Fix matchmaker_redis ack_alive fails with KeyError

Fix matchmaker_redis: ack_alive fails with KeyError on re-registration
attempt.

def ack_alive(self, key, host):
    topic = "%s.%s" % (key, host)
    if not self.redis.expire(topic, CONF.matchmaker_heartbeat_ttl):
        # If we could not update the expiration, the key
        # might have been pruned. Re-register, creating a new
        # key in Redis.
        self.register(self.host_topic[host], host)

self.host_topic is a dict with keys of tuple (key, host), not 'host',
register's first parameter is the topic like 'notification-info',
so modify it to key.
And it will not cause indefinite recursion, because when register end,
the key exist in redis, redis.expire will return True.

Add test case for ack_alive.

(backported from oslo.messaging; omitting master branch since it does
not have RPC module anymore.)

Closes-Bug: #1419718

Change-Id: I8d972afe89aec02a5c8f0d9dd4e216bc12c298a1

2 files changed, 7 insertions, 1 deletions

diff --git a/openstack/common/rpc/matchmaker_redis.py b/openstack/common/rpc/matchmaker_redis.py
index 215ab9e3..0ea69df0 100644
--- a/openstack/common/rpc/matchmaker_redis.py
+++ b/openstack/common/rpc/matchmaker_redis.py
@@ -109,7 +109,7 @@ class MatchMakerRedis(mm_common.HeartbeatMatchMakerBase):
             # If we could not update the expiration, the key
             # might have been pruned. Re-register, creating a new
             # key in Redis.
-            self.register(self.host_topic[host], host)
+            self.register(key, host)
 
     def is_alive(self, topic, host):
         ttl = self.redis.ttl(host)
diff --git a/tests/unit/rpc/test_matchmaker_redis.py b/tests/unit/rpc/test_matchmaker_redis.py
index 9ebd677d..492b560f 100644
--- a/tests/unit/rpc/test_matchmaker_redis.py
+++ b/tests/unit/rpc/test_matchmaker_redis.py
@@ -121,6 +121,12 @@ class MatchMakerRedisHeartbeatTestCase(test.BaseTestCase,
         # Tests that host is removed from results
         self.assertEqual(self.driver.queues(self.topic), [])
 
+    def test_ack_alive(self):
+        self.driver.ack_alive('ack_alive', 'controller1')
+        self.assertEqual(
+            sorted(self.driver.redis.smembers('ack_alive')),
+            ['ack_alive.controller1'])
+
 
 class MatchMakerRedisTestCase(test.BaseTestCase):
     """Generic tests that do not require a Redis server."""