OpenStack library for messaging
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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
# 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.
Shared code between AMQP based openstack.common.rpc implementations.
The code in this module is shared between the rpc implementations based on
AMQP. Specifically, this includes impl_kombu and impl_qpid. impl_carrot also
uses AMQP, but is deprecated and predates this code.
import collections
import logging
import uuid
from oslo_config import cfg
from oslo_utils import strutils
import six
from oslo_messaging._drivers import common as rpc_common
from oslo_messaging._drivers import pool
amqp_opts = [
help='Use durable queues in AMQP.'),
help='Auto-delete queues in AMQP.'),
# FIXME(markmc): this was toplevel in openstack.common.rpc
help='Size of RPC connection pool.'),
UNIQUE_ID = '_unique_id'
LOG = logging.getLogger(__name__)
class ConnectionPool(pool.Pool):
"""Class that implements a Pool of Connections."""
def __init__(self, conf, url, connection_cls):
self.connection_cls = connection_cls
self.conf = conf
self.url = url
super(ConnectionPool, self).__init__(self.conf.rpc_conn_pool_size)
self.reply_proxy = None
# TODO(comstud): Timeout connections not used in a while
def create(self):
LOG.debug('Pool creating new connection')
return self.connection_cls(self.conf, self.url)
def empty(self):
for item in self.iter_free():
class ConnectionContext(rpc_common.Connection):
"""The class that is actually returned to the create_connection() caller.
This is essentially a wrapper around Connection that supports 'with'.
It can also return a new Connection, or one from a pool.
The function will also catch when an instance of this class is to be
deleted. With that we can return Connections to the pool on exceptions
and so forth without making the caller be responsible for catching them.
If possible the function makes sure to return a connection to the pool.
def __init__(self, connection_pool, pooled=True):
"""Create a new connection, or get one from the pool."""
self.connection = None
self.connection_pool = connection_pool
if pooled:
self.connection = connection_pool.get()
# a non-pooled connection is requested, so create a new connection
self.connection = connection_pool.create()
self.pooled = pooled
def __enter__(self):
"""When with ConnectionContext() is used, return self."""
return self
def _done(self):
"""If the connection came from a pool, clean it up and put it back.
If it did not come from a pool, close it.
if self.connection:
if self.pooled:
# Reset the connection so it's ready for the next caller
# to grab from the pool
except Exception:
self.connection = None
def __exit__(self, exc_type, exc_value, tb):
"""End of 'with' statement. We're done here."""
def __del__(self):
"""Caller is done with this connection. Make sure we cleaned up."""
def close(self):
"""Caller is done with this connection."""
def __getattr__(self, key):
"""Proxy all other calls to the Connection instance."""
if self.connection:
return getattr(self.connection, key)
raise rpc_common.InvalidRPCConnectionReuse()
class RpcContext(rpc_common.CommonRpcContext):
"""Context that supports replying to a"""
def __init__(self, **kwargs):
self.msg_id = kwargs.pop('msg_id', None)
self.reply_q = kwargs.pop('reply_q', None)
self.conf = kwargs.pop('conf')
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(conf, msg):
"""Unpack context from msg."""
context_dict = {}
for key in list(msg.keys()):
key = six.text_type(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['conf'] = conf
ctx = RpcContext.from_dict(context_dict)
LOG.debug(u'unpacked context: %s',
return ctx
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 = six.iteritems(context)
context_d = six.iteritems(context.to_dict())
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.
def __init__(self, **kwargs):
self.prev_msgids = collections.deque([],
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.
msg_id = message_data.pop(UNIQUE_ID)
except KeyError:
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:
def _add_unique_id(msg):
"""Add unique_id for checking duplicate messages."""
unique_id = uuid.uuid4().hex
msg.update({UNIQUE_ID: unique_id})
LOG.debug('UNIQUE_ID is %s.', unique_id)