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Diffstat (limited to 'keystone/openstack/common/rpc/proxy.py')
| -rw-r--r-- | keystone/openstack/common/rpc/proxy.py | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/keystone/openstack/common/rpc/proxy.py b/keystone/openstack/common/rpc/proxy.py new file mode 100644 index 00000000..9cc61920 --- /dev/null +++ b/keystone/openstack/common/rpc/proxy.py @@ -0,0 +1,226 @@ +# vim: tabstop=4 shiftwidth=4 softtabstop=4 + +# Copyright 2012-2013 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. + +""" +A helper class for proxy objects to remote APIs. + +For more information about rpc API version numbers, see: + rpc/dispatcher.py +""" + + +from keystone.openstack.common import rpc +from keystone.openstack.common.rpc import common as rpc_common +from keystone.openstack.common.rpc import serializer as rpc_serializer + + +class RpcProxy(object): + """A helper class for rpc clients. + + This class is a wrapper around the RPC client API. It allows you to + specify the topic and API version in a single place. This is intended to + be used as a base class for a class that implements the client side of an + rpc API. + """ + + # The default namespace, which can be overriden in a subclass. + RPC_API_NAMESPACE = None + + def __init__(self, topic, default_version, version_cap=None, + serializer=None): + """Initialize an RpcProxy. + + :param topic: The topic to use for all messages. + :param default_version: The default API version to request in all + outgoing messages. This can be overridden on a per-message + basis. + :param version_cap: Optionally cap the maximum version used for sent + messages. + :param serializer: Optionaly (de-)serialize entities with a + provided helper. + """ + self.topic = topic + self.default_version = default_version + self.version_cap = version_cap + if serializer is None: + serializer = rpc_serializer.NoOpSerializer() + self.serializer = serializer + super(RpcProxy, self).__init__() + + def _set_version(self, msg, vers): + """Helper method to set the version in a message. + + :param msg: The message having a version added to it. + :param vers: The version number to add to the message. + """ + v = vers if vers else self.default_version + if (self.version_cap and not + rpc_common.version_is_compatible(self.version_cap, v)): + raise rpc_common.RpcVersionCapError(version_cap=self.version_cap) + msg['version'] = v + + def _get_topic(self, topic): + """Return the topic to use for a message.""" + return topic if topic else self.topic + + def can_send_version(self, version): + """Check to see if a version is compatible with the version cap.""" + return (not self.version_cap or + rpc_common.version_is_compatible(self.version_cap, version)) + + @staticmethod + def make_namespaced_msg(method, namespace, **kwargs): + return {'method': method, 'namespace': namespace, 'args': kwargs} + + def make_msg(self, method, **kwargs): + return self.make_namespaced_msg(method, self.RPC_API_NAMESPACE, + **kwargs) + + def _serialize_msg_args(self, context, kwargs): + """Helper method called to serialize message arguments. + + This calls our serializer on each argument, returning a new + set of args that have been serialized. + + :param context: The request context + :param kwargs: The arguments to serialize + :returns: A new set of serialized arguments + """ + new_kwargs = dict() + for argname, arg in kwargs.iteritems(): + new_kwargs[argname] = self.serializer.serialize_entity(context, + arg) + return new_kwargs + + def call(self, context, msg, topic=None, version=None, timeout=None): + """rpc.call() a remote method. + + :param context: The request context + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + :param timeout: (Optional) A timeout to use when waiting for the + response. If no timeout is specified, a default timeout will be + used that is usually sufficient. + + :returns: The return value from the remote method. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + real_topic = self._get_topic(topic) + try: + result = rpc.call(context, real_topic, msg, timeout) + return self.serializer.deserialize_entity(context, result) + except rpc.common.Timeout as exc: + raise rpc.common.Timeout( + exc.info, real_topic, msg.get('method')) + + def multicall(self, context, msg, topic=None, version=None, timeout=None): + """rpc.multicall() a remote method. + + :param context: The request context + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + :param timeout: (Optional) A timeout to use when waiting for the + response. If no timeout is specified, a default timeout will be + used that is usually sufficient. + + :returns: An iterator that lets you process each of the returned values + from the remote method as they arrive. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + real_topic = self._get_topic(topic) + try: + result = rpc.multicall(context, real_topic, msg, timeout) + return self.serializer.deserialize_entity(context, result) + except rpc.common.Timeout as exc: + raise rpc.common.Timeout( + exc.info, real_topic, msg.get('method')) + + def cast(self, context, msg, topic=None, version=None): + """rpc.cast() a remote method. + + :param context: The request context + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + + :returns: None. rpc.cast() does not wait on any return value from the + remote method. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + rpc.cast(context, self._get_topic(topic), msg) + + def fanout_cast(self, context, msg, topic=None, version=None): + """rpc.fanout_cast() a remote method. + + :param context: The request context + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + + :returns: None. rpc.fanout_cast() does not wait on any return value + from the remote method. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + rpc.fanout_cast(context, self._get_topic(topic), msg) + + def cast_to_server(self, context, server_params, msg, topic=None, + version=None): + """rpc.cast_to_server() a remote method. + + :param context: The request context + :param server_params: Server parameters. See rpc.cast_to_server() for + details. + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + + :returns: None. rpc.cast_to_server() does not wait on any + return values. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + rpc.cast_to_server(context, server_params, self._get_topic(topic), msg) + + def fanout_cast_to_server(self, context, server_params, msg, topic=None, + version=None): + """rpc.fanout_cast_to_server() a remote method. + + :param context: The request context + :param server_params: Server parameters. See rpc.cast_to_server() for + details. + :param msg: The message to send, including the method and args. + :param topic: Override the topic for this message. + :param version: (Optional) Override the requested API version in this + message. + + :returns: None. rpc.fanout_cast_to_server() does not wait on any + return values. + """ + self._set_version(msg, version) + msg['args'] = self._serialize_msg_args(context, msg['args']) + rpc.fanout_cast_to_server(context, server_params, + self._get_topic(topic), msg) |