[gst-devel] GStreamer status, 20 Sept 2005

[Stefan Kost]

Hi David,

David Schleef wrote:
> On Tue, Sep 20, 2005 at 04:44:52PM +0200, Andy Wingo wrote:
> 
>>In other changes, Stefan Kost checked in a patch to use GLib 2.8's
>>atomic refcounting for GObject, which was something Wim pushed hard for
>>in GLib's last development cycle. Of course, we still support the hacks
>>that allow GStreamer to work reliably with GLib as old as 2.4, but you
>>have to be careful when getting an object from GLib, as with
>>g_value_get_object.
> 
> 
> I don't see much advantage to having two possible code paths here.
> There really isn't a speed advantage, and all referencing/unreffing
> must still go through gst_object_[un]ref(), so there's no API
> advantage.
Why must someone use gst_object_Ref()/unref() on a glib-2.8 system. I GstObjects 
are g_objects then refcounting is done via g_objec_ref()/unref(). There aren't 
virtual methods we can override. If GstObject behaves different then we better 
not derive from GObject.

>  It almost seems to me to be inviting someone to write
> a sloppy gstreamer-based app that works with glib-2.8, but fails/leaks
> on <= 2.6.
It does already now. Example my class has a GST_TYPE_BIN property.
Right now I need to do:

bt_song_get_property ----------------
...
case SONG_BIN:
   g_value_set_object(value, self->priv->bin);
#ifndef HAVE_GLIB_2_8
   gst_object_ref(self->priv->bin);
#endif
   break;

bt_song_set_property -----------------
case SONG_BIN:
   g_object_try_unref(self->priv->bin);
   self->priv->bin=GST_BIN(g_value_dup_object(value));
#ifndef HAVE_GLIB_2_8
   gst_object_ref(self->priv->bin);
#endif
   GST_DEBUG("set the bin for the song: %p",self->priv->bin);
   break;

Otherwise the above code breaks, as g_object does not know about the ref-count 
hack and as GstObject is a GObject it treats it so.

Maybe all we need is
g_object_set_gst_object(value,obj);
g_value_dup_gst_object(value);
g_value_get_gst_object(value);


Ciao
   Stefan