Define self.client in MessagingCore

Currently self.client is referenced within MessagingCore,
but no definition is made in its constructor. Additionally
self.client is defined in children classes of MessagingCore.
This patchset defines self.client in the constructor of
MessagingCore and removes the redefinition in its children.

-self.client lazily loaded

Co-Authored-By: v-francoise <Vincent.FRANCOISE@b-com.com>
Change-Id: I14525a175bf1ebde3d2636024ad2f2219c79d6e1
Closes-Bug: #1521636

watcher/common/messaging/messaging_handler.py

@@ -38,11 +38,11 @@ CONF = cfg.CONF
 
 class MessagingHandler(threading.Thread):
 
-    def __init__(self, publisher_id, topic_watcher, endpoint, version,
+    def __init__(self, publisher_id, topic_name, endpoint, version,
                  serializer=None):
         super(MessagingHandler, self).__init__()
         self.publisher_id = publisher_id
-        self.topic_watcher = topic_watcher
+        self.topic_name = topic_name
         self.__endpoints = []
         self.__serializer = serializer
         self.__version = version
@@ -72,7 +72,7 @@ class MessagingHandler(threading.Thread):
         return om.Notifier(
             self.__transport,
             publisher_id=self.publisher_id,
-            topic=self.topic_watcher,
+            topic=self.topic_name,
             serializer=serializer
         )
 
@@ -87,7 +87,7 @@ class MessagingHandler(threading.Thread):
             self.__notifier = self.build_notifier()
             if len(self.__endpoints):
                 target = om.Target(
-                    topic=self.topic_watcher,
+                    topic=self.topic_name,
                     # For compatibility, we can override it with 'host' opt
                     server=CONF.host or socket.getfqdn(),
                     version=self.__version,
@@ -101,7 +101,7 @@ class MessagingHandler(threading.Thread):
             LOG.error(_LE("Messaging configuration error"))
 
     def run(self):
-        LOG.debug("configure MessagingHandler for %s" % self.topic_watcher)
+        LOG.debug("configure MessagingHandler for %s" % self.topic_name)
         self._configure()
         if len(self.__endpoints) > 0:
             LOG.debug("Starting up server")