text: # Copyright 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.
  
  __all__ = [
      'init',
      'cleanup',
      'set_defaults',
      'add_extra_exmods',
      'clear_extra_exmods',
      'get_allowed_exmods',
      'RequestContextSerializer',
      'get_client',
      'get_server',
      'get_notifier',
      'TRANSPORT_ALIASES',
  ]
  
  from oslo_config import cfg
  from oslo_log import log as logging
  import oslo_messaging as messaging
  from oslo_utils import importutils
  profiler = importutils.try_import('osprofiler.profiler')
  
  import cinder.context
  import cinder.exception
  from cinder.i18n import _LE, _LI
  from cinder import objects
  from cinder.objects import base
  
  CONF = cfg.CONF
  LOG = logging.getLogger(__name__)
  TRANSPORT = None
  NOTIFICATION_TRANSPORT = None
  NOTIFIER = None
  
  ALLOWED_EXMODS = [
      cinder.exception.__name__,
  ]
  EXTRA_EXMODS = []
  
  # NOTE(flaper87): The cinder.openstack.common.rpc entries are
  # for backwards compat with Havana rpc_backend configuration
  # values. The cinder.rpc entries are for compat with Folsom values.
  TRANSPORT_ALIASES = {
      'cinder.openstack.common.rpc.impl_kombu': 'rabbit',
      'cinder.openstack.common.rpc.impl_qpid': 'qpid',
      'cinder.openstack.common.rpc.impl_zmq': 'zmq',
      'cinder.rpc.impl_kombu': 'rabbit',
      'cinder.rpc.impl_qpid': 'qpid',
      'cinder.rpc.impl_zmq': 'zmq',
  }
  
  
  def init(conf):
      global TRANSPORT, NOTIFICATION_TRANSPORT, NOTIFIER
      exmods = get_allowed_exmods()
      TRANSPORT = messaging.get_transport(conf,
                                          allowed_remote_exmods=exmods,
                                          aliases=TRANSPORT_ALIASES)
      NOTIFICATION_TRANSPORT = messaging.get_notification_transport(
          conf,
          allowed_remote_exmods=exmods,
          aliases=TRANSPORT_ALIASES)
  
      serializer = RequestContextSerializer(messaging.JsonPayloadSerializer())
      NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                    serializer=serializer)
  
  
  def initialized():
      return None not in [TRANSPORT, NOTIFIER]
  
  
  def cleanup():
      global TRANSPORT, NOTIFICATION_TRANSPORT, NOTIFIER
      if NOTIFIER is None:
          LOG.exception(_LE("RPC cleanup: NOTIFIER is None"))
      TRANSPORT.cleanup()
      NOTIFICATION_TRANSPORT.cleanup()
      TRANSPORT = NOTIFICATION_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
  
  
  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):
          _context = context.to_dict()
          if profiler is not None:
              prof = profiler.get()
              if prof:
                  trace_info = {
                      "hmac_key": prof.hmac_key,
                      "base_id": prof.get_base_id(),
                      "parent_id": prof.get_id()
                  }
                  _context.update({"trace_info": trace_info})
          return _context
  
      def deserialize_context(self, context):
          trace_info = context.pop("trace_info", None)
          if trace_info:
              if profiler is not None:
                  profiler.init(**trace_info)
  
          return cinder.context.RequestContext.from_dict(context)
  
  
  def get_client(target, version_cap=None, serializer=None):
      assert TRANSPORT is not None
      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
      serializer = RequestContextSerializer(serializer)
      return messaging.get_rpc_server(TRANSPORT,
                                      target,
                                      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)
  
  
  LAST_RPC_VERSIONS = {}
  LAST_OBJ_VERSIONS = {}
  
  
  class RPCAPI(object):
      """Mixin class aggregating methods related to RPC API compatibility."""
  
      RPC_API_VERSION = '1.0'
      RPC_DEFAULT_VERSION = '1.0'
      TOPIC = ''
      BINARY = ''
  
      def __init__(self):
          target = messaging.Target(topic=self.TOPIC,
                                    version=self.RPC_API_VERSION)
          obj_version_cap = self.determine_obj_version_cap()
          serializer = base.CinderObjectSerializer(obj_version_cap)
  
          rpc_version_cap = self.determine_rpc_version_cap()
          self.client = get_client(target, version_cap=rpc_version_cap,
                                   serializer=serializer)
  
      def _compat_ver(self, current, *legacy):
          versions = (current,) + legacy
          for version in versions[:-1]:
              if self.client.can_send_version(version):
                  return version
          return versions[-1]
  
      def _get_cctxt(self, host=None, version=None, **kwargs):
          """Prepare client context
  
          Version parameter accepts single version string or tuple of strings.
          Compatible version can be obtained later using:
              cctxt = _get_cctxt(...)
              version = cctxt.target.version
          """
          if version is None:
              version = self.RPC_DEFAULT_VERSION
          if isinstance(version, tuple):
              version = self._compat_ver(*version)
          return self.client.prepare(version=version, **kwargs)
  
      @classmethod
      def determine_rpc_version_cap(cls):
          global LAST_RPC_VERSIONS
          if cls.BINARY in LAST_RPC_VERSIONS:
              return LAST_RPC_VERSIONS[cls.BINARY]
  
          version_cap = objects.Service.get_minimum_rpc_version(
              cinder.context.get_admin_context(), cls.BINARY)
          if not version_cap:
              # If there is no service we assume they will come up later and will
              # have the same version as we do.
              version_cap = cls.RPC_API_VERSION
          LOG.info(_LI('Automatically selected %(binary)s RPC version '
                       '%(version)s as minimum service version.'),
                   {'binary': cls.BINARY, 'version': version_cap})
          LAST_RPC_VERSIONS[cls.BINARY] = version_cap
          return version_cap
  
      @classmethod
      def determine_obj_version_cap(cls):
          global LAST_OBJ_VERSIONS
          if cls.BINARY in LAST_OBJ_VERSIONS:
              return LAST_OBJ_VERSIONS[cls.BINARY]
  
          version_cap = objects.Service.get_minimum_obj_version(
              cinder.context.get_admin_context(), cls.BINARY)
          # If there is no service we assume they will come up later and will
          # have the same version as we do.
          if not version_cap:
              version_cap = base.OBJ_VERSIONS.get_current()
          LOG.info(_LI('Automatically selected %(binary)s objects version '
                       '%(version)s as minimum service version.'),
                   {'binary': cls.BINARY, 'version': version_cap})
          LAST_OBJ_VERSIONS[cls.BINARY] = version_cap
          return version_cap
  