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OpenStack Study: ovsdb_monitor.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 eventlet from neutron.agent.linux import async_process from neutron.openstack.common import log as logging LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class OvsdbMonitor(async_process.AsyncProcess): """Manages an invocation of 'ovsdb-client monitor'."""
**** CubicPower OpenStack Study **** def __init__(self, table_name, columns=None, format=None, root_helper=None, respawn_interval=None): cmd = ['ovsdb-client', 'monitor', table_name] if columns: cmd.append(','.join(columns)) if format: cmd.append('--format=%s' % format) super(OvsdbMonitor, self).__init__(cmd, root_helper=root_helper, respawn_interval=respawn_interval)
**** CubicPower OpenStack Study **** def _read_stdout(self): data = self._process.stdout.readline() if not data: return #TODO(marun) The default root helper outputs exit errors to # stdout due to bug #1219530. This check can be moved to # _read_stderr once the error is correctly output to stderr. if self.root_helper and self.root_helper in data: self._stderr_lines.put(data) LOG.error(_('Error received from ovsdb monitor: %s') % data) else: self._stdout_lines.put(data) LOG.debug(_('Output received from ovsdb monitor: %s') % data) return data
**** CubicPower OpenStack Study **** def _read_stderr(self): data = super(OvsdbMonitor, self)._read_stderr() if data: LOG.error(_('Error received from ovsdb monitor: %s') % data) # Do not return value to ensure that stderr output will # stop the monitor.
**** CubicPower OpenStack Study **** class SimpleInterfaceMonitor(OvsdbMonitor): """Monitors the Interface table of the local host's ovsdb for changes. The has_updates() method indicates whether changes to the ovsdb Interface table have been detected since the monitor started or since the previous access. """
**** CubicPower OpenStack Study **** def __init__(self, root_helper=None, respawn_interval=None): super(SimpleInterfaceMonitor, self).__init__( 'Interface', columns=['name', 'ofport'], format='json', root_helper=root_helper, respawn_interval=respawn_interval, ) self.data_received = False @property
**** CubicPower OpenStack Study **** def is_active(self): return (self.data_received and self._kill_event and not self._kill_event.ready()) @property
**** CubicPower OpenStack Study **** def has_updates(self): """Indicate whether the ovsdb Interface table has been updated. True will be returned if the monitor process is not active. This 'failing open' minimizes the risk of falsely indicating the absence of updates at the expense of potential false positives. """ return bool(list(self.iter_stdout())) or not self.is_active
**** CubicPower OpenStack Study **** def start(self, block=False, timeout=5): super(SimpleInterfaceMonitor, self).start() if block: eventlet.timeout.Timeout(timeout) while not self.is_active: eventlet.sleep()
**** CubicPower OpenStack Study **** def _kill(self, *args, **kwargs): self.data_received = False super(SimpleInterfaceMonitor, self)._kill(*args, **kwargs)
**** CubicPower OpenStack Study **** def _read_stdout(self): data = super(SimpleInterfaceMonitor, self)._read_stdout() if data and not self.data_received: self.data_received = True return data
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