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OpenStack Study: manager.py**** CubicPower OpenStack Study ****
# Copyright 2010 United States Government as represented by the # Administrator of the National Aeronautics and Space Administration. # All Rights Reserved. # # 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. """Base Manager class. Managers are responsible for a certain aspect of the system. It is a logical grouping of code relating to a portion of the system. In general other components should be using the manager to make changes to the components that it is responsible for. For example, other components that need to deal with volumes in some way, should do so by calling methods on the VolumeManager instead of directly changing fields in the database. This allows us to keep all of the code relating to volumes in the same place. We have adopted a basic strategy of Smart managers and dumb data, which means rather than attaching methods to data objects, components should call manager methods that act on the data. Methods on managers that can be executed locally should be called directly. If a particular method must execute on a remote host, this should be done via rpc to the service that wraps the manager Managers should be responsible for most of the db access, and non-implementation specific data. Anything implementation specific that can't be generalized should be done by the Driver. In general, we prefer to have one manager with multiple drivers for different implementations, but sometimes it makes sense to have multiple managers. You can think of it this way: Abstract different overall strategies at the manager level(FlatNetwork vs VlanNetwork), and different implementations at the driver level(LinuxNetDriver vs CiscoNetDriver). Managers will often provide methods for initial setup of a host or periodic tasks to a wrapping service. This module provides Manager, a base class for managers. """ from oslo.config import cfg from nova.db import base from nova.openstack.common import log as logging from nova.openstack.common import periodic_task from nova import rpc CONF = cfg.CONF CONF.import_opt('host', 'nova.netconf') LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class Manager(base.Base, periodic_task.PeriodicTasks):
**** CubicPower OpenStack Study **** def __init__(self, host=None, db_driver=None, service_name='undefined'): if not host: host = CONF.host self.host = host self.backdoor_port = None self.service_name = service_name self.notifier = rpc.get_notifier(self.service_name, self.host) self.additional_endpoints = [] super(Manager, self).__init__(db_driver)
**** CubicPower OpenStack Study **** def periodic_tasks(self, context, raise_on_error=False): """Tasks to be run at a periodic interval.""" return self.run_periodic_tasks(context, raise_on_error=raise_on_error)
**** CubicPower OpenStack Study **** def init_host(self): """Hook to do additional manager initialization when one requests the service be started. This is called before any service record is created. Child classes should override this method. """ pass
**** CubicPower OpenStack Study **** def cleanup_host(self): """Hook to do cleanup work when the service shuts down. Child classes should override this method. """ pass
**** CubicPower OpenStack Study **** def pre_start_hook(self): """Hook to provide the manager the ability to do additional start-up work before any RPC queues/consumers are created. This is called after other initialization has succeeded and a service record is created. Child classes should override this method. """ pass
**** CubicPower OpenStack Study **** def post_start_hook(self): """Hook to provide the manager the ability to do additional start-up work immediately after a service creates RPC consumers and starts 'running'. Child classes should override this method. """ pass
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