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Diffstat (limited to 'keystone/openstack/common/rpc/__init__.py')
| -rw-r--r-- | keystone/openstack/common/rpc/__init__.py | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/keystone/openstack/common/rpc/__init__.py b/keystone/openstack/common/rpc/__init__.py new file mode 100644 index 00000000..248a7458 --- /dev/null +++ b/keystone/openstack/common/rpc/__init__.py @@ -0,0 +1,307 @@ +# 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 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. + +""" +A remote procedure call (rpc) abstraction. + +For some wrappers that add message versioning to rpc, see: + rpc.dispatcher + rpc.proxy +""" + +import inspect + +from oslo.config import cfg + +from keystone.openstack.common.gettextutils import _ # noqa +from keystone.openstack.common import importutils +from keystone.openstack.common import local +from keystone.openstack.common import log as logging + + +LOG = logging.getLogger(__name__) + + +rpc_opts = [ + cfg.StrOpt('rpc_backend', + default='%s.impl_kombu' % __package__, + help="The messaging module to use, defaults to kombu."), + cfg.IntOpt('rpc_thread_pool_size', + default=64, + help='Size of RPC thread pool'), + cfg.IntOpt('rpc_conn_pool_size', + default=30, + help='Size of RPC connection pool'), + cfg.IntOpt('rpc_response_timeout', + default=60, + help='Seconds to wait for a response from call or multicall'), + cfg.IntOpt('rpc_cast_timeout', + default=30, + help='Seconds to wait before a cast expires (TTL). ' + 'Only supported by impl_zmq.'), + cfg.ListOpt('allowed_rpc_exception_modules', + default=['keystone.openstack.common.exception', + 'nova.exception', + 'cinder.exception', + 'exceptions', + ], + help='Modules of exceptions that are permitted to be recreated' + 'upon receiving exception data from an rpc call.'), + cfg.BoolOpt('fake_rabbit', + default=False, + help='If passed, use a fake RabbitMQ provider'), + cfg.StrOpt('control_exchange', + default='openstack', + help='AMQP exchange to connect to if using RabbitMQ or Qpid'), +] + +CONF = cfg.CONF +CONF.register_opts(rpc_opts) + + +def set_defaults(control_exchange): + cfg.set_defaults(rpc_opts, + control_exchange=control_exchange) + + +def create_connection(new=True): + """Create a connection to the message bus used for rpc. + + For some example usage of creating a connection and some consumers on that + connection, see nova.service. + + :param new: Whether or not to create a new connection. A new connection + will be created by default. If new is False, the + implementation is free to return an existing connection from a + pool. + + :returns: An instance of openstack.common.rpc.common.Connection + """ + return _get_impl().create_connection(CONF, new=new) + + +def _check_for_lock(): + if not CONF.debug: + return None + + if ((hasattr(local.strong_store, 'locks_held') + and local.strong_store.locks_held)): + stack = ' :: '.join([frame[3] for frame in inspect.stack()]) + LOG.warn(_('A RPC is being made while holding a lock. The locks ' + 'currently held are %(locks)s. This is probably a bug. ' + 'Please report it. Include the following: [%(stack)s].'), + {'locks': local.strong_store.locks_held, + 'stack': stack}) + return True + + return False + + +def call(context, topic, msg, timeout=None, check_for_lock=False): + """Invoke a remote method that returns something. + + :param context: Information that identifies the user that has made this + request. + :param topic: The topic to send the rpc message to. This correlates to the + topic argument of + openstack.common.rpc.common.Connection.create_consumer() + and only applies when the consumer was created with + fanout=False. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + :param timeout: int, number of seconds to use for a response timeout. + If set, this overrides the rpc_response_timeout option. + :param check_for_lock: if True, a warning is emitted if a RPC call is made + with a lock held. + + :returns: A dict from the remote method. + + :raises: openstack.common.rpc.common.Timeout if a complete response + is not received before the timeout is reached. + """ + if check_for_lock: + _check_for_lock() + return _get_impl().call(CONF, context, topic, msg, timeout) + + +def cast(context, topic, msg): + """Invoke a remote method that does not return anything. + + :param context: Information that identifies the user that has made this + request. + :param topic: The topic to send the rpc message to. This correlates to the + topic argument of + openstack.common.rpc.common.Connection.create_consumer() + and only applies when the consumer was created with + fanout=False. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + + :returns: None + """ + return _get_impl().cast(CONF, context, topic, msg) + + +def fanout_cast(context, topic, msg): + """Broadcast a remote method invocation with no return. + + This method will get invoked on all consumers that were set up with this + topic name and fanout=True. + + :param context: Information that identifies the user that has made this + request. + :param topic: The topic to send the rpc message to. This correlates to the + topic argument of + openstack.common.rpc.common.Connection.create_consumer() + and only applies when the consumer was created with + fanout=True. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + + :returns: None + """ + return _get_impl().fanout_cast(CONF, context, topic, msg) + + +def multicall(context, topic, msg, timeout=None, check_for_lock=False): + """Invoke a remote method and get back an iterator. + + In this case, the remote method will be returning multiple values in + separate messages, so the return values can be processed as the come in via + an iterator. + + :param context: Information that identifies the user that has made this + request. + :param topic: The topic to send the rpc message to. This correlates to the + topic argument of + openstack.common.rpc.common.Connection.create_consumer() + and only applies when the consumer was created with + fanout=False. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + :param timeout: int, number of seconds to use for a response timeout. + If set, this overrides the rpc_response_timeout option. + :param check_for_lock: if True, a warning is emitted if a RPC call is made + with a lock held. + + :returns: An iterator. The iterator will yield a tuple (N, X) where N is + an index that starts at 0 and increases by one for each value + returned and X is the Nth value that was returned by the remote + method. + + :raises: openstack.common.rpc.common.Timeout if a complete response + is not received before the timeout is reached. + """ + if check_for_lock: + _check_for_lock() + return _get_impl().multicall(CONF, context, topic, msg, timeout) + + +def notify(context, topic, msg, envelope=False): + """Send notification event. + + :param context: Information that identifies the user that has made this + request. + :param topic: The topic to send the notification to. + :param msg: This is a dict of content of event. + :param envelope: Set to True to enable message envelope for notifications. + + :returns: None + """ + return _get_impl().notify(cfg.CONF, context, topic, msg, envelope) + + +def cleanup(): + """Clean up resoruces in use by implementation. + + Clean up any resources that have been allocated by the RPC implementation. + This is typically open connections to a messaging service. This function + would get called before an application using this API exits to allow + connections to get torn down cleanly. + + :returns: None + """ + return _get_impl().cleanup() + + +def cast_to_server(context, server_params, topic, msg): + """Invoke a remote method that does not return anything. + + :param context: Information that identifies the user that has made this + request. + :param server_params: Connection information + :param topic: The topic to send the notification to. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + + :returns: None + """ + return _get_impl().cast_to_server(CONF, context, server_params, topic, + msg) + + +def fanout_cast_to_server(context, server_params, topic, msg): + """Broadcast to a remote method invocation with no return. + + :param context: Information that identifies the user that has made this + request. + :param server_params: Connection information + :param topic: The topic to send the notification to. + :param msg: This is a dict in the form { "method" : "method_to_invoke", + "args" : dict_of_kwargs } + + :returns: None + """ + return _get_impl().fanout_cast_to_server(CONF, context, server_params, + topic, msg) + + +def queue_get_for(context, topic, host): + """Get a queue name for a given topic + host. + + This function only works if this naming convention is followed on the + consumer side, as well. For example, in nova, every instance of the + nova-foo service calls create_consumer() for two topics: + + foo + foo.<host> + + Messages sent to the 'foo' topic are distributed to exactly one instance of + the nova-foo service. The services are chosen in a round-robin fashion. + Messages sent to the 'foo.<host>' topic are sent to the nova-foo service on + <host>. + """ + return '%s.%s' % (topic, host) if host else topic + + +_RPCIMPL = None + + +def _get_impl(): + """Delay import of rpc_backend until configuration is loaded.""" + global _RPCIMPL + if _RPCIMPL is None: + try: + _RPCIMPL = importutils.import_module(CONF.rpc_backend) + except ImportError: + # For backwards compatibility with older nova config. + impl = CONF.rpc_backend.replace('nova.rpc', + 'nova.openstack.common.rpc') + _RPCIMPL = importutils.import_module(impl) + return _RPCIMPL |