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OpenStack Study: polling.py**** CubicPower OpenStack Study ****
# vim: tabstop=4 shiftwidth=4 softtabstop=4 # 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. import contextlib import eventlet from neutron.agent.linux import ovsdb_monitor from neutron.plugins.openvswitch.common import constants @contextlib.contextmanager
**** CubicPower OpenStack Study **** def get_polling_manager(minimize_polling=False, root_helper=None, ovsdb_monitor_respawn_interval=( constants.DEFAULT_OVSDBMON_RESPAWN)): if minimize_polling: pm = InterfacePollingMinimizer( root_helper=root_helper, ovsdb_monitor_respawn_interval=ovsdb_monitor_respawn_interval) pm.start() else: pm = AlwaysPoll() try: yield pm finally: if minimize_polling: pm.stop()
**** CubicPower OpenStack Study **** class BasePollingManager(object):
**** CubicPower OpenStack Study **** def __init__(self): self._force_polling = False self._polling_completed = True
**** CubicPower OpenStack Study **** def force_polling(self): self._force_polling = True
**** CubicPower OpenStack Study **** def polling_completed(self): self._polling_completed = True
**** CubicPower OpenStack Study **** def _is_polling_required(self): raise NotImplemented @property
**** CubicPower OpenStack Study **** def is_polling_required(self): # Always consume the updates to minimize polling. polling_required = self._is_polling_required() # Polling is required regardless of whether updates have been # detected. if self._force_polling: self._force_polling = False polling_required = True # Polling is required if not yet done for previously detected # updates. if not self._polling_completed: polling_required = True if polling_required: # Track whether polling has been completed to ensure that # polling can be required until the caller indicates via a # call to polling_completed() that polling has been # successfully performed. self._polling_completed = False return polling_required
**** CubicPower OpenStack Study **** class AlwaysPoll(BasePollingManager): @property
**** CubicPower OpenStack Study **** def is_polling_required(self): return True
**** CubicPower OpenStack Study **** class InterfacePollingMinimizer(BasePollingManager): """Monitors ovsdb to determine when polling is required."""
**** CubicPower OpenStack Study **** def __init__(self, root_helper=None, ovsdb_monitor_respawn_interval=( constants.DEFAULT_OVSDBMON_RESPAWN)): super(InterfacePollingMinimizer, self).__init__() self._monitor = ovsdb_monitor.SimpleInterfaceMonitor( root_helper=root_helper, respawn_interval=ovsdb_monitor_respawn_interval)
**** CubicPower OpenStack Study **** def start(self): self._monitor.start()
**** CubicPower OpenStack Study **** def stop(self): self._monitor.stop()
**** CubicPower OpenStack Study **** def _is_polling_required(self): # Maximize the chances of update detection having a chance to # collect output. eventlet.sleep() return self._monitor.has_updates
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