Re: Proper way to provide gtk+ app with asynchronous data?

[Russell Shaw <rjshaw netspace net au>]

Tristan Van Berkom wrote:
> Christer Palm wrote:
>
> > John Cupitt wrote:
> >
> > > Very simple and easy to program. I'm assuming writing 4 bytes to a
> > > pipe is atomic, I guess. I've not had problems (even on SMP machines),
> > > but it would be easy to add a global mutex for the pipe writers.
> > Oh, by the way. On a POSIX conformant system, a write to a pipe _is_ 
> > guaranteed to be atomic as long as it's no larger than PIPE_BUF (from 
> > limits.h) bytes. So 4 bytes should be safe.
>
>    Just to point out one of the million possible solutions to this age
> old problem ('cause I liked this solution alot when I heard of it, I have
> to admit I haven't had the oportunity to try it myself since), you can
> create your own GSource that pops off elements from a GAsyncQueue and
> use that "source" in your recieving thread and in your publishing thread
> you can push datum on to that queue and call `g_main_context_wakeup()'
> on the recieving thread's context (ofcourse you can wrap that up in a 
> pretty
> little convinient api...).
>
>     I'm not sure exactly how much you gain in performance by using this
> aproach, but I always though that using pipes to communicate between
> threads is a kind of hack.

Hi,
I'm trying to figure out how to wake up the main gtk gui thread when
new data is available in a GAsyncQueue (command_queue), so that i can
display the data in a gtk widget:


GAsyncQueue *command_queue;

static gpointer
command_thread(gpointer data)
{
...
  g_async_queue_push(command_queue,command);
...
}

int
main(int argc, char *argv[])
{
  gtk_init(&argc,&argv);
...
  command_queue=g_async_queue_new();

  GThread *thread=g_thread_create(command_thread,NULL,FALSE,NULL);

  struct GSourceFuncs source_funcs;

  /* what do i do here with source_funcs?*/

  GSource *source=g_source_new(source_funcs,sizeof(source_funcs));

  GMainContext *context=g_main_context_new();

  guint sid=g_source_attach(source,context);

  GMainLoop* loop=g_main_loop_new(context,FALSE);

  g_main_loop_run(loop);

  return 0;
}