[LAD] how to store deferred events in a real time audio app?

[Andres Cabrera]

Hi,

You might also want to have a look at how Supercollider does it:

http://www.supercolliderbook.net/

Look below for the chapter by Ross Bencina.

Cheers,
Andrés

On Tue, Dec 20, 2011 at 3:49 AM, Paul Davis <paul at linuxaudiosystems.com> wrote:
> On Mon, Dec 19, 2011 at 8:10 PM, Iain Duncan <iainduncanlists at gmail.com> wrote:
>
>> However, I would like to add the ability for the user to send a message and
>> have it get executed later, where later gets figured out by the engine ( ie
>> on the top of the next 8 bar phrase ). To do this, I need some way of
>> storing deferred events and having the engine check on each step whether
>> there were any deferred events stored for 'now'. I can think of a few ways
>> to do this, and all of them raise red flags for a real time thread.
>
> 1) don't allow out-of-order queuing
> 2) just use a FIFO (i.e. ye olde single-reader/single-writer lock free
> ringbuffer) to enqueue events between the engine and another thread
> (presumably a GUI)
>
> things get more complex if you insist on allowing out-of-order queuing
> and/or more than one thread is delivering events. but not a lot more.
> you can so multi-writer/single-reader FIFO in an RT safe way by
> requiring a lock to write, but none to read, which serializes writes
> and reduces it to an effectively single-writer/single reader
> situation.
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