1 files changed, 145 insertions, 0 deletions
diff --git a/keystone/openstack/common/rpc/matchmaker_redis.py b/keystone/openstack/common/rpc/matchmaker_redis.py
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+++ b/keystone/openstack/common/rpc/matchmaker_redis.py
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+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#    Copyright 2013 Cloudscaling Group, Inc
+#
+#    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.
+"""
+The MatchMaker classes should accept a Topic or Fanout exchange key and
+return keys for direct exchanges, per (approximate) AMQP parlance.
+"""
+
+from oslo.config import cfg
+
+from keystone.openstack.common import importutils
+from keystone.openstack.common import log as logging
+from keystone.openstack.common.rpc import matchmaker as mm_common
+
+redis = importutils.try_import('redis')
+
+
+matchmaker_redis_opts = [
+    cfg.StrOpt('host',
+               default='127.0.0.1',
+               help='Host to locate redis'),
+    cfg.IntOpt('port',
+               default=6379,
+               help='Use this port to connect to redis host.'),
+    cfg.StrOpt('password',
+               default=None,
+               help='Password for Redis server. (optional)'),
+]
+
+CONF = cfg.CONF
+opt_group = cfg.OptGroup(name='matchmaker_redis',
+                         title='Options for Redis-based MatchMaker')
+CONF.register_group(opt_group)
+CONF.register_opts(matchmaker_redis_opts, opt_group)
+LOG = logging.getLogger(__name__)
+
+
+class RedisExchange(mm_common.Exchange):
+    def __init__(self, matchmaker):
+        self.matchmaker = matchmaker
+        self.redis = matchmaker.redis
+        super(RedisExchange, self).__init__()
+
+
+class RedisTopicExchange(RedisExchange):
+    """Exchange where all topic keys are split, sending to second half.
+
+    i.e. "compute.host" sends a message to "compute" running on "host"
+    """
+    def run(self, topic):
+        while True:
+            member_name = self.redis.srandmember(topic)
+
+            if not member_name:
+                # If this happens, there are no
+                # longer any members.
+                break
+
+            if not self.matchmaker.is_alive(topic, member_name):
+                continue
+
+            host = member_name.split('.', 1)[1]
+            return [(member_name, host)]
+        return []
+
+
+class RedisFanoutExchange(RedisExchange):
+    """Return a list of all hosts."""
+    def run(self, topic):
+        topic = topic.split('~', 1)[1]
+        hosts = self.redis.smembers(topic)
+        good_hosts = filter(
+            lambda host: self.matchmaker.is_alive(topic, host), hosts)
+
+        return [(x, x.split('.', 1)[1]) for x in good_hosts]
+
+
+class MatchMakerRedis(mm_common.HeartbeatMatchMakerBase):
+    """MatchMaker registering and looking-up hosts with a Redis server."""
+    def __init__(self):
+        super(MatchMakerRedis, self).__init__()
+
+        if not redis:
+            raise ImportError("Failed to import module redis.")
+
+        self.redis = redis.StrictRedis(
+            host=CONF.matchmaker_redis.host,
+            port=CONF.matchmaker_redis.port,
+            password=CONF.matchmaker_redis.password)
+
+        self.add_binding(mm_common.FanoutBinding(), RedisFanoutExchange(self))
+        self.add_binding(mm_common.DirectBinding(), mm_common.DirectExchange())
+        self.add_binding(mm_common.TopicBinding(), RedisTopicExchange(self))
+
+    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.topic_host[host], host)
+
+    def is_alive(self, topic, host):
+        if self.redis.ttl(host) == -1:
+            self.expire(topic, host)
+            return False
+        return True
+
+    def expire(self, topic, host):
+        with self.redis.pipeline() as pipe:
+            pipe.multi()
+            pipe.delete(host)
+            pipe.srem(topic, host)
+            pipe.execute()
+
+    def backend_register(self, key, key_host):
+        with self.redis.pipeline() as pipe:
+            pipe.multi()
+            pipe.sadd(key, key_host)
+
+            # No value is needed, we just
+            # care if it exists. Sets aren't viable
+            # because only keys can expire.
+            pipe.set(key_host, '')
+
+            pipe.execute()
+
+    def backend_unregister(self, key, key_host):
+        with self.redis.pipeline() as pipe:
+            pipe.multi()
+            pipe.srem(key, key_host)
+            pipe.delete(key_host)
+            pipe.execute()