1 files changed, 114 insertions, 0 deletions
diff --git a/openstack/common/rpc/matchmaker_ring.py b/openstack/common/rpc/matchmaker_ring.py
new file mode 100644
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+++ b/openstack/common/rpc/matchmaker_ring.py
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+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#    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
+#
+#         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 except a Topic or Fanout exchange key and
+return keys for direct exchanges, per (approximate) AMQP parlance.
+"""
+
+import itertools
+import json
+
+from oslo.config import cfg
+
+from openstack.common.gettextutils import _
+from openstack.common import log as logging
+from openstack.common.rpc import matchmaker as mm
+
+
+matchmaker_opts = [
+    # Matchmaker ring file
+    cfg.StrOpt('ringfile',
+               deprecated_name='matchmaker_ringfile',
+               deprecated_group='DEFAULT',
+               default='/etc/oslo/matchmaker_ring.json',
+               help='Matchmaker ring file (JSON)'),
+]
+
+CONF = cfg.CONF
+CONF.register_opts(matchmaker_opts, 'matchmaker_ring')
+LOG = logging.getLogger(__name__)
+
+
+class RingExchange(mm.Exchange):
+    """
+    Match Maker where hosts are loaded from a static file containing
+    a hashmap (JSON formatted).
+
+    __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
+        else:
+            fh = open(CONF.matchmaker_ring.ringfile, 'r')
+            self.ring = json.load(fh)
+            fh.close()
+
+        self.ring0 = {}
+        for k in self.ring.keys():
+            self.ring0[k] = itertools.cycle(self.ring[k])
+
+    def _ring_has(self, key):
+        if key in self.ring0:
+            return True
+        return False
+
+
+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):
+            LOG.warn(
+                _("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):
+            LOG.warn(
+                _("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))