[LAD] file and communications for RT audio

[Stephen Sinclair]

On Thu, May 13, 2010 at 6:10 PM, Fons Adriaensen <fons at kokkinizita.net> wrote:
> On Thu, May 13, 2010 at 05:27:33PM -0400, Stephen Sinclair wrote:
>
>> 1) Have a secondary thread responsible for passing data to the audio
>> callback through a wait-free ring buffer.
>> 2) Read from a pipe, FIFO, or socket from another process (e.g.
>> popen), using select() or poll() to check when there is actually data
>> to read.
>> 3) Read from a file, using select()?
>> 4) The async I/O API.
>> 5) Interprocess shared memory, presumably using a semaphore of some
>> kind.  I guess this is similar to (1) but for inter-process
>> communication.
>
> (1) is the correct way. (5) may work if the other process and
> the way you talk to it are up to the task, that is if it just
> emulates (1) with the sender being another process.
>
> (2),(3),(4) are all real-time unsafe.

Thanks for the reply!  Now, just wondering a last thing about (1)
then, how might operations like read() in one thread affect another,
if at all?  For example, if I use a separate thread to read from a
pipe or socket, and pass it through a ring buffer to the audio
callback, is that the right way?  The thread will happily block on
read without somehow causing problems elsewhere?

I'm wary because I understand that some operations can affect a whole
process if you're not careful, even if you're using threads.  (Like
memory page misses and malloc.)

Steve