1af927e7fb
Part of blueprint versioned-rpc-apis. This commit includes the base support for versioned RPC APIs. It introduces the RpcProxy and RpcDispatcher classes that have common code for handling versioning on the client and server sides, respectively. RPC APIs will be converted one at a time using this infrastructure. Change-Id: I07bd82e9ff60c356123950e466caaffdfce79eba
408 lines
14 KiB
Python
408 lines
14 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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# Copyright 2011 - 2012, Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Shared code between AMQP based nova.rpc implementations.
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The code in this module is shared between the rpc implemenations based on AMQP.
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Specifically, this includes impl_kombu and impl_qpid. impl_carrot also uses
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AMQP, but is deprecated and predates this code.
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"""
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import inspect
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import sys
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import uuid
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from eventlet import greenpool
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from eventlet import pools
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from eventlet import semaphore
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from nova import context
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from nova import log as logging
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from nova.openstack.common import excutils
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from nova.openstack.common import local
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import nova.rpc.common as rpc_common
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LOG = logging.getLogger(__name__)
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class Pool(pools.Pool):
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"""Class that implements a Pool of Connections."""
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def __init__(self, conf, connection_cls, *args, **kwargs):
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self.connection_cls = connection_cls
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self.conf = conf
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kwargs.setdefault("max_size", self.conf.rpc_conn_pool_size)
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kwargs.setdefault("order_as_stack", True)
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super(Pool, self).__init__(*args, **kwargs)
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# TODO(comstud): Timeout connections not used in a while
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def create(self):
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LOG.debug('Pool creating new connection')
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return self.connection_cls(self.conf)
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def empty(self):
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while self.free_items:
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self.get().close()
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_pool_create_sem = semaphore.Semaphore()
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def get_connection_pool(conf, connection_cls):
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with _pool_create_sem:
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# Make sure only one thread tries to create the connection pool.
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if not connection_cls.pool:
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connection_cls.pool = Pool(conf, connection_cls)
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return connection_cls.pool
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class ConnectionContext(rpc_common.Connection):
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"""The class that is actually returned to the caller of
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create_connection(). This is a essentially a wrapper around
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Connection that supports 'with' and can return a new Connection or
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one from a pool. It will also catch when an instance of this class
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is to be deleted so that we can return Connections to the pool on
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exceptions and so forth without making the caller be responsible for
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catching all exceptions and making sure to return a connection to
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the pool.
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"""
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def __init__(self, conf, connection_pool, pooled=True, server_params=None):
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"""Create a new connection, or get one from the pool"""
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self.connection = None
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self.conf = conf
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self.connection_pool = connection_pool
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if pooled:
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self.connection = connection_pool.get()
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else:
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self.connection = connection_pool.connection_cls(conf,
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server_params=server_params)
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self.pooled = pooled
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def __enter__(self):
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"""When with ConnectionContext() is used, return self"""
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return self
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def _done(self):
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"""If the connection came from a pool, clean it up and put it back.
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If it did not come from a pool, close it.
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"""
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if self.connection:
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if self.pooled:
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# Reset the connection so it's ready for the next caller
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# to grab from the pool
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self.connection.reset()
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self.connection_pool.put(self.connection)
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else:
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try:
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self.connection.close()
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except Exception:
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pass
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self.connection = None
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def __exit__(self, exc_type, exc_value, tb):
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"""End of 'with' statement. We're done here."""
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self._done()
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def __del__(self):
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"""Caller is done with this connection. Make sure we cleaned up."""
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self._done()
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def close(self):
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"""Caller is done with this connection."""
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self._done()
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def create_consumer(self, topic, proxy, fanout=False):
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self.connection.create_consumer(topic, proxy, fanout)
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def consume_in_thread(self):
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self.connection.consume_in_thread()
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def __getattr__(self, key):
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"""Proxy all other calls to the Connection instance"""
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if self.connection:
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return getattr(self.connection, key)
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else:
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raise rpc_common.InvalidRPCConnectionReuse()
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def msg_reply(conf, msg_id, connection_pool, reply=None, failure=None,
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ending=False):
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"""Sends a reply or an error on the channel signified by msg_id.
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Failure should be a sys.exc_info() tuple.
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"""
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with ConnectionContext(conf, connection_pool) as conn:
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if failure:
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failure = rpc_common.serialize_remote_exception(failure)
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try:
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msg = {'result': reply, 'failure': failure}
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except TypeError:
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msg = {'result': dict((k, repr(v))
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for k, v in reply.__dict__.iteritems()),
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'failure': failure}
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if ending:
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msg['ending'] = True
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conn.direct_send(msg_id, msg)
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class RpcContext(context.RequestContext):
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"""Context that supports replying to a rpc.call"""
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def __init__(self, *args, **kwargs):
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self.msg_id = kwargs.pop('msg_id', None)
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self.conf = kwargs.pop('conf')
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super(RpcContext, self).__init__(*args, **kwargs)
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def reply(self, reply=None, failure=None, ending=False,
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connection_pool=None):
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if self.msg_id:
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msg_reply(self.conf, self.msg_id, connection_pool, reply, failure,
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ending)
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if ending:
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self.msg_id = None
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def unpack_context(conf, msg):
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"""Unpack context from msg."""
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context_dict = {}
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for key in list(msg.keys()):
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# NOTE(vish): Some versions of python don't like unicode keys
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# in kwargs.
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key = str(key)
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if key.startswith('_context_'):
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value = msg.pop(key)
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context_dict[key[9:]] = value
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context_dict['msg_id'] = msg.pop('_msg_id', None)
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context_dict['conf'] = conf
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ctx = RpcContext.from_dict(context_dict)
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rpc_common._safe_log(LOG.debug, _('unpacked context: %s'), ctx.to_dict())
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return ctx
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def pack_context(msg, context):
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"""Pack context into msg.
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Values for message keys need to be less than 255 chars, so we pull
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context out into a bunch of separate keys. If we want to support
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more arguments in rabbit messages, we may want to do the same
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for args at some point.
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"""
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context_d = dict([('_context_%s' % key, value)
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for (key, value) in context.to_dict().iteritems()])
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msg.update(context_d)
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class ProxyCallback(object):
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"""Calls methods on a proxy object based on method and args."""
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def __init__(self, conf, proxy, connection_pool):
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self.proxy = proxy
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self.pool = greenpool.GreenPool(conf.rpc_thread_pool_size)
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self.connection_pool = connection_pool
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self.conf = conf
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def __call__(self, message_data):
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"""Consumer callback to call a method on a proxy object.
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Parses the message for validity and fires off a thread to call the
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proxy object method.
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Message data should be a dictionary with two keys:
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method: string representing the method to call
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args: dictionary of arg: value
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Example: {'method': 'echo', 'args': {'value': 42}}
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"""
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# It is important to clear the context here, because at this point
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# the previous context is stored in local.store.context
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if hasattr(local.store, 'context'):
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del local.store.context
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rpc_common._safe_log(LOG.debug, _('received %s'), message_data)
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ctxt = unpack_context(self.conf, message_data)
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method = message_data.get('method')
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args = message_data.get('args', {})
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version = message_data.get('version', None)
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if not method:
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LOG.warn(_('no method for message: %s') % message_data)
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ctxt.reply(_('No method for message: %s') % message_data,
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connection_pool=self.connection_pool)
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return
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self.pool.spawn_n(self._process_data, ctxt, version, method, args)
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def _process_data(self, ctxt, version, method, args):
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"""Process a message in a new thread.
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If the proxy object we have has a dispatch method
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(see rpc.dispatcher.RpcDispatcher), pass it the version,
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method, and args and let it dispatch as appropriate. If not, use
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the old behavior of magically calling the specified method on the
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proxy we have here.
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"""
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ctxt.update_store()
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try:
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rval = self.proxy.dispatch(ctxt, version, method, **args)
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# Check if the result was a generator
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if inspect.isgenerator(rval):
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for x in rval:
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ctxt.reply(x, None, connection_pool=self.connection_pool)
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else:
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ctxt.reply(rval, None, connection_pool=self.connection_pool)
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# This final None tells multicall that it is done.
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ctxt.reply(ending=True, connection_pool=self.connection_pool)
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except Exception as e:
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LOG.exception('Exception during message handling')
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ctxt.reply(None, sys.exc_info(),
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connection_pool=self.connection_pool)
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class MulticallWaiter(object):
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def __init__(self, conf, connection, timeout):
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self._connection = connection
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self._iterator = connection.iterconsume(
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timeout=timeout or conf.rpc_response_timeout)
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self._result = None
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self._done = False
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self._got_ending = False
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self._conf = conf
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def done(self):
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if self._done:
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return
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self._done = True
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self._iterator.close()
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self._iterator = None
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self._connection.close()
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def __call__(self, data):
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"""The consume() callback will call this. Store the result."""
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if data['failure']:
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failure = data['failure']
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self._result = rpc_common.deserialize_remote_exception(self._conf,
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failure)
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elif data.get('ending', False):
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self._got_ending = True
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else:
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self._result = data['result']
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def __iter__(self):
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"""Return a result until we get a 'None' response from consumer"""
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if self._done:
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raise StopIteration
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while True:
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try:
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self._iterator.next()
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except Exception:
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with excutils.save_and_reraise_exception():
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self.done()
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if self._got_ending:
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self.done()
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raise StopIteration
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result = self._result
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if isinstance(result, Exception):
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self.done()
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raise result
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yield result
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def create_connection(conf, new, connection_pool):
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"""Create a connection"""
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return ConnectionContext(conf, connection_pool, pooled=not new)
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def multicall(conf, context, topic, msg, timeout, connection_pool):
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"""Make a call that returns multiple times."""
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# Can't use 'with' for multicall, as it returns an iterator
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# that will continue to use the connection. When it's done,
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# connection.close() will get called which will put it back into
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# the pool
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LOG.debug(_('Making asynchronous call on %s ...'), topic)
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msg_id = uuid.uuid4().hex
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msg.update({'_msg_id': msg_id})
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LOG.debug(_('MSG_ID is %s') % (msg_id))
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pack_context(msg, context)
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conn = ConnectionContext(conf, connection_pool)
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wait_msg = MulticallWaiter(conf, conn, timeout)
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conn.declare_direct_consumer(msg_id, wait_msg)
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conn.topic_send(topic, msg)
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return wait_msg
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def call(conf, context, topic, msg, timeout, connection_pool):
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"""Sends a message on a topic and wait for a response."""
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rv = multicall(conf, context, topic, msg, timeout, connection_pool)
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# NOTE(vish): return the last result from the multicall
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rv = list(rv)
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if not rv:
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return
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return rv[-1]
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def cast(conf, context, topic, msg, connection_pool):
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"""Sends a message on a topic without waiting for a response."""
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LOG.debug(_('Making asynchronous cast on %s...'), topic)
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pack_context(msg, context)
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with ConnectionContext(conf, connection_pool) as conn:
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conn.topic_send(topic, msg)
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def fanout_cast(conf, context, topic, msg, connection_pool):
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"""Sends a message on a fanout exchange without waiting for a response."""
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LOG.debug(_('Making asynchronous fanout cast...'))
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pack_context(msg, context)
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with ConnectionContext(conf, connection_pool) as conn:
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conn.fanout_send(topic, msg)
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def cast_to_server(conf, context, server_params, topic, msg, connection_pool):
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"""Sends a message on a topic to a specific server."""
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pack_context(msg, context)
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with ConnectionContext(conf, connection_pool, pooled=False,
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server_params=server_params) as conn:
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conn.topic_send(topic, msg)
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def fanout_cast_to_server(conf, context, server_params, topic, msg,
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connection_pool):
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"""Sends a message on a fanout exchange to a specific server."""
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pack_context(msg, context)
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with ConnectionContext(conf, connection_pool, pooled=False,
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server_params=server_params) as conn:
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conn.fanout_send(topic, msg)
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def notify(conf, context, topic, msg, connection_pool):
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"""Sends a notification event on a topic."""
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event_type = msg.get('event_type')
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LOG.debug(_('Sending %(event_type)s on %(topic)s'), locals())
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pack_context(msg, context)
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with ConnectionContext(conf, connection_pool) as conn:
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conn.notify_send(topic, msg)
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def cleanup(connection_pool):
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if connection_pool:
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connection_pool.empty()
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