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Make WaitForMultipleEvents atomic when waitAll is true #20

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Make WaitForMultipleEvents atomic when waitAll is true #20

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Commits on Nov 17, 2022

  1. Add failing test for atomicity of WaitForMultipleEvents w/ waitAll 

    Test contributed by @qwertymaster617, see [0] for associated issue.

[0]: #9
    @mqudsi
    mqudsi committed Nov 17, 2022
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  2. Make WaitForMultipleEvents atomic when waitAll is true 

    This patch significantly changes the behavior (and to an extent, the
performance) of pevents to more closely mimic the documented behavior of
`WaitForMultipleObjects` and `WaitForMultipleObjectsEx`.

As reported in #9, the previous behavior did not make any atomicity
guarantees when a call to `WaitForMultipleEvents()` was made with
`waitAll = true`, and WFME would attempt to serially obtain the events
in question, which could lead to a deadlock in case of circular locking
and auto-reset events.

The WFMO behavior documented on MSDN makes it clear that the Windows
implementation does not modify the signalled state of any of the manual
or auto reset events being awaited until the WFMO call is ready to
return, at which point either the one event in question or all the
events being awaited (dependent on `waitAll`) are atomically awaited.
    @mqudsi
    mqudsi committed Nov 17, 2022
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  3. Clarify behavior WFME contention over autoreset events

    @mqudsi
    mqudsi committed Nov 17, 2022
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  4. Remove technically incorrect assertion 

    If the initial number of events was zero and waitAll was set, this
assertion would fail incorrectly.
    @mqudsi
    mqudsi committed Nov 17, 2022
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  5. Prevent unbounded WFME cycling under heavy contention

    @mqudsi
    mqudsi committed Nov 17, 2022
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  6. Remove unused header include

    @mqudsi
    mqudsi committed Nov 17, 2022
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