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# Copyright 2016 Mirantis, 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.
import time
from oslo_messaging._drivers.zmq_driver import zmq_async
from oslo_messaging._drivers.zmq_driver import zmq_names
zmq = zmq_async.import_zmq()
class RoutingTable(object):
"""This class implements local routing-table cache
taken from matchmaker. Its purpose is to give the next routable
host id (remote DEALER's id) by request for specific target in
round-robin fashion.
"""
def __init__(self, conf, matchmaker):
self.conf = conf
self.matchmaker = matchmaker
self.routing_table = {}
self.routable_hosts = {}
def get_all_hosts(self, target):
self._update_routing_table(target)
return list(self.routable_hosts.get(str(target)) or [])
def get_routable_host(self, target):
self._update_routing_table(target)
hosts_for_target = self.routable_hosts[str(target)]
host = hosts_for_target.pop(0)
if not hosts_for_target:
self._renew_routable_hosts(target)
return host
def _is_tm_expired(self, tm):
return 0 <= self.conf.oslo_messaging_zmq.zmq_target_expire \
<= time.time() - tm
def _update_routing_table(self, target):
routing_record = self.routing_table.get(str(target))
if routing_record is None:
self._fetch_hosts(target)
self._renew_routable_hosts(target)
elif self._is_tm_expired(routing_record[1]):
self._fetch_hosts(target)
def _fetch_hosts(self, target):
self.routing_table[str(target)] = (self.matchmaker.get_hosts(
target, zmq_names.socket_type_str(zmq.DEALER)), time.time())
def _renew_routable_hosts(self, target):
hosts, _ = self.routing_table[str(target)]
self.routable_hosts[str(target)] = list(hosts)
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