#5532: Fix memory leak when a buddy disappears.

lib/sugar/presence/buddy.py

@@ -78,11 +78,16 @@ class Buddy(gobject.GObject):
 
         bobj = bus.get_object(self._PRESENCE_SERVICE, object_path)
         self._buddy = dbus.Interface(bobj, self._BUDDY_DBUS_INTERFACE)
-        self._buddy.connect_to_signal('IconChanged', self._icon_changed_cb,
-                                      byte_arrays=True)
-        self._buddy.connect_to_signal('JoinedActivity', self._joined_activity_cb)
-        self._buddy.connect_to_signal('LeftActivity', self._left_activity_cb)
-        self._buddy.connect_to_signal('PropertyChanged', self._property_changed_cb)
+
+        self._icon_changed_signal = self._buddy.connect_to_signal(
+                'IconChanged', self._icon_changed_cb, byte_arrays=True)
+        self._joined_activity_signal = self._buddy.connect_to_signal(
+                'JoinedActivity', self._joined_activity_cb)
+        self._left_activity_signal = self._buddy.connect_to_signal(
+                'LeftActivity', self._left_activity_cb)
+        self._property_changed_signal = self._buddy.connect_to_signal(
+                'PropertyChanged', self._property_changed_cb)
+
         self._properties = self._get_properties_helper()
 
         activities = self._buddy.GetJoinedActivities()
@@ -90,6 +95,12 @@ class Buddy(gobject.GObject):
             self._activities[op] = self._ps_new_object(op)
         self._icon = None
 
+    def destroy(self):
+        self._icon_changed_signal.remove()
+        self._joined_activity_signal.remove()
+        self._left_activity_signal.remove()
+        self._property_changed_signal.remove()
+        
     def _get_properties_helper(self):
         """Retrieve the Buddy's property dictionary from the service object
         """

lib/sugar/presence/presenceservice.py

@@ -156,10 +156,10 @@ class PresenceService(gobject.GObject):
         
         returns presence Buddy or Activity representation
         """
-        _logger.debug('Creating proxy for %s', object_path)
         obj = None
         try:
             obj = self._objcache[object_path]
+            _logger.debug('Reused proxy %r', obj)
         except KeyError:
             if object_path.startswith(self._PS_BUDDY_OP):
                 obj = Buddy(self._bus, self._new_object,
@@ -175,7 +175,7 @@ class PresenceService(gobject.GObject):
             else:
                 raise RuntimeError("Unknown object type")
             self._objcache[object_path] = obj
-        _logger.debug('Proxy is %r', obj)
+            _logger.debug('Created proxy %r', obj)
         return obj
 
     def _have_object(self, object_path):
@@ -200,7 +200,17 @@ class PresenceService(gobject.GObject):
         # Don't try to create a new object here if needed; it will probably
         # fail anyway because the object has already been destroyed in the PS
         if self._have_object(object_path):
-            self.emit('buddy-disappeared', self._new_object(object_path))
+            obj = self._objcache[object_path]
+            self.emit('buddy-disappeared', obj)
+
+            # We cannot maintain the object in the cache because that would keep
+            # a lot of objects from being collected. That includes UI objects
+            # due to signals using strong references.
+            # If we want to cache some despite the memory usage increase,
+            # we could use a LRU cache limited to some value.
+            del self._objcache[object_path]
+            obj.destroy()
+            
         return False
 
     def _buddy_disappeared_cb(self, object_path):