Re-use rpc transport

Blazar is currently not re-using the rpc transport, this
will cause connections to leak. This patch introduces
a commonly shared rpc pattern for openstack services
that ensures that the transport is always re-used.

Change-Id: Ib49d7820b2ce4bc6cc9bbbd91c075631b7fb56bb

blazar/rpc.py

@@ -0,0 +1,51 @@
+#    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.
+from oslo_config import cfg
+import oslo_messaging as messaging
+
+
+CONF = cfg.CONF
+TRANSPORT = None
+
+
+def init():
+    global TRANSPORT
+    if TRANSPORT is None:
+        TRANSPORT = create_transport(get_transport_url())
+
+
+def get_transport_url(url_str=None):
+    return messaging.TransportURL.parse(CONF, url_str)
+
+
+def get_client(target):
+    if TRANSPORT is None:
+        raise AssertionError("'TRANSPORT' must not be None")
+    return messaging.RPCClient(
+        TRANSPORT,
+        target,
+    )
+
+
+def get_server(target, endpoints):
+    if TRANSPORT is None:
+        raise AssertionError("'TRANSPORT' must not be None")
+    return messaging.get_rpc_server(
+        TRANSPORT,
+        target,
+        endpoints,
+        executor='eventlet',
+    )
+
+
+def create_transport(url):
+    return messaging.get_rpc_transport(CONF, url=url)

blazar/utils/service.py

@@ -19,10 +19,10 @@ import functools
 
 from oslo_config import cfg
 from oslo_log import log as logging
-import oslo_messaging as messaging
 from oslo_service import service
 
 from blazar import context
+from blazar import rpc
 
 LOG = logging.getLogger(__name__)
 
@@ -30,10 +30,8 @@ LOG = logging.getLogger(__name__)
 class RPCClient(object):
     def __init__(self, target):
         super(RPCClient, self).__init__()
-        self._client = messaging.RPCClient(
-            target=target,
-            transport=messaging.get_rpc_transport(cfg.CONF),
-        )
+        rpc.init()
+        self._client = rpc.get_client(target)
 
     def cast(self, name, **kwargs):
         ctx = context.current()
@@ -47,11 +45,10 @@ class RPCClient(object):
 class RPCServer(service.Service):
     def __init__(self, target):
         super(RPCServer, self).__init__()
-        self._server = messaging.get_rpc_server(
-            target=target,
-            transport=messaging.get_rpc_transport(cfg.CONF),
-            endpoints=[ContextEndpointHandler(self, target)],
-            executor='eventlet',
+        rpc.init()
+        self._server = rpc.get_server(
+            target,
+            endpoints=[ContextEndpointHandler(self, target)]
         )
 
     def start(self):