kosmos/kosmos/common/rpc.py

# Copyright 2015 Hewlett Packard Enterprise Development LP
#
# 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.

__all__ = [
    'init',
    'cleanup',
    'set_defaults',
    'add_extra_exmods',
    'clear_extra_exmods',
    'get_allowed_exmods',
    'RequestContextSerializer',
    'get_client',
    'get_server',
    'get_notifier',
]

import kosmos.common.context
import kosmos.common.exceptions
import oslo_messaging as messaging
from kosmos.objects.base import KosmosObject
from oslo_config import cfg
from oslo_messaging import server as msg_server
from oslo_messaging.rpc import dispatcher as rpc_dispatcher
from oslo_serialization import jsonutils
from oslo_versionedobjects.base import VersionedObjectSerializer

CONF = cfg.CONF
TRANSPORT = None
NOTIFIER = None


# NOTE: Additional entries to kosmos.exceptions goes here.
CONF.register_opts([
    cfg.ListOpt(
        'allowed_remote_exmods',
        default=[],
        help="Additional modules that contains allowed RPC exceptions.",
        deprecated_name='allowed_rpc_exception_modules')
])
ALLOWED_EXMODS = [
    kosmos.common.exceptions.__name__,
]
EXTRA_EXMODS = []


def init(conf):
    global TRANSPORT, NOTIFIER
    exmods = get_allowed_exmods()
    TRANSPORT = messaging.get_transport(conf,
                                        allowed_remote_exmods=exmods)

    serializer = RequestContextSerializer(JsonPayloadSerializer())
    NOTIFIER = messaging.Notifier(TRANSPORT, serializer=serializer)


def initialized():
    return None not in [TRANSPORT, NOTIFIER]


def cleanup():
    global TRANSPORT, NOTIFIER
    assert TRANSPORT is not None
    assert NOTIFIER is not None
    TRANSPORT.cleanup()
    TRANSPORT = NOTIFIER = None


def set_defaults(control_exchange):
    messaging.set_transport_defaults(control_exchange)


def add_extra_exmods(*args):
    EXTRA_EXMODS.extend(args)


def clear_extra_exmods():
    del EXTRA_EXMODS[:]


def get_allowed_exmods():
    return ALLOWED_EXMODS + EXTRA_EXMODS + CONF.allowed_remote_exmods


class JsonPayloadSerializer(messaging.NoOpSerializer):
    @staticmethod
    def serialize_entity(context, entity):
        return jsonutils.to_primitive(entity, convert_instances=True)


class KosmosObjectSerializer(VersionedObjectSerializer):

    OBJ_BASE_CLASS = KosmosObject


class RequestContextSerializer(messaging.Serializer):

    def __init__(self, base):
        self._base = base

    def serialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.serialize_entity(context, entity)

    def deserialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.deserialize_entity(context, entity)

    def serialize_context(self, context):
        return context.to_dict()

    def deserialize_context(self, context):
        return kosmos.common.context.KosmosContext.from_dict(context)


class RPCDispatcher(rpc_dispatcher.RPCDispatcher):
    def _dispatch(self, *args, **kwds):
        try:
            return super(RPCDispatcher, self)._dispatch(*args, **kwds)
        except Exception as e:
            if getattr(e, 'expected', False):
                raise rpc_dispatcher.ExpectedException()
            else:
                raise


def get_transport_url(url_str=None):
    return messaging.TransportURL.parse(CONF, url_str)


def get_client(target, version_cap=None, serializer=None):
    assert TRANSPORT is not None
    if serializer is None:
        serializer = KosmosObjectSerializer()
    serializer = RequestContextSerializer(serializer)
    return messaging.RPCClient(TRANSPORT,
                               target,
                               version_cap=version_cap,
                               serializer=serializer)


def get_server(target, endpoints, serializer=None):
    assert TRANSPORT is not None
    if serializer is None:
        serializer = KosmosObjectSerializer()
    serializer = RequestContextSerializer(serializer)

    dispatcher = RPCDispatcher(target, endpoints, serializer)
    return msg_server.MessageHandlingServer(TRANSPORT, dispatcher, 'eventlet')


def get_listener(targets, endpoints, serializer=None):
    assert TRANSPORT is not None
    if serializer is None:
        serializer = JsonPayloadSerializer()
    return messaging.get_notification_listener(TRANSPORT,
                                               targets,
                                               endpoints,
                                               executor='eventlet',
                                               serializer=serializer)


def get_notifier(service=None, host=None, publisher_id=None):
    assert NOTIFIER is not None
    if not publisher_id:
        publisher_id = "%s.%s" % (service, host or CONF.host)
    return NOTIFIER.prepare(publisher_id=publisher_id)