OpenStack library for messaging
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# Copyright 2011-2013 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
# 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 except a Topic or Fanout exchange key and
return keys for direct exchanges, per (approximate) AMQP parlance.
import itertools
import json
import logging
from oslo.config import cfg
from oslo.messaging._drivers import matchmaker as mm
# FIXME(markmc): remove this
_ = lambda s: s
matchmaker_opts = [
# Matchmaker ring file
help='Matchmaker ring file (JSON).'),
CONF.register_opts(matchmaker_opts, 'matchmaker_ring')
LOG = logging.getLogger(__name__)
class RingExchange(mm.Exchange):
"""Match Maker where hosts are loaded from a static JSON formatted file.
__init__ takes optional ring dictionary argument, otherwise
loads the ringfile from CONF.mathcmaker_ringfile.
def __init__(self, ring=None):
super(RingExchange, self).__init__()
if ring:
self.ring = ring
fh = open(CONF.matchmaker_ring.ringfile, 'r')
self.ring = json.load(fh)
self.ring0 = {}
for k in self.ring.keys():
self.ring0[k] = itertools.cycle(self.ring[k])
def _ring_has(self, key):
return key in self.ring0
class RoundRobinRingExchange(RingExchange):
"""A Topic Exchange based on a hashmap."""
def __init__(self, ring=None):
super(RoundRobinRingExchange, self).__init__(ring)
def run(self, key):
if not self._ring_has(key):
_("No key defining hosts for topic '%s', "
"see ringfile"), key
return []
host = next(self.ring0[key])
return [(key + '.' + host, host)]
class FanoutRingExchange(RingExchange):
"""Fanout Exchange based on a hashmap."""
def __init__(self, ring=None):
super(FanoutRingExchange, self).__init__(ring)
def run(self, key):
# Assume starts with "fanout~", strip it for lookup.
nkey = key.split('fanout~')[1:][0]
if not self._ring_has(nkey):
_("No key defining hosts for topic '%s', "
"see ringfile"), nkey
return []
return map(lambda x: (key + '.' + x, x), self.ring[nkey])
class MatchMakerRing(mm.MatchMakerBase):
"""Match Maker where hosts are loaded from a static hashmap."""
def __init__(self, ring=None):
super(MatchMakerRing, self).__init__()
self.add_binding(mm.FanoutBinding(), FanoutRingExchange(ring))
self.add_binding(mm.DirectBinding(), mm.DirectExchange())
self.add_binding(mm.TopicBinding(), RoundRobinRingExchange(ring))