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# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright 2011 - 2012, 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.
"""
Utilities for drivers based on the AMQPDriverBase.
This module contains utility code used by drivers based on the AMQPDriverBase
class. Specifically this includes the impl_rabbit driver.
"""
import collections
import uuid
from oslo_config import cfg
from oslo_messaging._drivers import common as rpc_common
amqp_opts = [
cfg.BoolOpt('amqp_durable_queues',
default=False,
help='Use durable queues in AMQP. If rabbit_quorum_queue '
'is enabled, queues will be durable and this value will '
'be ignored.'),
cfg.BoolOpt('amqp_auto_delete',
default=False,
deprecated_group='DEFAULT',
help='Auto-delete queues in AMQP.'),
]
UNIQUE_ID = '_unique_id'
class RpcContext(rpc_common.CommonRpcContext):
"""Context that supports replying to a rpc.call."""
def __init__(self, **kwargs):
self.msg_id = kwargs.pop('msg_id', None)
self.reply_q = kwargs.pop('reply_q', None)
super(RpcContext, self).__init__(**kwargs)
def deepcopy(self):
values = self.to_dict()
values['conf'] = self.conf
values['msg_id'] = self.msg_id
values['reply_q'] = self.reply_q
return self.__class__(**values)
def unpack_context(msg):
"""Unpack context from msg."""
context_dict = {}
for key in list(msg.keys()):
key = str(key)
if key.startswith('_context_'):
value = msg.pop(key)
context_dict[key[9:]] = value
context_dict['msg_id'] = msg.pop('_msg_id', None)
context_dict['reply_q'] = msg.pop('_reply_q', None)
context_dict['client_timeout'] = msg.pop('_timeout', None)
return RpcContext.from_dict(context_dict)
def pack_context(msg, context):
"""Pack context into msg.
Values for message keys need to be less than 255 chars, so we pull
context out into a bunch of separate keys. If we want to support
more arguments in rabbit messages, we may want to do the same
for args at some point.
"""
if isinstance(context, dict):
context_d = context.items()
else:
context_d = context.to_dict().items()
msg.update(('_context_%s' % key, value)
for (key, value) in context_d)
class _MsgIdCache(object):
"""This class checks any duplicate messages."""
# NOTE: This value is considered can be a configuration item, but
# it is not necessary to change its value in most cases,
# so let this value as static for now.
DUP_MSG_CHECK_SIZE = 16
def __init__(self, **kwargs):
self.prev_msgids = collections.deque([],
maxlen=self.DUP_MSG_CHECK_SIZE)
def check_duplicate_message(self, message_data):
"""AMQP consumers may read same message twice when exceptions occur
before ack is returned. This method prevents doing it.
"""
try:
msg_id = message_data.pop(UNIQUE_ID)
except KeyError:
return
if msg_id in self.prev_msgids:
raise rpc_common.DuplicateMessageError(msg_id=msg_id)
return msg_id
def add(self, msg_id):
if msg_id and msg_id not in self.prev_msgids:
self.prev_msgids.append(msg_id)
def _add_unique_id(msg):
"""Add unique_id for checking duplicate messages."""
unique_id = uuid.uuid4().hex
msg.update({UNIQUE_ID: unique_id})
class AMQPDestinationNotFound(Exception):
pass
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