Mehdi Abaakouk e785a5d994 Make the dispatcher responsible of the message ack
This patch make the dispatcher responsible of the message
acknowledgement.

This is the preliminar step to be able to requeue message.

Partial implements blueprint notification-subscriber-server

Change-Id: If74b47d5e23976d407deb27df7395b1982963c75
2014-02-18 08:31:30 +01:00

424 lines
15 KiB
Python

# 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.
__all__ = ['AMQPDriverBase']
import logging
import threading
import uuid
from six import moves
from oslo import messaging
from oslo.messaging._drivers import amqp as rpc_amqp
from oslo.messaging._drivers import base
from oslo.messaging._drivers import common as rpc_common
LOG = logging.getLogger(__name__)
class AMQPIncomingMessage(base.IncomingMessage):
def __init__(self, listener, ctxt, message, msg_id, reply_q):
super(AMQPIncomingMessage, self).__init__(listener, ctxt,
dict(message))
self.msg_id = msg_id
self.reply_q = reply_q
self.acknowledge = message.acknowledge
def _send_reply(self, conn, reply=None, failure=None,
ending=False, log_failure=True):
if failure:
failure = rpc_common.serialize_remote_exception(failure,
log_failure)
msg = {'result': reply, 'failure': failure}
if ending:
msg['ending'] = True
rpc_amqp._add_unique_id(msg)
# If a reply_q exists, add the msg_id to the reply and pass the
# reply_q to direct_send() to use it as the response queue.
# Otherwise use the msg_id for backward compatibility.
if self.reply_q:
msg['_msg_id'] = self.msg_id
conn.direct_send(self.reply_q, rpc_common.serialize_msg(msg))
else:
conn.direct_send(self.msg_id, rpc_common.serialize_msg(msg))
def reply(self, reply=None, failure=None, log_failure=True):
with self.listener.driver._get_connection() as conn:
self._send_reply(conn, reply, failure, log_failure=log_failure)
self._send_reply(conn, ending=True)
class AMQPListener(base.Listener):
def __init__(self, driver, conn):
super(AMQPListener, self).__init__(driver)
self.conn = conn
self.msg_id_cache = rpc_amqp._MsgIdCache()
self.incoming = []
def __call__(self, message):
# FIXME(markmc): logging isn't driver specific
rpc_common._safe_log(LOG.debug, 'received %s', dict(message))
self.msg_id_cache.check_duplicate_message(message)
ctxt = rpc_amqp.unpack_context(self.conf, message)
self.incoming.append(AMQPIncomingMessage(self,
ctxt.to_dict(),
message,
ctxt.msg_id,
ctxt.reply_q))
def poll(self):
while True:
if self.incoming:
return self.incoming.pop(0)
self.conn.consume(limit=1)
class ReplyWaiters(object):
WAKE_UP = object()
def __init__(self):
self._queues = {}
self._wrn_threshold = 10
def get(self, msg_id, timeout):
try:
return self._queues[msg_id].get(block=True, timeout=timeout)
except moves.queue.Empty:
raise messaging.MessagingTimeout('Timed out waiting for a reply '
'to message ID %s' % msg_id)
def check(self, msg_id):
try:
return self._queues[msg_id].get(block=False)
except moves.queue.Empty:
return None
def put(self, msg_id, message_data):
queue = self._queues.get(msg_id)
if not queue:
LOG.warn('No calling threads waiting for msg_id : %(msg_id)s'
', message : %(data)s', {'msg_id': msg_id,
'data': message_data})
LOG.warn('_queues: %s' % str(self._queues))
else:
queue.put(message_data)
def wake_all(self, except_id):
msg_ids = [i for i in self._queues.keys() if i != except_id]
for msg_id in msg_ids:
self.put(msg_id, self.WAKE_UP)
def add(self, msg_id, queue):
self._queues[msg_id] = queue
if len(self._queues) > self._wrn_threshold:
LOG.warn('Number of call queues is greater than warning '
'threshold: %d. There could be a leak.' %
self._wrn_threshold)
self._wrn_threshold *= 2
def remove(self, msg_id):
del self._queues[msg_id]
class ReplyWaiter(object):
def __init__(self, conf, reply_q, conn, allowed_remote_exmods):
self.conf = conf
self.conn = conn
self.reply_q = reply_q
self.allowed_remote_exmods = allowed_remote_exmods
self.conn_lock = threading.Lock()
self.incoming = []
self.msg_id_cache = rpc_amqp._MsgIdCache()
self.waiters = ReplyWaiters()
conn.declare_direct_consumer(reply_q, self)
def __call__(self, message):
message.acknowledge()
self.incoming.append(message)
def listen(self, msg_id):
queue = moves.queue.Queue()
self.waiters.add(msg_id, queue)
def unlisten(self, msg_id):
self.waiters.remove(msg_id)
def _process_reply(self, data):
result = None
ending = False
self.msg_id_cache.check_duplicate_message(data)
if data['failure']:
failure = data['failure']
result = rpc_common.deserialize_remote_exception(
failure, self.allowed_remote_exmods)
elif data.get('ending', False):
ending = True
else:
result = data['result']
return result, ending
def _poll_connection(self, msg_id, timeout):
while True:
while self.incoming:
message_data = self.incoming.pop(0)
incoming_msg_id = message_data.pop('_msg_id', None)
if incoming_msg_id == msg_id:
return self._process_reply(message_data)
self.waiters.put(incoming_msg_id, message_data)
try:
self.conn.consume(limit=1, timeout=timeout)
except rpc_common.Timeout:
raise messaging.MessagingTimeout('Timed out waiting for a '
'reply to message ID %s'
% msg_id)
def _poll_queue(self, msg_id, timeout):
message = self.waiters.get(msg_id, timeout)
if message is self.waiters.WAKE_UP:
return None, None, True # lock was released
reply, ending = self._process_reply(message)
return reply, ending, False
def _check_queue(self, msg_id):
while True:
message = self.waiters.check(msg_id)
if message is self.waiters.WAKE_UP:
continue
if message is None:
return None, None, True # queue is empty
reply, ending = self._process_reply(message)
return reply, ending, False
def wait(self, msg_id, timeout):
#
# NOTE(markmc): we're waiting for a reply for msg_id to come in for on
# the reply_q, but there may be other threads also waiting for replies
# to other msg_ids
#
# Only one thread can be consuming from the queue using this connection
# and we don't want to hold open a connection per thread, so instead we
# have the first thread take responsibility for passing replies not
# intended for itself to the appropriate thread.
#
final_reply = None
while True:
if self.conn_lock.acquire(False):
# Ok, we're the thread responsible for polling the connection
try:
# Check the queue to see if a previous lock-holding thread
# queued up a reply already
while True:
reply, ending, empty = self._check_queue(msg_id)
if empty:
break
if not ending:
final_reply = reply
else:
return final_reply
# Now actually poll the connection
while True:
reply, ending = self._poll_connection(msg_id, timeout)
if not ending:
final_reply = reply
else:
return final_reply
finally:
self.conn_lock.release()
# We've got our reply, tell the other threads to wake up
# so that one of them will take over the responsibility for
# polling the connection
self.waiters.wake_all(msg_id)
else:
# We're going to wait for the first thread to pass us our reply
reply, ending, trylock = self._poll_queue(msg_id, timeout)
if trylock:
# The first thread got its reply, let's try and take over
# the responsibility for polling
continue
if not ending:
final_reply = reply
else:
return final_reply
class AMQPDriverBase(base.BaseDriver):
def __init__(self, conf, url, connection_pool,
default_exchange=None, allowed_remote_exmods=[]):
super(AMQPDriverBase, self).__init__(conf, url, default_exchange,
allowed_remote_exmods)
self._server_params = self._server_params_from_url(self._url)
self._default_exchange = default_exchange
# FIXME(markmc): temp hack
if self._default_exchange:
self.conf.set_override('control_exchange', self._default_exchange)
self._connection_pool = connection_pool
self._reply_q_lock = threading.Lock()
self._reply_q = None
self._reply_q_conn = None
self._waiter = None
def _server_params_from_url(self, url):
sp = {}
if url.virtual_host is not None:
sp['virtual_host'] = url.virtual_host
if url.hosts:
# FIXME(markmc): support multiple hosts
host = url.hosts[0]
sp['hostname'] = host.hostname
if host.port is not None:
sp['port'] = host.port
sp['username'] = host.username or ''
sp['password'] = host.password or ''
return sp
def _get_connection(self, pooled=True):
# FIXME(markmc): we don't yet have a connection pool for each
# Transport instance, so we'll only use the pool with the
# transport configuration from the config file
server_params = self._server_params or None
if server_params:
pooled = False
return rpc_amqp.ConnectionContext(self.conf,
self._connection_pool,
pooled=pooled,
server_params=server_params)
def _get_reply_q(self):
with self._reply_q_lock:
if self._reply_q is not None:
return self._reply_q
reply_q = 'reply_' + uuid.uuid4().hex
conn = self._get_connection(pooled=False)
self._waiter = ReplyWaiter(self.conf, reply_q, conn,
self._allowed_remote_exmods)
self._reply_q = reply_q
self._reply_q_conn = conn
return self._reply_q
def _send(self, target, ctxt, message,
wait_for_reply=None, timeout=None, envelope=True):
# FIXME(markmc): remove this temporary hack
class Context(object):
def __init__(self, d):
self.d = d
def to_dict(self):
return self.d
context = Context(ctxt)
msg = message
if wait_for_reply:
msg_id = uuid.uuid4().hex
msg.update({'_msg_id': msg_id})
LOG.debug('MSG_ID is %s' % (msg_id))
msg.update({'_reply_q': self._get_reply_q()})
rpc_amqp._add_unique_id(msg)
rpc_amqp.pack_context(msg, context)
if envelope:
msg = rpc_common.serialize_msg(msg)
if wait_for_reply:
self._waiter.listen(msg_id)
try:
with self._get_connection() as conn:
if target.fanout:
conn.fanout_send(target.topic, msg)
else:
topic = target.topic
if target.server:
topic = '%s.%s' % (target.topic, target.server)
conn.topic_send(topic, msg, timeout=timeout)
if wait_for_reply:
result = self._waiter.wait(msg_id, timeout)
if isinstance(result, Exception):
raise result
return result
finally:
if wait_for_reply:
self._waiter.unlisten(msg_id)
def send(self, target, ctxt, message, wait_for_reply=None, timeout=None):
return self._send(target, ctxt, message, wait_for_reply, timeout)
def send_notification(self, target, ctxt, message, version):
return self._send(target, ctxt, message, envelope=(version == 2.0))
def listen(self, target):
conn = self._get_connection(pooled=False)
listener = AMQPListener(self, conn)
conn.declare_topic_consumer(target.topic, listener)
conn.declare_topic_consumer('%s.%s' % (target.topic, target.server),
listener)
conn.declare_fanout_consumer(target.topic, listener)
return listener
def listen_for_notifications(self, targets_and_priorities):
conn = self._get_connection(pooled=False)
listener = AMQPListener(self, conn)
for target, priority in targets_and_priorities:
conn.declare_topic_consumer('%s.%s' % (target.topic, priority),
callback=listener,
exchange_name=target.exchange)
return listener
def cleanup(self):
if self._connection_pool:
self._connection_pool.empty()
self._connection_pool = None