engine: Clean up some object lifecycle leaks

pygobject doesn't seem to choke on debug_leak_check anymore, so we
can use it to find object leaks. just doing a few for now since it's
generally not a big deal.

virtManager/connection.py

@@ -869,6 +869,13 @@ class vmmConnection(vmmGObject):
     def _cleanup(self):
         self.close()
 
+        self._objects = None
+        self._backend.cb_fetch_all_guests = None
+        self._backend.cb_fetch_all_pools = None
+        self._backend.cb_fetch_all_nodedevs = None
+        self._backend.cb_fetch_all_vols = None
+        self._backend.cb_clear_cache = None
+
     def open(self):
         if not self.is_disconnected():
             return

virtManager/engine.py

@@ -45,8 +45,13 @@ from .error import vmmErrorDialog
 from .systray import vmmSystray
 from .delete import vmmDeleteDialog
 
-# Enable this to get a report of leaked objects on app shutdown
-# gtk3/pygobject has issues here as of Fedora 18
+# Enabling this will tell us, at app exit time, which vmmGObjects were not
+# garbage collected. This is caused by circular references to other objects,
+# like a signal that wasn't disconnected. It's not a big deal, but if we
+# have objects that can be created and destroyed a lot over the course of
+# the app lifecycle, every non-garbage collected class is a memory leak.
+# So it's nice to poke at this every now and then and try to track down
+# what we need to add to class _cleanup handling.
 debug_ref_leaks = False
 
 DETAILS_PERF = 1
@@ -147,7 +152,7 @@ class vmmEngine(vmmGObject):
         if self.systray:
             return
 
-        self.systray = vmmSystray(self)
+        self.systray = vmmSystray()
         self.systray.connect("action-toggle-manager", self._do_toggle_manager)
         self.systray.connect("action-suspend-domain", self._do_suspend_domain)
         self.systray.connect("action-resume-domain", self._do_resume_domain)
@@ -163,6 +168,10 @@ class vmmEngine(vmmGObject):
         self.systray.connect("action-clone-domain", self._do_show_clone)
         self.systray.connect("action-exit-app", self.exit_app)
 
+        self.connect("conn-added", self.systray.conn_added)
+        self.connect("conn-removed", self.systray.conn_removed)
+
+
     def system_tray_changed(self, *ignore):
         systray_enabled = self.config.get_view_system_tray()
         if self.windows == 0 and not systray_enabled:
@@ -347,6 +356,8 @@ class vmmEngine(vmmGObject):
                     % (conn.get_uri(), e))
                 self.idle_add(self._handle_tick_error, error_msg, tb)
 
+            # Need to clear reference to make leak check happy
+            conn = None
             self._tick_queue.task_done()
         return 1
 

virtManager/systray.py

@@ -53,7 +53,7 @@ class vmmSystray(vmmGObject):
         "action-exit-app": (GObject.SignalFlags.RUN_FIRST, None, []),
     }
 
-    def __init__(self, engine):
+    def __init__(self):
         vmmGObject.__init__(self)
 
         self.topwin = None
@@ -66,9 +66,6 @@ class vmmSystray(vmmGObject):
         self.systray_icon = None
         self.systray_indicator = False
 
-        engine.connect("conn-added", self.conn_added)
-        engine.connect("conn-removed", self.conn_removed)
-
         # Are we using Application Indicators?
         if AppIndicator3 is not None:
             self.systray_indicator = True
@@ -97,8 +94,14 @@ class vmmSystray(vmmGObject):
             self.systray_menu = None
 
         self.systray_icon = None
+        self.conn_menuitems = None
+        self.conn_vm_menuitems = None
+        self.vm_action_dict = None
 
-    # Initialization routines
+
+    ###########################
+    # Initialization routines #
+    ###########################
 
     def init_systray_menu(self):
         """