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