[PATCH2/2] winmm: PlaySound concurrency cleanup.

[Eric Pouech]

sharing a global variable between threads without proper sync protection or
atomic operation is the wrong thing to do
moreover you're doing several unrelated changes in the same patch, please
split up

A+

2011/3/28 <Joerg-Cyril.Hoehle at t-systems.com>

> Hi,
>
> - PlaySound_Alloc does not call _Free anymore, so it does not use WINMM_cs
>  anymore, which makes it easier to reason about use of critical sections.
> - psStopEvent was never used like an event rather than a boolean.
> - No need to muck with WHDR_DONE.
> - No need to keep the unused thread handle object around.
> - Abort the playloop in case of error, like I did for mciwave.  The error
>  may not be transient.
>
> - Free waveHdr and hEvent after closing hWave.  Either you believe that
>  WAVERR_STILLPLAYING can happen, then obviously waveHdr is in use and must
>  not yet be freed, or you believe checking for STILLPLAYING is a waste of
>  code because waveOutReset must have done its job.
>
>  I should have added an ERR() message.
>
>  One should think again about what to do in such a case.  Why/when would
>  sleep help?  User-friendlier might be not to wait, not to free WaveHdr
>  and accept to leak resources in such a case.
>
>  Actually, waveOutClose can fail with STILLPLAYING because waveOutReset
>  can fail.  If you look at winealsa, you'll see it uses CreateEvent to
>  synchronously wait for acknowledge of the message.  Now guess what
>  happens if CreateEvent fails because memory is tight?
>  What happens in the app when waveOutClose's CreateEvent fails?
>  It's always tough to reason about the many error paths.
>
> Regards,
>        Jörg Höhle
>
>
>
>


-- 
-- 
Eric Pouech
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