¡@
OpenStack Study: rpc_driver.py**** CubicPower OpenStack Study ****
# Copyright (c) 2012 Rackspace Hosting # All Rights Reserved. # Copyright 2013 Red Hat, 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. """ Cells RPC Communication Driver """ from oslo.config import cfg from oslo import messaging from nova.cells import driver from nova import rpc cell_rpc_driver_opts = [ cfg.StrOpt('rpc_driver_queue_base', default='cells.intercell', help="Base queue name to use when communicating between " "cells. Various topics by message type will be " "appended to this.")] CONF = cfg.CONF CONF.register_opts(cell_rpc_driver_opts, group='cells') CONF.import_opt('call_timeout', 'nova.cells.opts', group='cells') rpcapi_cap_opt = cfg.StrOpt('intercell', help='Set a version cap for messages sent between cells services') CONF.register_opt(rpcapi_cap_opt, 'upgrade_levels')
**** CubicPower OpenStack Study **** class CellsRPCDriver(driver.BaseCellsDriver): """Driver for cell<->cell communication via RPC. This is used to setup the RPC consumers as well as to send a message to another cell. One instance of this class will be created for every neighbor cell that we find in the DB and it will be associated with the cell in its CellState. One instance is also created by the cells manager for setting up the consumers. """
**** CubicPower OpenStack Study **** def __init__(self, *args, **kwargs): super(CellsRPCDriver, self).__init__(*args, **kwargs) self.rpc_servers = [] self.intercell_rpcapi = InterCellRPCAPI()
**** CubicPower OpenStack Study **** def start_servers(self, msg_runner): """Start RPC servers. Start up 2 separate servers for handling inter-cell communication via RPC. Both handle the same types of messages, but requests/replies are separated to solve potential deadlocks. (If we used the same queue for both, it's possible to exhaust the RPC thread pool while we wait for replies.. such that we'd never consume a reply.) """ topic_base = CONF.cells.rpc_driver_queue_base proxy_manager = InterCellRPCDispatcher(msg_runner) for msg_type in msg_runner.get_message_types(): target = messaging.Target(topic='%s.%s' % (topic_base, msg_type), server=CONF.host) # NOTE(comstud): We do not need to use the object serializer # on this because object serialization is taken care for us in # the nova.cells.messaging module. server = rpc.get_server(target, endpoints=[proxy_manager]) server.start() self.rpc_servers.append(server)
**** CubicPower OpenStack Study **** def stop_servers(self): """Stop RPC servers. NOTE: Currently there's no hooks when stopping services to have managers cleanup, so this is not currently called. """ for server in self.rpc_servers: server.stop()
**** CubicPower OpenStack Study **** def send_message_to_cell(self, cell_state, message): """Use the IntercellRPCAPI to send a message to a cell.""" self.intercell_rpcapi.send_message_to_cell(cell_state, message)
**** CubicPower OpenStack Study **** class InterCellRPCAPI(object): """Client side of the Cell<->Cell RPC API. The CellsRPCDriver uses this to make calls to another cell. API version history: 1.0 - Initial version. ... Grizzly supports message version 1.0. So, any changes to existing methods in 2.x after that point should be done such that they can handle the version_cap being set to 1.0. """ VERSION_ALIASES = { 'grizzly': '1.0', }
**** CubicPower OpenStack Study **** def __init__(self): super(InterCellRPCAPI, self).__init__() self.version_cap = ( self.VERSION_ALIASES.get(CONF.upgrade_levels.intercell, CONF.upgrade_levels.intercell))
**** CubicPower OpenStack Study **** def _get_client(self, next_hop, topic): """Turn the DB information for a cell into a messaging.RPCClient.""" transport_url = next_hop.db_info['transport_url'] transport = messaging.get_transport(cfg.CONF, transport_url, rpc.TRANSPORT_ALIASES) target = messaging.Target(topic=topic, version='1.0') serializer = rpc.RequestContextSerializer(None) return messaging.RPCClient(transport, target, version_cap=self.version_cap, serializer=serializer)
**** CubicPower OpenStack Study **** def send_message_to_cell(self, cell_state, message): """Send a message to another cell by JSON-ifying the message and making an RPC cast to 'process_message'. If the message says to fanout, do it. The topic that is used will be 'CONF.rpc_driver_queue_base. """ topic_base = CONF.cells.rpc_driver_queue_base topic = '%s.%s' % (topic_base, message.message_type) cctxt = self._get_client(cell_state, topic) if message.fanout: cctxt = cctxt.prepare(fanout=message.fanout) return cctxt.cast(message.ctxt, 'process_message', message=message.to_json())
**** CubicPower OpenStack Study **** class InterCellRPCDispatcher(object): """RPC Dispatcher to handle messages received from other cells. All messages received here have come from a sibling cell. Depending on the ultimate target and type of message, we may process the message in this cell, relay the message to another sibling cell, or both. This logic is
**** CubicPower OpenStack Study **** def __init__(self, msg_runner): """Init the Intercell RPC Dispatcher.""" self.msg_runner = msg_runner
**** CubicPower OpenStack Study **** def process_message(self, _ctxt, message): """We received a message from another cell. Use the MessageRunner to turn this from JSON back into an instance of the correct Message class. Then process it! """ message = self.msg_runner.message_from_json(message) message.process()
|