Make the dispatcher responsible of the message ack

This patch make the dispatcher responsible of the message
acknowledgement.

This is the preliminar step to be able to requeue message.

Partial implements blueprint notification-subscriber-server

Change-Id: If74b47d5e23976d407deb27df7395b1982963c75

oslo/messaging/_drivers/amqpdriver.py

@@ -90,9 +90,7 @@ class AMQPListener(base.Listener):
     def poll(self):
         while True:
             if self.incoming:
-                message = self.incoming.pop(0)
-                message.acknowledge()
-                return message
+                return self.incoming.pop(0)
             self.conn.consume(limit=1)
 
 

oslo/messaging/notify/dispatcher.py

@@ -60,6 +60,7 @@ class NotificationDispatcher(object):
     @contextlib.contextmanager
     def __call__(self, incoming):
         yield lambda: self._dispatch_and_handle_error(incoming)
+        incoming.acknowledge()
 
     def _dispatch_and_handle_error(self, incoming):
         """Dispatch a notification message to the appropriate endpoint method.

oslo/messaging/rpc/dispatcher.py

@@ -124,6 +124,7 @@ class RPCDispatcher(object):
 
     @contextlib.contextmanager
     def __call__(self, incoming):
+        incoming.acknowledge()
         yield lambda: self._dispatch_and_reply(incoming)
 
     def _dispatch_and_reply(self, incoming):