[linux-audio-dev] Multithreaded programming for a poll model?

[Chris Cannam]

On Thursday 17 Jun 2004 7:08 pm, Mario Lang wrote:
> I think for this to work, I'd need some
> prebuffering in between, and the audio thread somehow singaling to
> the decoder thread when the buffer is too empty to safely continue
> sleeping so that the decoder can start to fill more data into the
> buffer.

One way to do this is to use pthread conditions.  Have a ring buffer 
between your decoder and RT threads, with the decoder sleeping for 
short periods of time between reads using pthread_cond_timedwait or 
similar.  This causes the thread to sleep until a certain time has 
elapsed or a condition has been signalled.  You can then signal from 
the RT thread using pthread_cond_signal to wake up the decoder thread 
each time something is read from the ring buffer.

This is pretty much what we're doing in Rosegarden 0.9.8, but now that 
I describe it, I realise I don't know for absolutely sure whether 
pthread_cond_signal is itself RT-safe.  More information or better 
alternatives are welcome.


Chris