ReentrantSemaphore - Implement EnterAsync with timeout

[robert-at-pieces]

Is your feature request related to a problem? Please describe.

SemaphoreSlim and AsyncSemaphore have been banned via analyzers with the replacement preference being ReentrantSemaphore due to it being JTF aware.

AsyncSemaphore's EnterAsync implementation allows for a timeout parameter

ReentrantSemaphore's ExecuteAsync implementation always enters the underlying AsyncSemphare with an infinite timeout

Describe the solution you'd like

AsyncSemaphore supports an EnterAsync timeout. I would like to see ReentrantSemaphore allow for this parameter to be passed as an argument during ExecuteAsync.

Describe alternatives you've considered

Unless I am mistaken,
You can partially work around this by passing a cancellation token that times out, but this timeout is not specific to acquiring the lock. If the critical section is a long running operation, it is possible that a passed in cancellation token would cancel even though entrance into the critical section was achieved.

[weltkante]

it is possible that a passed in cancellation token would cancel even though entrance into the critical section was achieved

but then the call would have succeed and not thrown, so the caller would have first seen that it entered and acquired the lock, construct whatever scope is necessary to safely release it when leaving the scope, and only then (by its own choice) may or may not check the cancellation token again

any other implementation would be bugged regardless of your particular usecase via a timeout and it would never be safe to pass a cancellation token

so while having a particular API with timeout support probably might be more efficient it shouldn't be necessary for correctness

[robert-at-pieces]

@weltkante

Thank you for the response. Perhaps I did misunderstand the 'ExecuteAsync' implementation.

Would it be correct to say that once the the operation callback is invoked OperationCancelled exception will not be thrown and it is the caller's responsibility to check the CancellationToken inside of the Task that was passed as a parameter?

[weltkante]

yes, all checks in the code happen before, and if the operation itself wants to check it then it'll do it on its own terms

(also I'm not part of the repo team, just subscribed to the issue list, so feel free to wait for an 'official' confirmation)