dsound: use event based threads, v2

[Maarten Lankhorst]

Op 21-12-12 11:59, Joerg-Cyril.Hoehle at t-systems.com schreef:
> Maarten,
>
>> +    hres = IAudioClient_GetStreamLatency(device->client, &period);
>> +        device->sleeptime = period_ms * 5 / 2;
>> +		ret = WaitForSingleObject(dev->sleepev, dev->sleeptime);
> Although it's a minor point, as we're solely discussing the case of the
> timeout when mmdevapi doesn't call SetEvent, I wonder why you insist
> on using GetStreamLatency as the basis of your timeout computations
> instead of GetDevicePeriod.
>
> You know that wineXYZ.drv use the device period as the basis for their
> SetEvent, thus IMHO the timeout too should be based on it, instead
> of a GetStreamLatency we know next to nothing about.
>
> If you visit testbot jobs 23521 and 23514, you'll see that I've
> measured the event rates.  Sadly, all testbot VMs report a
> GetStreamLatency of 10.6666ms too close to the DefaultPeriod of
> 10.0000ms to tell for sure which is used as the average period.
>
<snip>

Because I'm using it later on in the rework to tell how much to queue.
In my rework, I try to write at most 3 * GetStreamLatency, so even if
for some reason no event is ever delivered, you would never get an
underrun.

This is why I choose streamlatency instead of getdeviceperiod. Also
since it may be a different value, who says it's only going to be bigger
than the default period? It could theoretically be smaller, still..

~Maarten