > >>>> if
> > >>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc
> would
> > >>>> have
> > >>>>>>>>> more
> > >>>>>>>>>>>>>>>>>> overhead
> > >>>>>>>>>>>>>>>>>>>>>>> than
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested
> method
> > >>>> call
> > >>>>>>> for
> > >>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than
> > RichFunctions).
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or
> > do I
> > >>>>> miss
> > >>>>>>>>>>>>>>>>>> something?)
> > >>>>>>>>>>>>>>>>>>>>> and
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more
> > top
> > >>>>> level
> > >>>>>>>>>>>>>>>> interface
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
> > >>>> `close()`
> > >>>>>>> and
> > >>>>>>>>>>>>>> also
> > >>>>>>>>>>>>>>>>>>>>>>> interfaces
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no
> abstract
> > >>>>> classes
> > >>>>>>>>>>>>>>>> required).
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP
> to
> > >>>>>>> include
> > >>>>>>>>>>>>>> rich
> > >>>>>>>>>>>>>>>>>>>>>>> functions.
> > >>>>>>>>>>>>>>>>>>>>>>>>> I
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of
> deep
> > >>>>> copying
> > >>>>>>>>> of
> > >>>>>>>>>>>>>>> keys.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu
> > Fenniak
> > >> <
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
> > >>>>>>>>> immutability of
> > >>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>> key
> > >>>>>>>>>>>>>>>>>>>>> is
> > >>>>>>>>>>>>>>>>>>>>>>>>> the
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
> > >> requiring
> > >>>>> the
> > >>>>>>>>> key
> > >>>>>>>>>>>>>> to
> > >>>>>>>>>>>>>>>> be
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> serializable
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
> > >>>>>>>>> performance
> > >>>>>>>>>>>>>>> risk.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable
> type
> > >>>>>>>>> constraints
> > >>>>>>>>>>>>>>> of
> > >>>>>>>>>>>>>>>>>>>> some
> > >>>>>>>>>>>>>>>>>>>>>>>>> kind.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> :-)
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias
> J.
> > >>>> Sax
> > >>>>> <
> > >>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow
> > this
> > >>>>> path,
> > >>>>>>>>> it
> > >>>>>>>>>>>>>>>> should
> > >>>>>>>>>>>>>>>>>>>>> cover
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
--
-- Guozhang
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Jeyhun Karimov <je...@gmail.com>.
Hi,
Sorry for late reply. Just to make everybody in sync, the current version
of KIP supports lambdas. "withKey" (ValueMapperWithKey) interfaces are
independent, meaning they do not extend from "withoutKey" (ValueMapper)
interfaces.
I agree with Guozhang, and I am personally a bit reluctant to increase
overloaded methods in public APIs but it seems this is only way to solve
all related jira issues.
However, the most overloaded methods will be with ValueJoiner type, which
will be with ValueJoinerWithKey with new overloaded methods. Other
interfaces require mostly 1 extra overload.
>> I would suggest not doing it if user pop it up, but rather suggesting
them
>> to use `map`
I agree with Matthias as the core idea of this KIP was to collect all
related jira issues and propose one-shot solution for all. Afterwards, we
broke its scope into 2 KIPs (149 and 159).
Cheers,
Jeyhun
On Mon, Jun 5, 2017 at 7:55 AM Matthias J. Sax <ma...@confluent.io>
wrote:
> I guess I missunderstood you. Your are right that overloading the method
> would also work. As both interfaces will be independent from each other,
> there should be no problem.
>
> The initial proposal was to use
>
> > interface ValueMapperWithKey extends ValueMapper
>
> and this would break Lambda. We totally missed, that we don't need new
> methods but only only overlaods. Great you point this out! I was not
> quite happy with the newly added methods.
>
> >> I would suggest not doing it if user pop it up, but rather suggesting
> them
> >> to use `map`
>
> But this might introduce unnecessary re-partitioning for downstream
> operators. I don't thinks that a good suggestion. But if we only add new
> overloads for mapValue(), flatMapValue() etc, I don't see a big issue
> with "overstaffing" the API (what is btw a very valid concern).
>
>
> -Matthias
>
>
> On 6/4/17 10:37 PM, Guozhang Wang wrote:
> > On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <ma...@confluent.io>
> > wrote:
> >
> >> We started with this proposal but it does not allow for Lambdas (in case
> >> you want key access). Do you think preserving Lambdas is not important
> >> enough for this case -- I agree that there is some price to be paid to
> >> keep Lambdas.
> >>
> >
> > Not sure if I understand this comment.. My main point is not on changing
> > the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
> > even if we want to keep them all, I'd suggest we just implement the added
> > APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc, which
> > seems simpler to me. Does that affect lambda expression usage?
> >
> >>
> >> About API consistency: I can't remember a concrete user request to have
> >> key access in all operators. But I am pretty sure, if we only add it for
> >> some, this request will pop up quickly. IMHO, it's better to do it all
> >> in one shot. (But I am not strict about it if most people think we
> >> should limit it to what was requested by users.)
> >>
> >>
> > I would suggest not doing it if user pop it up, but rather suggesting
> them
> > to use `map` etc directly but set the key unchanged rather than
> providing a
> > new operator for it. To me some syntax sugars like this seems of less
> > valuable than others (like print / writeAsText / foreach that are all
> > depending on peek), and keeping adding them will just make the DSL too
> > “overstaffed”.
> >
> >
> >>
> >> -Matthias
> >>
> >> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> >>> With KIP-159, the added "valueMapperWithKey" and
> >> "valueTransformerWithKey"
> >>> along seem to be just adding a few syntax-sugars? E.g. we can simply
> >>> implement:
> >>>
> >>> mapValues(ValueMapperWithKey mapperWithKey)
> >>>
> >>> as
> >>>
> >>> map((k, v) -> (k, mapperWithKey(k, v))
> >>>
> >>> ----------------------
> >>>
> >>> I'm not sure how many users would really need such syntax sugars, and
> >> even
> >>> they do, we can support them easily as the above implementations;
> >>>
> >>> Similarly for "ReducerWithKey", it can be implemented as `Aggregator<K,
> >> V,
> >>> V>`, and people who needs key access can just use `aggregate` directly.
> >>>
> >>> The function which I think is really of valuable is
> `ValueJoinerWithKey`,
> >>> and that seems to be the original request from users while others are
> >>> coming from "API consistency" concerns. Personally I'd prefer only keep
> >> the
> >>> last one (`InitializerWithKey` might also have some value, but I have
> not
> >>> seen people widely requesting it in their DSL usage yet; if there is a
> >>> common request we can keep it in this KIP as well). WDYT?
> >>>
> >>> Guozhang
> >>>
> >>>
> >>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <je.karimov@gmail.com
> >
> >>> wrote:
> >>>
> >>>> Thanks for clarification Matthias, now everything is clear.
> >>>>
> >>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <
> matthias@confluent.io>
> >>>> wrote:
> >>>>
> >>>>> I don't think we can drop ValueTransformerSupplier. If you don't have
> >> an
> >>>>> supplier, you only get a single instance of your function. But for a
> >>>>> stateful transformation, we need multiple instances (one for each
> task)
> >>>>> of ValueTransformer.
> >>>>>
> >>>>> We don't need suppliers for functions like "ValueMapper" etc because
> >>>>> those are stateless and thus, we can reuse a single instance over
> >>>>> multiple tasks -- but we can't do this for ValueTransformer (and
> >>>> similar).
> >>>>>
> >>>>> Btw: This reminds me about KIP-159: with regard to the RichFunction
> we
> >>>>> might need a supplier pattern, too. (I'll comment on the other
> thread,
> >>>>> too.)
> >>>>>
> >>>>>
> >>>>> -Matthias
> >>>>>
> >>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> I updated KIP.
> >>>>>> Just to avoid misunderstanding, I meant deprecating
> >>>>> ValueTransformerSupplier
> >>>>>> and I am ok with ValueTransformer.
> >>>>>> So instead of using ValueTransformerSupplier can't we directly use
> >>>>>> ValueTransformer
> >>>>>> or ValueTransformerWithKey?
> >>>>>>
> >>>>>> Btw, in current design all features of ValueTransformer will be
> >>>> available
> >>>>>> in ValueTransformerWithKey interface.
> >>>>>>
> >>>>>> Cheers,
> >>>>>> Jeyhun
> >>>>>>
> >>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> >> matthias@confluent.io
> >>>>>
> >>>>>> wrote:
> >>>>>>
> >>>>>>> Thanks Jeyhun.
> >>>>>>>
> >>>>>>> About ValueTransformer: I don't think we can remove it. Note,
> >>>>>>> ValueTransformer allows to attach a state and also allows to
> register
> >>>>>>> punctuations. Both those features will not be available via
> withKey()
> >>>>>>> interfaces.
> >>>>>>>
> >>>>>>> -Matthias
> >>>>>>>
> >>>>>>>
> >>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> >>>>>>>> Hi Matthias,
> >>>>>>>>
> >>>>>>>> Thanks for your comments.
> >>>>>>>>
> >>>>>>>> I tested the deep copy approach. It has significant overhead.
> >>>>> Especially
> >>>>>>>> for "light" and stateless operators it slows down the topology
> >>>>>>>> significantly (> 20% ). I think "warning" users about
> not-changing
> >>>> the
> >>>>>>> key
> >>>>>>>> is better warning them about possible performance loss.
> >>>>>>>>
> >>>>>>>> About the interfaces, additionally I considered adding
> >>>>>>> InitializerWithKey,
> >>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
> >>>>> included
> >>>>>>> in
> >>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my bad.
> >>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> >>>>>>>>
> >>>>>>>> One thing I want to mention is that, maybe we should deprecate
> >>>> methods
> >>>>>>> with
> >>>>>>>> argument type ValueTransformerSupplier
> >> (KStream.transformValues(...))
> >>>>> and
> >>>>>>>> and as a whole the ValueTransformerSupplier interface.
> >>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type instead
> >>>>> without
> >>>>>>>> additional supplier layer.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Cheers,
> >>>>>>>> Jeyhun
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> >>>> matthias@confluent.io
> >>>>>>
> >>>>>>>> wrote:
> >>>>>>>>
> >>>>>>>>> One more question:
> >>>>>>>>>
> >>>>>>>>> Should we add any of
> >>>>>>>>> - InitizialierWithKey
> >>>>>>>>> - ReducerWithKey
> >>>>>>>>> - ValueTransformerWithKey
> >>>>>>>>>
> >>>>>>>>> To get consistent/complete API, it might be a good idea. Any
> >>>> thoughts?
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> -Matthias
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> >>>>>>>>>> Jeyhun,
> >>>>>>>>>>
> >>>>>>>>>> I was just wondering if you did look into the key-deep-copy idea
> >> we
> >>>>>>>>>> discussed. I am curious to see what the impact might be.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> -Matthias
> >>>>>>>>>>
> >>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>> Hi,
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks for your comments. I rethink about including rich
> >> functions
> >>>>>>> into
> >>>>>>>>>>> this KIP.
> >>>>>>>>>>> I think once we include rich functions in this KIP and then fix
> >>>>>>>>>>> ProcessorContext in another KIP and incorporate with existing
> >> rich
> >>>>>>>>>>> functions, the code will not be backwards compatible.
> >>>>>>>>>>>
> >>>>>>>>>>> I see Damian's and your point more clearly now.
> >>>>>>>>>>>
> >>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
> >>>>> updated
> >>>>>>>>> the
> >>>>>>>>>>> KIP), I will try also initiate another KIP for rich functions.
> >>>>>>>>>>>
> >>>>>>>>>>> Cheers,
> >>>>>>>>>>> Jeyhun
> >>>>>>>>>>>
> >>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> >>>>>>> matthias@confluent.io
> >>>>>>>>>>
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> With the current KIP, using ValueMapper and ValueMapperWithKey
> >>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on. To
> >>>> fix
> >>>>>>> the
> >>>>>>>>>>>> original issue to allow key access, RichFunctions are not
> >>>> required
> >>>>>>>>> IMHO.
> >>>>>>>>>>>>
> >>>>>>>>>>>> I initially put the RichFunction idea on the table, because I
> >> was
> >>>>>>>>> hoping
> >>>>>>>>>>>> to get a uniform API. And I think, is was good to consider
> them
> >>>> --
> >>>>>>>>>>>> however, the discussion showed that they are not necessary for
> >>>> key
> >>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions in
> >> an
> >>>>> own
> >>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
> >> main
> >>>>>>>>>>>> challenge for this. And introducing RichFunctions with
> >>>>> parameter-less
> >>>>>>>>>>>> init() method, seem not to help too much. We would get an
> >>>>>>>>> "intermediate"
> >>>>>>>>>>>> API that we want to change anyway later on...
> >>>>>>>>>>>>
> >>>>>>>>>>>> As you put already much effort into RichFunction, feel free do
> >>>> push
> >>>>>>>>> this
> >>>>>>>>>>>> further and start a new KIP (we can do this even in parallel)
> --
> >>>> we
> >>>>>>>>>>>> don't want to slow you down :) But it make the discussion and
> >>>> code
> >>>>>>>>>>>> review easier, if we separate both IMHO.
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>> Hi Damian,
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Thanks for your comments. I think providing to users
> >> *interface*
> >>>>>>>>> rather
> >>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also
> raised
> >>>>> this
> >>>>>>>>>>>> issue
> >>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Regarding with passing additional contextual information, I
> >>>> think
> >>>>> it
> >>>>>>>>> is a
> >>>>>>>>>>>>> tradeoff,
> >>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method in
> >>>>>>> another
> >>>>>>>>> PR
> >>>>>>>>>>>>> and solve Rich functions afterwards
> >>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
> >>>>> providing
> >>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
> >>>> parameters
> >>>>>>> to
> >>>>>>>>>>>> this
> >>>>>>>>>>>>> afterwards (like improvement)
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> To me, the second approach seems more incremental. However
> you
> >>>> are
> >>>>>>>>> right,
> >>>>>>>>>>>>> the names might confuse the users.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> >>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> >>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> >>>> damian.guy@gmail.com
> >>>>>>
> >>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> >>>> RichFunction
> >>>>>>>>> which
> >>>>>>>>>>>> is
> >>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it
> to
> >>>>> pass
> >>>>>>>>> some
> >>>>>>>>>>>>>> additional contextual information, i.e., the `RecordContext`
> >>>> that
> >>>>>>>>>>>> contains
> >>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with
> it
> >>>> not
> >>>>>>>>>>>> passing
> >>>>>>>>>>>>>> this contextual information, but is the naming incorrect?
> I'm
> >>>> not
> >>>>>>>>> sure,
> >>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until
> we
> >>>> can
> >>>>>>> do
> >>>>>>>>> it
> >>>>>>>>>>>>>> properly with the correct context?
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
> >>>>>>>>>>>> RichValueJoiner,
> >>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be interfaces?
> >>>>>>>>> Generally we
> >>>>>>>>>>>>>> should provide users with Intefaces to code against, not
> >>>> classes.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Thanks,
> >>>>>>>>>>>>>> Damian
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> >>>>> je.karimov@gmail.com>
> >>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better
> overview.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> The only reason that I used abstract class instead of
> >>>> interface
> >>>>>>> for
> >>>>>>>>>>>> Rich
> >>>>>>>>>>>>>>> functions is that in future if we will have some
> >>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>> abstract classes,
> >>>>>>>>>>>>>>> we can easily extend:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR> implements
> >>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> >>>>>>>>>>>>>> AbstractRichFunction*{
> >>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
> >>>>>>> inheritance.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> However, I think we can easily change it (from abstract
> class
> >>>> ->
> >>>>>>>>>>>>>> interface)
> >>>>>>>>>>>>>>> if you think interface is a better fit.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> >>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
> >>>>> improved
> >>>>>>>>> now
> >>>>>>>>>>>>>> --
> >>>>>>>>>>>>>>>> great job!
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
> >>>> classes
> >>>>>>> and
> >>>>>>>>>>>> not
> >>>>>>>>>>>>>>>> interfaces?
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>>>> interfaces
> >>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> >>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So they
> >>>>> don't
> >>>>>>>>> have
> >>>>>>>>>>>>>>>> direct
> >>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only
> one
> >>>>>>>>> method ,
> >>>>>>>>>>>>>> so
> >>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>> can use lambdas.
> >>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play?
> Inside
> >>>>> Rich
> >>>>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular
> *withKey*
> >>>> and
> >>>>>>> and
> >>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We get
> >>>>> those
> >>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>> and wrap into Rich function while building the topology,
> >> and
> >>>>>>> send
> >>>>>>>>> to
> >>>>>>>>>>>>>>>>> Processor.
> >>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions implement
> >>>>>>>>> *withKey*
> >>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition. In
> >>>> this
> >>>>>>>>> case,
> >>>>>>>>>>>>>>> while
> >>>>>>>>>>>>>>>>> building the topology we do a type check if the object
> type
> >>>> is
> >>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for
> Rich
> >>>>>>>>> functions
> >>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>> does not affect using lambdas.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> need
> >>>> to
> >>>>>>>>> have a
> >>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>> RichFunction
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for
> *withKey*
> >>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will remove
> >> the
> >>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient
> to
> >>>>>>>>> support
> >>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >> "extended
> >>>>>>> API".
> >>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> >>>> more
> >>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> >>>>>>> because
> >>>>>>>>> we
> >>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> >>>> value
> >>>>> in
> >>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one
> extra
> >>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is *withKey*
> >>>>>>> version
> >>>>>>>>> of
> >>>>>>>>>>>>>>>>> particular interface.
> >>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
> >>>>> function
> >>>>>>>>>>>>>>>> implements
> >>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
> >>>>>>>>> differentiate
> >>>>>>>>>>>>>>>> them
> >>>>>>>>>>>>>>>>> while building the topology.
> >>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
> >>>>> comment:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can we
> >>>> have
> >>>>> a
> >>>>>>>>>>>>>> design
> >>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
> >>>> might
> >>>>>>> make
> >>>>>>>>>>>>>>> sense
> >>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> However, I don't think that this complicates the overall
> >>>>> design
> >>>>>>>>>>>>>>>>> significantly.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
> >> to
> >>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> >>>> this
> >>>>>>>>> also
> >>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >>>> before
> >>>>>>>>> driving
> >>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
> >>>> functions
> >>>>>>> as I
> >>>>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to library.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Any comments are appreciated.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> >>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> thanks for the update.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>>>> interfaces
> >>>>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we
> need
> >>>> to
> >>>>>>>>> have a
> >>>>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >>>> RichFunction
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
> >> sense
> >>>>>>>>> anymore,
> >>>>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> >>>>>>>>> implementation of
> >>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you would
> >>>>>>>>> implement a
> >>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient
> >> to
> >>>>>>>>> support
> >>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> >> "extended
> >>>>>>> API".
> >>>>>>>>>>>>>> For
> >>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> >>>> more
> >>>>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> >>>>>>> because
> >>>>>>>>> we
> >>>>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> >>>> value
> >>>>> in
> >>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make
> sense
> >>>> to
> >>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> >>>> this
> >>>>>>>>> also
> >>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >>>> before
> >>>>>>>>> driving
> >>>>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Thoughts?
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your
> comments.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> little
> >>>>>>> bit? I
> >>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> >> problem
> >>>>> is.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an interface
> >>>> that
> >>>>>>> has
> >>>>>>>>>>>>>> just
> >>>>>>>>>>>>>>>> one
> >>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single function
> >>>>>>>>> contract".
> >>>>>>>>>>>>>>>>>>> So basically once we extend some interface from another
> >>>> (in
> >>>>>>> our
> >>>>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
> >> lambdas
> >>>>> in
> >>>>>>>>> the
> >>>>>>>>>>>>>>>>>> extended
> >>>>>>>>>>>>>>>>>>> interface.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
> >>>>>>> reformat
> >>>>>>>>> the
> >>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> help.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - I will work on the KIP.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> >>>> overlaods
> >>>>>>>>> added
> >>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
> >>>> add
> >>>>>>> any
> >>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and public
> >>>> APIs
> >>>>>>> to
> >>>>>>>>> be
> >>>>>>>>>>>>>>>>>>> changed (KStream-KTable
> >>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
> >>>>> structure:
> >>>>>>>>> we
> >>>>>>>>>>>>>>>>>> overload
> >>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> >>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
> >>>> inside
> >>>>>>> the
> >>>>>>>>>>>>>>>>>> processor
> >>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
> >>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the overall
> >>>> idea
> >>>>>>> with
> >>>>>>>>>>>>>> only
> >>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all
> changes.
> >>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)*
> and*
> >>>>>>>>> close()*
> >>>>>>>>>>>>>>>>>> methods
> >>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>>>> void close () {}
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> I thought that we can override them once in
> >>>>>>>>> *AbstractRichFunction*
> >>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>> extent new Rich functions from *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease
> the
> >>>>>>>>>>>>>>> maintenance.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> >>>> Merger,
> >>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
> >>>> all,
> >>>>>>> but
> >>>>>>>>> we
> >>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> >>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique applies
> >> to
> >>>>> all
> >>>>>>>>> this
> >>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
> >>>> wanted
> >>>>>>> to
> >>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>> overall intuition.
> >>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` -- `ValueXXWithKey`
> >> --
> >>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>>> interfaces
> >>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should
> not
> >>>>> force
> >>>>>>>>>>>>>> users
> >>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> >> functions
> >>>>>>> every
> >>>>>>>>>>>>>> time
> >>>>>>>>>>>>>>>>>> they
> >>>>>>>>>>>>>>>>>>> use Rich functions.
> >>>>>>>>>>>>>>>>>>> If one needs, she can override the respective methods.
> >>>>>>> However,
> >>>>>>>>> I
> >>>>>>>>>>>>>> am
> >>>>>>>>>>>>>>>> open
> >>>>>>>>>>>>>>>>>>> for discussion.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> spread
> >>>> any
> >>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> >>>> done
> >>>>>>>>> before
> >>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> too
> >>>>>>> large.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
> >>>>> *init(ProcessorContext)*
> >>>>>>>>>>>>>> method
> >>>>>>>>>>>>>>>>>>> persistent among the library (which use
> ProcessorContext
> >>>> as
> >>>>> an
> >>>>>>>>>>>>>>> input),
> >>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> >>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and @mjsax
> >>>>>>>>> mentioned)
> >>>>>>>>>>>>>>>> whether
> >>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access to
> >>>>>>>>>>>>>>>> *ProcessorContext*
> >>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
> >>>>>>>>>>>>>>>>>>> initiate another KIP before this.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>
> >>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> >>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> >>>>>>>>> damian.guy@gmail.com>
> >>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext`
> spread
> >>>>> any
> >>>>>>>>>>>>>> further
> >>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> >>>> done
> >>>>>>>>> before
> >>>>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming
> too
> >>>>>>> large.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> >>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is too
> >>>>> broad
> >>>>>>> in
> >>>>>>>>>>>>>>>> general
> >>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and it's
> >>>> also
> >>>>>>>>>>>>>> reflected
> >>>>>>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
> >>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the `RichFunction`
> >>>>>>>>> approach in
> >>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the scope
> >> of
> >>>>>>> this
> >>>>>>>>> KIP
> >>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for it
> >>>> and
> >>>>>>>>> delay
> >>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>>>>> until the other one is done?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> >>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach. Do
> >> we
> >>>>>>>>> really
> >>>>>>>>>>>>>>> want
> >>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext` ?
> It
> >>>>> has
> >>>>>>> a
> >>>>>>>>>>>>>> bunch
> >>>>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of
> the
> >>>>> DSL
> >>>>>>>>>>>>>>> methods,
> >>>>>>>>>>>>>>>>>>>> i.e,
> >>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
> >> etc.
> >>>>> It
> >>>>>>> is
> >>>>>>>>>>>>>> far
> >>>>>>>>>>>>>>>> too
> >>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a narrower
> >>>>>>>>> interface
> >>>>>>>>>>>>>>> like
> >>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
> >>>>>>>>>>>>>>>> methods/interfaces
> >>>>>>>>>>>>>>>>>>>>> later
> >>>>>>>>>>>>>>>>>>>>>> than to remove them
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> >>>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> >>>>> little
> >>>>>>>>> bit?
> >>>>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> >>>>> problem
> >>>>>>>>> is.
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess
> it's
> >>>> up
> >>>>>>> to
> >>>>>>>>>>>>>> you.
> >>>>>>>>>>>>>>>>>>>> Maybe a
> >>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you
> maybe
> >>>>>>>>> reformat
> >>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> >>>> help.
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> >>>>>>> overlaods
> >>>>>>>>>>>>>>> added
> >>>>>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
> >> to
> >>>>> add
> >>>>>>>>> any
> >>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer,
> ForeachAction,
> >>>>>>> Merger,
> >>>>>>>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add
> to
> >>>>> all,
> >>>>>>>>> but
> >>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make
> sense
> >>>>>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> >>>> `ValueXXWithKey`
> >>>>> --
> >>>>>>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>>>> interfaces
> >>>>>>>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot extend
> >>>> the
> >>>>>>> two
> >>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>> if
> >>>>>>>>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1].
> Maybe I
> >>>>>>> should
> >>>>>>>>>>>>>>> change
> >>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP to
> >>>> only
> >>>>>>>>>>>>>>>> ValueMapper,
> >>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> >>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/
> confluence/display/KAFKA/KIP-
> >>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
> >>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
> >>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper` we
> >>>> don't
> >>>>>>>>> need
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
> >> happens
> >>>>>>> when
> >>>>>>>>>>>>>>>> building
> >>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> >>>> KafkaStream#start()
> >>>>>>> we
> >>>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>>>> need
> >>>>>>>>>>>>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use `ValueMapperWithKey`)
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> >>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> >>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
> >> super
> >>>>> V,
> >>>>>>> ?
> >>>>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>>>>>> VR>
> >>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> >>>>>>>>>>>>>>>>>>>>>>>>>> with
> >>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> >>>> mapValues(ValueMapperWithKey<?
> >>>>>>>>> super
> >>>>>>>>>>>>>> V,
> >>>>>>>>>>>>>>> ?
> >>>>>>>>>>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>>>>>>>>>>> VR>
> >>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still have
> to
> >>>>>>> check
> >>>>>>>>> it
> >>>>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
> >>>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into
> the
> >>>>> rich
> >>>>>>>>>>>>>>> function.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal
> Borowiecki
> >> <
> >>>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
> >> wondering,
> >>>>> if
> >>>>>>> we
> >>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>> do
> >>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a
> RichFunction
> >>>>> and
> >>>>>>>>>>>>>>>>>>>>> non-RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>> at
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions all
> >> the
> >>>>>>> time.
> >>>>>>>>>>>>>>> Thus,
> >>>>>>>>>>>>>>>> on
> >>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> DSL
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
> >>>> non-RichFunction,
> >>>>>>> we
> >>>>>>>>>>>>>> wrap
> >>>>>>>>>>>>>>> it
> >>>>>>>>>>>>>>>>>>>> by a
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
> >>>> Streams.
> >>>>>>> This
> >>>>>>>>>>>>>>>>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the key:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
> >>>> snippet):
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
> >>>>>>>>>>>>>> RichValueMapper()
> >>>>>>>>>>>>>>> {
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper; //
> >>>> set
> >>>>> by
> >>>>>>>>>>>>>>>>>> constructor
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
> >> value1,
> >>>>>>>>> final V2
> >>>>>>>>>>>>>>>>>>>> value2)
> >>>>>>>>>>>>>>>>>>>>> {
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
> >>>> value2);
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not
> sure
> >>>> if
> >>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc would
> >>>> have
> >>>>>>>>> more
> >>>>>>>>>>>>>>>>>> overhead
> >>>>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested method
> >>>> call
> >>>>>>> for
> >>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than
> RichFunctions).
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or
> do I
> >>>>> miss
> >>>>>>>>>>>>>>>>>> something?)
> >>>>>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more
> top
> >>>>> level
> >>>>>>>>>>>>>>>> interface
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
> >>>> `close()`
> >>>>>>> and
> >>>>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no abstract
> >>>>> classes
> >>>>>>>>>>>>>>>> required).
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP to
> >>>>>>> include
> >>>>>>>>>>>>>> rich
> >>>>>>>>>>>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of deep
> >>>>> copying
> >>>>>>>>> of
> >>>>>>>>>>>>>>> keys.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu
> Fenniak
> >> <
> >>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
> >>>>>>>>> immutability of
> >>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>> key
> >>>>>>>>>>>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
> >> requiring
> >>>>> the
> >>>>>>>>> key
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>>>>>>>> serializable
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
> >>>>>>>>> performance
> >>>>>>>>>>>>>>> risk.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable type
> >>>>>>>>> constraints
> >>>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>> some
> >>>>>>>>>>>>>>>>>>>>>>>>> kind.
> >>>>>>>>>>>>>>>>>>>>>>>>>>> :-)
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias J.
> >>>> Sax
> >>>>> <
> >>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow
> this
> >>>>> path,
> >>>>>>>>> it
> >>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>> cover
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by "Matthias J. Sax" <ma...@confluent.io>.
I guess I missunderstood you. Your are right that overloading the method
would also work. As both interfaces will be independent from each other,
there should be no problem.
The initial proposal was to use
> interface ValueMapperWithKey extends ValueMapper
and this would break Lambda. We totally missed, that we don't need new
methods but only only overlaods. Great you point this out! I was not
quite happy with the newly added methods.
>> I would suggest not doing it if user pop it up, but rather suggesting them
>> to use `map`
But this might introduce unnecessary re-partitioning for downstream
operators. I don't thinks that a good suggestion. But if we only add new
overloads for mapValue(), flatMapValue() etc, I don't see a big issue
with "overstaffing" the API (what is btw a very valid concern).
-Matthias
On 6/4/17 10:37 PM, Guozhang Wang wrote:
> On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <ma...@confluent.io>
> wrote:
>
>> We started with this proposal but it does not allow for Lambdas (in case
>> you want key access). Do you think preserving Lambdas is not important
>> enough for this case -- I agree that there is some price to be paid to
>> keep Lambdas.
>>
>
> Not sure if I understand this comment.. My main point is not on changing
> the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
> even if we want to keep them all, I'd suggest we just implement the added
> APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc, which
> seems simpler to me. Does that affect lambda expression usage?
>
>>
>> About API consistency: I can't remember a concrete user request to have
>> key access in all operators. But I am pretty sure, if we only add it for
>> some, this request will pop up quickly. IMHO, it's better to do it all
>> in one shot. (But I am not strict about it if most people think we
>> should limit it to what was requested by users.)
>>
>>
> I would suggest not doing it if user pop it up, but rather suggesting them
> to use `map` etc directly but set the key unchanged rather than providing a
> new operator for it. To me some syntax sugars like this seems of less
> valuable than others (like print / writeAsText / foreach that are all
> depending on peek), and keeping adding them will just make the DSL too
> “overstaffed”.
>
>
>>
>> -Matthias
>>
>> On 6/4/17 6:23 PM, Guozhang Wang wrote:
>>> With KIP-159, the added "valueMapperWithKey" and
>> "valueTransformerWithKey"
>>> along seem to be just adding a few syntax-sugars? E.g. we can simply
>>> implement:
>>>
>>> mapValues(ValueMapperWithKey mapperWithKey)
>>>
>>> as
>>>
>>> map((k, v) -> (k, mapperWithKey(k, v))
>>>
>>> ----------------------
>>>
>>> I'm not sure how many users would really need such syntax sugars, and
>> even
>>> they do, we can support them easily as the above implementations;
>>>
>>> Similarly for "ReducerWithKey", it can be implemented as `Aggregator<K,
>> V,
>>> V>`, and people who needs key access can just use `aggregate` directly.
>>>
>>> The function which I think is really of valuable is `ValueJoinerWithKey`,
>>> and that seems to be the original request from users while others are
>>> coming from "API consistency" concerns. Personally I'd prefer only keep
>> the
>>> last one (`InitializerWithKey` might also have some value, but I have not
>>> seen people widely requesting it in their DSL usage yet; if there is a
>>> common request we can keep it in this KIP as well). WDYT?
>>>
>>> Guozhang
>>>
>>>
>>> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <je...@gmail.com>
>>> wrote:
>>>
>>>> Thanks for clarification Matthias, now everything is clear.
>>>>
>>>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <ma...@confluent.io>
>>>> wrote:
>>>>
>>>>> I don't think we can drop ValueTransformerSupplier. If you don't have
>> an
>>>>> supplier, you only get a single instance of your function. But for a
>>>>> stateful transformation, we need multiple instances (one for each task)
>>>>> of ValueTransformer.
>>>>>
>>>>> We don't need suppliers for functions like "ValueMapper" etc because
>>>>> those are stateless and thus, we can reuse a single instance over
>>>>> multiple tasks -- but we can't do this for ValueTransformer (and
>>>> similar).
>>>>>
>>>>> Btw: This reminds me about KIP-159: with regard to the RichFunction we
>>>>> might need a supplier pattern, too. (I'll comment on the other thread,
>>>>> too.)
>>>>>
>>>>>
>>>>> -Matthias
>>>>>
>>>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I updated KIP.
>>>>>> Just to avoid misunderstanding, I meant deprecating
>>>>> ValueTransformerSupplier
>>>>>> and I am ok with ValueTransformer.
>>>>>> So instead of using ValueTransformerSupplier can't we directly use
>>>>>> ValueTransformer
>>>>>> or ValueTransformerWithKey?
>>>>>>
>>>>>> Btw, in current design all features of ValueTransformer will be
>>>> available
>>>>>> in ValueTransformerWithKey interface.
>>>>>>
>>>>>> Cheers,
>>>>>> Jeyhun
>>>>>>
>>>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
>> matthias@confluent.io
>>>>>
>>>>>> wrote:
>>>>>>
>>>>>>> Thanks Jeyhun.
>>>>>>>
>>>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>>>> ValueTransformer allows to attach a state and also allows to register
>>>>>>> punctuations. Both those features will not be available via withKey()
>>>>>>> interfaces.
>>>>>>>
>>>>>>> -Matthias
>>>>>>>
>>>>>>>
>>>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>>>> Hi Matthias,
>>>>>>>>
>>>>>>>> Thanks for your comments.
>>>>>>>>
>>>>>>>> I tested the deep copy approach. It has significant overhead.
>>>>> Especially
>>>>>>>> for "light" and stateless operators it slows down the topology
>>>>>>>> significantly (> 20% ). I think "warning" users about not-changing
>>>> the
>>>>>>> key
>>>>>>>> is better warning them about possible performance loss.
>>>>>>>>
>>>>>>>> About the interfaces, additionally I considered adding
>>>>>>> InitializerWithKey,
>>>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
>>>>> included
>>>>>>> in
>>>>>>>> PR but not in KIP. I will also include them in KIP, sorry my bad.
>>>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>>>
>>>>>>>> One thing I want to mention is that, maybe we should deprecate
>>>> methods
>>>>>>> with
>>>>>>>> argument type ValueTransformerSupplier
>> (KStream.transformValues(...))
>>>>> and
>>>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>>>> We can use ValueTransformer/ValueTransformerWithKey type instead
>>>>> without
>>>>>>>> additional supplier layer.
>>>>>>>>
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Jeyhun
>>>>>>>>
>>>>>>>>
>>>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>>>> matthias@confluent.io
>>>>>>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> One more question:
>>>>>>>>>
>>>>>>>>> Should we add any of
>>>>>>>>> - InitizialierWithKey
>>>>>>>>> - ReducerWithKey
>>>>>>>>> - ValueTransformerWithKey
>>>>>>>>>
>>>>>>>>> To get consistent/complete API, it might be a good idea. Any
>>>> thoughts?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -Matthias
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>>>> Jeyhun,
>>>>>>>>>>
>>>>>>>>>> I was just wondering if you did look into the key-deep-copy idea
>> we
>>>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> -Matthias
>>>>>>>>>>
>>>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> Thanks for your comments. I rethink about including rich
>> functions
>>>>>>> into
>>>>>>>>>>> this KIP.
>>>>>>>>>>> I think once we include rich functions in this KIP and then fix
>>>>>>>>>>> ProcessorContext in another KIP and incorporate with existing
>> rich
>>>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>>>
>>>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>>>
>>>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
>>>>> updated
>>>>>>>>> the
>>>>>>>>>>> KIP), I will try also initiate another KIP for rich functions.
>>>>>>>>>>>
>>>>>>>>>>> Cheers,
>>>>>>>>>>> Jeyhun
>>>>>>>>>>>
>>>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>>>> matthias@confluent.io
>>>>>>>>>>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> With the current KIP, using ValueMapper and ValueMapperWithKey
>>>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on. To
>>>> fix
>>>>>>> the
>>>>>>>>>>>> original issue to allow key access, RichFunctions are not
>>>> required
>>>>>>>>> IMHO.
>>>>>>>>>>>>
>>>>>>>>>>>> I initially put the RichFunction idea on the table, because I
>> was
>>>>>>>>> hoping
>>>>>>>>>>>> to get a uniform API. And I think, is was good to consider them
>>>> --
>>>>>>>>>>>> however, the discussion showed that they are not necessary for
>>>> key
>>>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions in
>> an
>>>>> own
>>>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
>> main
>>>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>>>> parameter-less
>>>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>>>> "intermediate"
>>>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>>>
>>>>>>>>>>>> As you put already much effort into RichFunction, feel free do
>>>> push
>>>>>>>>> this
>>>>>>>>>>>> further and start a new KIP (we can do this even in parallel) --
>>>> we
>>>>>>>>>>>> don't want to slow you down :) But it make the discussion and
>>>> code
>>>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks for your comments. I think providing to users
>> *interface*
>>>>>>>>> rather
>>>>>>>>>>>>> than *abstract class* should be preferred (Matthias also raised
>>>>> this
>>>>>>>>>>>> issue
>>>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Regarding with passing additional contextual information, I
>>>> think
>>>>> it
>>>>>>>>> is a
>>>>>>>>>>>>> tradeoff,
>>>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method in
>>>>>>> another
>>>>>>>>> PR
>>>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
>>>>> providing
>>>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>>>> parameters
>>>>>>> to
>>>>>>>>>>>> this
>>>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>>>
>>>>>>>>>>>>> To me, the second approach seems more incremental. However you
>>>> are
>>>>>>>>> right,
>>>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>>>> damian.guy@gmail.com
>>>>>>
>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>>>> RichFunction
>>>>>>>>> which
>>>>>>>>>>>> is
>>>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it to
>>>>> pass
>>>>>>>>> some
>>>>>>>>>>>>>> additional contextual information, i.e., the `RecordContext`
>>>> that
>>>>>>>>>>>> contains
>>>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with it
>>>> not
>>>>>>>>>>>> passing
>>>>>>>>>>>>>> this contextual information, but is the naming incorrect? I'm
>>>> not
>>>>>>>>> sure,
>>>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until we
>>>> can
>>>>>>> do
>>>>>>>>> it
>>>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
>>>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>>>> RichInitializer etc. Why can't they not just be interfaces?
>>>>>>>>> Generally we
>>>>>>>>>>>>>> should provide users with Intefaces to code against, not
>>>> classes.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>> Damian
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>>>> je.karimov@gmail.com>
>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better overview.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> The only reason that I used abstract class instead of
>>>> interface
>>>>>>> for
>>>>>>>>>>>> Rich
>>>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR> implements
>>>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>>>> inheritance.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> However, I think we can easily change it (from abstract class
>>>> ->
>>>>>>>>>>>>>> interface)
>>>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
>>>>> improved
>>>>>>>>> now
>>>>>>>>>>>>>> --
>>>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
>>>> classes
>>>>>>> and
>>>>>>>>>>>> not
>>>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>> interfaces
>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So they
>>>>> don't
>>>>>>>>> have
>>>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only one
>>>>>>>>> method ,
>>>>>>>>>>>>>> so
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play? Inside
>>>>> Rich
>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular *withKey*
>>>> and
>>>>>>> and
>>>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We get
>>>>> those
>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>> and wrap into Rich function while building the topology,
>> and
>>>>>>> send
>>>>>>>>> to
>>>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions implement
>>>>>>>>> *withKey*
>>>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition. In
>>>> this
>>>>>>>>> case,
>>>>>>>>>>>>>>> while
>>>>>>>>>>>>>>>>> building the topology we do a type check if the object type
>>>> is
>>>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for Rich
>>>>>>>>> functions
>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
>>>> to
>>>>>>>>> have a
>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>> RichFunction
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> As I said above, currently we support lambdas for *withKey*
>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>> well. However, I agree with your idea and I will remove
>> the
>>>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
>>>>>>>>> support
>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>> "extended
>>>>>>> API".
>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
>>>> more
>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
>>>>>>> because
>>>>>>>>> we
>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>> value
>>>>> in
>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Just to clarify, with current design we have only one extra
>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is *withKey*
>>>>>>> version
>>>>>>>>> of
>>>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
>>>>> function
>>>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
>>>>>>>>> differentiate
>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
>>>>> comment:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can we
>>>> have
>>>>> a
>>>>>>>>>>>>>> design
>>>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
>>>> might
>>>>>>> make
>>>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> However, I don't think that this complicates the overall
>>>>> design
>>>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
>> to
>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
>>>> this
>>>>>>>>> also
>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>> before
>>>>>>>>> driving
>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>>>> functions
>>>>>>> as I
>>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>> think that they bring extra layer of overhead to library.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>>>> interfaces
>>>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
>>>> to
>>>>>>>>> have a
>>>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>>>> RichFunction
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
>> sense
>>>>>>>>> anymore,
>>>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>>>> implementation of
>>>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you would
>>>>>>>>> implement a
>>>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient
>> to
>>>>>>>>> support
>>>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
>> "extended
>>>>>>> API".
>>>>>>>>>>>>>> For
>>>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
>>>> more
>>>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
>>>>>>> because
>>>>>>>>> we
>>>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>>>> value
>>>>> in
>>>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
>>>> to
>>>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
>>>> this
>>>>>>>>> also
>>>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>>>> before
>>>>>>>>> driving
>>>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your comments.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a little
>>>>>>> bit? I
>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>> problem
>>>>> is.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an interface
>>>> that
>>>>>>> has
>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>>>> abstract method, and thus represents a single function
>>>>>>>>> contract".
>>>>>>>>>>>>>>>>>>> So basically once we extend some interface from another
>>>> (in
>>>>>>> our
>>>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
>> lambdas
>>>>> in
>>>>>>>>> the
>>>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
>>>>>>> reformat
>>>>>>>>> the
>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would help.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>> overlaods
>>>>>>>>> added
>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
>>>> add
>>>>>>> any
>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and public
>>>> APIs
>>>>>>> to
>>>>>>>>> be
>>>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
>>>>> structure:
>>>>>>>>> we
>>>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
>>>> inside
>>>>>>> the
>>>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
>>>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the overall
>>>> idea
>>>>>>> with
>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all changes.
>>>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)* and*
>>>>>>>>> close()*
>>>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>> extent new Rich functions from *AbstractRichFunction*.
>>>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease the
>>>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>>>> Merger,
>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
>>>> all,
>>>>>>> but
>>>>>>>>> we
>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique applies
>> to
>>>>> all
>>>>>>>>> this
>>>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
>>>> wanted
>>>>>>> to
>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` -- `ValueXXWithKey`
>> --
>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>> interfaces
>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should not
>>>>> force
>>>>>>>>>>>>>> users
>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
>> functions
>>>>>>> every
>>>>>>>>>>>>>> time
>>>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>>>> If one needs, she can override the respective methods.
>>>>>>> However,
>>>>>>>>> I
>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
>>>> any
>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
>>>> done
>>>>>>>>> before
>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
>>>>>>> large.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>>>> *init(ProcessorContext)*
>>>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>>>> persistent among the library (which use ProcessorContext
>>>> as
>>>>> an
>>>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and @mjsax
>>>>>>>>> mentioned)
>>>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>>>> continue this KIP without providing users an access to
>>>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
>>>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>
>>>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
>>>>> any
>>>>>>>>>>>>>> further
>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
>>>> done
>>>>>>>>> before
>>>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
>>>>>>> large.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is too
>>>>> broad
>>>>>>> in
>>>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and it's
>>>> also
>>>>>>>>>>>>>> reflected
>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the `RichFunction`
>>>>>>>>> approach in
>>>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the scope
>> of
>>>>>>> this
>>>>>>>>> KIP
>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for it
>>>> and
>>>>>>>>> delay
>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach. Do
>> we
>>>>>>>>> really
>>>>>>>>>>>>>>> want
>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext` ? It
>>>>> has
>>>>>>> a
>>>>>>>>>>>>>> bunch
>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of the
>>>>> DSL
>>>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
>> etc.
>>>>> It
>>>>>>> is
>>>>>>>>>>>>>> far
>>>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a narrower
>>>>>>>>> interface
>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
>>>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>>>> little
>>>>>>>>> bit?
>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>>>> problem
>>>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess it's
>>>> up
>>>>>>> to
>>>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
>>>>>>>>> reformat
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
>>>> help.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>>>> overlaods
>>>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
>> to
>>>>> add
>>>>>>>>> any
>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>>>>>>> Merger,
>>>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
>>>>> all,
>>>>>>>>> but
>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>>>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>>>> `ValueXXWithKey`
>>>>> --
>>>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>>>> interfaces
>>>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot extend
>>>> the
>>>>>>> two
>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1]. Maybe I
>>>>>>> should
>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP to
>>>> only
>>>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
>>>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper` we
>>>> don't
>>>>>>>>> need
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
>> happens
>>>>>>> when
>>>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>>>> KafkaStream#start()
>>>>>>> we
>>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>>>> check as we will always use `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
>> super
>>>>> V,
>>>>>>> ?
>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>>>> mapValues(ValueMapperWithKey<?
>>>>>>>>> super
>>>>>>>>>>>>>> V,
>>>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still have to
>>>>>>> check
>>>>>>>>> it
>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into the
>>>>> rich
>>>>>>>>>>>>>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal Borowiecki
>> <
>>>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
>> wondering,
>>>>> if
>>>>>>> we
>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a RichFunction
>>>>> and
>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>> at
>>>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions all
>> the
>>>>>>> time.
>>>>>>>>>>>>>>> Thus,
>>>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
>>>> non-RichFunction,
>>>>>>> we
>>>>>>>>>>>>>> wrap
>>>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>>>> by a
>>>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
>>>> Streams.
>>>>>>> This
>>>>>>>>>>>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the key:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
>>>> snippet):
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
>>>>>>>>>>>>>> RichValueMapper()
>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper; //
>>>> set
>>>>> by
>>>>>>>>>>>>>>>>>> constructor
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
>> value1,
>>>>>>>>> final V2
>>>>>>>>>>>>>>>>>>>> value2)
>>>>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
>>>> value2);
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not sure
>>>> if
>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc would
>>>> have
>>>>>>>>> more
>>>>>>>>>>>>>>>>>> overhead
>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested method
>>>> call
>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than RichFunctions).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or do I
>>>>> miss
>>>>>>>>>>>>>>>>>> something?)
>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more top
>>>>> level
>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
>>>> `close()`
>>>>>>> and
>>>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no abstract
>>>>> classes
>>>>>>>>>>>>>>>> required).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP to
>>>>>>> include
>>>>>>>>>>>>>> rich
>>>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of deep
>>>>> copying
>>>>>>>>> of
>>>>>>>>>>>>>>> keys.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu Fenniak
>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
>>>>>>>>> immutability of
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
>> requiring
>>>>> the
>>>>>>>>> key
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>>> serializable
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
>>>>>>>>> performance
>>>>>>>>>>>>>>> risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable type
>>>>>>>>> constraints
>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>>>>>> kind.
>>>>>>>>>>>>>>>>>>>>>>>>>>> :-)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias J.
>>>> Sax
>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow this
>>>>> path,
>>>>>>>>> it
>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>> cover
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> About guarding the key -- I am still not sure
>>>>> what
>>>>>>>>> to
>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>> about
>>>>>>>>>>>>>>>>>>>>>>> it...
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Maybe it might be enough to document it (and
>>>>> name
>>>>>>>>> the
>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `readOnlyKey` to make is very clear).
>>>>> Ultimately,
>>>>>>> I
>>>>>>>>>>>>>> would
>>>>>>>>>>>>>>>>>>>> prefer
>>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> guard against any modification, but I have no
>>>>> good
>>>>>>>>> idea
>>>>>>>>>>>>>>> how
>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>>>>>>>>> this.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Not sure what others think about the risk of
>>>>>>>>> corrupted
>>>>>>>>>>>>>>>>>>>>>>> partitioning
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (what would be a user error and we could say,
>>>>>>> well,
>>>>>>>>> bad
>>>>>>>>>>>>>>>> luck,
>>>>>>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>>>>>>>>>>> got
>>>>>>>>>>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bug in your code, that's not our fault), vs
>>>> deep
>>>>>>>>> copy
>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>>>> potential
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> performance hit (that we can't quantity atm
>>>>>>> without
>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> test).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> We do have a performance system test. Maybe
>>>> it's
>>>>>>>>> worth
>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>> apply
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the deep copy strategy and run the test. It's
>>>>> very
>>>>>>>>>>>>>> basic
>>>>>>>>>>>>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> test only, but might give some insight. If
>> you
>>>>>>> want
>>>>>>>>> to
>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>> this,
>>>>>>>>>>>>>>>>>>>>>>> look
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> into folder "tests" for general test setup,
>>>> and
>>>>>>> into
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "tests/kafaktests/benchmarks/streams" to
>> find
>>>>> find
>>>>>>>>> the
>>>>>>>>>>>>>>> perf
>>>>>>>>>>>>>>>>>>>>> test.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/5/17 8:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I think extending KIP to include
>>>> RichFunctions
>>>>>>>>> totally
>>>>>>>>>>>>>>>>>> makes
>>>>>>>>>>>>>>>>>>>>>>>>> sense.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> So,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> we don't want to guard the keys because it
>>>> is
>>>>>>>>>>>>>> costly.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If we introduce RichFunctions I think it
>>>> should
>>>>>>>>> not be
>>>>>>>>>>>>>>>>>>>> limited
>>>>>>>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the 3
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces proposed in KIP but to wide range
>>>> of
>>>>>>>>>>>>>>>> interfaces.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 12:04 AM Matthias J.
>>>>> Sax <
>>>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> One follow up. There was this email on the
>>>>> user
>>>>>>>>> list:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> http://search-hadoop.com/m/Kafka/uyzND17KhCaBzPSZ1?subj=
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Shouldn+t+the+initializer+of+a+stream+aggregate+accept+the+
>>>>>>>>>>>>>>>>>>>> key+
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It might make sense so include
>> Initializer,
>>>>>>> Adder,
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>> Substractor
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> inferface, too.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And we should double check if there are
>>>> other
>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>> might
>>>>>>>>>>>>>>>>>>>>>>>>>>> miss
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> atm.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/4/17 1:31 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for updating the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Deep copying the key will work for sure,
>>>> but
>>>>> I
>>>>>>> am
>>>>>>>>>>>>>>>> actually
>>>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>>>> little
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bit
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> worried about performance impact... We
>>>> might
>>>>>>>>> want to
>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>>>> test
>>>>>>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> quantify this impact.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: this remind me about the idea of
>>>>>>>>> `RichFunction`
>>>>>>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>>>> that
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> would allow users to access record
>> metadata
>>>>>>> (like
>>>>>>>>>>>>>>>>>>>> timestamp,
>>>>>>>>>>>>>>>>>>>>>>>>>>> offset,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> partition etc) within DSL. This would be
>> a
>>>>>>>>> similar
>>>>>>>>>>>>>>>>>> concept.
>>>>>>>>>>>>>>>>>>>>>>>>> Thus, I
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wondering, if it would make sense to
>>>> enlarge
>>>>>>> the
>>>>>>>>>>>>>> scope
>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>>>> by
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> that? WDYT?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/3/17 2:08 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Mathieu,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback. I followed similar
>>>>>>> approach
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>> updated
>>>>>>>>>>>>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accordingly. I tried to guard the key in
>>>>>>>>> Processors
>>>>>>>>>>>>>>>>>>>> sending
>>>>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>>>> copy
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> an
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> actual key.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because I am doing deep copy of an
>>>> object, I
>>>>>>>>> think
>>>>>>>>>>>>>>>> memory
>>>>>>>>>>>>>>>>>>>>> can
>>>>>>>>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bottleneck
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in some use-cases.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 2, 2017 at 5:10 PM Mathieu
>>>>>>> Fenniak <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach would change ValueMapper
>>>>>>>>> (...etc) to
>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>> classes,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, which is also a backwards
>>>>>>>>> incompatible
>>>>>>>>>>>>>>>>>>>> change.
>>>>>>>>>>>>>>>>>>>>>>> An
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> alternative
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> approach that would be backwards
>>>> compatible
>>>>>>>>> would
>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>> define
>>>>>>>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, and provide overrides where
>>>>> those
>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>> are
>>>>>>>>>>>>>>>>>>>>>>>>>>> used.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Unfortunately, making the key parameter
>>>> as
>>>>>>>>> "final"
>>>>>>>>>>>>>>>>>>>> doesn't
>>>>>>>>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> about guarding against key change. It
>>>> only
>>>>>>>>>>>>>> prevents
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> variable
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> from being reassigned. If the key type
>>>> is
>>>>> a
>>>>>>>>>>>>>> mutable
>>>>>>>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>>>>>>>>>>>> (eg.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> byte[]),
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> it can still be mutated. (eg. key[0] =
>>>> 0).
>>>>>>> But
>>>>>>>>>>>>>> I'm
>>>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>>>>>>>>>>> sure
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> there's
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much that can be done about that.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 1, 2017 at 5:39 PM, Jeyhun
>>>>>>> Karimov
>>>>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> je.karimov@gmail.com
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The concerns makes sense. Although we
>>>> can
>>>>>>>>> guard
>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>>>> immutable
>>>>>>>>>>>>>>>>>>>>>>>>>>> keys
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> current implementation (with few
>>>>> changes), I
>>>>>>>>>>>>>> didn't
>>>>>>>>>>>>>>>>>>>>> consider
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backward
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> compatibility.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In this case 2 solutions come to my
>>>> mind.
>>>>> In
>>>>>>>>> both
>>>>>>>>>>>>>>>>>> cases,
>>>>>>>>>>>>>>>>>>>>>>> user
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accesses
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> key in Object type, as passing extra
>>>> type
>>>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>>>> will
>>>>>>>>>>>>>>>>>>>>>>> break
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backwards-compatibility. So user has
>>>> to
>>>>>>> cast
>>>>>>>>> to
>>>>>>>>>>>>>>>> actual
>>>>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>>>>>>>> type.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>
>>>> --
>>>> -Cheers
>>>>
>>>> Jeyhun
>>>>
>>>
>>>
>>>
>>
>>
>
>
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by Guozhang Wang <wa...@gmail.com>.
On Sun, Jun 4, 2017 at 8:41 PM, Matthias J. Sax <ma...@confluent.io>
wrote:
> We started with this proposal but it does not allow for Lambdas (in case
> you want key access). Do you think preserving Lambdas is not important
> enough for this case -- I agree that there is some price to be paid to
> keep Lambdas.
>
Not sure if I understand this comment.. My main point is not on changing
the proposal but just reduce it scope to `ValueJoinerWithKey` only; and
even if we want to keep them all, I'd suggest we just implement the added
APIs by using the `KeyValueMapper` for `ValueMapperWithKeys`, etc, which
seems simpler to me. Does that affect lambda expression usage?
>
> About API consistency: I can't remember a concrete user request to have
> key access in all operators. But I am pretty sure, if we only add it for
> some, this request will pop up quickly. IMHO, it's better to do it all
> in one shot. (But I am not strict about it if most people think we
> should limit it to what was requested by users.)
>
>
I would suggest not doing it if user pop it up, but rather suggesting them
to use `map` etc directly but set the key unchanged rather than providing a
new operator for it. To me some syntax sugars like this seems of less
valuable than others (like print / writeAsText / foreach that are all
depending on peek), and keeping adding them will just make the DSL too
“overstaffed”.
>
> -Matthias
>
> On 6/4/17 6:23 PM, Guozhang Wang wrote:
> > With KIP-159, the added "valueMapperWithKey" and
> "valueTransformerWithKey"
> > along seem to be just adding a few syntax-sugars? E.g. we can simply
> > implement:
> >
> > mapValues(ValueMapperWithKey mapperWithKey)
> >
> > as
> >
> > map((k, v) -> (k, mapperWithKey(k, v))
> >
> > ----------------------
> >
> > I'm not sure how many users would really need such syntax sugars, and
> even
> > they do, we can support them easily as the above implementations;
> >
> > Similarly for "ReducerWithKey", it can be implemented as `Aggregator<K,
> V,
> > V>`, and people who needs key access can just use `aggregate` directly.
> >
> > The function which I think is really of valuable is `ValueJoinerWithKey`,
> > and that seems to be the original request from users while others are
> > coming from "API consistency" concerns. Personally I'd prefer only keep
> the
> > last one (`InitializerWithKey` might also have some value, but I have not
> > seen people widely requesting it in their DSL usage yet; if there is a
> > common request we can keep it in this KIP as well). WDYT?
> >
> > Guozhang
> >
> >
> > On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <je...@gmail.com>
> > wrote:
> >
> >> Thanks for clarification Matthias, now everything is clear.
> >>
> >> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <ma...@confluent.io>
> >> wrote:
> >>
> >>> I don't think we can drop ValueTransformerSupplier. If you don't have
> an
> >>> supplier, you only get a single instance of your function. But for a
> >>> stateful transformation, we need multiple instances (one for each task)
> >>> of ValueTransformer.
> >>>
> >>> We don't need suppliers for functions like "ValueMapper" etc because
> >>> those are stateless and thus, we can reuse a single instance over
> >>> multiple tasks -- but we can't do this for ValueTransformer (and
> >> similar).
> >>>
> >>> Btw: This reminds me about KIP-159: with regard to the RichFunction we
> >>> might need a supplier pattern, too. (I'll comment on the other thread,
> >>> too.)
> >>>
> >>>
> >>> -Matthias
> >>>
> >>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
> >>>> Hi,
> >>>>
> >>>> I updated KIP.
> >>>> Just to avoid misunderstanding, I meant deprecating
> >>> ValueTransformerSupplier
> >>>> and I am ok with ValueTransformer.
> >>>> So instead of using ValueTransformerSupplier can't we directly use
> >>>> ValueTransformer
> >>>> or ValueTransformerWithKey?
> >>>>
> >>>> Btw, in current design all features of ValueTransformer will be
> >> available
> >>>> in ValueTransformerWithKey interface.
> >>>>
> >>>> Cheers,
> >>>> Jeyhun
> >>>>
> >>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <
> matthias@confluent.io
> >>>
> >>>> wrote:
> >>>>
> >>>>> Thanks Jeyhun.
> >>>>>
> >>>>> About ValueTransformer: I don't think we can remove it. Note,
> >>>>> ValueTransformer allows to attach a state and also allows to register
> >>>>> punctuations. Both those features will not be available via withKey()
> >>>>> interfaces.
> >>>>>
> >>>>> -Matthias
> >>>>>
> >>>>>
> >>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
> >>>>>> Hi Matthias,
> >>>>>>
> >>>>>> Thanks for your comments.
> >>>>>>
> >>>>>> I tested the deep copy approach. It has significant overhead.
> >>> Especially
> >>>>>> for "light" and stateless operators it slows down the topology
> >>>>>> significantly (> 20% ). I think "warning" users about not-changing
> >> the
> >>>>> key
> >>>>>> is better warning them about possible performance loss.
> >>>>>>
> >>>>>> About the interfaces, additionally I considered adding
> >>>>> InitializerWithKey,
> >>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
> >>> included
> >>>>> in
> >>>>>> PR but not in KIP. I will also include them in KIP, sorry my bad.
> >>>>>> Including ReducerWithKey definitely makes sense. Thanks.
> >>>>>>
> >>>>>> One thing I want to mention is that, maybe we should deprecate
> >> methods
> >>>>> with
> >>>>>> argument type ValueTransformerSupplier
> (KStream.transformValues(...))
> >>> and
> >>>>>> and as a whole the ValueTransformerSupplier interface.
> >>>>>> We can use ValueTransformer/ValueTransformerWithKey type instead
> >>> without
> >>>>>> additional supplier layer.
> >>>>>>
> >>>>>>
> >>>>>> Cheers,
> >>>>>> Jeyhun
> >>>>>>
> >>>>>>
> >>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
> >> matthias@confluent.io
> >>>>
> >>>>>> wrote:
> >>>>>>
> >>>>>>> One more question:
> >>>>>>>
> >>>>>>> Should we add any of
> >>>>>>> - InitizialierWithKey
> >>>>>>> - ReducerWithKey
> >>>>>>> - ValueTransformerWithKey
> >>>>>>>
> >>>>>>> To get consistent/complete API, it might be a good idea. Any
> >> thoughts?
> >>>>>>>
> >>>>>>>
> >>>>>>> -Matthias
> >>>>>>>
> >>>>>>>
> >>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
> >>>>>>>> Jeyhun,
> >>>>>>>>
> >>>>>>>> I was just wondering if you did look into the key-deep-copy idea
> we
> >>>>>>>> discussed. I am curious to see what the impact might be.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> -Matthias
> >>>>>>>>
> >>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>> Hi,
> >>>>>>>>>
> >>>>>>>>> Thanks for your comments. I rethink about including rich
> functions
> >>>>> into
> >>>>>>>>> this KIP.
> >>>>>>>>> I think once we include rich functions in this KIP and then fix
> >>>>>>>>> ProcessorContext in another KIP and incorporate with existing
> rich
> >>>>>>>>> functions, the code will not be backwards compatible.
> >>>>>>>>>
> >>>>>>>>> I see Damian's and your point more clearly now.
> >>>>>>>>>
> >>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
> >>> updated
> >>>>>>> the
> >>>>>>>>> KIP), I will try also initiate another KIP for rich functions.
> >>>>>>>>>
> >>>>>>>>> Cheers,
> >>>>>>>>> Jeyhun
> >>>>>>>>>
> >>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
> >>>>> matthias@confluent.io
> >>>>>>>>
> >>>>>>>>> wrote:
> >>>>>>>>>
> >>>>>>>>>> With the current KIP, using ValueMapper and ValueMapperWithKey
> >>>>>>>>>> interfaces, RichFunction seems to be an independent add-on. To
> >> fix
> >>>>> the
> >>>>>>>>>> original issue to allow key access, RichFunctions are not
> >> required
> >>>>>>> IMHO.
> >>>>>>>>>>
> >>>>>>>>>> I initially put the RichFunction idea on the table, because I
> was
> >>>>>>> hoping
> >>>>>>>>>> to get a uniform API. And I think, is was good to consider them
> >> --
> >>>>>>>>>> however, the discussion showed that they are not necessary for
> >> key
> >>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions in
> an
> >>> own
> >>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a
> main
> >>>>>>>>>> challenge for this. And introducing RichFunctions with
> >>> parameter-less
> >>>>>>>>>> init() method, seem not to help too much. We would get an
> >>>>>>> "intermediate"
> >>>>>>>>>> API that we want to change anyway later on...
> >>>>>>>>>>
> >>>>>>>>>> As you put already much effort into RichFunction, feel free do
> >> push
> >>>>>>> this
> >>>>>>>>>> further and start a new KIP (we can do this even in parallel) --
> >> we
> >>>>>>>>>> don't want to slow you down :) But it make the discussion and
> >> code
> >>>>>>>>>> review easier, if we separate both IMHO.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> -Matthias
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>> Hi Damian,
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks for your comments. I think providing to users
> *interface*
> >>>>>>> rather
> >>>>>>>>>>> than *abstract class* should be preferred (Matthias also raised
> >>> this
> >>>>>>>>>> issue
> >>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
> >>>>>>>>>>>
> >>>>>>>>>>> Regarding with passing additional contextual information, I
> >> think
> >>> it
> >>>>>>> is a
> >>>>>>>>>>> tradeoff,
> >>>>>>>>>>> 1) first, we fix the context parameter for *init() *method in
> >>>>> another
> >>>>>>> PR
> >>>>>>>>>>> and solve Rich functions afterwards
> >>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
> >>> providing
> >>>>>>>>>>> (not-complete) Rich functions and integrate the context
> >> parameters
> >>>>> to
> >>>>>>>>>> this
> >>>>>>>>>>> afterwards (like improvement)
> >>>>>>>>>>>
> >>>>>>>>>>> To me, the second approach seems more incremental. However you
> >> are
> >>>>>>> right,
> >>>>>>>>>>> the names might confuse the users.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
> >>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
> >>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> Cheers,
> >>>>>>>>>>> Jeyhun
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
> >> damian.guy@gmail.com
> >>>>
> >>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> Hi,
> >>>>>>>>>>>>
> >>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
> >> RichFunction
> >>>>>>> which
> >>>>>>>>>> is
> >>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it to
> >>> pass
> >>>>>>> some
> >>>>>>>>>>>> additional contextual information, i.e., the `RecordContext`
> >> that
> >>>>>>>>>> contains
> >>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with it
> >> not
> >>>>>>>>>> passing
> >>>>>>>>>>>> this contextual information, but is the naming incorrect? I'm
> >> not
> >>>>>>> sure,
> >>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until we
> >> can
> >>>>> do
> >>>>>>> it
> >>>>>>>>>>>> properly with the correct context?
> >>>>>>>>>>>>
> >>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
> >>>>>>>>>> RichValueJoiner,
> >>>>>>>>>>>> RichInitializer etc. Why can't they not just be interfaces?
> >>>>>>> Generally we
> >>>>>>>>>>>> should provide users with Intefaces to code against, not
> >> classes.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Thanks,
> >>>>>>>>>>>> Damian
> >>>>>>>>>>>>
> >>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
> >>> je.karimov@gmail.com>
> >>>>>>>>>> wrote:
> >>>>>>>>>>>>
> >>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better overview.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> The only reason that I used abstract class instead of
> >> interface
> >>>>> for
> >>>>>>>>>> Rich
> >>>>>>>>>>>>> functions is that in future if we will have some
> >>>>>>> AbstractRichFunction
> >>>>>>>>>>>>> abstract classes,
> >>>>>>>>>>>>> we can easily extend:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR> implements
> >>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
> >>>>>>>>>>>> AbstractRichFunction*{
> >>>>>>>>>>>>> }
> >>>>>>>>>>>>> With interfaces we are only limited to interfaces for
> >>>>> inheritance.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> However, I think we can easily change it (from abstract class
> >> ->
> >>>>>>>>>>>> interface)
> >>>>>>>>>>>>> if you think interface is a better fit.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
> >>>>>>> matthias@confluent.io
> >>>>>>>>>>>
> >>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
> >>> improved
> >>>>>>> now
> >>>>>>>>>>>> --
> >>>>>>>>>>>>>> great job!
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
> >> classes
> >>>>> and
> >>>>>>>>>> not
> >>>>>>>>>>>>>> interfaces?
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Overall, I like the KIP a lot!
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Thanks for your comments.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>> interfaces
> >>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Maybe I misunderstood your comment.
> >>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So they
> >>> don't
> >>>>>>> have
> >>>>>>>>>>>>>> direct
> >>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
> >>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only one
> >>>>>>> method ,
> >>>>>>>>>>>> so
> >>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>> can use lambdas.
> >>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play? Inside
> >>> Rich
> >>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>> And we use Rich functions in 2 places:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular *withKey*
> >> and
> >>>>> and
> >>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We get
> >>> those
> >>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>> and wrap into Rich function while building the topology,
> and
> >>>>> send
> >>>>>>> to
> >>>>>>>>>>>>>>> Processor.
> >>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions implement
> >>>>>>> *withKey*
> >>>>>>>>>>>>>>> interface). As a result no lamdas here by definition. In
> >> this
> >>>>>>> case,
> >>>>>>>>>>>>> while
> >>>>>>>>>>>>>>> building the topology we do a type check if the object type
> >> is
> >>>>>>>>>>>>>>> *withKey* or *RichFunction*.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for Rich
> >>>>>>> functions
> >>>>>>>>>>>>> and
> >>>>>>>>>>>>>>> does not affect using lambdas.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
> >> to
> >>>>>>> have a
> >>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >> RichFunction
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> As I said above, currently we support lambdas for *withKey*
> >>>>>>>>>>>> interfaces
> >>>>>>>>>>>>> as
> >>>>>>>>>>>>>>> well. However, I agree with your idea and I will remove
> the
> >>>>>>>>>>>>>>> AbstractRichFunction from the design.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
> >>>>>>> support
> >>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> "extended
> >>>>> API".
> >>>>>>>>>>>> For
> >>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> >> more
> >>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> >>>>> because
> >>>>>>> we
> >>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> >> value
> >>> in
> >>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Just to clarify, with current design we have only one extra
> >>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is *withKey*
> >>>>> version
> >>>>>>> of
> >>>>>>>>>>>>>>> particular interface.
> >>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
> >>> function
> >>>>>>>>>>>>>> implements
> >>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
> >>>>>>> differentiate
> >>>>>>>>>>>>>> them
> >>>>>>>>>>>>>>> while building the topology.
> >>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
> >>> comment:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can we
> >> have
> >>> a
> >>>>>>>>>>>> design
> >>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
> >> might
> >>>>> make
> >>>>>>>>>>>>> sense
> >>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> However, I don't think that this complicates the overall
> >>> design
> >>>>>>>>>>>>>>> significantly.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
> to
> >>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> >> this
> >>>>>>> also
> >>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >> before
> >>>>>>> driving
> >>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
> >> functions
> >>>>> as I
> >>>>>>>>>>>>> don't
> >>>>>>>>>>>>>>> think that they bring extra layer of overhead to library.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Any comments are appreciated.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
> >>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> thanks for the update.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
> >>>>>>> `AbstractRichFunction`
> >>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
> >>> interfaces
> >>>>>>>>>>>> AFAIK.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
> >> to
> >>>>>>> have a
> >>>>>>>>>>>>>>>> interface approach like this
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> - ValueMapper
> >>>>>>>>>>>>>>>> - ValueMapperWithKey
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
> >> RichFunction
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make
> sense
> >>>>>>> anymore,
> >>>>>>>>>>>>> as
> >>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
> >>>>>>> implementation of
> >>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you would
> >>>>>>> implement a
> >>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient
> to
> >>>>>>> support
> >>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any
> "extended
> >>>>> API".
> >>>>>>>>>>>> For
> >>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
> >>>>>>> AbstractRichFunction
> >>>>>>>>>>>>>>>> would allow to only care about getting the key.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
> >> more
> >>>>>>>>>>>>> overloaded
> >>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
> >>>>> because
> >>>>>>> we
> >>>>>>>>>>>>> have
> >>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
> >> value
> >>> in
> >>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
> >> to
> >>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
> >> this
> >>>>>>> also
> >>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
> >> before
> >>>>>>> driving
> >>>>>>>>>>>>>>>> this KIP further.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Thoughts?
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your comments.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a little
> >>>>> bit? I
> >>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> problem
> >>> is.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an interface
> >> that
> >>>>> has
> >>>>>>>>>>>> just
> >>>>>>>>>>>>>> one
> >>>>>>>>>>>>>>>>> abstract method, and thus represents a single function
> >>>>>>> contract".
> >>>>>>>>>>>>>>>>> So basically once we extend some interface from another
> >> (in
> >>>>> our
> >>>>>>>>>>>> case,
> >>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use
> lambdas
> >>> in
> >>>>>>> the
> >>>>>>>>>>>>>>>> extended
> >>>>>>>>>>>>>>>>> interface.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
> >>>>> reformat
> >>>>>>> the
> >>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would help.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - I will work on the KIP.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> >> overlaods
> >>>>>>> added
> >>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
> >> add
> >>>>> any
> >>>>>>> new
> >>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - Actually there are more than one Processor and public
> >> APIs
> >>>>> to
> >>>>>>> be
> >>>>>>>>>>>>>>>>> changed (KStream-KTable
> >>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
> >>> structure:
> >>>>>>> we
> >>>>>>>>>>>>>>>> overload
> >>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
> >>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
> >> inside
> >>>>> the
> >>>>>>>>>>>>>>>> processor
> >>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
> >>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the overall
> >> idea
> >>>>> with
> >>>>>>>>>>>> only
> >>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all changes.
> >>>>>>>>>>>>>>>>> Anyway I will update the KIP.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)* and*
> >>>>>>> close()*
> >>>>>>>>>>>>>>>> methods
> >>>>>>>>>>>>>>>>> in every Rich function with empty body like:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> @Override
> >>>>>>>>>>>>>>>>> void close () {}
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I thought that we can override them once in
> >>>>>>> *AbstractRichFunction*
> >>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>> extent new Rich functions from *AbstractRichFunction*.
> >>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease the
> >>>>>>>>>>>>> maintenance.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> >> Merger,
> >>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
> >> all,
> >>>>> but
> >>>>>>> we
> >>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> >> (e.g.,
> >>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique applies
> to
> >>> all
> >>>>>>> this
> >>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
> >> wanted
> >>>>> to
> >>>>>>>>>>>> give
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>> overall intuition.
> >>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` -- `ValueXXWithKey`
> --
> >>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >> interfaces
> >>>>>>> only?
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should not
> >>> force
> >>>>>>>>>>>> users
> >>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()*
> functions
> >>>>> every
> >>>>>>>>>>>> time
> >>>>>>>>>>>>>>>> they
> >>>>>>>>>>>>>>>>> use Rich functions.
> >>>>>>>>>>>>>>>>> If one needs, she can override the respective methods.
> >>>>> However,
> >>>>>>> I
> >>>>>>>>>>>> am
> >>>>>>>>>>>>>> open
> >>>>>>>>>>>>>>>>> for discussion.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
> >> any
> >>>>>>>>>>>> further
> >>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> >> done
> >>>>>>> before
> >>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
> >>>>> large.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> That is good point. I wanted to make
> >>> *init(ProcessorContext)*
> >>>>>>>>>>>> method
> >>>>>>>>>>>>>>>>> persistent among the library (which use ProcessorContext
> >> as
> >>> an
> >>>>>>>>>>>>> input),
> >>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
> >>>>>>>>>>>>>>>>> So the important question is that (as @dguy and @mjsax
> >>>>>>> mentioned)
> >>>>>>>>>>>>>> whether
> >>>>>>>>>>>>>>>>> continue this KIP without providing users an access to
> >>>>>>>>>>>>>> *ProcessorContext*
> >>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
> >>>>>>>>>>>>>>>>> initiate another KIP before this.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>
> >>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
> >>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
> >>>>>>> damian.guy@gmail.com>
> >>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
> >>> any
> >>>>>>>>>>>> further
> >>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
> >> done
> >>>>>>> before
> >>>>>>>>>>>>>> this?
> >>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
> >>>>> large.
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
> >>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is too
> >>> broad
> >>>>> in
> >>>>>>>>>>>>>> general
> >>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and it's
> >> also
> >>>>>>>>>>>> reflected
> >>>>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
> >>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> So I am wondering, if you question the `RichFunction`
> >>>>>>> approach in
> >>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the scope
> of
> >>>>> this
> >>>>>>> KIP
> >>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for it
> >> and
> >>>>>>> delay
> >>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>>> until the other one is done?
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
> >>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach. Do
> we
> >>>>>>> really
> >>>>>>>>>>>>> want
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>> give
> >>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext` ? It
> >>> has
> >>>>> a
> >>>>>>>>>>>> bunch
> >>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of the
> >>> DSL
> >>>>>>>>>>>>> methods,
> >>>>>>>>>>>>>>>>>> i.e,
> >>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule`
> etc.
> >>> It
> >>>>> is
> >>>>>>>>>>>> far
> >>>>>>>>>>>>>> too
> >>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a narrower
> >>>>>>> interface
> >>>>>>>>>>>>> like
> >>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
> >>>>>>>>>>>>>> methods/interfaces
> >>>>>>>>>>>>>>>>>>> later
> >>>>>>>>>>>>>>>>>>>> than to remove them
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
> >>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
> >>> little
> >>>>>>> bit?
> >>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>> cannot
> >>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
> >>> problem
> >>>>>>> is.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess it's
> >> up
> >>>>> to
> >>>>>>>>>>>> you.
> >>>>>>>>>>>>>>>>>> Maybe a
> >>>>>>>>>>>>>>>>>>>>> committer can comment on this?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Further comments:
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
> >>>>>>> reformat
> >>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>> wiki
> >>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
> >> help.
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
> >>>>> overlaods
> >>>>>>>>>>>>> added
> >>>>>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need
> to
> >>> add
> >>>>>>> any
> >>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>> overloads)
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
> >>>>> Merger,
> >>>>>>>>>>>>>>>>>> Predicate,
> >>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
> >>> all,
> >>>>>>> but
> >>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
> >>>>> (e.g.,
> >>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
> >> `ValueXXWithKey`
> >>> --
> >>>>>>>>>>>>>>>>>> `RichValueXX`
> >>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
> >>> interfaces
> >>>>>>>>>>>> only?
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot extend
> >> the
> >>>>> two
> >>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>> if
> >>>>>>>>>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1]. Maybe I
> >>>>> should
> >>>>>>>>>>>>> change
> >>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP to
> >> only
> >>>>>>>>>>>>>> ValueMapper,
> >>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
> >>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> [1]
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
> >>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
> >>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
> >>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper` we
> >> don't
> >>>>>>> need
> >>>>>>>>>>>> the
> >>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>> overlaod.
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this
> happens
> >>>>> when
> >>>>>>>>>>>>>> building
> >>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
> >> KafkaStream#start()
> >>>>> we
> >>>>>>>>>>>> don't
> >>>>>>>>>>>>>>>> need
> >>>>>>>>>>>>>>>>>>> any
> >>>>>>>>>>>>>>>>>>>>>>> check as we will always use `ValueMapperWithKey`)
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
> >>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
> >>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<?
> super
> >>> V,
> >>>>> ?
> >>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>>>> VR>
> >>>>>>>>>>>>>>>>>>>>>>>> mapper);
> >>>>>>>>>>>>>>>>>>>>>>>> with
> >>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
> >> mapValues(ValueMapperWithKey<?
> >>>>>>> super
> >>>>>>>>>>>> V,
> >>>>>>>>>>>>> ?
> >>>>>>>>>>>>>>>>>>> extends
> >>>>>>>>>>>>>>>>>>>>>>> VR>
> >>>>>>>>>>>>>>>>>>>>>>>> mapper);
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still have to
> >>>>> check
> >>>>>>> it
> >>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>>>> ValueMapper
> >>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into the
> >>> rich
> >>>>>>>>>>>>> function.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal Borowiecki
> <
> >>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am
> wondering,
> >>> if
> >>>>> we
> >>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>> do
> >>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a RichFunction
> >>> and
> >>>>>>>>>>>>>>>>>>> non-RichFunction
> >>>>>>>>>>>>>>>>>>>>>>> at
> >>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions all
> the
> >>>>> time.
> >>>>>>>>>>>>> Thus,
> >>>>>>>>>>>>>> on
> >>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>> DSL
> >>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
> >> non-RichFunction,
> >>>>> we
> >>>>>>>>>>>> wrap
> >>>>>>>>>>>>> it
> >>>>>>>>>>>>>>>>>> by a
> >>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
> >> Streams.
> >>>>> This
> >>>>>>>>>>>>>>>>>>> RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the key:
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
> >> snippet):
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
> >>>>>>>>>>>> RichValueMapper()
> >>>>>>>>>>>>> {
> >>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper; //
> >> set
> >>> by
> >>>>>>>>>>>>>>>> constructor
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1
> value1,
> >>>>>>> final V2
> >>>>>>>>>>>>>>>>>> value2)
> >>>>>>>>>>>>>>>>>>> {
> >>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
> >> value2);
> >>>>>>>>>>>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>>>>>>>>>>> }
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not sure
> >> if
> >>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc would
> >> have
> >>>>>>> more
> >>>>>>>>>>>>>>>> overhead
> >>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested method
> >> call
> >>>>> for
> >>>>>>>>>>>>>>>>>>>>> non-RichFunction
> >>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than RichFunctions).
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or do I
> >>> miss
> >>>>>>>>>>>>>>>> something?)
> >>>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more top
> >>> level
> >>>>>>>>>>>>>> interface
> >>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
> >> `close()`
> >>>>> and
> >>>>>>>>>>>> also
> >>>>>>>>>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no abstract
> >>> classes
> >>>>>>>>>>>>>> required).
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP to
> >>>>> include
> >>>>>>>>>>>> rich
> >>>>>>>>>>>>>>>>>>>>> functions.
> >>>>>>>>>>>>>>>>>>>>>>> I
> >>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of deep
> >>> copying
> >>>>>>> of
> >>>>>>>>>>>>> keys.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu Fenniak
> <
> >>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> >>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
> >>>>>>> immutability of
> >>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>> key
> >>>>>>>>>>>>>>>>>>> is
> >>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than
> requiring
> >>> the
> >>>>>>> key
> >>>>>>>>>>>> to
> >>>>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>>>>>> serializable
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
> >>>>>>> performance
> >>>>>>>>>>>>> risk.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable type
> >>>>>>> constraints
> >>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>> some
> >>>>>>>>>>>>>>>>>>>>>>> kind.
> >>>>>>>>>>>>>>>>>>>>>>>>> :-)
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias J.
> >> Sax
> >>> <
> >>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow this
> >>> path,
> >>>>>>> it
> >>>>>>>>>>>>>> should
> >>>>>>>>>>>>>>>>>>> cover
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> About guarding the key -- I am still not sure
> >>> what
> >>>>>>> to
> >>>>>>>>>>>> do
> >>>>>>>>>>>>>>>> about
> >>>>>>>>>>>>>>>>>>>>> it...
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Maybe it might be enough to document it (and
> >>> name
> >>>>>>> the
> >>>>>>>>>>>> key
> >>>>>>>>>>>>>>>>>>>>> parameter
> >>>>>>>>>>>>>>>>>>>>>>>>> like
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> `readOnlyKey` to make is very clear).
> >>> Ultimately,
> >>>>> I
> >>>>>>>>>>>> would
> >>>>>>>>>>>>>>>>>> prefer
> >>>>>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> guard against any modification, but I have no
> >>> good
> >>>>>>> idea
> >>>>>>>>>>>>> how
> >>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>> do
> >>>>>>>>>>>>>>>>>>>>>>>>> this.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Not sure what others think about the risk of
> >>>>>>> corrupted
> >>>>>>>>>>>>>>>>>>>>> partitioning
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> (what would be a user error and we could say,
> >>>>> well,
> >>>>>>> bad
> >>>>>>>>>>>>>> luck,
> >>>>>>>>>>>>>>>>>>> you
> >>>>>>>>>>>>>>>>>>>>>>> got
> >>>>>>>>>>>>>>>>>>>>>>>>> a
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> bug in your code, that's not our fault), vs
> >> deep
> >>>>>>> copy
> >>>>>>>>>>>>> with
> >>>>>>>>>>>>>> a
> >>>>>>>>>>>>>>>>>>>>>>> potential
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> performance hit (that we can't quantity atm
> >>>>> without
> >>>>>>> any
> >>>>>>>>>>>>>>>>>>>>> performance
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> test).
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> We do have a performance system test. Maybe
> >> it's
> >>>>>>> worth
> >>>>>>>>>>>>> for
> >>>>>>>>>>>>>>>> you
> >>>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>> apply
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> the deep copy strategy and run the test. It's
> >>> very
> >>>>>>>>>>>> basic
> >>>>>>>>>>>>>>>>>>>>> performance
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> test only, but might give some insight. If
> you
> >>>>> want
> >>>>>>> to
> >>>>>>>>>>>> do
> >>>>>>>>>>>>>>>>>> this,
> >>>>>>>>>>>>>>>>>>>>> look
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> into folder "tests" for general test setup,
> >> and
> >>>>> into
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> "tests/kafaktests/benchmarks/streams" to
> find
> >>> find
> >>>>>>> the
> >>>>>>>>>>>>> perf
> >>>>>>>>>>>>>>>>>>> test.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/5/17 8:55 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Matthias,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I think extending KIP to include
> >> RichFunctions
> >>>>>>> totally
> >>>>>>>>>>>>>>>> makes
> >>>>>>>>>>>>>>>>>>>>>>> sense.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> So,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> we don't want to guard the keys because it
> >> is
> >>>>>>>>>>>> costly.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If we introduce RichFunctions I think it
> >> should
> >>>>>>> not be
> >>>>>>>>>>>>>>>>>> limited
> >>>>>>>>>>>>>>>>>>>>> only
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> the 3
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces proposed in KIP but to wide range
> >> of
> >>>>>>>>>>>>>> interfaces.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 12:04 AM Matthias J.
> >>> Sax <
> >>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> One follow up. There was this email on the
> >>> user
> >>>>>>> list:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>> http://search-hadoop.com/m/Kafka/uyzND17KhCaBzPSZ1?subj=
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>> Shouldn+t+the+initializer+of+a+stream+aggregate+accept+the+
> >>>>>>>>>>>>>>>>>> key+
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It might make sense so include
> Initializer,
> >>>>> Adder,
> >>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>> Substractor
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> inferface, too.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And we should double check if there are
> >> other
> >>>>>>>>>>>> interface
> >>>>>>>>>>>>>> we
> >>>>>>>>>>>>>>>>>>> might
> >>>>>>>>>>>>>>>>>>>>>>>>> miss
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> atm.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/4/17 1:31 PM, Matthias J. Sax wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for updating the KIP.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Deep copying the key will work for sure,
> >> but
> >>> I
> >>>>> am
> >>>>>>>>>>>>>> actually
> >>>>>>>>>>>>>>>>>> a
> >>>>>>>>>>>>>>>>>>>>>>> little
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> bit
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> worried about performance impact... We
> >> might
> >>>>>>> want to
> >>>>>>>>>>>>> do
> >>>>>>>>>>>>>>>>>> some
> >>>>>>>>>>>>>>>>>>>>> test
> >>>>>>>>>>>>>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> quantify this impact.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: this remind me about the idea of
> >>>>>>> `RichFunction`
> >>>>>>>>>>>>>>>>>>> interface
> >>>>>>>>>>>>>>>>>>>>>>> that
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> would allow users to access record
> metadata
> >>>>> (like
> >>>>>>>>>>>>>>>>>> timestamp,
> >>>>>>>>>>>>>>>>>>>>>>>>> offset,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> partition etc) within DSL. This would be
> a
> >>>>>>> similar
> >>>>>>>>>>>>>>>> concept.
> >>>>>>>>>>>>>>>>>>>>>>> Thus, I
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> am
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wondering, if it would make sense to
> >> enlarge
> >>>>> the
> >>>>>>>>>>>> scope
> >>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>> this
> >>>>>>>>>>>>>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>>>>>>>>> by
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> that? WDYT?
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/3/17 2:08 AM, Jeyhun Karimov wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Mathieu,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback. I followed similar
> >>>>> approach
> >>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>> updated
> >>>>>>>>>>>>>>>>>>>>> PR
> >>>>>>>>>>>>>>>>>>>>>>>>> and
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> KIP
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accordingly. I tried to guard the key in
> >>>>>>> Processors
> >>>>>>>>>>>>>>>>>> sending
> >>>>>>>>>>>>>>>>>>> a
> >>>>>>>>>>>>>>>>>>>>>>> copy
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> of
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> an
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> actual key.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because I am doing deep copy of an
> >> object, I
> >>>>>>> think
> >>>>>>>>>>>>>> memory
> >>>>>>>>>>>>>>>>>>> can
> >>>>>>>>>>>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bottleneck
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in some use-cases.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 2, 2017 at 5:10 PM Mathieu
> >>>>> Fenniak <
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Jeyhun,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach would change ValueMapper
> >>>>>>> (...etc) to
> >>>>>>>>>>>>> be
> >>>>>>>>>>>>>>>>>>>>> classes,
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> rather
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> than
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, which is also a backwards
> >>>>>>> incompatible
> >>>>>>>>>>>>>>>>>> change.
> >>>>>>>>>>>>>>>>>>>>> An
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> alternative
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> approach that would be backwards
> >> compatible
> >>>>>>> would
> >>>>>>>>>>>> be
> >>>>>>>>>>>>>> to
> >>>>>>>>>>>>>>>>>>>>> define
> >>>>>>>>>>>>>>>>>>>>>>>>> new
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, and provide overrides where
> >>> those
> >>>>>>>>>>>>>> interfaces
> >>>>>>>>>>>>>>>>>>> are
> >>>>>>>>>>>>>>>>>>>>>>>>> used.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Unfortunately, making the key parameter
> >> as
> >>>>>>> "final"
> >>>>>>>>>>>>>>>>>> doesn't
> >>>>>>>>>>>>>>>>>>>>>>> change
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> much
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> about guarding against key change. It
> >> only
> >>>>>>>>>>>> prevents
> >>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>> parameter
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> variable
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> from being reassigned. If the key type
> >> is
> >>> a
> >>>>>>>>>>>> mutable
> >>>>>>>>>>>>>>>>>> object
> >>>>>>>>>>>>>>>>>>>>>>> (eg.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> byte[]),
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> it can still be mutated. (eg. key[0] =
> >> 0).
> >>>>> But
> >>>>>>>>>>>> I'm
> >>>>>>>>>>>>>> not
> >>>>>>>>>>>>>>>>>>>>> really
> >>>>>>>>>>>>>>>>>>>>>>>>> sure
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> there's
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much that can be done about that.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 1, 2017 at 5:39 PM, Jeyhun
> >>>>> Karimov
> >>>>>>> <
> >>>>>>>>>>>>>>>>>>>>>>>>>>>> je.karimov@gmail.com
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The concerns makes sense. Although we
> >> can
> >>>>>>> guard
> >>>>>>>>>>>> for
> >>>>>>>>>>>>>>>>>>>>> immutable
> >>>>>>>>>>>>>>>>>>>>>>>>> keys
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> in
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> current implementation (with few
> >>> changes), I
> >>>>>>>>>>>> didn't
> >>>>>>>>>>>>>>>>>>> consider
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> backward
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> compatibility.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In this case 2 solutions come to my
> >> mind.
> >>> In
> >>>>>>> both
> >>>>>>>>>>>>>>>> cases,
> >>>>>>>>>>>>>>>>>>>>> user
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> accesses
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> key in Object type, as passing extra
> >> type
> >>>>>>>>>>>> parameter
> >>>>>>>>>>>>>>>> will
> >>>>>>>>>>>>>>>>>>>>> break
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backwards-compatibility. So user has
> >> to
> >>>>> cast
> >>>>>>> to
> >>>>>>>>>>>>>> actual
> >>>>>>>>>>>>>>>>>>> key
> >>>>>>>>>>>>>>>>>>>>>>>>> type.
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>>>>>>
> >>
> >> --
> >> -Cheers
> >>
> >> Jeyhun
> >>
> >
> >
> >
>
>
--
-- Guozhang
Re: [DISCUSS]: KIP-149: Enabling key access in ValueTransformer,
ValueMapper, and ValueJoiner
Posted by "Matthias J. Sax" <ma...@confluent.io>.
We started with this proposal but it does not allow for Lambdas (in case
you want key access). Do you think preserving Lambdas is not important
enough for this case -- I agree that there is some price to be paid to
keep Lambdas.
About API consistency: I can't remember a concrete user request to have
key access in all operators. But I am pretty sure, if we only add it for
some, this request will pop up quickly. IMHO, it's better to do it all
in one shot. (But I am not strict about it if most people think we
should limit it to what was requested by users.)
-Matthias
On 6/4/17 6:23 PM, Guozhang Wang wrote:
> With KIP-159, the added "valueMapperWithKey" and "valueTransformerWithKey"
> along seem to be just adding a few syntax-sugars? E.g. we can simply
> implement:
>
> mapValues(ValueMapperWithKey mapperWithKey)
>
> as
>
> map((k, v) -> (k, mapperWithKey(k, v))
>
> ----------------------
>
> I'm not sure how many users would really need such syntax sugars, and even
> they do, we can support them easily as the above implementations;
>
> Similarly for "ReducerWithKey", it can be implemented as `Aggregator<K, V,
> V>`, and people who needs key access can just use `aggregate` directly.
>
> The function which I think is really of valuable is `ValueJoinerWithKey`,
> and that seems to be the original request from users while others are
> coming from "API consistency" concerns. Personally I'd prefer only keep the
> last one (`InitializerWithKey` might also have some value, but I have not
> seen people widely requesting it in their DSL usage yet; if there is a
> common request we can keep it in this KIP as well). WDYT?
>
> Guozhang
>
>
> On Sun, May 28, 2017 at 10:16 AM, Jeyhun Karimov <je...@gmail.com>
> wrote:
>
>> Thanks for clarification Matthias, now everything is clear.
>>
>> On Sun, May 28, 2017 at 6:21 PM Matthias J. Sax <ma...@confluent.io>
>> wrote:
>>
>>> I don't think we can drop ValueTransformerSupplier. If you don't have an
>>> supplier, you only get a single instance of your function. But for a
>>> stateful transformation, we need multiple instances (one for each task)
>>> of ValueTransformer.
>>>
>>> We don't need suppliers for functions like "ValueMapper" etc because
>>> those are stateless and thus, we can reuse a single instance over
>>> multiple tasks -- but we can't do this for ValueTransformer (and
>> similar).
>>>
>>> Btw: This reminds me about KIP-159: with regard to the RichFunction we
>>> might need a supplier pattern, too. (I'll comment on the other thread,
>>> too.)
>>>
>>>
>>> -Matthias
>>>
>>> On 5/28/17 5:45 AM, Jeyhun Karimov wrote:
>>>> Hi,
>>>>
>>>> I updated KIP.
>>>> Just to avoid misunderstanding, I meant deprecating
>>> ValueTransformerSupplier
>>>> and I am ok with ValueTransformer.
>>>> So instead of using ValueTransformerSupplier can't we directly use
>>>> ValueTransformer
>>>> or ValueTransformerWithKey?
>>>>
>>>> Btw, in current design all features of ValueTransformer will be
>> available
>>>> in ValueTransformerWithKey interface.
>>>>
>>>> Cheers,
>>>> Jeyhun
>>>>
>>>> On Sun, May 28, 2017 at 6:15 AM Matthias J. Sax <matthias@confluent.io
>>>
>>>> wrote:
>>>>
>>>>> Thanks Jeyhun.
>>>>>
>>>>> About ValueTransformer: I don't think we can remove it. Note,
>>>>> ValueTransformer allows to attach a state and also allows to register
>>>>> punctuations. Both those features will not be available via withKey()
>>>>> interfaces.
>>>>>
>>>>> -Matthias
>>>>>
>>>>>
>>>>> On 5/27/17 1:25 PM, Jeyhun Karimov wrote:
>>>>>> Hi Matthias,
>>>>>>
>>>>>> Thanks for your comments.
>>>>>>
>>>>>> I tested the deep copy approach. It has significant overhead.
>>> Especially
>>>>>> for "light" and stateless operators it slows down the topology
>>>>>> significantly (> 20% ). I think "warning" users about not-changing
>> the
>>>>> key
>>>>>> is better warning them about possible performance loss.
>>>>>>
>>>>>> About the interfaces, additionally I considered adding
>>>>> InitializerWithKey,
>>>>>> AggregatorWithKey and ValueTransformerWithKey. I think they are
>>> included
>>>>> in
>>>>>> PR but not in KIP. I will also include them in KIP, sorry my bad.
>>>>>> Including ReducerWithKey definitely makes sense. Thanks.
>>>>>>
>>>>>> One thing I want to mention is that, maybe we should deprecate
>> methods
>>>>> with
>>>>>> argument type ValueTransformerSupplier (KStream.transformValues(...))
>>> and
>>>>>> and as a whole the ValueTransformerSupplier interface.
>>>>>> We can use ValueTransformer/ValueTransformerWithKey type instead
>>> without
>>>>>> additional supplier layer.
>>>>>>
>>>>>>
>>>>>> Cheers,
>>>>>> Jeyhun
>>>>>>
>>>>>>
>>>>>> On Thu, May 25, 2017 at 1:07 AM Matthias J. Sax <
>> matthias@confluent.io
>>>>
>>>>>> wrote:
>>>>>>
>>>>>>> One more question:
>>>>>>>
>>>>>>> Should we add any of
>>>>>>> - InitizialierWithKey
>>>>>>> - ReducerWithKey
>>>>>>> - ValueTransformerWithKey
>>>>>>>
>>>>>>> To get consistent/complete API, it might be a good idea. Any
>> thoughts?
>>>>>>>
>>>>>>>
>>>>>>> -Matthias
>>>>>>>
>>>>>>>
>>>>>>> On 5/24/17 3:47 PM, Matthias J. Sax wrote:
>>>>>>>> Jeyhun,
>>>>>>>>
>>>>>>>> I was just wondering if you did look into the key-deep-copy idea we
>>>>>>>> discussed. I am curious to see what the impact might be.
>>>>>>>>
>>>>>>>>
>>>>>>>> -Matthias
>>>>>>>>
>>>>>>>> On 5/20/17 2:03 AM, Jeyhun Karimov wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Thanks for your comments. I rethink about including rich functions
>>>>> into
>>>>>>>>> this KIP.
>>>>>>>>> I think once we include rich functions in this KIP and then fix
>>>>>>>>> ProcessorContext in another KIP and incorporate with existing rich
>>>>>>>>> functions, the code will not be backwards compatible.
>>>>>>>>>
>>>>>>>>> I see Damian's and your point more clearly now.
>>>>>>>>>
>>>>>>>>> Conclusion: we include only withKey interfaces in this KIP (I
>>> updated
>>>>>>> the
>>>>>>>>> KIP), I will try also initiate another KIP for rich functions.
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>> Jeyhun
>>>>>>>>>
>>>>>>>>> On Fri, May 19, 2017 at 10:50 PM Matthias J. Sax <
>>>>> matthias@confluent.io
>>>>>>>>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> With the current KIP, using ValueMapper and ValueMapperWithKey
>>>>>>>>>> interfaces, RichFunction seems to be an independent add-on. To
>> fix
>>>>> the
>>>>>>>>>> original issue to allow key access, RichFunctions are not
>> required
>>>>>>> IMHO.
>>>>>>>>>>
>>>>>>>>>> I initially put the RichFunction idea on the table, because I was
>>>>>>> hoping
>>>>>>>>>> to get a uniform API. And I think, is was good to consider them
>> --
>>>>>>>>>> however, the discussion showed that they are not necessary for
>> key
>>>>>>>>>> access. Thus, it seems to be better to handle RichFunctions in an
>>> own
>>>>>>>>>> KIP. The ProcessorContext/RecordContext issues seems to be a main
>>>>>>>>>> challenge for this. And introducing RichFunctions with
>>> parameter-less
>>>>>>>>>> init() method, seem not to help too much. We would get an
>>>>>>> "intermediate"
>>>>>>>>>> API that we want to change anyway later on...
>>>>>>>>>>
>>>>>>>>>> As you put already much effort into RichFunction, feel free do
>> push
>>>>>>> this
>>>>>>>>>> further and start a new KIP (we can do this even in parallel) --
>> we
>>>>>>>>>> don't want to slow you down :) But it make the discussion and
>> code
>>>>>>>>>> review easier, if we separate both IMHO.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> -Matthias
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 5/19/17 2:25 AM, Jeyhun Karimov wrote:
>>>>>>>>>>> Hi Damian,
>>>>>>>>>>>
>>>>>>>>>>> Thanks for your comments. I think providing to users *interface*
>>>>>>> rather
>>>>>>>>>>> than *abstract class* should be preferred (Matthias also raised
>>> this
>>>>>>>>>> issue
>>>>>>>>>>> ), anyway I changed the corresponding parts of KIP.
>>>>>>>>>>>
>>>>>>>>>>> Regarding with passing additional contextual information, I
>> think
>>> it
>>>>>>> is a
>>>>>>>>>>> tradeoff,
>>>>>>>>>>> 1) first, we fix the context parameter for *init() *method in
>>>>> another
>>>>>>> PR
>>>>>>>>>>> and solve Rich functions afterwards
>>>>>>>>>>> 2) first, we fix the requested issues on jira ([1-3]) with
>>> providing
>>>>>>>>>>> (not-complete) Rich functions and integrate the context
>> parameters
>>>>> to
>>>>>>>>>> this
>>>>>>>>>>> afterwards (like improvement)
>>>>>>>>>>>
>>>>>>>>>>> To me, the second approach seems more incremental. However you
>> are
>>>>>>> right,
>>>>>>>>>>> the names might confuse the users.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> [1] https://issues.apache.org/jira/browse/KAFKA-4218
>>>>>>>>>>> [2] https://issues.apache.org/jira/browse/KAFKA-4726
>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/KAFKA-3745
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Cheers,
>>>>>>>>>>> Jeyhun
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Fri, May 19, 2017 at 10:42 AM Damian Guy <
>> damian.guy@gmail.com
>>>>
>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> I see you've removed the `ProcessorContext` from the
>> RichFunction
>>>>>>> which
>>>>>>>>>> is
>>>>>>>>>>>> good, but why is it a `RichFunction`? I'd have expected it to
>>> pass
>>>>>>> some
>>>>>>>>>>>> additional contextual information, i.e., the `RecordContext`
>> that
>>>>>>>>>> contains
>>>>>>>>>>>> just the topic, partition, timestamp, offset. I'm ok with it
>> not
>>>>>>>>>> passing
>>>>>>>>>>>> this contextual information, but is the naming incorrect? I'm
>> not
>>>>>>> sure,
>>>>>>>>>>>> tbh. I'm wondering if we should drop `RichFunctions` until we
>> can
>>>>> do
>>>>>>> it
>>>>>>>>>>>> properly with the correct context?
>>>>>>>>>>>>
>>>>>>>>>>>> Also, i don't like the abstract classes: RichValueMapper,
>>>>>>>>>> RichValueJoiner,
>>>>>>>>>>>> RichInitializer etc. Why can't they not just be interfaces?
>>>>>>> Generally we
>>>>>>>>>>>> should provide users with Intefaces to code against, not
>> classes.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Damian
>>>>>>>>>>>>
>>>>>>>>>>>> On Fri, 19 May 2017 at 00:50 Jeyhun Karimov <
>>> je.karimov@gmail.com>
>>>>>>>>>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks. I initiated the PR as well, to get a better overview.
>>>>>>>>>>>>>
>>>>>>>>>>>>> The only reason that I used abstract class instead of
>> interface
>>>>> for
>>>>>>>>>> Rich
>>>>>>>>>>>>> functions is that in future if we will have some
>>>>>>> AbstractRichFunction
>>>>>>>>>>>>> abstract classes,
>>>>>>>>>>>>> we can easily extend:
>>>>>>>>>>>>>
>>>>>>>>>>>>> public abstract class RichValueMapper<K, V, VR> implements
>>>>>>>>>>>>> ValueMapperWithKey<K, V, VR>, RichFunction *extends
>>>>>>>>>>>> AbstractRichFunction*{
>>>>>>>>>>>>> }
>>>>>>>>>>>>> With interfaces we are only limited to interfaces for
>>>>> inheritance.
>>>>>>>>>>>>>
>>>>>>>>>>>>> However, I think we can easily change it (from abstract class
>> ->
>>>>>>>>>>>> interface)
>>>>>>>>>>>>> if you think interface is a better fit.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Fri, May 19, 2017 at 1:00 AM Matthias J. Sax <
>>>>>>> matthias@confluent.io
>>>>>>>>>>>
>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks for the update and explanations. The KIP is quite
>>> improved
>>>>>>> now
>>>>>>>>>>>> --
>>>>>>>>>>>>>> great job!
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> One more question: Why are RichValueMapper etc abstract
>> classes
>>>>> and
>>>>>>>>>> not
>>>>>>>>>>>>>> interfaces?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Overall, I like the KIP a lot!
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 5/16/17 7:03 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks for your comments.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>> interfaces
>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Maybe I misunderstood your comment.
>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* are interfaces. So they
>>> don't
>>>>>>> have
>>>>>>>>>>>>>> direct
>>>>>>>>>>>>>>> relation with *AbstractRichFunction*.
>>>>>>>>>>>>>>> *withKey* and and *withOnlyValue* interfaces have only one
>>>>>>> method ,
>>>>>>>>>>>> so
>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>> can use lambdas.
>>>>>>>>>>>>>>> Where does the *AbstractRichFunction* comes to play? Inside
>>> Rich
>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>> And we use Rich functions in 2 places:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 1. User doesn't use rich functions. Just regular *withKey*
>> and
>>>>> and
>>>>>>>>>>>>>>> *withOnlyValue* interfaces(both support lambdas) . We get
>>> those
>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>> and wrap into Rich function while building the topology, and
>>>>> send
>>>>>>> to
>>>>>>>>>>>>>>> Processor.
>>>>>>>>>>>>>>> 2. User does use rich functions (Rich functions implement
>>>>>>> *withKey*
>>>>>>>>>>>>>>> interface). As a result no lamdas here by definition. In
>> this
>>>>>>> case,
>>>>>>>>>>>>> while
>>>>>>>>>>>>>>> building the topology we do a type check if the object type
>> is
>>>>>>>>>>>>>>> *withKey* or *RichFunction*.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So *AbstractRichFunction* is just syntactic sugar for Rich
>>>>>>> functions
>>>>>>>>>>>>> and
>>>>>>>>>>>>>>> does not affect using lambdas.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
>> to
>>>>>>> have a
>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>> RichFunction
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> As I said above, currently we support lambdas for *withKey*
>>>>>>>>>>>> interfaces
>>>>>>>>>>>>> as
>>>>>>>>>>>>>>> well. However, I agree with your idea and I will remove the
>>>>>>>>>>>>>>> AbstractRichFunction from the design.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
>>>>>>> support
>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any "extended
>>>>> API".
>>>>>>>>>>>> For
>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
>> more
>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
>>>>> because
>>>>>>> we
>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>> value
>>> in
>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Just to clarify, with current design we have only one extra
>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>> method per *withOnlyValue* interface: which is *withKey*
>>>>> version
>>>>>>> of
>>>>>>>>>>>>>>> particular interface.
>>>>>>>>>>>>>>> We don't need extra overload for Rich function as Rich
>>> function
>>>>>>>>>>>>>> implements
>>>>>>>>>>>>>>> *withKey* interface as a result they have same type. We
>>>>>>> differentiate
>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>> while building the topology.
>>>>>>>>>>>>>>> We supported lambdas for *withKey* APIs because of the
>>> comment:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> @Jeyhun: I did not put any thought into this, but can we
>> have
>>> a
>>>>>>>>>>>> design
>>>>>>>>>>>>>>>> that allows for both? Also, with regard to lambdas, it
>> might
>>>>> make
>>>>>>>>>>>>> sense
>>>>>>>>>>>>>>>> to allow for both `V -> newV` and `(K, V) -> newV` ?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> However, I don't think that this complicates the overall
>>> design
>>>>>>>>>>>>>>> significantly.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense to
>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
>> this
>>>>>>> also
>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>> before
>>>>>>> driving
>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Based on our discussion I think we should keep Rich
>> functions
>>>>> as I
>>>>>>>>>>>>> don't
>>>>>>>>>>>>>>> think that they bring extra layer of overhead to library.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Any comments are appreciated.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Tue, May 16, 2017 at 12:10 AM Matthias J. Sax <
>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> thanks for the update.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I think supporting Lambdas for `withKey` and
>>>>>>> `AbstractRichFunction`
>>>>>>>>>>>>>>>> don't go together, as Lambdas are only supported for
>>> interfaces
>>>>>>>>>>>> AFAIK.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thus, if we want to support Lambdas for `withKey`, we need
>> to
>>>>>>> have a
>>>>>>>>>>>>>>>> interface approach like this
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> - RichFunction -> only adding init() and close()
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> - ValueMapper
>>>>>>>>>>>>>>>> - ValueMapperWithKey
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> - RichValueMapper extends ValueMapperWithKey,
>> RichFunction
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> For this approach, AbstractRichFunction does not make sense
>>>>>>> anymore,
>>>>>>>>>>>>> as
>>>>>>>>>>>>>>>> the only purpose of `RichFunction` is to allow the
>>>>>>> implementation of
>>>>>>>>>>>>>>>> init() and close() -- if you don't want those, you would
>>>>>>> implement a
>>>>>>>>>>>>>>>> different interface (ie, ValueMapperWithKey)
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> As an alternative, we could argue, that it is sufficient to
>>>>>>> support
>>>>>>>>>>>>>>>> Lambdas for the "plain" API only, but not for any "extended
>>>>> API".
>>>>>>>>>>>> For
>>>>>>>>>>>>>>>> this, RichFunction could add key+init+close and
>>>>>>> AbstractRichFunction
>>>>>>>>>>>>>>>> would allow to only care about getting the key.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Not sure, which one is better. I don't like the idea of
>> more
>>>>>>>>>>>>> overloaded
>>>>>>>>>>>>>>>> methods to get Lambdas for `withKey` interfaces too much
>>>>> because
>>>>>>> we
>>>>>>>>>>>>> have
>>>>>>>>>>>>>>>> already so many overlaods. On the other hand, I do see
>> value
>>> in
>>>>>>>>>>>>>>>> supporting Lambdas for `withKey`.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Depending on what we want to support, it might make sense
>> to
>>>>>>>>>>>>>>>> include/exclude RichFunctions from this KIP -- and thus,
>> this
>>>>>>> also
>>>>>>>>>>>>>>>> determines if we should have a "ProcessorContext KIP"
>> before
>>>>>>> driving
>>>>>>>>>>>>>>>> this KIP further.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thoughts?
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 5/15/17 11:01 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Sorry for super late response. Thanks for your comments.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a little
>>>>> bit? I
>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the problem
>>> is.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - From [1] says "A functional interface is an interface
>> that
>>>>> has
>>>>>>>>>>>> just
>>>>>>>>>>>>>> one
>>>>>>>>>>>>>>>>> abstract method, and thus represents a single function
>>>>>>> contract".
>>>>>>>>>>>>>>>>> So basically once we extend some interface from another
>> (in
>>>>> our
>>>>>>>>>>>> case,
>>>>>>>>>>>>>>>>> ValueMapperWithKey from ValueMapper) we cannot use lambdas
>>> in
>>>>>>> the
>>>>>>>>>>>>>>>> extended
>>>>>>>>>>>>>>>>> interface.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
>>>>> reformat
>>>>>>> the
>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would help.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - I will work on the KIP.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>> overlaods
>>>>>>> added
>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
>> add
>>>>> any
>>>>>>> new
>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - Actually there are more than one Processor and public
>> APIs
>>>>> to
>>>>>>> be
>>>>>>>>>>>>>>>>> changed (KStream-KTable
>>>>>>>>>>>>>>>>> joins is one case). However all of them has similar
>>> structure:
>>>>>>> we
>>>>>>>>>>>>>>>> overload
>>>>>>>>>>>>>>>>> the *method* with *methodWithKey*,
>>>>>>>>>>>>>>>>> wrap it into the Rich function, send to processor and
>> inside
>>>>> the
>>>>>>>>>>>>>>>> processor
>>>>>>>>>>>>>>>>> call *init* and *close* methods of the Rich function.
>>>>>>>>>>>>>>>>> As I wrote in KIP, I wanted to demonstrate the overall
>> idea
>>>>> with
>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>> *ValueMapper* as the same can be applied to all changes.
>>>>>>>>>>>>>>>>> Anyway I will update the KIP.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Instead of overriding the *init(ProcessorContext p)* and*
>>>>>>> close()*
>>>>>>>>>>>>>>>> methods
>>>>>>>>>>>>>>>>> in every Rich function with empty body like:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>> void init(ProcessorContext context) {}
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> @Override
>>>>>>>>>>>>>>>>> void close () {}
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I thought that we can override them once in
>>>>>>> *AbstractRichFunction*
>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>> extent new Rich functions from *AbstractRichFunction*.
>>>>>>>>>>>>>>>>> Basically this can eliminate code copy-paste and ease the
>>>>>>>>>>>>> maintenance.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>> Merger,
>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
>> all,
>>>>> but
>>>>>>> we
>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>> (e.g.,
>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Definitely agree. As I said, the same technique applies to
>>> all
>>>>>>> this
>>>>>>>>>>>>>>>>> interfaces and I didn't want to explode the KIP, just
>> wanted
>>>>> to
>>>>>>>>>>>> give
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>> overall intuition.
>>>>>>>>>>>>>>>>> However, I will update the KIP as I said.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` -- `ValueXXWithKey` --
>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>> interfaces
>>>>>>> only?
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Sure we can. However the main intuition is we should not
>>> force
>>>>>>>>>>>> users
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>> implement *init(ProcessorContext)* and *close()* functions
>>>>> every
>>>>>>>>>>>> time
>>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>>>> use Rich functions.
>>>>>>>>>>>>>>>>> If one needs, she can override the respective methods.
>>>>> However,
>>>>>>> I
>>>>>>>>>>>> am
>>>>>>>>>>>>>> open
>>>>>>>>>>>>>>>>> for discussion.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
>> any
>>>>>>>>>>>> further
>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
>> done
>>>>>>> before
>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
>>>>> large.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> That is good point. I wanted to make
>>> *init(ProcessorContext)*
>>>>>>>>>>>> method
>>>>>>>>>>>>>>>>> persistent among the library (which use ProcessorContext
>> as
>>> an
>>>>>>>>>>>>> input),
>>>>>>>>>>>>>>>>> therefore I put *ProcessorContext* as an input.
>>>>>>>>>>>>>>>>> So the important question is that (as @dguy and @mjsax
>>>>>>> mentioned)
>>>>>>>>>>>>>> whether
>>>>>>>>>>>>>>>>> continue this KIP without providing users an access to
>>>>>>>>>>>>>> *ProcessorContext*
>>>>>>>>>>>>>>>>> (change *init (ProcessorContext)* to * init()* ) or
>>>>>>>>>>>>>>>>> initiate another KIP before this.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~mr/se/8/java-se-8-pfd-spec/java-
>>>>>>>>>>>>>>>> se-8-jls-pfd-diffs.pdf
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On Mon, May 15, 2017 at 7:15 PM, Damian Guy <
>>>>>>> damian.guy@gmail.com>
>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> I'd rather not see the use of `ProcessorContext` spread
>>> any
>>>>>>>>>>>> further
>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>> it currently is. So maybe we need another KIP that is
>> done
>>>>>>> before
>>>>>>>>>>>>>> this?
>>>>>>>>>>>>>>>>>> Otherwise i think the scope of this KIP is becoming too
>>>>> large.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On Mon, 15 May 2017 at 18:06 Matthias J. Sax <
>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I agree that that `ProcessorContext` interface is too
>>> broad
>>>>> in
>>>>>>>>>>>>>> general
>>>>>>>>>>>>>>>>>>> -- this is even true for transform/process, and it's
>> also
>>>>>>>>>>>> reflected
>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>> the API improvement list we want to do.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/
>>>>>>>>>>>>>>>>>> Kafka+Streams+Discussions
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> So I am wondering, if you question the `RichFunction`
>>>>>>> approach in
>>>>>>>>>>>>>>>>>>> general? Or if you suggest to either extend the scope of
>>>>> this
>>>>>>> KIP
>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> include this---or maybe better, do another KIP for it
>> and
>>>>>>> delay
>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>> until the other one is done?
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On 5/15/17 2:35 AM, Damian Guy wrote:
>>>>>>>>>>>>>>>>>>>> Thanks for the KIP.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> I'm not convinced on the `RichFunction` approach. Do we
>>>>>>> really
>>>>>>>>>>>>> want
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> give
>>>>>>>>>>>>>>>>>>>> every DSL method access to the `ProcessorContext` ? It
>>> has
>>>>> a
>>>>>>>>>>>> bunch
>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>> methods on it that seem in-appropriate for some of the
>>> DSL
>>>>>>>>>>>>> methods,
>>>>>>>>>>>>>>>>>> i.e,
>>>>>>>>>>>>>>>>>>>> `register`, `getStateStore`, `forward`, `schedule` etc.
>>> It
>>>>> is
>>>>>>>>>>>> far
>>>>>>>>>>>>>> too
>>>>>>>>>>>>>>>>>>>> broad. I think it would be better to have a narrower
>>>>>>> interface
>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>> `RecordContext` - remembering it is easier to add
>>>>>>>>>>>>>> methods/interfaces
>>>>>>>>>>>>>>>>>>> later
>>>>>>>>>>>>>>>>>>>> than to remove them
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> On Sat, 13 May 2017 at 22:26 Matthias J. Sax <
>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Jeyhun,
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> I am not an expert on Lambdas. Can you elaborate a
>>> little
>>>>>>> bit?
>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>> cannot
>>>>>>>>>>>>>>>>>>>>> follow the explanation in the KIP to see what the
>>> problem
>>>>>>> is.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> For updating the KIP title I don't know -- guess it's
>> up
>>>>> to
>>>>>>>>>>>> you.
>>>>>>>>>>>>>>>>>> Maybe a
>>>>>>>>>>>>>>>>>>>>> committer can comment on this?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Further comments:
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - The KIP get a little hard to read -- can you maybe
>>>>>>> reformat
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>> wiki
>>>>>>>>>>>>>>>>>>>>> page a little bit? I think using `CodeBlock` would
>> help.
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - What about KStream-KTable joins? You don't have
>>>>> overlaods
>>>>>>>>>>>>> added
>>>>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>> them. Why? (Even if I still hope that we don't need to
>>> add
>>>>>>> any
>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>> overloads)
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - Why do we need `AbstractRichFunction`?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> - What about interfaces Initializer, ForeachAction,
>>>>> Merger,
>>>>>>>>>>>>>>>>>> Predicate,
>>>>>>>>>>>>>>>>>>>>> Reducer? I don't want to say we should/need to add to
>>> all,
>>>>>>> but
>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>>>> discuss all of them and add where it does make sense
>>>>> (e.g.,
>>>>>>>>>>>>>>>>>>>>> RichForachAction does make sense IMHO)
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> Btw: I like the hierarchy `ValueXX` --
>> `ValueXXWithKey`
>>> --
>>>>>>>>>>>>>>>>>> `RichValueXX`
>>>>>>>>>>>>>>>>>>>>> in general -- but why can't we do all this with
>>> interfaces
>>>>>>>>>>>> only?
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> On 5/11/17 7:00 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Thanks for your comments. I think we cannot extend
>> the
>>>>> two
>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>> if
>>>>>>>>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>>>>> want to keep lambdas. I updated the KIP [1]. Maybe I
>>>>> should
>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>> title, because now we are not limiting the KIP to
>> only
>>>>>>>>>>>>>> ValueMapper,
>>>>>>>>>>>>>>>>>>>>>> ValueTransformer and ValueJoiner.
>>>>>>>>>>>>>>>>>>>>>> Please feel free to comment.
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-
>>>>>>>>>>>>>>>>>> 149%3A+Enabling+key+access+in+ValueTransformer%2C+
>>>>>>>>>>>>>>>>>> ValueMapper%2C+and+ValueJoiner
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 7:36 PM Matthias J. Sax <
>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> If `ValueMapperWithKey` extends `ValueMapper` we
>> don't
>>>>>>> need
>>>>>>>>>>>> the
>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>> overlaod.
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> And yes, we need to do one check -- but this happens
>>>>> when
>>>>>>>>>>>>>> building
>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> topology. At runtime (I mean after
>> KafkaStream#start()
>>>>> we
>>>>>>>>>>>> don't
>>>>>>>>>>>>>>>> need
>>>>>>>>>>>>>>>>>>> any
>>>>>>>>>>>>>>>>>>>>>>> check as we will always use `ValueMapperWithKey`)
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>> On 5/9/17 2:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback.
>>>>>>>>>>>>>>>>>>>>>>>> Then we need to overload method
>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR> mapValues(ValueMapper<? super
>>> V,
>>>>> ?
>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>>>>>>>>>> <VR> KStream<K, VR>
>> mapValues(ValueMapperWithKey<?
>>>>>>> super
>>>>>>>>>>>> V,
>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>>>>>> extends
>>>>>>>>>>>>>>>>>>>>>>> VR>
>>>>>>>>>>>>>>>>>>>>>>>> mapper);
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> and in runtime (inside processor) we still have to
>>>>> check
>>>>>>> it
>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>> ValueMapper
>>>>>>>>>>>>>>>>>>>>>>>> or ValueMapperWithKey before wrapping it into the
>>> rich
>>>>>>>>>>>>> function.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 9, 2017 at 10:56 AM Michal Borowiecki <
>>>>>>>>>>>>>>>>>>>>>>>> michal.borowiecki@openbet.com> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> +1 :)
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>> On 08/05/17 23:52, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> I was reading the updated KIP and I am wondering,
>>> if
>>>>> we
>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>> design a little different.
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Instead of distinguishing between a RichFunction
>>> and
>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>> at
>>>>>>>>>>>>>>>>>>>>>>>>>> runtime level, we would use RichFunctions all the
>>>>> time.
>>>>>>>>>>>>> Thus,
>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>> DSL
>>>>>>>>>>>>>>>>>>>>>>>>>> entry level, if a user provides a
>> non-RichFunction,
>>>>> we
>>>>>>>>>>>> wrap
>>>>>>>>>>>>> it
>>>>>>>>>>>>>>>>>> by a
>>>>>>>>>>>>>>>>>>>>>>>>>> RichFunction that is fully implemented by
>> Streams.
>>>>> This
>>>>>>>>>>>>>>>>>>> RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>> would just forward the call omitting the key:
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Just to sketch the idea (incomplete code
>> snippet):
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> public StreamsRichValueMapper implements
>>>>>>>>>>>> RichValueMapper()
>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>> private ValueMapper userProvidedMapper; //
>> set
>>> by
>>>>>>>>>>>>>>>> constructor
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> public VR apply(final K key, final V1 value1,
>>>>>>> final V2
>>>>>>>>>>>>>>>>>> value2)
>>>>>>>>>>>>>>>>>>> {
>>>>>>>>>>>>>>>>>>>>>>>>>>> return userProvidedMapper(value1,
>> value2);
>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> From a performance point of view, I am not sure
>> if
>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>> "if(isRichFunction)" including casts etc would
>> have
>>>>>>> more
>>>>>>>>>>>>>>>> overhead
>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>> this approach (we would do more nested method
>> call
>>>>> for
>>>>>>>>>>>>>>>>>>>>> non-RichFunction
>>>>>>>>>>>>>>>>>>>>>>>>>> which should be more common than RichFunctions).
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> This approach should not effect lambdas (or do I
>>> miss
>>>>>>>>>>>>>>>> something?)
>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>> might be cleaner, as we could have one more top
>>> level
>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>>>>> `RichFunction` with methods `init()` and
>> `close()`
>>>>> and
>>>>>>>>>>>> also
>>>>>>>>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>>>>>>>>> for `RichValueMapper` etc. (thus, no abstract
>>> classes
>>>>>>>>>>>>>> required).
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> Any thoughts?
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/6/17 5:29 PM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments. I extended PR and KIP to
>>>>> include
>>>>>>>>>>>> rich
>>>>>>>>>>>>>>>>>>>>> functions.
>>>>>>>>>>>>>>>>>>>>>>> I
>>>>>>>>>>>>>>>>>>>>>>>>>>> will still have to evaluate the cost of deep
>>> copying
>>>>>>> of
>>>>>>>>>>>>> keys.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 8:02 PM Mathieu Fenniak <
>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hey Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> My opinion would be that documenting the
>>>>>>> immutability of
>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>> is
>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>> best approach available. Better than requiring
>>> the
>>>>>>> key
>>>>>>>>>>>> to
>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>> serializable
>>>>>>>>>>>>>>>>>>>>>>>>>>>> (as with Jeyhun's last pass at the PR), no
>>>>>>> performance
>>>>>>>>>>>>> risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> It'd be different if Java had immutable type
>>>>>>> constraints
>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>>>> kind.
>>>>>>>>>>>>>>>>>>>>>>>>> :-)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 11:31 AM, Matthias J.
>> Sax
>>> <
>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io>
>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Agreed about RichFunction. If we follow this
>>> path,
>>>>>>> it
>>>>>>>>>>>>>> should
>>>>>>>>>>>>>>>>>>> cover
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all(?) DSL interfaces.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> About guarding the key -- I am still not sure
>>> what
>>>>>>> to
>>>>>>>>>>>> do
>>>>>>>>>>>>>>>> about
>>>>>>>>>>>>>>>>>>>>> it...
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Maybe it might be enough to document it (and
>>> name
>>>>>>> the
>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>>>>>>>>>>> like
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> `readOnlyKey` to make is very clear).
>>> Ultimately,
>>>>> I
>>>>>>>>>>>> would
>>>>>>>>>>>>>>>>>> prefer
>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> guard against any modification, but I have no
>>> good
>>>>>>> idea
>>>>>>>>>>>>> how
>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>>>>>>>>> this.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Not sure what others think about the risk of
>>>>>>> corrupted
>>>>>>>>>>>>>>>>>>>>> partitioning
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (what would be a user error and we could say,
>>>>> well,
>>>>>>> bad
>>>>>>>>>>>>>> luck,
>>>>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>>>>>>>>> got
>>>>>>>>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bug in your code, that's not our fault), vs
>> deep
>>>>>>> copy
>>>>>>>>>>>>> with
>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>> potential
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> performance hit (that we can't quantity atm
>>>>> without
>>>>>>> any
>>>>>>>>>>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>>>>>>>>>>>> test).
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> We do have a performance system test. Maybe
>> it's
>>>>>>> worth
>>>>>>>>>>>>> for
>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>> apply
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the deep copy strategy and run the test. It's
>>> very
>>>>>>>>>>>> basic
>>>>>>>>>>>>>>>>>>>>> performance
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> test only, but might give some insight. If you
>>>>> want
>>>>>>> to
>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>> this,
>>>>>>>>>>>>>>>>>>>>> look
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> into folder "tests" for general test setup,
>> and
>>>>> into
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "tests/kafaktests/benchmarks/streams" to find
>>> find
>>>>>>> the
>>>>>>>>>>>>> perf
>>>>>>>>>>>>>>>>>>> test.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/5/17 8:55 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> I think extending KIP to include
>> RichFunctions
>>>>>>> totally
>>>>>>>>>>>>>>>> makes
>>>>>>>>>>>>>>>>>>>>>>> sense.
>>>>>>>>>>>>>>>>>>>>>>>>>>>> So,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> we don't want to guard the keys because it
>> is
>>>>>>>>>>>> costly.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If we introduce RichFunctions I think it
>> should
>>>>>>> not be
>>>>>>>>>>>>>>>>>> limited
>>>>>>>>>>>>>>>>>>>>> only
>>>>>>>>>>>>>>>>>>>>>>>>>>>> the 3
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces proposed in KIP but to wide range
>> of
>>>>>>>>>>>>>> interfaces.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Please correct me if I am wrong.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, May 5, 2017 at 12:04 AM Matthias J.
>>> Sax <
>>>>>>>>>>>>>>>>>>>>>>>>> matthias@confluent.io
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> One follow up. There was this email on the
>>> user
>>>>>>> list:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>> http://search-hadoop.com/m/Kafka/uyzND17KhCaBzPSZ1?subj=
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>> Shouldn+t+the+initializer+of+a+stream+aggregate+accept+the+
>>>>>>>>>>>>>>>>>> key+
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> It might make sense so include Initializer,
>>>>> Adder,
>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>> Substractor
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> inferface, too.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And we should double check if there are
>> other
>>>>>>>>>>>> interface
>>>>>>>>>>>>>> we
>>>>>>>>>>>>>>>>>>> might
>>>>>>>>>>>>>>>>>>>>>>>>> miss
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> atm.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/4/17 1:31 PM, Matthias J. Sax wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for updating the KIP.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Deep copying the key will work for sure,
>> but
>>> I
>>>>> am
>>>>>>>>>>>>>> actually
>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>> little
>>>>>>>>>>>>>>>>>>>>>>>>>>>> bit
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> worried about performance impact... We
>> might
>>>>>>> want to
>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>>> some
>>>>>>>>>>>>>>>>>>>>> test
>>>>>>>>>>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> quantify this impact.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Btw: this remind me about the idea of
>>>>>>> `RichFunction`
>>>>>>>>>>>>>>>>>>> interface
>>>>>>>>>>>>>>>>>>>>>>> that
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> would allow users to access record metadata
>>>>> (like
>>>>>>>>>>>>>>>>>> timestamp,
>>>>>>>>>>>>>>>>>>>>>>>>> offset,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> partition etc) within DSL. This would be a
>>>>>>> similar
>>>>>>>>>>>>>>>> concept.
>>>>>>>>>>>>>>>>>>>>>>> Thus, I
>>>>>>>>>>>>>>>>>>>>>>>>>>>> am
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wondering, if it would make sense to
>> enlarge
>>>>> the
>>>>>>>>>>>> scope
>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>> by
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> that? WDYT?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -Matthias
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 5/3/17 2:08 AM, Jeyhun Karimov wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Mathieu,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for feedback. I followed similar
>>>>> approach
>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>> updated
>>>>>>>>>>>>>>>>>>>>> PR
>>>>>>>>>>>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> KIP
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accordingly. I tried to guard the key in
>>>>>>> Processors
>>>>>>>>>>>>>>>>>> sending
>>>>>>>>>>>>>>>>>>> a
>>>>>>>>>>>>>>>>>>>>>>> copy
>>>>>>>>>>>>>>>>>>>>>>>>>>>> of
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> an
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> actual key.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because I am doing deep copy of an
>> object, I
>>>>>>> think
>>>>>>>>>>>>>> memory
>>>>>>>>>>>>>>>>>>> can
>>>>>>>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> bottleneck
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in some use-cases.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Jeyhun
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, May 2, 2017 at 5:10 PM Mathieu
>>>>> Fenniak <
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mathieu.fenniak@replicon.com>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi Jeyhun,
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This approach would change ValueMapper
>>>>>>> (...etc) to
>>>>>>>>>>>>> be
>>>>>>>>>>>>>>>>>>>>> classes,
>>>>>>>>>>>>>>>>>>>>>>>>>>>> rather
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, which is also a backwards
>>>>>>> incompatible
>>>>>>>>>>>>>>>>>> change.
>>>>>>>>>>>>>>>>>>>>> An
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> alternative
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> approach that would be backwards
>> compatible
>>>>>>> would
>>>>>>>>>>>> be
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>>>>>>> define
>>>>>>>>>>>>>>>>>>>>>>>>> new
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> interfaces, and provide overrides where
>>> those
>>>>>>>>>>>>>> interfaces
>>>>>>>>>>>>>>>>>>> are
>>>>>>>>>>>>>>>>>>>>>>>>> used.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Unfortunately, making the key parameter
>> as
>>>>>>> "final"
>>>>>>>>>>>>>>>>>> doesn't
>>>>>>>>>>>>>>>>>>>>>>> change
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> about guarding against key change. It
>> only
>>>>>>>>>>>> prevents
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> variable
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> from being reassigned. If the key type
>> is
>>> a
>>>>>>>>>>>> mutable
>>>>>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>>>>>>>>>> (eg.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> byte[]),
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> it can still be mutated. (eg. key[0] =
>> 0).
>>>>> But
>>>>>>>>>>>> I'm
>>>>>>>>>>>>>> not
>>>>>>>>>>>>>>>>>>>>> really
>>>>>>>>>>>>>>>>>>>>>>>>> sure
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> there's
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> much that can be done about that.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mathieu
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Mon, May 1, 2017 at 5:39 PM, Jeyhun
>>>>> Karimov
>>>>>>> <
>>>>>>>>>>>>>>>>>>>>>>>>>>>> je.karimov@gmail.com
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Thanks for comments.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The concerns makes sense. Although we
>> can
>>>>>>> guard
>>>>>>>>>>>> for
>>>>>>>>>>>>>>>>>>>>> immutable
>>>>>>>>>>>>>>>>>>>>>>>>> keys
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> current implementation (with few
>>> changes), I
>>>>>>>>>>>> didn't
>>>>>>>>>>>>>>>>>>> consider
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backward
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> compatibility.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In this case 2 solutions come to my
>> mind.
>>> In
>>>>>>> both
>>>>>>>>>>>>>>>> cases,
>>>>>>>>>>>>>>>>>>>>> user
>>>>>>>>>>>>>>>>>>>>>>>>>>>>> accesses
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> key in Object type, as passing extra
>> type
>>>>>>>>>>>> parameter
>>>>>>>>>>>>>>>> will
>>>>>>>>>>>>>>>>>>>>> break
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> backwards-compatibility. So user has
>> to
>>>>> cast
>>>>>>> to
>>>>>>>>>>>>>> actual
>>>>>>>>>>>>>>>>>>> key
>>>>>>>>>>>>>>>>>>>>>>>>> type.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>
>>
>> --
>> -Cheers
>>
>> Jeyhun
>>
>
>
>