Cherry pick oslo rpc HA fixes

Get 2 commits from oslo-rpc fixing HA failover:
* Ia148baa6e1ec632789ac3621c85173c2c16f3918 (fixed HA failover, Qpid
 part)
* I67923cb024bbd143edc8edccf35b9b400df31eb3 (fixed HA failover, RabbitMQ
 part)
Closes-Bug: #1261631

Change-Id: I154a1e4230cf956e0d6a71a8e717866d0cd17a12

cinder/openstack/common/rpc/impl_kombu.py

@@ -438,6 +438,9 @@ def __init__(self, conf, server_params=None):
 
         self.params_list = params_list
 
+        brokers_count = len(self.params_list)
+        self.next_broker_indices = itertools.cycle(range(brokers_count))
+
         self.memory_transport = self.conf.fake_rabbit
 
         self.connection = None
@@ -510,7 +513,7 @@ def reconnect(self):
 
         attempt = 0
         while True:
-            params = self.params_list[attempt % len(self.params_list)]
+            params = self.params_list[next(self.next_broker_indices)]
             attempt += 1
             try:
                 self._connect(params)

cinder/openstack/common/rpc/impl_qpid.py

@@ -407,6 +407,10 @@ def __init__(self, conf, server_params=None):
         self.brokers = params['qpid_hosts']
         self.username = params['username']
         self.password = params['password']
+
+        brokers_count = len(self.brokers)
+        self.next_broker_indices = itertools.cycle(range(brokers_count))
+
         self.connection_create(self.brokers[0])
         self.reconnect()
 
@@ -434,7 +438,6 @@ def _lookup_consumer(self, receiver):
 
     def reconnect(self):
         """Handles reconnecting and re-establishing sessions and queues"""
-        attempt = 0
         delay = 1
         while True:
             # Close the session if necessary
@@ -444,8 +447,7 @@ def reconnect(self):
                 except qpid_exceptions.MessagingError:
                     pass
 
-            broker = self.brokers[attempt % len(self.brokers)]
-            attempt += 1
+            broker = self.brokers[next(self.next_broker_indices)]
 
             try:
                 self.connection_create(broker)