Merge lp:~soren/nova/rpc-call-concurrency into lp:~hudson-openstack/nova/trunk

[Soren Hansen]

Create a new AMQP connection by default.

It turns out that rpc.call has the same problem as rpc.cast. This time I saw it
when two clients attempted to call GetConsoleOutput at the same time.

I changed new's default to True and changed everywhere else to rely on the default.

I left the code implementing the singleton in, so that if we switch to another amqp
library that deals better with this, we can just change the default again.

[Jay Pipes (jaypipes)]

I'm not sure why there is even an option to set instance(False), but that's a separate gripe. This fixes the problem.

review: Approve

[Devin Carlen (devcamcar)]

lgtm

review: Approve

=== modified file 'nova/rpc.py'
--- nova/rpc.py	2011-02-10 13:56:24 +0000
+++ nova/rpc.py	2011-02-11 11:40:08 +0000
@@ -46,7 +46,7 @@
 class Connection(carrot_connection.BrokerConnection):
     """Connection instance object"""
     @classmethod
-    def instance(cls, new=False):
+    def instance(cls, new=True):
         """Returns the instance"""
         if new or not hasattr(cls, '_instance'):
             params = dict(hostname=FLAGS.rabbit_host,
@@ -246,7 +246,7 @@
         LOG.error(_("Returning exception %s to caller"), message)
         LOG.error(tb)
         failure = (failure[0].__name__, str(failure[1]), tb)
-    conn = Connection.instance(True)
+    conn = Connection.instance()
     publisher = DirectPublisher(connection=conn, msg_id=msg_id)
     try:
         publisher.send({'result': reply, 'failure': failure})
@@ -319,7 +319,7 @@
                 self.result = data['result']
 
     wait_msg = WaitMessage()
-    conn = Connection.instance(True)
+    conn = Connection.instance()
     consumer = DirectConsumer(connection=conn, msg_id=msg_id)
     consumer.register_callback(wait_msg)
 
@@ -346,7 +346,7 @@
     """Sends a message on a topic without waiting for a response"""
     LOG.debug(_("Making asynchronous cast..."))
     _pack_context(msg, context)
-    conn = Connection.instance(True)
+    conn = Connection.instance()
     publisher = TopicPublisher(connection=conn, topic=topic)
     publisher.send(msg)
     publisher.close()