Issue in DirectFB-GTK Port Event dispatch mechanism

["Jerin" <jerinjacob tataelxsi co in>]

Hi All,

We are currently involved in bringing up a multi-threaded graphics
abstraction layer on top of GTK-DFB. We are facing issues with the event
dispatch mechanism of GTK-DFB. On further analysis, we find that the
GTK-X11's event dispatch mechanism is a bit different from that of GTK-DFB.

The GTK-X11's event dispatch is thread safe i.e Please find below the
GTK-X11's event dispatch function code.

static gboolean
gdk_event_dispatch (GSource    *source,
		    GSourceFunc callback,
		    gpointer    user_data)
{
  GdkDisplay *display = ((GdkDisplaySource*)source)->display;
  GdkEvent *event;

 ------------> GDK_THREADS_ENTER ();<--------------

  _gdk_events_queue (display);
  event = _gdk_event_unqueue (display);

  if (event)
    {
      if (_gdk_event_func)
	(*_gdk_event_func) (event, _gdk_event_data);

      gdk_event_free (event);
    }

  ------------> GDK_THREADS_LEAVE ();<---------------

  return TRUE;
}

In comparison to this we find that GTK-DFB's event dispatch code is not
thread safe.

static void
dfb_events_dispatch (void)
{
  GdkDisplay *display = gdk_display_get_default ();
  GdkEvent   *event;

 ------------>" THREAD PROTECTION MISSING"<--------------

  while ((event = _gdk_event_unqueue (display)) != NULL)
    {
      if (_gdk_event_func)
        (*_gdk_event_func) (event, _gdk_event_data);

      gdk_event_free (event);
    }

 ------------>" THREAD PROTECTION MISSING"<--------------
}


It would be of great help for us if someone could throw some light on the
queries below.

1. Was this implementation of GTK-DFB's event dispatching made not thread
safe? If so what is the reason behind it?

2. How is the application expected to be designed for the GTK-DFB
environment?

3. Is it advisable to port a multi-threaded graphics abstraction layer on
top of GTK-DFB?

Regards,
Jerin



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