group-based-policy/gbpservice/nfp/core/rpc.py

#    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.


from oslo_config import cfg as oslo_config

from oslo_service import loopingcall as oslo_looping_call
from oslo_service import periodic_task as oslo_periodic_task
from oslo_service import service as oslo_service

from neutron.agent import rpc as n_agent_rpc
from neutron.common import rpc as n_rpc

from neutron_lib import context as n_context

from gbpservice.nfp.core import log as nfp_logging

LOG = nfp_logging.getLogger(__name__)

n_rpc.init(oslo_config.CONF)

"""RPC Service class.

    This class is implemented from neutron.common.rpc
    because neutron limit itself to single rpc manager
    per topic while oslo allows multiple.
    Using this class, one can register multiple rpc
    managers with oslo.
"""


class RpcService(oslo_service.Service):

    def __init__(self, topic, managers=None):
        # Not taking host and serializer as neutron rpc does not support
        # passing any host and serializer- it picks up the host from
        # 'cfg.CONF.host' and consider serializer as None

        super(RpcService, self).__init__()
        self.topic = topic
        self.endpoints = managers or []

    def start(self):
        LOG.debug("RPCAgent listening on topic=%s", self.topic)
        super(RpcService, self).start()

        self.conn = n_rpc.create_connection()
        LOG.debug("Creating Consumer connection for Service %s",
                  self.topic)

        self.conn.create_consumer(self.topic, self.endpoints)

        # Hook to allow the manager to do other initializations after
        # the rpc connection is created.
        for manager in self.endpoints:
            if callable(getattr(manager, 'initialize_service_hook', None)):
                self.manager.initialize_service_hook(self)

        # Consume from all consumers in threads
        self.conn.consume_in_threads()

    def stop(self):
        # Try to shut the connection down, but if we get any sort of
        # errors, go ahead and ignore them.. as we're shutting down anyway
        try:
            self.conn.close()
        except Exception:
            pass
        super(RpcService, self).stop()


"""Wrapper class for Neutron RpcAgent definition.

    NFP modules will use this class for the agent definition.
    Associates the state reporting of agent to ease
    the usage for modules.
"""


class RpcAgent(object):

    def __init__(
            self, sc, host=None,
            topic=None, manager=None, report_state=None, priority=0):
        # report_state =
        #   {<agent_state_keys>, 'plugin_topic': '', 'report_interval': ''}

        self.sc = sc
        # The argument 'host' will be ignored as neutron rpc does not
        # support passing any host -it picks up from 'cfg.CONF.host'
        self.host = oslo_config.CONF.host
        self.topic = topic
        self.manager = manager
        self.priority = priority
        # Check if the agent needs to report state
        if report_state:
            self._report_state = ReportState(report_state)

    def report_state(self):
        if hasattr(self, '_report_state'):
            LOG.debug("Agent (%s) reporting state",
                      (self.identify()))
            self._report_state.report()

    def identify(self):
        return "(host=%s,topic=%s)" % (self.host, self.topic)


"""This class implements the state reporting for neutron *aaS agents

    One common place of handling of reporting logic.
    Each nfp module just need to register the reporting data and
    plugin topic.
"""


class ReportState(object):

    def __init__(self, data):
        self._n_context = n_context.get_admin_context_without_session()
        self._data = data
        self._topic = data.pop('plugin_topic', None)
        self._interval = data.pop('report_interval', 0)
        self._state_rpc = n_agent_rpc.PluginReportStateAPI(
            self._topic)

    def report(self):
        try:
            LOG.debug("Reporting state with data (%s)",
                      (self._data))
            self._state_rpc.report_state(self._n_context, self._data)
            self._data.pop('start_flag', None)
        except AttributeError:
            # This means the server does not support report_state
            message = "Neutron server does not support state report."
            "Agent State reporting will be disabled"
            LOG.info(message)
            return
        except Exception:
            message = "Stopped reporting agent state!"
            LOG.exception(message)

"""Periodic task to report neutron *aaS agent state.

    Derived from oslo periodic task, to report the agents state
    if any, to neutron *aaS plugin.
"""


class ReportStateTask(oslo_periodic_task.PeriodicTasks):

    def __init__(self, conf, controller):
        super(ReportStateTask, self).__init__(conf)
        self._controller = controller
        # Start a looping at the defined pulse
        pulse = oslo_looping_call.FixedIntervalLoopingCall(
            self.run_periodic_tasks, None, None)
        pulse.start(
            interval=5, initial_delay=None)

    @oslo_periodic_task.periodic_task(spacing=10)
    def report_state(self, context):
        # trigger the state reporting
        self._controller.report_state()