113 lines
3.3 KiB
Python
113 lines
3.3 KiB
Python
# Copyright 2013 Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import contextlib
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import eventlet
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from neutron.agent.linux import ovsdb_monitor
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from neutron.plugins.openvswitch.common import constants
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@contextlib.contextmanager
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def get_polling_manager(minimize_polling=False,
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root_helper=None,
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ovsdb_monitor_respawn_interval=(
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constants.DEFAULT_OVSDBMON_RESPAWN)):
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if minimize_polling:
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pm = InterfacePollingMinimizer(
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root_helper=root_helper,
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ovsdb_monitor_respawn_interval=ovsdb_monitor_respawn_interval)
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pm.start()
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else:
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pm = AlwaysPoll()
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try:
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yield pm
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finally:
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if minimize_polling:
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pm.stop()
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class BasePollingManager(object):
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def __init__(self):
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self._force_polling = False
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self._polling_completed = True
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def force_polling(self):
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self._force_polling = True
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def polling_completed(self):
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self._polling_completed = True
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def _is_polling_required(self):
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raise NotImplemented
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@property
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def is_polling_required(self):
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# Always consume the updates to minimize polling.
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polling_required = self._is_polling_required()
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# Polling is required regardless of whether updates have been
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# detected.
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if self._force_polling:
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self._force_polling = False
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polling_required = True
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# Polling is required if not yet done for previously detected
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# updates.
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if not self._polling_completed:
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polling_required = True
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if polling_required:
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# Track whether polling has been completed to ensure that
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# polling can be required until the caller indicates via a
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# call to polling_completed() that polling has been
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# successfully performed.
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self._polling_completed = False
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return polling_required
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class AlwaysPoll(BasePollingManager):
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@property
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def is_polling_required(self):
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return True
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class InterfacePollingMinimizer(BasePollingManager):
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"""Monitors ovsdb to determine when polling is required."""
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def __init__(self, root_helper=None,
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ovsdb_monitor_respawn_interval=(
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constants.DEFAULT_OVSDBMON_RESPAWN)):
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super(InterfacePollingMinimizer, self).__init__()
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self._monitor = ovsdb_monitor.SimpleInterfaceMonitor(
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root_helper=root_helper,
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respawn_interval=ovsdb_monitor_respawn_interval)
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def start(self):
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self._monitor.start()
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def stop(self):
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self._monitor.stop()
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def _is_polling_required(self):
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# Maximize the chances of update detection having a chance to
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# collect output.
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eventlet.sleep()
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return self._monitor.has_updates
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