Implement blueprint host-topic-matchmaking
Change-Id: I382b731bbc64e92db9d06f4e9ee497b1cc0f7d26
This commit is contained in:
Eric Windisch
257
nova/rpc/matchmaker.py
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257
nova/rpc/matchmaker.py
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2011 Cloudscaling Group, Inc
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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The MatchMaker classes should except a Topic or Fanout exchange key and
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return keys for direct exchanges, per (approximate) AMQP parlance.
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"""
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import contextlib
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import itertools
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import json
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import logging
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from nova.openstack.common import cfg
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matchmaker_opts = [
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# Matchmaker ring file
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cfg.StrOpt('matchmaker_ringfile',
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default='/etc/nova/matchmaker_ring.json',
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help='Matchmaker ring file (JSON)'),
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]
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CONF = cfg.CONF
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CONF.register_opts(matchmaker_opts)
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LOG = logging.getLogger(__name__)
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contextmanager = contextlib.contextmanager
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class MatchMakerException(Exception):
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"""Signified a match could not be found."""
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message = _("Match not found by MatchMaker.")
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class Exchange(object):
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"""
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Implements lookups.
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Subclass this to support hashtables, dns, etc.
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"""
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def __init__(self):
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pass
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def run(self, key):
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raise NotImplementedError()
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class Binding(object):
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"""
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A binding on which to perform a lookup.
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"""
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def __init__(self):
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pass
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def test(self, key):
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raise NotImplementedError()
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class MatchMakerBase(object):
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"""Match Maker Base Class."""
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def __init__(self):
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# Array of tuples. Index [2] toggles negation, [3] is last-if-true
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self.bindings = []
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def add_binding(self, binding, rule, last=True):
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self.bindings.append((binding, rule, False, last))
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#NOTE(ewindisch): kept the following method in case we implement the
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# underlying support.
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#def add_negate_binding(self, binding, rule, last=True):
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# self.bindings.append((binding, rule, True, last))
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def queues(self, key):
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workers = []
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# bit is for negate bindings - if we choose to implement it.
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# last stops processing rules if this matches.
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for (binding, exchange, bit, last) in self.bindings:
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if binding.test(key):
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workers.extend(exchange.run(key))
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# Support last.
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if last:
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return workers
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return workers
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class DirectBinding(Binding):
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"""
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Specifies a host in the key via a '.' character
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Although dots are used in the key, the behavior here is
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that it maps directly to a host, thus direct.
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"""
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def test(self, key):
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if '.' in key:
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return True
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return False
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class TopicBinding(Binding):
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"""
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Where a 'bare' key without dots.
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AMQP generally considers topic exchanges to be those *with* dots,
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but we deviate here in terminology as the behavior here matches
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that of a topic exchange (whereas where there are dots, behavior
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matches that of a direct exchange.
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"""
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def test(self, key):
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if '.' not in key:
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return True
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return False
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class FanoutBinding(Binding):
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"""Match on fanout keys, where key starts with 'fanout.' string."""
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def test(self, key):
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if key.startswith('fanout~'):
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return True
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return False
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class StubExchange(Exchange):
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"""Exchange that does nothing."""
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def run(self, key):
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return [(key, None)]
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class RingExchange(Exchange):
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"""
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Match Maker where hosts are loaded from a static file containing
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a hashmap (JSON formatted).
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__init__ takes optional ring dictionary argument, otherwise
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loads the ringfile from CONF.mathcmaker_ringfile.
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"""
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def __init__(self, ring=None):
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super(RingExchange, self).__init__()
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if ring:
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self.ring = ring
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else:
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fh = open(CONF.matchmaker_ringfile, 'r')
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self.ring = json.load(fh)
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fh.close()
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self.ring0 = {}
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for k in self.ring.keys():
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self.ring0[k] = itertools.cycle(self.ring[k])
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def _ring_has(self, key):
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if key in self.ring0:
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return True
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return False
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class RoundRobinRingExchange(RingExchange):
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"""A Topic Exchange based on a hashmap."""
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def __init__(self, ring=None):
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super(RoundRobinRingExchange, self).__init__(ring)
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def run(self, key):
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if not self._ring_has(key):
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LOG.warn(
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_("No key defining hosts for topic '%s', "
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"see ringfile") % (key, )
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)
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return []
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host = next(self.ring0[key])
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return [(key + '.' + host, host)]
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class FanoutRingExchange(RingExchange):
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"""Fanout Exchange based on a hashmap."""
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def __init__(self, ring=None):
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super(FanoutRingExchange, self).__init__(ring)
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def run(self, key):
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# Assume starts with "fanout~", strip it for lookup.
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nkey = key.split('fanout~')[1:][0]
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if not self._ring_has(nkey):
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LOG.warn(
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_("No key defining hosts for topic '%s', "
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"see ringfile") % (nkey, )
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)
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return []
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return map(lambda x: (key + '.' + x, x), self.ring[nkey])
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class LocalhostExchange(Exchange):
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"""Exchange where all direct topics are local."""
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def __init__(self):
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super(Exchange, self).__init__()
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def run(self, key):
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return [(key.split('.')[0] + '.localhost', 'localhost')]
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class DirectExchange(Exchange):
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"""
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Exchange where all topic keys are split, sending to second half.
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i.e. "compute.host" sends a message to "compute" running on "host"
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"""
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def __init__(self):
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super(Exchange, self).__init__()
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def run(self, key):
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b, e = key.split('.', 1)
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return [(b, e)]
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class MatchMakerRing(MatchMakerBase):
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"""
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Match Maker where hosts are loaded from a static hashmap.
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"""
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def __init__(self, ring=None):
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super(MatchMakerRing, self).__init__()
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self.add_binding(FanoutBinding(), FanoutRingExchange(ring))
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self.add_binding(DirectBinding(), DirectExchange())
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self.add_binding(TopicBinding(), RoundRobinRingExchange(ring))
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class MatchMakerLocalhost(MatchMakerBase):
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"""
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Match Maker where all bare topics resolve to localhost.
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Useful for testing.
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"""
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def __init__(self):
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super(MatchMakerLocalhost, self).__init__()
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self.add_binding(FanoutBinding(), LocalhostExchange())
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self.add_binding(DirectBinding(), DirectExchange())
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self.add_binding(TopicBinding(), LocalhostExchange())
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class MatchMakerStub(MatchMakerBase):
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"""
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Match Maker where topics are untouched.
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Useful for testing, or for AMQP/brokered queues.
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Will not work where knowledge of hosts is known (i.e. zeromq)
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"""
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def __init__(self):
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super(MatchMakerLocalhost, self).__init__()
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self.add_binding(FanoutBinding(), StubExchange())
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self.add_binding(DirectBinding(), StubExchange())
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self.add_binding(TopicBinding(), StubExchange())
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58
nova/tests/rpc/test_matchmaker.py
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58
nova/tests/rpc/test_matchmaker.py
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@@ -0,0 +1,58 @@
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2012 Cloudscaling Group, Inc
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from nova import log as logging
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from nova.rpc import matchmaker
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from nova import test
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LOG = logging.getLogger(__name__)
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class _MatchMakerTestCase(test.TestCase):
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def test_valid_host_matches(self):
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queues = self.driver.queues(self.topic)
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matched_hosts = map(lambda x: x[1], queues)
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for host in matched_hosts:
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self.assertIn(host, self.hosts)
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def test_fanout_host_matches(self):
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"""For known hosts, see if they're in fanout."""
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queues = self.driver.queues("fanout~" + self.topic)
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matched_hosts = map(lambda x: x[1], queues)
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LOG.info("Received result from matchmaker: %s", queues)
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for host in self.hosts:
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self.assertIn(host, matched_hosts)
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class MatchMakerFileTestCase(_MatchMakerTestCase):
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def setUp(self):
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self.topic = "test"
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self.hosts = ['hello', 'world', 'foo', 'bar', 'baz']
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ring = {
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self.topic: self.hosts
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}
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self.driver = matchmaker.MatchMakerRing(ring)
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super(MatchMakerFileTestCase, self).setUp()
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class MatchMakerLocalhostTestCase(_MatchMakerTestCase):
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def setUp(self):
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self.driver = matchmaker.MatchMakerLocalhost()
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self.topic = "test"
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self.hosts = ['localhost']
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super(MatchMakerLocalhostTestCase, self).setUp()
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