Make it easier to add namespaced rpc APIs.

Add an additional argument to the base create_rpc_dispatcher() method.
When a manager wants to override create_rpc_dispatcher() to add more
callbacks in their own rpc namespaces, it can just call the parent class
with the additional APIs to include.

Change-Id: I9cba8b176b35f55ba9d71365d0a8bf25d2ae311f

nova/manager.py

@@ -86,14 +86,18 @@ class Manager(base.Base, periodic_task.PeriodicTasks):
         pluginmgr = pluginmanager.PluginManager('nova', self.__class__)
         pluginmgr.load_plugins()
 
-    def create_rpc_dispatcher(self, backdoor_port=None):
+    def create_rpc_dispatcher(self, backdoor_port=None, additional_apis=None):
         '''Get the rpc dispatcher for this manager.
 
         If a manager would like to set an rpc API version, or support more than
         one class as the target of rpc messages, override this method.
         '''
+        apis = []
+        if additional_apis:
+            apis.extend(additional_apis)
         base_rpc = baserpc.BaseRPCAPI(self.service_name, backdoor_port)
-        return rpc_dispatcher.RpcDispatcher([self, base_rpc])
+        apis.extend([self, base_rpc])
+        return rpc_dispatcher.RpcDispatcher(apis)
 
     def periodic_tasks(self, context, raise_on_error=False):
         """Tasks to be run at a periodic interval."""

nova/tests/test_manager.py

@@ -0,0 +1,35 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (C) 2013, Red Hat, Inc.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+Unit Tests for nova.manager
+"""
+
+from nova import manager
+from nova import test
+
+
+class ManagerTestCase(test.TestCase):
+    def test_additional_apis_for_dispatcher(self):
+        class MyAPI(object):
+            pass
+
+        m = manager.Manager()
+        api = MyAPI()
+        dispatch = m.create_rpc_dispatcher(additional_apis=[api])
+
+        self.assertEqual(len(dispatch.callbacks), 3)
+        self.assertTrue(api in dispatch.callbacks)