Re: [Discuss-gnuradio] Thread-Safe Blocking?

[Robert McGwier]

I think the question was probably more than "what tools" but I could be 
wrong.  Let me attempt more just in case.

gr-audio-osx should NEVER be blocked awaiting anything in gr.  A sound 
system callback wants to feed and be fed and never get blocked.  When it 
has new data, it should issue a semaphore release on the dsp/data  
processing system and the processing system should guarantee that it has 
data waiting BEFORE this callback is fired.   Should these fail,  error 
handling needs to be introduced.  I use ring buffers for message or data 
passing.  If I use ring buffers for message passing,  the messages tell 
what member of the buffer pool is full of data for my use.  This saves 
one level of data copying.  There is no choice but to copy data coming 
to/from the sound system since that typically hands you a member of its 
buffer pool which you will lose access to immediately upon return from 
the call back.

Did any of this help at all?
Bob


Eric Blossom wrote:

> On Tue, Dec 13, 2005 at 03:19:34PM -0500, Michael Dickens wrote:
>  
>
> > In implementing gr-audio-osx, I've figured out (after much debugging)  
> > that 2 threads are conflicting (GR is 1 thread, CoreAudio is the  
> > other), and thus I need a semaphore or equivalent ... needs to be  
> > thread-safe.  Does GR have a preference of what to use for this?  Or  
> > is it OS- and programmer-dependent?  Thanks! - MLD
> >
> > ps> gr-audio-osx -almost- works, excepting this one issue (as far as  
> > I have found).  Once that's resolved, I'll do some internal testing  
> > at UND over the holidays to flush out any other issues.  Look for a  
> > release sometime in early January.
> >    
>
> We use the omnithread abstraction.  This gives us a C++ friendly
> interface to Posix (and NT) threads.  See
> gnuradio-core/doc/other/omnithread.pdf
>
> Eric
>
>
>
>
>
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>  


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