Fix queue connection bugs

Fix logging if queue disconnects
Reconnect if queue comes back

nova/rpc.py

@@ -63,6 +63,10 @@ class Connection(connection.BrokerConnection):
             cls._instance = cls(**params)
         return cls._instance
 
+    @classmethod
+    def recreate(cls):
+        del cls._instance
+        return cls.instance()
 
 class Consumer(messaging.Consumer):
     # TODO(termie): it would be nice to give these some way of automatically
@@ -79,9 +83,20 @@ class Consumer(messaging.Consumer):
 
     attachToTornado = attach_to_tornado
 
-    @exception.wrap_exception
     def fetch(self, *args, **kwargs):
+        try:
+            if getattr(self, 'failed_connection', False):
+                # attempt to reconnect
+                self.conn = Connection.recreate()
+                self.backend = self.conn.create_backend()
             super(Consumer, self).fetch(*args, **kwargs)
+            if getattr(self, 'failed_connection', False):
+                logging.error("Reconnected to queue")
+                self.failed_connection = False
+        except Exception, ex:
+            if not getattr(self, 'failed_connection', False):
+                logging.exception("Failed to fetch message from queue")
+                self.failed_connection = True
 
     def attach_to_twisted(self):
         loop = task.LoopingCall(self.fetch, enable_callbacks=True)