Don't include msg_id or reply_q in casts

On the server side, we only send replies if the request included a
_msg_id key. Also, the _reply_q key is only used when we wish to send a
reply.

So, in order to retain the exact same on-the-wire behaviour and ensure
servers aren't sending replies where none is needed, only include these
keys if we're doing a call (i.e. wait_for_reply=True).

Change-Id: Iac329493252be7d94b1ebe24f00e4d3f5c61d269

oslo/messaging/_drivers/amqpdriver.py

@@ -316,14 +316,15 @@ class AMQPDriverBase(base.BaseDriver):
         context = Context(ctxt)
         msg = message
 
-        msg_id = uuid.uuid4().hex
-        msg.update({'_msg_id': msg_id})
-        LOG.debug('MSG_ID is %s' % (msg_id))
+        if wait_for_reply:
+            msg_id = uuid.uuid4().hex
+            msg.update({'_msg_id': msg_id})
+            LOG.debug('MSG_ID is %s' % (msg_id))
+            msg.update({'_reply_q': self._get_reply_q()})
+
         rpc_amqp._add_unique_id(msg)
         rpc_amqp.pack_context(msg, context)
 
-        msg.update({'_reply_q': self._get_reply_q()})
-
         if envelope:
             msg = rpc_common.serialize_msg(msg)
 

tests/test_rabbit.py

@@ -97,7 +97,7 @@ class TestRabbitTransportURL(test_utils.BaseTestCase):
 
         target = messaging.Target(topic='testtopic')
 
-        driver.send(target, {}, {})
+        driver.listen(target)
 
         self.assertEquals(passed_params[0], self.expected)
 
@@ -368,10 +368,9 @@ class TestRequestWireFormat(test_utils.BaseTestCase):
         received = msgs[0]
         received['oslo.message'] = jsonutils.loads(received['oslo.message'])
 
+        # FIXME(markmc): add _msg_id and _reply_q check
         expected_msg = {
-            '_msg_id': self.uuids[0].hex,
-            '_unique_id': self.uuids[1].hex,
-            '_reply_q': 'reply_' + self.uuids[2].hex,
+            '_unique_id': self.uuids[0].hex,
         }
         expected_msg.update(self.expected)
         expected_msg.update(self.expected_ctxt)