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Diffstat (limited to 'openstack/common/rpc/amqp.py')
| -rw-r--r-- | openstack/common/rpc/amqp.py | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/openstack/common/rpc/amqp.py b/openstack/common/rpc/amqp.py new file mode 100644 index 0000000..a79a3aa --- /dev/null +++ b/openstack/common/rpc/amqp.py @@ -0,0 +1,416 @@ +# 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. +# 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. + +""" +Shared code between AMQP based nova.rpc implementations. + +The code in this module is shared between the rpc implemenations based on AMQP. +Specifically, this includes impl_kombu and impl_qpid. impl_carrot also uses +AMQP, but is deprecated and predates this code. +""" + +import inspect +import logging +import sys +import uuid + +from eventlet import greenpool +from eventlet import pools +from eventlet import semaphore + +from openstack.common import excutils +from openstack.common import local +import openstack.common.rpc.common as rpc_common + + +LOG = logging.getLogger(__name__) + + +class Pool(pools.Pool): + """Class that implements a Pool of Connections.""" + def __init__(self, conf, connection_cls, *args, **kwargs): + self.connection_cls = connection_cls + self.conf = conf + kwargs.setdefault("max_size", self.conf.rpc_conn_pool_size) + kwargs.setdefault("order_as_stack", True) + super(Pool, self).__init__(*args, **kwargs) + + # TODO(comstud): Timeout connections not used in a while + def create(self): + LOG.debug('Pool creating new connection') + return self.connection_cls(self.conf) + + def empty(self): + while self.free_items: + self.get().close() + + +_pool_create_sem = semaphore.Semaphore() + + +def get_connection_pool(conf, connection_cls): + with _pool_create_sem: + # Make sure only one thread tries to create the connection pool. + if not connection_cls.pool: + connection_cls.pool = Pool(conf, connection_cls) + return connection_cls.pool + + +class ConnectionContext(rpc_common.Connection): + """The class that is actually returned to the caller of + create_connection(). 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, conf, connection_pool, pooled=True, server_params=None): + """Create a new connection, or get one from the pool""" + self.connection = None + self.conf = conf + self.connection_pool = connection_pool + if pooled: + self.connection = connection_pool.get() + else: + self.connection = connection_pool.connection_cls(conf, + server_params=server_params) + 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 + self.connection.reset() + self.connection_pool.put(self.connection) + else: + try: + self.connection.close() + except Exception: + pass + self.connection = None + + def __exit__(self, exc_type, exc_value, tb): + """End of 'with' statement. We're done here.""" + self._done() + + def __del__(self): + """Caller is done with this connection. Make sure we cleaned up.""" + self._done() + + def close(self): + """Caller is done with this connection.""" + self._done() + + def create_consumer(self, topic, proxy, fanout=False): + self.connection.create_consumer(topic, proxy, fanout) + + def create_worker(self, topic, proxy, pool_name): + self.connection.create_worker(topic, proxy, pool_name) + + def consume_in_thread(self): + self.connection.consume_in_thread() + + def __getattr__(self, key): + """Proxy all other calls to the Connection instance""" + if self.connection: + return getattr(self.connection, key) + else: + raise rpc_common.InvalidRPCConnectionReuse() + + +def msg_reply(conf, msg_id, connection_pool, reply=None, failure=None, + ending=False): + """Sends a reply or an error on the channel signified by msg_id. + + Failure should be a sys.exc_info() tuple. + + """ + with ConnectionContext(conf, connection_pool) as conn: + if failure: + failure = rpc_common.serialize_remote_exception(failure) + + try: + msg = {'result': reply, 'failure': failure} + except TypeError: + msg = {'result': dict((k, repr(v)) + for k, v in reply.__dict__.iteritems()), + 'failure': failure} + if ending: + msg['ending'] = True + conn.direct_send(msg_id, msg) + + +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.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 + return self.__class__(**values) + + def reply(self, reply=None, failure=None, ending=False, + connection_pool=None): + if self.msg_id: + msg_reply(self.conf, self.msg_id, connection_pool, reply, failure, + ending) + if ending: + self.msg_id = None + + +def unpack_context(conf, msg): + """Unpack context from msg.""" + context_dict = {} + for key in list(msg.keys()): + # NOTE(vish): Some versions of python don't like unicode keys + # in kwargs. + 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['conf'] = conf + ctx = RpcContext.from_dict(context_dict) + rpc_common._safe_log(LOG.debug, _('unpacked context: %s'), ctx.to_dict()) + 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. + + """ + context_d = dict([('_context_%s' % key, value) + for (key, value) in context.to_dict().iteritems()]) + msg.update(context_d) + + +class ProxyCallback(object): + """Calls methods on a proxy object based on method and args.""" + + def __init__(self, conf, proxy, connection_pool): + self.proxy = proxy + self.pool = greenpool.GreenPool(conf.rpc_thread_pool_size) + self.connection_pool = connection_pool + self.conf = conf + + def __call__(self, message_data): + """Consumer callback to call a method on a proxy object. + + Parses the message for validity and fires off a thread to call the + proxy object method. + + 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}} + + """ + # It is important to clear the context here, because at this point + # the previous context is stored in local.store.context + if hasattr(local.store, 'context'): + del local.store.context + rpc_common._safe_log(LOG.debug, _('received %s'), message_data) + ctxt = unpack_context(self.conf, message_data) + method = message_data.get('method') + args = message_data.get('args', {}) + version = message_data.get('version', None) + if not method: + LOG.warn(_('no method for message: %s') % message_data) + ctxt.reply(_('No method for message: %s') % message_data, + connection_pool=self.connection_pool) + return + self.pool.spawn_n(self._process_data, ctxt, version, method, args) + + def _process_data(self, ctxt, version, method, args): + """Process a message in a new thread. + + If the proxy object we have has a dispatch method + (see rpc.dispatcher.RpcDispatcher), pass it the version, + method, and args and let it dispatch as appropriate. If not, use + the old behavior of magically calling the specified method on the + proxy we have here. + """ + ctxt.update_store() + try: + rval = self.proxy.dispatch(ctxt, version, method, **args) + # Check if the result was a generator + if inspect.isgenerator(rval): + for x in rval: + ctxt.reply(x, None, connection_pool=self.connection_pool) + else: + ctxt.reply(rval, None, connection_pool=self.connection_pool) + # This final None tells multicall that it is done. + ctxt.reply(ending=True, connection_pool=self.connection_pool) + except Exception as e: + LOG.exception('Exception during message handling') + ctxt.reply(None, sys.exc_info(), + connection_pool=self.connection_pool) + + +class MulticallWaiter(object): + def __init__(self, conf, connection, timeout): + self._connection = connection + self._iterator = connection.iterconsume( + timeout=timeout or conf.rpc_response_timeout) + self._result = None + self._done = False + self._got_ending = False + self._conf = conf + + def done(self): + if self._done: + return + self._done = True + self._iterator.close() + self._iterator = None + self._connection.close() + + def __call__(self, data): + """The consume() callback will call this. Store the result.""" + if data['failure']: + failure = data['failure'] + self._result = rpc_common.deserialize_remote_exception(self._conf, + failure) + + elif data.get('ending', False): + self._got_ending = True + else: + self._result = data['result'] + + def __iter__(self): + """Return a result until we get a 'None' response from consumer""" + if self._done: + raise StopIteration + while True: + try: + self._iterator.next() + except Exception: + with excutils.save_and_reraise_exception(): + self.done() + if self._got_ending: + self.done() + raise StopIteration + result = self._result + if isinstance(result, Exception): + self.done() + raise result + yield result + + +def create_connection(conf, new, connection_pool): + """Create a connection""" + return ConnectionContext(conf, connection_pool, pooled=not new) + + +def multicall(conf, context, topic, msg, timeout, connection_pool): + """Make a call that returns multiple times.""" + # Can't use 'with' for multicall, as it returns an iterator + # that will continue to use the connection. When it's done, + # connection.close() will get called which will put it back into + # the pool + LOG.debug(_('Making asynchronous call on %s ...'), topic) + msg_id = uuid.uuid4().hex + msg.update({'_msg_id': msg_id}) + LOG.debug(_('MSG_ID is %s') % (msg_id)) + pack_context(msg, context) + + conn = ConnectionContext(conf, connection_pool) + wait_msg = MulticallWaiter(conf, conn, timeout) + conn.declare_direct_consumer(msg_id, wait_msg) + conn.topic_send(topic, msg) + return wait_msg + + +def call(conf, context, topic, msg, timeout, connection_pool): + """Sends a message on a topic and wait for a response.""" + rv = multicall(conf, context, topic, msg, timeout, connection_pool) + # NOTE(vish): return the last result from the multicall + rv = list(rv) + if not rv: + return + return rv[-1] + + +def cast(conf, context, topic, msg, connection_pool): + """Sends a message on a topic without waiting for a response.""" + LOG.debug(_('Making asynchronous cast on %s...'), topic) + pack_context(msg, context) + with ConnectionContext(conf, connection_pool) as conn: + conn.topic_send(topic, msg) + + +def fanout_cast(conf, context, topic, msg, connection_pool): + """Sends a message on a fanout exchange without waiting for a response.""" + LOG.debug(_('Making asynchronous fanout cast...')) + pack_context(msg, context) + with ConnectionContext(conf, connection_pool) as conn: + conn.fanout_send(topic, msg) + + +def cast_to_server(conf, context, server_params, topic, msg, connection_pool): + """Sends a message on a topic to a specific server.""" + pack_context(msg, context) + with ConnectionContext(conf, connection_pool, pooled=False, + server_params=server_params) as conn: + conn.topic_send(topic, msg) + + +def fanout_cast_to_server(conf, context, server_params, topic, msg, + connection_pool): + """Sends a message on a fanout exchange to a specific server.""" + pack_context(msg, context) + with ConnectionContext(conf, connection_pool, pooled=False, + server_params=server_params) as conn: + conn.fanout_send(topic, msg) + + +def notify(conf, context, topic, msg, connection_pool): + """Sends a notification event on a topic.""" + event_type = msg.get('event_type') + LOG.debug(_('Sending %(event_type)s on %(topic)s'), locals()) + pack_context(msg, context) + with ConnectionContext(conf, connection_pool) as conn: + conn.notify_send(topic, msg) + + +def cleanup(connection_pool): + if connection_pool: + connection_pool.empty() |