Make the ghostpad a parent of the internal pad again for better backward compatibility. Don't write code that relies ...

Original commit message from CVS:
* docs/design/part-gstghostpad.txt:
* gst/gstghostpad.c: (gst_ghost_pad_dispose),
(gst_ghost_pad_new_full):
Make the ghostpad a parent of the internal pad again for better backward
compatibility. Don't write code that relies on this however.
* gst/gstpad.c: (gst_pad_activate_pull), (gst_pad_activate_push),
(gst_pad_link_check_hierarchy):
Require that parents should be GstElements in the hierarchy check.

ChangeLog

@@ -1,3 +1,15 @@
+2007-02-20  Wim Taymans  <wim@fluendo.com>
+
+	* docs/design/part-gstghostpad.txt:
+	* gst/gstghostpad.c: (gst_ghost_pad_dispose),
+	(gst_ghost_pad_new_full):
+	Make the ghostpad a parent of the internal pad again for better backward
+	compatibility. Don't write code that relies on this however.
+
+	* gst/gstpad.c: (gst_pad_activate_pull), (gst_pad_activate_push),
+	(gst_pad_link_check_hierarchy):
+	Require that parents should be GstElements in the hierarchy check.
+
 2007-02-20  Wim Taymans  <wim@fluendo.com>
 
 	* gst/gstbin.c: (bin_replace_message), (gst_bin_add_func),

docs/design/part-gstghostpad.txt

@@ -66,6 +66,8 @@ Ghostpads
   	    | target *----->//
 	    (------------)
 
+  The GstGhostPad (X) is also set as the parent of the GstProxyPad (Y).
+
   The target is a pointer to the internal pads peer. It is an optimisation to
   quickly get to the peer of a ghostpad without having to dereference the
   internal->peer.

gst/gstghostpad.c

@@ -707,9 +707,8 @@ gst_ghost_pad_dispose (GObject * object)
   GST_PROXY_PAD_INTERNAL (internal) = NULL;
 
   /* disposes of the internal pad, since the ghostpad is the only possible object
-   * that has a refcount on the internal pad.
-   */
-  gst_object_unref (internal);
+   * that has a refcount on the internal pad. */
+  gst_object_unparent (GST_OBJECT_CAST (internal));
 
   GST_PROXY_UNLOCK (pad);
 
@@ -782,17 +781,17 @@ gst_ghost_pad_new_full (const gchar * name, GstPadDirection dir,
 
   GST_PROXY_LOCK (ret);
 
-  /* don't set parent, we can't link the internal pads if parents/grandparents
-   * are different, just take ownership. */
-  gst_object_ref (internal);
-  gst_object_sink (internal);
+  /* now make the ghostpad a parent of the internal pad */
+  if (!gst_object_set_parent (GST_OBJECT_CAST (internal),
+          GST_OBJECT_CAST (ret)))
+    goto parent_failed;
 
-  /* The ghostpad is the owner of the internal pad and is the only object that
+  /* The ghostpad is the parent of the internal pad and is the only object that
    * can have a refcount on the internal pad.
    * At this point, the GstGhostPad has a refcount of 1, and the internal pad has
    * a refcount of 1.
    * When the refcount of the GstGhostPad drops to 0, the ghostpad will dispose
-   * it's refcount on the internal pad in the dispose method by un-reffing it.
+   * it's refcount on the internal pad in the dispose method by un-parenting it.
    * This is why we don't take extra refcounts in the assignments below
    */
   GST_PROXY_PAD_INTERNAL (ret) = internal;
@@ -816,6 +815,19 @@ gst_ghost_pad_new_full (const gchar * name, GstPadDirection dir,
   GST_PROXY_UNLOCK (ret);
 
   return ret;
+
+  /* ERRORS */
+parent_failed:
+  {
+    GST_WARNING_OBJECT (ret, "Could not set internal pad %s:%s",
+        GST_DEBUG_PAD_NAME (internal));
+    g_critical ("Could not set internal pad %s:%s",
+        GST_DEBUG_PAD_NAME (internal));
+    GST_PROXY_UNLOCK (ret);
+    gst_object_unref (ret);
+    gst_object_unref (internal);
+    return NULL;
+  }
 }
 
 /**

gst/gstpad.c

@@ -1697,6 +1697,10 @@ gst_pad_link_check_hierarchy (GstPad * src, GstPad * sink)
   if (G_UNLIKELY (psrc == NULL || psink == NULL))
     goto no_parent;
 
+  /* only care about parents that are elements */
+  if (G_UNLIKELY (!GST_IS_ELEMENT (psrc) || !GST_IS_ELEMENT (psink)))
+    goto no_element_parent;
+
   /* if the parents are the same, we have a loop */
   if (G_UNLIKELY (psrc == psink))
     goto same_parents;
@@ -1721,6 +1725,13 @@ no_parent:
         GST_PTR_FORMAT, psrc, psink);
     return TRUE;
   }
+no_element_parent:
+  {
+    GST_CAT_DEBUG (GST_CAT_CAPS,
+        "one of the pads has no element parent %" GST_PTR_FORMAT " and %"
+        GST_PTR_FORMAT, psrc, psink);
+    return TRUE;
+  }
 same_parents:
   {
     GST_CAT_DEBUG (GST_CAT_CAPS, "pads have same parent %" GST_PTR_FORMAT,