Re: Threads

[Craig Bakalian <craigbakalian verizon net>]

On 10/19/2013 07:11 AM, Paul Davis wrote:
> There are dozens if not hundreds of "examples" of this - any JACK 
> client with a GUI.
>
> But to get an idea of the basic idea, take a look in the JACK example 
> clients and/or tools. jack_capture would be a good place to start, 
> since it faces the problem of handing over incoming (audio) data to 
> another thread.
>
> And no, you are not writing "the data" to a pipe from the JACK 
> callback. The key ideas are (a) to move the data to another thread you 
> need to use a lock-free data structure (b) if you need to wake the 
> other thread (i.e. because it doesn't simply wake up periodically and 
> use whatever new data you've delivered), you need to use the *most* 
> RT-safe method you can. There are no absolutely RT-safe methods. A 
> semaphore (on Linux anyway) is the best, writing a byte to a pipe is 
> the 2nd best.
>
> You cannot make calls from the JACK callback that may block - you 
> cannot write to disk, read from disk, take locks, etc, etc.
>
> This really should not be going to the gtk-list anymore. It has 
> roughly nothing to do with gtk and more or less everything to do with 
> JACK.

Hi Paul,

If it has nothing to do with JACK, then why on earth was it working 
before the latest release of gtk in ubuntu 13.10?  Why could I write 
data out from the JACK callback with no issues before??  It has nothing 
to do with the JACK callback and everything to do with the overly secure 
removal of

gdk_threads_enter();
gdk_thread_leave();

My application was working perfectly until the removal of these 
functions.  Furthermore, once I remove the insert to the gtktextbuffer 
from the callback, all is well.  And, the error that pops up is that the 
gtktextbuffer layout can't get a line number. This has nothing to do 
with JACK and everything to do with threads in gtk.

What on earth should I expect anything more than "get this off this 
list" from I guy whose first response on a HELP list is "Your design is 
wrong".  It is obvious to me you don't know what my JACK callback is 
doing.  And your pipe explanation is a real hack.  I understand it now, 
and it won't work.  No matter what, the darn gtktextbuffer is only going 
to take an insert from something inside gtk.  Overly secure aint the words!

I re wrote my MAKE file to use gtk2, which works.  I quick solution.  
Next, I am moving to QT.

Craig Bakalian