107 lines
3.6 KiB
Python
107 lines
3.6 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 eventlet
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from neutron.agent.linux import async_process
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from neutron.i18n import _LE
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from neutron.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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class OvsdbMonitor(async_process.AsyncProcess):
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"""Manages an invocation of 'ovsdb-client monitor'."""
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def __init__(self, table_name, columns=None, format=None,
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root_helper=None, respawn_interval=None):
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cmd = ['ovsdb-client', 'monitor', table_name]
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if columns:
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cmd.append(','.join(columns))
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if format:
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cmd.append('--format=%s' % format)
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super(OvsdbMonitor, self).__init__(cmd,
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root_helper=root_helper,
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respawn_interval=respawn_interval)
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def _read_stdout(self):
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data = self._process.stdout.readline()
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if not data:
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return
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self._stdout_lines.put(data)
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LOG.debug('Output received from ovsdb monitor: %s', data)
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return data
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def _read_stderr(self):
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data = super(OvsdbMonitor, self)._read_stderr()
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if data:
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LOG.error(_LE('Error received from ovsdb monitor: %s'), data)
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# Do not return value to ensure that stderr output will
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# stop the monitor.
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class SimpleInterfaceMonitor(OvsdbMonitor):
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"""Monitors the Interface table of the local host's ovsdb for changes.
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The has_updates() method indicates whether changes to the ovsdb
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Interface table have been detected since the monitor started or
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since the previous access.
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"""
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def __init__(self, root_helper=None, respawn_interval=None):
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super(SimpleInterfaceMonitor, self).__init__(
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'Interface',
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columns=['name', 'ofport'],
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format='json',
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root_helper=root_helper,
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respawn_interval=respawn_interval,
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)
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self.data_received = False
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@property
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def is_active(self):
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return (self.data_received and
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self._kill_event and
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not self._kill_event.ready())
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@property
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def has_updates(self):
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"""Indicate whether the ovsdb Interface table has been updated.
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True will be returned if the monitor process is not active.
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This 'failing open' minimizes the risk of falsely indicating
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the absence of updates at the expense of potential false
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positives.
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"""
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return bool(list(self.iter_stdout())) or not self.is_active
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def start(self, block=False, timeout=5):
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super(SimpleInterfaceMonitor, self).start()
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if block:
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with eventlet.timeout.Timeout(timeout):
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while not self.is_active:
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eventlet.sleep()
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def _kill(self, *args, **kwargs):
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self.data_received = False
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super(SimpleInterfaceMonitor, self)._kill(*args, **kwargs)
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def _read_stdout(self):
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data = super(SimpleInterfaceMonitor, self)._read_stdout()
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if data and not self.data_received:
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self.data_received = True
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return data
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