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

[Tristan Van Berkom <vantr touchtunes com>]

Dmitry M. Shatrov wrote:
[ ... ]
> Could you point to some additional documentation on how to actually 
> create own `GSource`s? An example? I'm stuck with it just because plain 
> glib docs didn't give me understanding of what is what, and google was 
> also successfull in keeping the secret.

A good example would be the g-io-channel sources, take a look at
giounix.c, a GSource must provide four functions to integrated it
as an event source into the main loop (see:
http://developer.gnome.org/doc/API/2.0/glib/glib-The-Main-Event-Loop.html
for an enlightening discusion on how the mainloop functions) :

GSourceFuncs g_io_watch_funcs = {
  g_io_unix_prepare,   // I believe this is called every time the mainloop
                       // for this thread/process is ready to go into
                       // "wait state", you'll need to check into that for sure.

  g_io_unix_check,     // is this source ready to be dispatched ?

  g_io_unix_dispatch,  // call the appropriate callback for this source

  g_io_unix_finalize   // free allocated stuff etc... (called when the
                       // user calls g_source_remove or when the user
                       // callback returns FALSE).
};

You would basicly want your "check" function to return TRUE when
there is data on the GAsyncQueue.

To create a source (g_io_add_watch):

static GSource *
g_io_unix_create_watch (GIOChannel   *channel,
			GIOCondition  condition)
{
  GSource *source;
  GIOUnixWatch *watch;
  /*...*/

  /* Here the "watch" is and extended version of the GSource structure;
   * glib will use the "g_io_watch_funcs" to work with the source and
   * anything else you will need to know you can use this extended struct
   * for (example, you will probably want to know what GAsyncQueue you
   * are going to pop stuff off of in your "check" func).
   */
  source = g_source_new (&g_io_watch_funcs, sizeof (GIOUnixWatch));
  watch = (GIOUnixWatch *)source;

  /*...*/
}

Hope this helps ;-)

Cheers,
                                      -Tristan