<Sound Dev> [12] Review Request: 8207150 Clip.isRunning() may return true after Clip.stop() was called

[Philip Race]

Approved.

-phil.

On 8/4/18, 4:43 PM, Sergey Bylokhov wrote:
> On 03/08/2018 17:44, Phil Race wrote:
>> I don't know what your notation for the race condition means. Please 
>> expand and explain in more detail how this happens and add it to the 
>> bug report as well as here.
>
> Below some parts of the code which are executed when we play audio in 
> write(...) and when we stop the playing.
>
> ====================================================
>>> The problem exists in our DirectAudioDevice implementation. Before 
>>> we play the audio we have this check in write():
>>> if (!isActive() && doIO) {
>>>     setActive(true);
>>>     setStarted(true);
>>> }
>>>
>>> And to stop the clip we have this:
>>> synchronized(lock) {
>>>     // need to set doIO to false before notifying the
>>>     // read/write thread, that's why isStartedRunning()
>>>     // cannot be used
>>>     doIO = false;
>>>     lock.notifyAll();
>>> }
>>> setActive(false);
>>> setStarted(false);
> ====================================================
>
>>> Note that it is possible to get the next race.
>>> 1 write() -> if(doIO) is true
>>> 2 stop() -> doIO=false + setActive(false) + setStarted(false)
>>> 3 write() -> setActive(true) + setStarted(true)
>
> The notion above means:
> (1) in the write method we execute "if(doIO)" when doIO is true.
> (2) in the stop() method we set doIO to false and call
>    setActive(false);
>    setStarted(false);
> (3) in the write method we call:
>    setActive(true);
>    setStarted(true);
>
> So we stop play of audio at step (2) but the clip still reports itself 
> as "running".
>
>