gtk: Fix race between queue_draw and destroy

In GTK dispose can be called before the last ref is reached. This
happens when you close the container window. The dispose will be
explicitly called, and destroyed notify will be fired. This patch
fixes this race by properly tracking the widget state.

In the sink, we now set the widget pointer to NULL, so the widget
will properly get created again if you set your pipeline to NULL
state after the widget was destroy, and set it back to PLAYING.

https://bugzilla.gnome.org/show_bug.cgi?id=751104

1 files changed, 29 insertions, 9 deletions

diff --git a/ext/gtk/gtkgstwidget.c b/ext/gtk/gtkgstwidget.c
index 3e2f9bb28..3fbb0ca4e 100644
--- a/ext/gtk/gtkgstwidget.c
+++ b/ext/gtk/gtkgstwidget.c
@@ -69,6 +69,10 @@ struct _GtkGstWidgetPrivate
   GstBuffer *buffer;
   GstCaps *caps;
   GstVideoInfo v_info;
+
+  /* Pending queued idles callback */
+  guint draw_id;
+  guint resize_id;
 };
 
 static void
@@ -226,6 +230,12 @@ gtk_gst_widget_finalize (GObject * object)
   gst_buffer_replace (&widget->priv->buffer, NULL);
   g_mutex_clear (&widget->priv->lock);
 
+  if (widget->priv->draw_id)
+    g_source_remove (widget->priv->draw_id);
+
+  if (widget->priv->resize_id)
+    g_source_remove (widget->priv->resize_id);
+
   G_OBJECT_CLASS (gtk_gst_widget_parent_class)->finalize (object);
 }
 
@@ -331,6 +341,10 @@ gtk_gst_widget_new (void)
 static gboolean
 _queue_draw (GtkGstWidget * widget)
 {
+  g_mutex_lock (&widget->priv->lock);
+  widget->priv->draw_id = 0;
+  g_mutex_unlock (&widget->priv->lock);
+
   gtk_widget_queue_draw (GTK_WIDGET (widget));
 
   return G_SOURCE_REMOVE;
@@ -339,8 +353,6 @@ _queue_draw (GtkGstWidget * widget)
 void
 gtk_gst_widget_set_buffer (GtkGstWidget * widget, GstBuffer * buffer)
 {
-  GMainContext *main_context = g_main_context_default ();
-
   g_return_if_fail (GTK_IS_GST_WIDGET (widget));
   g_return_if_fail (buffer == NULL || widget->priv->negotiated);
 
@@ -348,14 +360,21 @@ gtk_gst_widget_set_buffer (GtkGstWidget * widget, GstBuffer * buffer)
 
   gst_buffer_replace (&widget->priv->buffer, buffer);
 
-  g_mutex_unlock (&widget->priv->lock);
+  if (!widget->priv->draw_id) {
+    widget->priv->draw_id = g_idle_add_full (G_PRIORITY_DEFAULT,
+        (GSourceFunc) _queue_draw, widget, NULL);
+  }
 
-  g_main_context_invoke (main_context, (GSourceFunc) _queue_draw, widget);
+  g_mutex_unlock (&widget->priv->lock);
 }
 
 static gboolean
 _queue_resize (GtkGstWidget * widget)
 {
+  g_mutex_lock (&widget->priv->lock);
+  widget->priv->resize_id = 0;
+  g_mutex_unlock (&widget->priv->lock);
+
   gtk_widget_queue_resize (GTK_WIDGET (widget));
 
   return G_SOURCE_REMOVE;
@@ -424,7 +443,6 @@ _calculate_par (GtkGstWidget * widget, GstVideoInfo * info)
 gboolean
 gtk_gst_widget_set_caps (GtkGstWidget * widget, GstCaps * caps)
 {
-  GMainContext *main_context = g_main_context_default ();
   GstVideoInfo v_info;
 
   g_return_val_if_fail (GTK_IS_GST_WIDGET (widget), FALSE);
@@ -455,15 +473,17 @@ gtk_gst_widget_set_caps (GtkGstWidget * widget, GstCaps * caps)
     return FALSE;
   }
 
+  gst_buffer_replace (&widget->priv->buffer, NULL);
   gst_caps_replace (&widget->priv->caps, caps);
   widget->priv->v_info = v_info;
   widget->priv->negotiated = TRUE;
 
-  g_mutex_unlock (&widget->priv->lock);
-
-  gtk_widget_queue_resize (GTK_WIDGET (widget));
+  if (!widget->priv->resize_id) {
+    widget->priv->resize_id = g_idle_add_full (G_PRIORITY_DEFAULT,
+        (GSourceFunc) _queue_resize, widget, NULL);
+  }
 
-  g_main_context_invoke (main_context, (GSourceFunc) _queue_resize, widget);
+  g_mutex_unlock (&widget->priv->lock);
 
   return TRUE;
 }