Re: [LAD] [Jack-Devel] jack2's dbus name

On Thu, 18.06.09 13:51, Paul Davis (paul@email-addr-hidden) wrote:

> On Thu, Jun 18, 2009 at 12:21 PM, Lennart Poettering <mzynq@email-addr-hiddenwrote:
>
> >
> >
> > This is a bit more complex than you might think. Jack's thread
> > management is very unflexible and insists on controlling the entire
> > thread life cycle, only calling into client code in very few
> > occasions.
>
>
> You might want to check out the more recent API additions:
>
> jack_cycle_wait()
> jack_cycle_signal()
>
> which were created for precisely the sort of reasons you are describing.

That sounds like it was what I need.

So, how would I use this? I figure something like this:

<snip>
void* my_thread(void*arg) {
    for (;;) {
        n = jack_cycle_wait(client);
        process_my_data(n);
        jack_cycle_signal(client, 0);
        do_my_other_work_if_there_is_any();
    }
}

jack_set_process_thread(client, foo_func);
</snip>

Is that the rough idea? Hmm, with the other RT loops I have in PA I
usually just dispatch a single my own events and then immediately
check the IO device again, possibly dealing with the IO stuff first,
and only after finishing that I dispatch the next of my own events and
immediately check for IO again. That way I make sure that IO always
takes priority over dispatching those events. i.e. something along the
lines of:

<snip>
void *my_thread(void *arg) {
    for (;;) {
        n = how_much_shall_i_process();
        if (n > 0) {
            process_my_data(n);
            continue;
        }
        n = how_many_events_to_dispatch();
        if (n > 0) {
            process_one_event();
            continue;
        }
        wait_for_io();
}
</snip>

So, to map this to JACK, I would prefer if jack_cycle_wait() would
also exist in a non-blocking variant. i.e. something that can return 0
if there's nothing to process, but doesn't necessarily wait.

(we probably should stop the cross-posting, though)

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4
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