Re: Review Request 35715: Added revocable resource state validation.

[Niklas Nielsen <ni...@qni.dk>]

> On June 21, 2015, 11:47 a.m., Vinod Kone wrote:
> > src/common/resources.cpp, lines 479-487
> > <https://reviews.apache.org/r/35715/diff/1/?file=989223#file989223line479>
> >
> >     These checks are done in master's validation.cpp
> 
> Michael Park wrote:
>     Ah sorry, I missed that.
>     
>     This reminded me of the discussion Jie and I had for [r32140](https://reviews.apache.org/r/32140/) regarding where validations should live. I think this validation belongs here rather than in master validation.
>     What we concluded from the discussion was that `Resources::validate` should perform necessary validation to satisfy the invariant of the `Resource` object.
>     This enables methods that operate on `Resource` (e.g. `Resources::isRevocable`) to assume its validity.
>     
>     My notes:
>     > Synced with Jie on IRC regarding this topic. We agreed that `Resources::validate` needs to capture the invariant of the `Resource` object which means it needs to invalidate the `role == "*" && has_reservation()` state. This invariant is required for all the predicates as well as functions such as `reserved()` and `unreserved()` to have well-defined behavior.
>     
>     Jie's note:
>     > Discussed with Mpark offline. We agreed that rule for Resources::validate is that it should only perform necessary validation to make sure all methods in Resources are well hahaved, and the validation around * and reservation info is necessary for 'reserved/unreserved' to work properly. Thus dropping the issue around validation.
> 
> Michael Park wrote:
>     I found Jie's comment regarding this: https://reviews.apache.org/r/33865/#comment133597
>     
>     @Jie: My thought here was that these checks are necessary to make `isRevocable` well-defined. The same way the check for `"*" resource cannot be dynamically reserved` is necessary to make `isDynamicallyReserved` and others well-defined?
> 
> Jie Yu wrote:
>     @Mpark,
>     
>     I think the following check is in Resources::validate because otherwise isReserved will break (e.g., role = `*` and reservation is not set, isReserved(resource, `*`) will return true).
>     
>     ```
>     if (resource.role() == "*" && resource.has_reservation()) {
>       return Error(
>           "Invalid reservation: role \"*\" cannot be dynamically reserved");
>     }
>     ```
> 
> Michael Park wrote:
>     @Jie,
>     > e.g., role = * and reservation is not set, isReserved(resource, *) will return true
>     
>     If you meant `role = * and reservation _is_ set`, then yes.
>     
>     I'm saying that exact reasoning is also why these checks should be in `Resources::validate`, because otherwise `isRevocable` will break.
>     e.g. `reservation is set and revocable is set`, `isRevocable` will return true.
> 
> Niklas Nielsen wrote:
>     Hey guys - did you reach a conclusion?

MPark; how can we get closure on this?


- Niklas


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On June 21, 2015, noon, Michael Park wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/35715/
> -----------------------------------------------------------
> 
> (Updated June 21, 2015, noon)
> 
> 
> Review request for mesos, Jie Yu, Niklas Nielsen, and Vinod Kone.
> 
> 
> Repository: mesos
> 
> 
> Description
> -------
> 
> In `mesos.proto`, it specifies the expected state of revocable resource:
> 
> ```
> // ... Note that if this is set, 'disk' or 'reservation' cannot be set.
> optional RevocableInfo revocable = 9;
> ```
>   
> This expectation should be validated in `Resources::validate(const Resource& resoure)`
> 
> 
> Diffs
> -----
> 
>   src/common/resources.cpp eb5476a0365fe65f474afd0ab7a52ad7f1e04521 
>   src/tests/resources_tests.cpp 9f96b14a6a4ce416d044934dd7ab4d28e4bc7332 
> 
> Diff: https://reviews.apache.org/r/35715/diff/
> 
> 
> Testing
> -------
> 
> Added `RevocableResourceTest.Validation` + `make check`
> 
> 
> Thanks,
> 
> Michael Park
> 
>