FEATURE: add interface compatible constant version of thread local var #823
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I'm not actively involved in this gem anymore, but I think this PR would be a good addition, FWIW. |
pitr-ch
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@SamSaffron Sorry for overlooking the PR. I'll update it and have a look at merging it. |
ThreadLocalVar can be expensive as it spins a thread in finalizers. In some cases consumers may want to swap in a constant value implementations that is very cheap. `Concurrent::ConstantThreadLocalVar` is interface compatible with AbstractThreadLocalVar, however does not allow any changing of .value
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| @default_block.call |
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This evaluates the @default_block on each value read, so it may return different values each time value is called. I think that if the default_block is provided the ConstantThreadLocalVar should still store the computed value per thread (since it might differ). So the implementation could inherit from ThreadLocalVar, disallow using value= , and it would be good if it optimises @default case (the value is equal for all threads).
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@SamSaffron is it still worth me getting this merged? |
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I am mixed Chris ... I ended up working around the issue here: rails/rails#37200 The finalizer approach though is a bit problematic in many ways, but the workaround in pure Ruby is simple enough. The problem with adding the API here though is that we have no real world consumers for it anymore. |
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Closing as no immediate need and we're trying to get on top of the backlog of this gem. Feel free to re-suggest in the future. |
ThreadLocalVar can be expensive as it spins a thread in finalizers. In some
cases consumers may want to swap in a constant value implementations that
is very cheap.
Concurrent::ConstantThreadLocalVaris interface compatible withAbstractThreadLocalVar, however does not allow any changing of .value
See more context in: rails/rails#36949
@pitr-ch how do you feel about this? Would you prefer this here or in Rails?