341 lines
12 KiB
Python
341 lines
12 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
|
|
|
|
# Copyright 2010 United States Government as represented by the
|
|
# Administrator of the National Aeronautics and Space Administration.
|
|
# All Rights Reserved.
|
|
#
|
|
# 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.
|
|
|
|
"""
|
|
AMQP-based RPC. Queues have consumers and publishers.
|
|
No fan-out support yet.
|
|
"""
|
|
|
|
import json
|
|
import logging
|
|
import sys
|
|
import uuid
|
|
|
|
from carrot import connection as carrot_connection
|
|
from carrot import messaging
|
|
from twisted.internet import defer
|
|
from twisted.internet import task
|
|
|
|
from nova import exception
|
|
from nova import fakerabbit
|
|
from nova import flags
|
|
|
|
|
|
FLAGS = flags.FLAGS
|
|
|
|
|
|
LOG = logging.getLogger('amqplib')
|
|
LOG.setLevel(logging.DEBUG)
|
|
|
|
|
|
class Connection(carrot_connection.BrokerConnection):
|
|
"""Connection instance object"""
|
|
@classmethod
|
|
def instance(cls):
|
|
"""Returns the instance"""
|
|
if not hasattr(cls, '_instance'):
|
|
params = dict(hostname=FLAGS.rabbit_host,
|
|
port=FLAGS.rabbit_port,
|
|
userid=FLAGS.rabbit_userid,
|
|
password=FLAGS.rabbit_password,
|
|
virtual_host=FLAGS.rabbit_virtual_host)
|
|
|
|
if FLAGS.fake_rabbit:
|
|
params['backend_cls'] = fakerabbit.Backend
|
|
|
|
# NOTE(vish): magic is fun!
|
|
# pylint: disable-msg=W0142
|
|
cls._instance = cls(**params)
|
|
return cls._instance
|
|
|
|
@classmethod
|
|
def recreate(cls):
|
|
"""Recreates the connection instance
|
|
|
|
This is necessary to recover from some network errors/disconnects"""
|
|
del cls._instance
|
|
return cls.instance()
|
|
|
|
|
|
class Consumer(messaging.Consumer):
|
|
"""Consumer base class
|
|
|
|
Contains methods for connecting the fetch method to async loops
|
|
"""
|
|
def __init__(self, *args, **kwargs):
|
|
self.failed_connection = False
|
|
super(Consumer, self).__init__(*args, **kwargs)
|
|
|
|
# TODO(termie): it would be nice to give these some way of automatically
|
|
# cleaning up after themselves
|
|
def attach_to_tornado(self, io_inst=None):
|
|
"""Attach a callback to tornado that fires 10 times a second"""
|
|
from tornado import ioloop
|
|
if io_inst is None:
|
|
io_inst = ioloop.IOLoop.instance()
|
|
|
|
injected = ioloop.PeriodicCallback(
|
|
lambda: self.fetch(enable_callbacks=True), 100, io_loop=io_inst)
|
|
injected.start()
|
|
return injected
|
|
|
|
attachToTornado = attach_to_tornado
|
|
|
|
def fetch(self, no_ack=None, auto_ack=None, enable_callbacks=False):
|
|
"""Wraps the parent fetch with some logic for failed connections"""
|
|
# TODO(vish): the logic for failed connections and logging should be
|
|
# refactored into some sort of connection manager object
|
|
try:
|
|
if self.failed_connection:
|
|
# NOTE(vish): conn is defined in the parent class, we can
|
|
# recreate it as long as we create the backend too
|
|
# pylint: disable-msg=W0201
|
|
self.conn = Connection.recreate()
|
|
self.backend = self.conn.create_backend()
|
|
super(Consumer, self).fetch(no_ack, auto_ack, enable_callbacks)
|
|
if self.failed_connection:
|
|
logging.error("Reconnected to queue")
|
|
self.failed_connection = False
|
|
# NOTE(vish): This is catching all errors because we really don't
|
|
# exceptions to be logged 10 times a second if some
|
|
# persistent failure occurs.
|
|
except Exception: # pylint: disable-msg=W0703
|
|
if not self.failed_connection:
|
|
logging.exception("Failed to fetch message from queue")
|
|
self.failed_connection = True
|
|
|
|
def attach_to_twisted(self):
|
|
"""Attach a callback to twisted that fires 10 times a second"""
|
|
loop = task.LoopingCall(self.fetch, enable_callbacks=True)
|
|
loop.start(interval=0.1)
|
|
|
|
|
|
class Publisher(messaging.Publisher):
|
|
"""Publisher base class"""
|
|
pass
|
|
|
|
|
|
class TopicConsumer(Consumer):
|
|
"""Consumes messages on a specific topic"""
|
|
exchange_type = "topic"
|
|
|
|
def __init__(self, connection=None, topic="broadcast"):
|
|
self.queue = topic
|
|
self.routing_key = topic
|
|
self.exchange = FLAGS.control_exchange
|
|
self.durable = False
|
|
super(TopicConsumer, self).__init__(connection=connection)
|
|
|
|
|
|
class AdapterConsumer(TopicConsumer):
|
|
"""Calls methods on a proxy object based on method and args"""
|
|
def __init__(self, connection=None, topic="broadcast", proxy=None):
|
|
LOG.debug('Initing the Adapter Consumer for %s' % (topic))
|
|
self.proxy = proxy
|
|
super(AdapterConsumer, self).__init__(connection=connection,
|
|
topic=topic)
|
|
|
|
@exception.wrap_exception
|
|
def receive(self, message_data, message):
|
|
"""Magically looks for a method on the proxy object and calls it
|
|
|
|
Message data should be a dictionary with two keys:
|
|
method: string representing the method to call
|
|
args: dictionary of arg: value
|
|
|
|
Example: {'method': 'echo', 'args': {'value': 42}}
|
|
"""
|
|
LOG.debug('received %s' % (message_data))
|
|
msg_id = message_data.pop('_msg_id', None)
|
|
|
|
method = message_data.get('method')
|
|
args = message_data.get('args', {})
|
|
message.ack()
|
|
if not method:
|
|
# NOTE(vish): we may not want to ack here, but that means that bad
|
|
# messages stay in the queue indefinitely, so for now
|
|
# we just log the message and send an error string
|
|
# back to the caller
|
|
LOG.warn('no method for message: %s' % (message_data))
|
|
msg_reply(msg_id, 'No method for message: %s' % message_data)
|
|
return
|
|
|
|
node_func = getattr(self.proxy, str(method))
|
|
node_args = dict((str(k), v) for k, v in args.iteritems())
|
|
# NOTE(vish): magic is fun!
|
|
# pylint: disable-msg=W0142
|
|
d = defer.maybeDeferred(node_func, **node_args)
|
|
if msg_id:
|
|
d.addCallback(lambda rval: msg_reply(msg_id, rval, None))
|
|
d.addErrback(lambda e: msg_reply(msg_id, None, e))
|
|
return
|
|
|
|
|
|
class TopicPublisher(Publisher):
|
|
"""Publishes messages on a specific topic"""
|
|
exchange_type = "topic"
|
|
|
|
def __init__(self, connection=None, topic="broadcast"):
|
|
self.routing_key = topic
|
|
self.exchange = FLAGS.control_exchange
|
|
self.durable = False
|
|
super(TopicPublisher, self).__init__(connection=connection)
|
|
|
|
|
|
class DirectConsumer(Consumer):
|
|
"""Consumes messages directly on a channel specified by msg_id"""
|
|
exchange_type = "direct"
|
|
|
|
def __init__(self, connection=None, msg_id=None):
|
|
self.queue = msg_id
|
|
self.routing_key = msg_id
|
|
self.exchange = msg_id
|
|
self.auto_delete = True
|
|
super(DirectConsumer, self).__init__(connection=connection)
|
|
|
|
|
|
class DirectPublisher(Publisher):
|
|
"""Publishes messages directly on a channel specified by msg_id"""
|
|
exchange_type = "direct"
|
|
|
|
def __init__(self, connection=None, msg_id=None):
|
|
self.routing_key = msg_id
|
|
self.exchange = msg_id
|
|
self.auto_delete = True
|
|
super(DirectPublisher, self).__init__(connection=connection)
|
|
|
|
|
|
def msg_reply(msg_id, reply=None, failure=None):
|
|
"""Sends a reply or an error on the channel signified by msg_id
|
|
|
|
failure should be a twisted failure object"""
|
|
if failure:
|
|
message = failure.getErrorMessage()
|
|
traceback = failure.getTraceback()
|
|
logging.error("Returning exception %s to caller", message)
|
|
logging.error(traceback)
|
|
failure = (failure.type.__name__, str(failure.value), traceback)
|
|
conn = Connection.instance()
|
|
publisher = DirectPublisher(connection=conn, msg_id=msg_id)
|
|
try:
|
|
publisher.send({'result': reply, 'failure': failure})
|
|
except TypeError:
|
|
publisher.send(
|
|
{'result': dict((k, repr(v))
|
|
for k, v in reply.__dict__.iteritems()),
|
|
'failure': failure})
|
|
publisher.close()
|
|
|
|
|
|
class RemoteError(exception.Error):
|
|
"""Signifies that a remote class has raised an exception
|
|
|
|
Containes a string representation of the type of the original exception,
|
|
the value of the original exception, and the traceback. These are
|
|
sent to the parent as a joined string so printing the exception
|
|
contains all of the relevent info."""
|
|
def __init__(self, exc_type, value, traceback):
|
|
self.exc_type = exc_type
|
|
self.value = value
|
|
self.traceback = traceback
|
|
super(RemoteError, self).__init__("%s %s\n%s" % (exc_type,
|
|
value,
|
|
traceback))
|
|
|
|
|
|
def call(topic, msg):
|
|
"""Sends a message on a topic and wait for a response"""
|
|
LOG.debug("Making asynchronous call...")
|
|
msg_id = uuid.uuid4().hex
|
|
msg.update({'_msg_id': msg_id})
|
|
LOG.debug("MSG_ID is %s" % (msg_id))
|
|
|
|
conn = Connection.instance()
|
|
d = defer.Deferred()
|
|
consumer = DirectConsumer(connection=conn, msg_id=msg_id)
|
|
|
|
def deferred_receive(data, message):
|
|
"""Acks message and callbacks or errbacks"""
|
|
message.ack()
|
|
if data['failure']:
|
|
return d.errback(RemoteError(*data['failure']))
|
|
else:
|
|
return d.callback(data['result'])
|
|
|
|
consumer.register_callback(deferred_receive)
|
|
injected = consumer.attach_to_tornado()
|
|
|
|
# clean up after the injected listened and return x
|
|
d.addCallback(lambda x: injected.stop() and x or x)
|
|
|
|
publisher = TopicPublisher(connection=conn, topic=topic)
|
|
publisher.send(msg)
|
|
publisher.close()
|
|
return d
|
|
|
|
|
|
def cast(topic, msg):
|
|
"""Sends a message on a topic without waiting for a response"""
|
|
LOG.debug("Making asynchronous cast...")
|
|
conn = Connection.instance()
|
|
publisher = TopicPublisher(connection=conn, topic=topic)
|
|
publisher.send(msg)
|
|
publisher.close()
|
|
|
|
|
|
def generic_response(message_data, message):
|
|
"""Logs a result and exits"""
|
|
LOG.debug('response %s', message_data)
|
|
message.ack()
|
|
sys.exit(0)
|
|
|
|
|
|
def send_message(topic, message, wait=True):
|
|
"""Sends a message for testing"""
|
|
msg_id = uuid.uuid4().hex
|
|
message.update({'_msg_id': msg_id})
|
|
LOG.debug('topic is %s', topic)
|
|
LOG.debug('message %s', message)
|
|
|
|
if wait:
|
|
consumer = messaging.Consumer(connection=Connection.instance(),
|
|
queue=msg_id,
|
|
exchange=msg_id,
|
|
auto_delete=True,
|
|
exchange_type="direct",
|
|
routing_key=msg_id)
|
|
consumer.register_callback(generic_response)
|
|
|
|
publisher = messaging.Publisher(connection=Connection.instance(),
|
|
exchange=FLAGS.control_exchange,
|
|
durable=False,
|
|
exchange_type="topic",
|
|
routing_key=topic)
|
|
publisher.send(message)
|
|
publisher.close()
|
|
|
|
if wait:
|
|
consumer.wait()
|
|
|
|
|
|
if __name__ == "__main__":
|
|
# NOTE(vish): you can send messages from the command line using
|
|
# topic and a json sting representing a dictionary
|
|
# for the method
|
|
send_message(sys.argv[1], json.loads(sys.argv[2]))
|