3109941e5e
Newton will be the first release of support for this new message bus technology. Make users aware that this feature is 'bleeding edge' and queuing is not supported in this release. Change-Id: I44ba5507d941823e2dfa92d52dae4b85e9bda493
288 lines
11 KiB
Python
288 lines
11 KiB
Python
# Copyright 2016, 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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Utilities that map from a Target address to a proper AMQP 1.0 address.
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This module defines a utility class that translates a high level oslo.messaging
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address (Target) into the message-level address used on the message bus. This
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translation may be statically configured or determined when the connection to
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the message bus is made.
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The Target members that are used to generate the address are:
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* exchange
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* topic
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* server flag
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* fanout flag
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In addition a 'service' tag is associated with the address. This tag determines
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the service associated with an address (e.g. rpc or notification) so
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that traffic can be partitioned based on its use.
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"""
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import abc
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import logging
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from oslo_messaging._i18n import _LW
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from oslo_messaging.target import Target
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__all__ = [
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"keyify",
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"AddresserFactory",
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"SERVICE_RPC",
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"SERVICE_NOTIFY"
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]
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SERVICE_RPC = 0
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SERVICE_NOTIFY = 1
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LOG = logging.getLogger(__name__)
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def keyify(address, service=SERVICE_RPC):
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"""Create a hashable key from a Target and service that will uniquely
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identify the generated address. This key is used to map the abstract
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oslo.messaging address to its corresponding AMQP link(s). This mapping may
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be done before the connection is established.
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"""
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if isinstance(address, Target):
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# service is important because the resolved address may be
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# different based on whether or not this Target is used for
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# notifications or RPC
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return ("Target:{t={%s} e={%s} s={%s} f={%s} service={%s}}" %
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(address.topic, address.exchange, address.server,
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address.fanout, service))
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else:
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# absolute address can be used without modification
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return "String:{%s}" % address
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class Addresser(object):
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"""Base class message bus address generator. Used to convert an
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oslo.messaging address into an AMQP 1.0 address string used over the
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connection to the message bus.
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"""
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def __init__(self, default_exchange):
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self._default_exchange = default_exchange
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def resolve(self, target, service):
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if not isinstance(target, Target):
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# an already resolved address
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return target
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# Return a link address for a given target
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if target.fanout:
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return self.multicast_address(target, service)
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elif target.server:
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return self.unicast_address(target, service)
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else:
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return self.anycast_address(target, service)
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@abc.abstractmethod
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def multicast_address(self, target, service):
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"""Address used to broadcast to all subscribers
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"""
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@abc.abstractmethod
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def unicast_address(self, target, service):
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"""Address used to target a specific subscriber (direct)
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"""
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@abc.abstractmethod
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def anycast_address(self, target, service):
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"""Address used for shared subscribers (competing consumers)
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"""
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class LegacyAddresser(Addresser):
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"""Legacy addresses are in the following format:
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multicast: '$broadcast_prefix.$exchange.$topic.all'
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unicast: '$server_prefix.$exchange.$topic.$server'
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anycast: '$group_prefix.$exchange.$topic'
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Legacy addresses do not distinguish RPC traffic from Notification traffic
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"""
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def __init__(self, default_exchange, server_prefix, broadcast_prefix,
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group_prefix):
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super(LegacyAddresser, self).__init__(default_exchange)
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self._server_prefix = server_prefix
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self._broadcast_prefix = broadcast_prefix
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self._group_prefix = group_prefix
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def multicast_address(self, target, service):
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return self._concatenate([self._broadcast_prefix,
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target.exchange or self._default_exchange,
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target.topic, "all"])
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def unicast_address(self, target, service=SERVICE_RPC):
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return self._concatenate([self._server_prefix,
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target.exchange or self._default_exchange,
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target.topic, target.server])
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def anycast_address(self, target, service=SERVICE_RPC):
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return self._concatenate([self._group_prefix,
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target.exchange or self._default_exchange,
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target.topic])
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def _concatenate(self, items):
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return ".".join(filter(bool, items))
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# for debug:
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def _is_multicast(self, address):
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return address.startswith(self._broadcast_prefix)
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def _is_unicast(self, address):
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return address.startswith(self._server_prefix)
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def _is_anycast(self, address):
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return address.startswith(self._group_prefix)
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def _is_service(self, address, service):
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# legacy addresses are the same for RPC or Notifications
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return True
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class RoutableAddresser(Addresser):
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"""Routable addresses have different formats based their use. It starts
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with a prefix that is determined by the type of traffic (RPC or
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Notifications). The prefix is followed by a description of messaging
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delivery semantics. The delivery may be one of: 'multicast', 'unicast', or
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'anycast'. The delivery semantics are followed by information pulled from
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the Target. The template is:
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$prefix/$semantics/$exchange/$topic[/$server]
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Examples based on the default prefix and semantic values:
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rpc-unicast: "openstack.org/om/rpc/unicast/$exchange/$topic/$server"
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notify-anycast: "openstack.org/om/notify/anycast/$exchange/$topic"
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"""
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def __init__(self, default_exchange, rpc_exchange, rpc_prefix,
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notify_exchange, notify_prefix, unicast_tag, multicast_tag,
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anycast_tag):
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super(RoutableAddresser, self).__init__(default_exchange)
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if not self._default_exchange:
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self._default_exchange = "openstack"
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# templates for address generation:
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_rpc = rpc_prefix + "/"
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self._rpc_prefix = _rpc
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self._rpc_unicast = _rpc + unicast_tag
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self._rpc_multicast = _rpc + multicast_tag
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self._rpc_anycast = _rpc + anycast_tag
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_notify = notify_prefix + "/"
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self._notify_prefix = _notify
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self._notify_unicast = _notify + unicast_tag
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self._notify_multicast = _notify + multicast_tag
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self._notify_anycast = _notify + anycast_tag
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self._exchange = [
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# SERVICE_RPC:
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rpc_exchange or self._default_exchange or 'rpc',
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# SERVICE_NOTIFY:
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notify_exchange or self._default_exchange or 'notify'
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]
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def multicast_address(self, target, service=SERVICE_RPC):
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if service == SERVICE_RPC:
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prefix = self._rpc_multicast
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else:
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prefix = self._notify_multicast
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return "%s/%s/%s" % (prefix,
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target.exchange or self._exchange[service],
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target.topic)
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def unicast_address(self, target, service=SERVICE_RPC):
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if service == SERVICE_RPC:
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prefix = self._rpc_unicast
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else:
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prefix = self._notify_unicast
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if target.server:
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return "%s/%s/%s/%s" % (prefix,
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target.exchange or self._exchange[service],
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target.topic,
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target.server)
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return "%s/%s/%s" % (prefix,
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target.exchange or self._exchange[service],
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target.topic)
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def anycast_address(self, target, service=SERVICE_RPC):
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if service == SERVICE_RPC:
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prefix = self._rpc_anycast
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else:
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prefix = self._notify_anycast
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return "%s/%s/%s" % (prefix,
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target.exchange or self._exchange[service],
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target.topic)
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# for debug:
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def _is_multicast(self, address):
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return (address.startswith(self._rpc_multicast) or
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address.startswith(self._notify_multicast))
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def _is_unicast(self, address):
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return (address.startswith(self._rpc_unicast) or
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address.startswith(self._notify_unicast))
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def _is_anycast(self, address):
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return (address.startswith(self._rpc_anycast) or
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address.startswith(self._notify_anycast))
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def _is_service(self, address, service):
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return address.startswith(self._rpc_prefix if service == SERVICE_RPC
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else self._notify_prefix)
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class AddresserFactory(object):
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"""Generates the proper Addresser based on configuration and the type of
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message bus the driver is connected to.
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"""
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def __init__(self, default_exchange, mode, **kwargs):
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self._default_exchange = default_exchange
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self._mode = mode
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self._kwargs = kwargs
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def __call__(self, remote_properties):
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# for backwards compatiblity use legacy if dynamic and we're connected
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# to qpidd or we cannot identify the message bus. This can be
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# overridden via the configuration.
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product = remote_properties.get('product', 'qpid-cpp')
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# TODO(kgiusti): Router support was added in Newton. Remove this
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# warning post Newton, once the driver has stabilized.
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if product == "qpid-dispatch-router":
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w = _LW("This is the initial release of support for message"
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" routing technology. Be aware that messages are not"
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" queued and may be discarded if there are no consumers"
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" present.")
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LOG.warning(w)
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if self._mode == 'legacy' or (self._mode == 'dynamic'
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and product == 'qpid-cpp'):
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return LegacyAddresser(self._default_exchange,
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self._kwargs['legacy_server_prefix'],
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self._kwargs['legacy_broadcast_prefix'],
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self._kwargs['legacy_group_prefix'])
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else:
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return RoutableAddresser(self._default_exchange,
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self._kwargs.get("rpc_exchange"),
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self._kwargs["rpc_prefix"],
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self._kwargs.get("notify_exchange"),
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self._kwargs["notify_prefix"],
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self._kwargs["unicast"],
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self._kwargs["multicast"],
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self._kwargs["anycast"])
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