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When we added `ResourceQuantities`, we wanted to support two use cases:
```
guarantees: absent == 0 (i.e. zero_by_default)
limits: absent == +inf (i.e. inf_by_default)
```
This is why zeros are currently stored (unlike `Resources` objects, where they
are removed): having the ability to distinguish between 0 and absent allows us
to support both use cases. However, the introduction of equality and
containment operations are not so obvious:
```
equality: the approach in this patch is providing inf_by_default equality
semantics AFAICT
containment: the approach in the subsequent patch is providing neither
zero_by_default or inf_by_default equality semantics
```
I think that in order to introduce equality and containment, we may have to
address some earlier feedback on `ResourceQuantities`, which was to require a
contruction-time choice between `ZERO_BY_DEFAULT` and `INF_BY_DEFAULT`
semantics. This would be stored as a variable in order to determine (1) whether
to store zeros, (2) how to evaluate equality and containment between two
quantities.
Thoughts?
- Benjamin Mahler
On Jan. 23, 2019, 12:12 p.m., Benjamin Bannier wrote:
>
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> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/69819/
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>
> (Updated Jan. 23, 2019, 12:12 p.m.)
>
>
> Review request for mesos, Benjamin Mahler and Meng Zhu.
>
>
> Bugs: MESOS-9523
> https://issues.apache.org/jira/browse/MESOS-9523
>
>
> Repository: mesos
>
>
> Description
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>
> This patch adds an `operator==` for `ResourceQuantities`. The operator
> is declared as a `friend` of `ResourceQuantities` so we can directly
> compare the two `ResourceQuantities::quantities` which can be less
> expensive.
>
>
> Diffs
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>
> src/common/resource_quantities.hpp 11eb426104577bbbbb7977c2307df3e4917085cd
> src/common/resource_quantities.cpp 320983929cd7d14973c4b98d6ed5338de690ff5f
>
>
> Diff: https://reviews.apache.org/r/69819/diff/1/
>
>
> Testing
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>
> `make check`
>
>
> Thanks,
>
> Benjamin Bannier
>
>
