[gnome-software] Fix a crash when using gs_app_subsume() in a thread

[Richard Hughes <rhughes src gnome org>]

commit d56e950ee7b4d57489006eaefe95729c31f7a0c8
Author: Richard Hughes <richard hughsie com>
Date:   Wed Jan 22 09:34:47 2014 +0000

    Fix a crash when using gs_app_subsume() in a thread

 src/gs-app.c |   24 +++++++++++++++++++++++-
 1 files changed, 23 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-app.c b/src/gs-app.c
index f176e94..9558598 100644
--- a/src/gs-app.c
+++ b/src/gs-app.c
@@ -89,6 +89,7 @@ struct GsAppPrivate
        GPtrArray               *related; /* of GsApp */
        GPtrArray               *history; /* of GsApp */
        guint64                  install_date;
+       guint                    subsume_idle_id;
 };
 
 enum {
@@ -290,9 +291,24 @@ gs_app_to_string (GsApp *app)
 }
 
 /**
+ * gs_app_subsume_notify_cb:
+ **/
+static gboolean
+gs_app_subsume_notify_cb (gpointer user_data)
+{
+       GsApp *app = GS_APP (user_data);
+       g_object_thaw_notify (G_OBJECT (app));
+       app->priv->subsume_idle_id = 0;
+       return G_SOURCE_REMOVE;
+}
+
+/**
  * gs_app_subsume:
  *
  * Imports all the useful data from @other into @app.
+ *
+ * IMPORTANT: This method can be called from a thread, but because of this
+ * the g_object_notify() calls are done in an idle callback.
  **/
 void
 gs_app_subsume (GsApp *app, GsApp *other)
@@ -303,6 +319,12 @@ gs_app_subsume (GsApp *app, GsApp *other)
        GsAppPrivate *priv2 = other->priv;
        const gchar *tmp;
 
+       /* check we're not doing crazy things */
+       if (app->priv->subsume_idle_id != 0) {
+               g_warning ("Called gs_app_subsume() with idle pending");
+               return;
+       }
+
        /* wait for all the properties to be set */
        g_object_freeze_notify (G_OBJECT (app));
 
@@ -346,7 +368,7 @@ gs_app_subsume (GsApp *app, GsApp *other)
        g_list_free (keys);
 
        /* now emit all the changed signals */
-       g_object_thaw_notify (G_OBJECT (app));
+       priv->subsume_idle_id = g_idle_add (gs_app_subsume_notify_cb, app);
 }
 
 /**