diff options
Diffstat (limited to 'openstack/common/rpc/matchmaker.py')
-rw-r--r-- | openstack/common/rpc/matchmaker.py | 122 |
1 files changed, 52 insertions, 70 deletions
diff --git a/openstack/common/rpc/matchmaker.py b/openstack/common/rpc/matchmaker.py index 98a8f43..e51636d 100644 --- a/openstack/common/rpc/matchmaker.py +++ b/openstack/common/rpc/matchmaker.py @@ -48,8 +48,8 @@ class MatchMakerException(Exception): class Exchange(object): - """ - Implements lookups. + """Implements lookups. + Subclass this to support hashtables, dns, etc. """ def __init__(self): @@ -60,9 +60,7 @@ class Exchange(object): class Binding(object): - """ - A binding on which to perform a lookup. - """ + """A binding on which to perform a lookup.""" def __init__(self): pass @@ -71,10 +69,10 @@ class Binding(object): class MatchMakerBase(object): - """ - Match Maker Base Class. - Build off HeartbeatMatchMakerBase if building a - heartbeat-capable MatchMaker. + """Match Maker Base Class. + + Build off HeartbeatMatchMakerBase if building a heartbeat-capable + MatchMaker. """ def __init__(self): # Array of tuples. Index [2] toggles negation, [3] is last-if-true @@ -84,58 +82,47 @@ class MatchMakerBase(object): 'registration or heartbeat.') def register(self, key, host): - """ - Register a host on a backend. + """Register a host on a backend. + Heartbeats, if applicable, may keepalive registration. """ pass def ack_alive(self, key, host): - """ - Acknowledge that a key.host is alive. - Used internally for updating heartbeats, - but may also be used publically to acknowledge - a system is alive (i.e. rpc message successfully - sent to host) + """Acknowledge that a key.host is alive. + + Used internally for updating heartbeats, but may also be used + publically to acknowledge a system is alive (i.e. rpc message + successfully sent to host) """ pass def is_alive(self, topic, host): - """ - Checks if a host is alive. - """ + """Checks if a host is alive.""" pass def expire(self, topic, host): - """ - Explicitly expire a host's registration. - """ + """Explicitly expire a host's registration.""" pass def send_heartbeats(self): - """ - Send all heartbeats. + """Send all heartbeats. + Use start_heartbeat to spawn a heartbeat greenthread, which loops this method. """ pass def unregister(self, key, host): - """ - Unregister a topic. - """ + """Unregister a topic.""" pass def start_heartbeat(self): - """ - Spawn heartbeat greenthread. - """ + """Spawn heartbeat greenthread.""" pass def stop_heartbeat(self): - """ - Destroys the heartbeat greenthread. - """ + """Destroys the heartbeat greenthread.""" pass def add_binding(self, binding, rule, last=True): @@ -162,10 +149,10 @@ class MatchMakerBase(object): class HeartbeatMatchMakerBase(MatchMakerBase): - """ - Base for a heart-beat capable MatchMaker. - Provides common methods for registering, - unregistering, and maintaining heartbeats. + """Base for a heart-beat capable MatchMaker. + + Provides common methods for registering, unregistering, and maintaining + heartbeats. """ def __init__(self): self.hosts = set() @@ -175,8 +162,8 @@ class HeartbeatMatchMakerBase(MatchMakerBase): super(HeartbeatMatchMakerBase, self).__init__() def send_heartbeats(self): - """ - Send all heartbeats. + """Send all heartbeats. + Use start_heartbeat to spawn a heartbeat greenthread, which loops this method. """ @@ -184,32 +171,31 @@ class HeartbeatMatchMakerBase(MatchMakerBase): self.ack_alive(key, host) def ack_alive(self, key, host): - """ - Acknowledge that a host.topic is alive. - Used internally for updating heartbeats, - but may also be used publically to acknowledge - a system is alive (i.e. rpc message successfully - sent to host) + """Acknowledge that a host.topic is alive. + + Used internally for updating heartbeats, but may also be used + publically to acknowledge a system is alive (i.e. rpc message + successfully sent to host) """ raise NotImplementedError("Must implement ack_alive") def backend_register(self, key, host): - """ - Implements registration logic. + """Implements registration logic. + Called by register(self,key,host) """ raise NotImplementedError("Must implement backend_register") def backend_unregister(self, key, key_host): - """ - Implements de-registration logic. + """Implements de-registration logic. + Called by unregister(self,key,host) """ raise NotImplementedError("Must implement backend_unregister") def register(self, key, host): - """ - Register a host on a backend. + """Register a host on a backend. + Heartbeats, if applicable, may keepalive registration. """ self.hosts.add(host) @@ -221,9 +207,7 @@ class HeartbeatMatchMakerBase(MatchMakerBase): self.ack_alive(key, host) def unregister(self, key, host): - """ - Unregister a topic. - """ + """Unregister a topic.""" if (key, host) in self.host_topic: del self.host_topic[(key, host)] @@ -234,8 +218,8 @@ class HeartbeatMatchMakerBase(MatchMakerBase): {'key': key, 'host': host}) def start_heartbeat(self): - """ - Implementation of MatchMakerBase.start_heartbeat + """Implementation of MatchMakerBase.start_heartbeat. + Launches greenthread looping send_heartbeats(), yielding for CONF.matchmaker_heartbeat_freq seconds between iterations. @@ -252,16 +236,14 @@ class HeartbeatMatchMakerBase(MatchMakerBase): self._heart = eventlet.spawn(do_heartbeat) def stop_heartbeat(self): - """ - Destroys the heartbeat greenthread. - """ + """Destroys the heartbeat greenthread.""" if self._heart: self._heart.kill() class DirectBinding(Binding): - """ - Specifies a host in the key via a '.' character + """Specifies a host in the key via a '.' character. + Although dots are used in the key, the behavior here is that it maps directly to a host, thus direct. """ @@ -272,8 +254,8 @@ class DirectBinding(Binding): class TopicBinding(Binding): - """ - Where a 'bare' key without dots. + """Where a 'bare' key without dots. + AMQP generally considers topic exchanges to be those *with* dots, but we deviate here in terminology as the behavior here matches that of a topic exchange (whereas where there are dots, behavior @@ -310,8 +292,8 @@ class LocalhostExchange(Exchange): class DirectExchange(Exchange): - """ - Exchange where all topic keys are split, sending to second half. + """Exchange where all topic keys are split, sending to second half. + i.e. "compute.host" sends a message to "compute.host" running on "host" """ def __init__(self): @@ -323,8 +305,8 @@ class DirectExchange(Exchange): class MatchMakerLocalhost(MatchMakerBase): - """ - Match Maker where all bare topics resolve to localhost. + """Match Maker where all bare topics resolve to localhost. + Useful for testing. """ def __init__(self, host='localhost'): @@ -335,8 +317,8 @@ class MatchMakerLocalhost(MatchMakerBase): class MatchMakerStub(MatchMakerBase): - """ - Match Maker where topics are untouched. + """Match Maker where topics are untouched. + Useful for testing, or for AMQP/brokered queues. Will not work where knowledge of hosts is known (i.e. zeromq) """ |