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Posted to dev@ratis.apache.org by Rui Wang <am...@apache.org> on 2021/02/03 20:55:56 UTC
Question about ApplyTransactionSerial and ApplyTransaction
Hi community,
StateMachine Interface has both ApplyTransactionSerial and
ApplyTransaction, and these two function definition are:
TransactionContext applyTransactionSerial(TransactionContext trx);
CompletableFuture<Message> applyTransaction(TransactionContext trx);
The comments about ApplyTransactionSerial says " This step is called
sequentially in strict serial order that the transactions have been
committed in the log."
The comments about ApplyTransaction says " This method can be called
concurrently with the other calls, and there is no guarantee that the calls
will be ordered according to the log commit order."
So my question is, shouldn't there another API "Message
applyTransactionSerial(TransactionContext trx)" that both guarantees to
apply in the order of the log while it allows return a Message?
"TransactionContext applyTransactionSerial(TransactionContext trx);" does
not return a Message (for the sake of applying the transaction to the state
machine and return a result).
"CompletableFuture<Message> applyTransaction(TransactionContext trx);"
could apply transaction concurrently thus raft log ordering is not
guaranteed.
-Rui
Re: Question about ApplyTransactionSerial and ApplyTransaction
Posted by Tsz Wo Sze <sz...@gmail.com>.
> ... we probably need to add an extra field in TransactionContext for this
purpose.
We may use TransactionContext.setStateMachineContext(..). State machine
could put whatever it wants.
Tsz-Wo
On Fri, Feb 5, 2021 at 3:15 AM Rui Wang <am...@apache.org> wrote:
> Filed a patch to clarify in the javadoc:
> https://github.com/apache/incubator-ratis/pull/416
>
>
> -Rui
>
> On Thu, Feb 4, 2021 at 11:01 AM Rui Wang <am...@apache.org> wrote:
>
> > Thanks Tsz-Wo for your detailed explanation! I think returning to a
> > completed future makes sense!
> >
> > I explored to put an immediate result by applyTransactionSerial(), I
> might
> > be wrong: we probably need to add an extra field in TransactionContext
> > for this purpose.
> >
> > -Rui
> >
> > On Thu, Feb 4, 2021 at 2:03 AM Tsz Wo Sze <sz...@gmail.com> wrote:
> >
> >> The javadoc of applyTransaction(..) may not be very clear.
> >> The applyTransaction(..) itself is called in the log order. However,
> >> since
> >> it returns a future, the state machine can complete the returned futures
> >> in
> >> a different order. The StateMachine implementation can choose to
> return a
> >> completed future for the ordering guarantee.
> >>
> >> For example, in ArithmeticStateMachine.applyTransaction(..), the result
> >> message is computed inside the method. The future is already completed
> >> before returning; see line 172.
> >>
> >>
> >> //ArithmeticStateMachine.java, line 172
> >>
> >> final CompletableFuture<Message> f =
> >> CompletableFuture.completedFuture(Expression.Utils.toMessage(r));
> >>
> >>
> >> Another way is to put an intermediate output in the TransactionContext
> >> returned by applyTransactionSerial(..). Then, applyTransaction(..) can
> >> simply take the intermediate output and then return it.
> >>
> >> Hope it helps.
> >> Tsz-Wo
> >>
> >> On Thu, Feb 4, 2021 at 4:56 AM Rui Wang <am...@apache.org> wrote:
> >>
> >> > Hi community,
> >> >
> >> > StateMachine Interface has both ApplyTransactionSerial and
> >> > ApplyTransaction, and these two function definition are:
> >> >
> >> > TransactionContext applyTransactionSerial(TransactionContext trx);
> >> >
> >> > CompletableFuture<Message> applyTransaction(TransactionContext trx);
> >> >
> >> >
> >> > The comments about ApplyTransactionSerial says " This step is called
> >> > sequentially in strict serial order that the transactions have been
> >> > committed in the log."
> >> >
> >> > The comments about ApplyTransaction says " This method can be called
> >> > concurrently with the other calls, and there is no guarantee that the
> >> calls
> >> > will be ordered according to the log commit order."
> >> >
> >> > So my question is, shouldn't there another API "Message
> >> > applyTransactionSerial(TransactionContext trx)" that both guarantees
> to
> >> > apply in the order of the log while it allows return a Message?
> >> >
> >> >
> >> > "TransactionContext applyTransactionSerial(TransactionContext trx);"
> >> does
> >> > not return a Message (for the sake of applying the transaction to the
> >> state
> >> > machine and return a result).
> >> > "CompletableFuture<Message> applyTransaction(TransactionContext trx);"
> >> > could apply transaction concurrently thus raft log ordering is not
> >> > guaranteed.
> >> >
> >> >
> >> > -Rui
> >> >
> >>
> >
>
Re: Question about ApplyTransactionSerial and ApplyTransaction
Posted by Rui Wang <am...@apache.org>.
Filed a patch to clarify in the javadoc:
https://github.com/apache/incubator-ratis/pull/416
-Rui
On Thu, Feb 4, 2021 at 11:01 AM Rui Wang <am...@apache.org> wrote:
> Thanks Tsz-Wo for your detailed explanation! I think returning to a
> completed future makes sense!
>
> I explored to put an immediate result by applyTransactionSerial(), I might
> be wrong: we probably need to add an extra field in TransactionContext
> for this purpose.
>
> -Rui
>
> On Thu, Feb 4, 2021 at 2:03 AM Tsz Wo Sze <sz...@gmail.com> wrote:
>
>> The javadoc of applyTransaction(..) may not be very clear.
>> The applyTransaction(..) itself is called in the log order. However,
>> since
>> it returns a future, the state machine can complete the returned futures
>> in
>> a different order. The StateMachine implementation can choose to return a
>> completed future for the ordering guarantee.
>>
>> For example, in ArithmeticStateMachine.applyTransaction(..), the result
>> message is computed inside the method. The future is already completed
>> before returning; see line 172.
>>
>>
>> //ArithmeticStateMachine.java, line 172
>>
>> final CompletableFuture<Message> f =
>> CompletableFuture.completedFuture(Expression.Utils.toMessage(r));
>>
>>
>> Another way is to put an intermediate output in the TransactionContext
>> returned by applyTransactionSerial(..). Then, applyTransaction(..) can
>> simply take the intermediate output and then return it.
>>
>> Hope it helps.
>> Tsz-Wo
>>
>> On Thu, Feb 4, 2021 at 4:56 AM Rui Wang <am...@apache.org> wrote:
>>
>> > Hi community,
>> >
>> > StateMachine Interface has both ApplyTransactionSerial and
>> > ApplyTransaction, and these two function definition are:
>> >
>> > TransactionContext applyTransactionSerial(TransactionContext trx);
>> >
>> > CompletableFuture<Message> applyTransaction(TransactionContext trx);
>> >
>> >
>> > The comments about ApplyTransactionSerial says " This step is called
>> > sequentially in strict serial order that the transactions have been
>> > committed in the log."
>> >
>> > The comments about ApplyTransaction says " This method can be called
>> > concurrently with the other calls, and there is no guarantee that the
>> calls
>> > will be ordered according to the log commit order."
>> >
>> > So my question is, shouldn't there another API "Message
>> > applyTransactionSerial(TransactionContext trx)" that both guarantees to
>> > apply in the order of the log while it allows return a Message?
>> >
>> >
>> > "TransactionContext applyTransactionSerial(TransactionContext trx);"
>> does
>> > not return a Message (for the sake of applying the transaction to the
>> state
>> > machine and return a result).
>> > "CompletableFuture<Message> applyTransaction(TransactionContext trx);"
>> > could apply transaction concurrently thus raft log ordering is not
>> > guaranteed.
>> >
>> >
>> > -Rui
>> >
>>
>
Re: Question about ApplyTransactionSerial and ApplyTransaction
Posted by Rui Wang <am...@apache.org>.
Thanks Tsz-Wo for your detailed explanation! I think returning to a
completed future makes sense!
I explored to put an immediate result by applyTransactionSerial(), I might
be wrong: we probably need to add an extra field in TransactionContext for
this purpose.
-Rui
On Thu, Feb 4, 2021 at 2:03 AM Tsz Wo Sze <sz...@gmail.com> wrote:
> The javadoc of applyTransaction(..) may not be very clear.
> The applyTransaction(..) itself is called in the log order. However, since
> it returns a future, the state machine can complete the returned futures in
> a different order. The StateMachine implementation can choose to return a
> completed future for the ordering guarantee.
>
> For example, in ArithmeticStateMachine.applyTransaction(..), the result
> message is computed inside the method. The future is already completed
> before returning; see line 172.
>
>
> //ArithmeticStateMachine.java, line 172
>
> final CompletableFuture<Message> f =
> CompletableFuture.completedFuture(Expression.Utils.toMessage(r));
>
>
> Another way is to put an intermediate output in the TransactionContext
> returned by applyTransactionSerial(..). Then, applyTransaction(..) can
> simply take the intermediate output and then return it.
>
> Hope it helps.
> Tsz-Wo
>
> On Thu, Feb 4, 2021 at 4:56 AM Rui Wang <am...@apache.org> wrote:
>
> > Hi community,
> >
> > StateMachine Interface has both ApplyTransactionSerial and
> > ApplyTransaction, and these two function definition are:
> >
> > TransactionContext applyTransactionSerial(TransactionContext trx);
> >
> > CompletableFuture<Message> applyTransaction(TransactionContext trx);
> >
> >
> > The comments about ApplyTransactionSerial says " This step is called
> > sequentially in strict serial order that the transactions have been
> > committed in the log."
> >
> > The comments about ApplyTransaction says " This method can be called
> > concurrently with the other calls, and there is no guarantee that the
> calls
> > will be ordered according to the log commit order."
> >
> > So my question is, shouldn't there another API "Message
> > applyTransactionSerial(TransactionContext trx)" that both guarantees to
> > apply in the order of the log while it allows return a Message?
> >
> >
> > "TransactionContext applyTransactionSerial(TransactionContext trx);" does
> > not return a Message (for the sake of applying the transaction to the
> state
> > machine and return a result).
> > "CompletableFuture<Message> applyTransaction(TransactionContext trx);"
> > could apply transaction concurrently thus raft log ordering is not
> > guaranteed.
> >
> >
> > -Rui
> >
>
Re: Question about ApplyTransactionSerial and ApplyTransaction
Posted by Tsz Wo Sze <sz...@gmail.com>.
The javadoc of applyTransaction(..) may not be very clear.
The applyTransaction(..) itself is called in the log order. However, since
it returns a future, the state machine can complete the returned futures in
a different order. The StateMachine implementation can choose to return a
completed future for the ordering guarantee.
For example, in ArithmeticStateMachine.applyTransaction(..), the result
message is computed inside the method. The future is already completed
before returning; see line 172.
//ArithmeticStateMachine.java, line 172
final CompletableFuture<Message> f =
CompletableFuture.completedFuture(Expression.Utils.toMessage(r));
Another way is to put an intermediate output in the TransactionContext
returned by applyTransactionSerial(..). Then, applyTransaction(..) can
simply take the intermediate output and then return it.
Hope it helps.
Tsz-Wo
On Thu, Feb 4, 2021 at 4:56 AM Rui Wang <am...@apache.org> wrote:
> Hi community,
>
> StateMachine Interface has both ApplyTransactionSerial and
> ApplyTransaction, and these two function definition are:
>
> TransactionContext applyTransactionSerial(TransactionContext trx);
>
> CompletableFuture<Message> applyTransaction(TransactionContext trx);
>
>
> The comments about ApplyTransactionSerial says " This step is called
> sequentially in strict serial order that the transactions have been
> committed in the log."
>
> The comments about ApplyTransaction says " This method can be called
> concurrently with the other calls, and there is no guarantee that the calls
> will be ordered according to the log commit order."
>
> So my question is, shouldn't there another API "Message
> applyTransactionSerial(TransactionContext trx)" that both guarantees to
> apply in the order of the log while it allows return a Message?
>
>
> "TransactionContext applyTransactionSerial(TransactionContext trx);" does
> not return a Message (for the sake of applying the transaction to the state
> machine and return a result).
> "CompletableFuture<Message> applyTransaction(TransactionContext trx);"
> could apply transaction concurrently thus raft log ordering is not
> guaranteed.
>
>
> -Rui
>