148 lines
5.3 KiB
Python
148 lines
5.3 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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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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"""Base Manager class.
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Managers are responsible for a certain aspect of the system. It is a logical
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grouping of code relating to a portion of the system. In general other
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components should be using the manager to make changes to the components that
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it is responsible for.
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For example, other components that need to deal with volumes in some way,
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should do so by calling methods on the VolumeManager instead of directly
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changing fields in the database. This allows us to keep all of the code
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relating to volumes in the same place.
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We have adopted a basic strategy of Smart managers and dumb data, which means
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rather than attaching methods to data objects, components should call manager
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methods that act on the data.
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Methods on managers that can be executed locally should be called directly. If
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a particular method must execute on a remote host, this should be done via rpc
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to the service that wraps the manager
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Managers should be responsible for most of the db access, and
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non-implementation specific data. Anything implementation specific that can't
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be generalized should be done by the Driver.
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In general, we prefer to have one manager with multiple drivers for different
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implementations, but sometimes it makes sense to have multiple managers. You
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can think of it this way: Abstract different overall strategies at the manager
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level(FlatNetwork vs VlanNetwork), and different implementations at the driver
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level(LinuxNetDriver vs CiscoNetDriver).
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Managers will often provide methods for initial setup of a host or periodic
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tasks to a wrapping service.
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This module provides Manager, a base class for managers.
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"""
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from oslo_config import cfg
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from oslo_log import log
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from oslo_service import periodic_task
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from manila.db import base
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from manila.scheduler import rpcapi as scheduler_rpcapi
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from manila import version
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CONF = cfg.CONF
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LOG = log.getLogger(__name__)
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class PeriodicTasks(periodic_task.PeriodicTasks):
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def __init__(self):
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super(PeriodicTasks, self).__init__(CONF)
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class Manager(base.Base, PeriodicTasks):
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@property
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def RPC_API_VERSION(self):
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"""Redefine this in child classes."""
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raise NotImplementedError
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@property
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def target(self):
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"""This property is used by oslo_messaging.
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https://wiki.openstack.org/wiki/Oslo/Messaging#API_Version_Negotiation
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"""
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if not hasattr(self, '_target'):
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import oslo_messaging as messaging
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self._target = messaging.Target(version=self.RPC_API_VERSION)
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return self._target
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def __init__(self, host=None, db_driver=None):
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if not host:
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host = CONF.host
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self.host = host
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self.additional_endpoints = []
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super(Manager, self).__init__(db_driver)
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def periodic_tasks(self, context, raise_on_error=False):
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"""Tasks to be run at a periodic interval."""
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return self.run_periodic_tasks(context, raise_on_error=raise_on_error)
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def init_host(self):
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"""Handle initialization if this is a standalone service.
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Child classes should override this method.
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"""
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pass
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def service_version(self, context):
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return version.version_string()
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def service_config(self, context):
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config = {}
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for key in CONF:
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config[key] = CONF.get(key, None)
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return config
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class SchedulerDependentManager(Manager):
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"""Periodically send capability updates to the Scheduler services.
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Services that need to update the Scheduler of their capabilities
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should derive from this class. Otherwise they can derive from
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manager.Manager directly. Updates are only sent after
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update_service_capabilities is called with non-None values.
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"""
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def __init__(self, host=None, db_driver=None, service_name='undefined'):
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self.last_capabilities = None
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self.service_name = service_name
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self.scheduler_rpcapi = scheduler_rpcapi.SchedulerAPI()
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super(SchedulerDependentManager, self).__init__(host, db_driver)
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def update_service_capabilities(self, capabilities):
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"""Remember these capabilities to send on next periodic update."""
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self.last_capabilities = capabilities
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@periodic_task.periodic_task
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def _publish_service_capabilities(self, context):
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"""Pass data back to the scheduler at a periodic interval."""
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if self.last_capabilities:
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LOG.debug('Notifying Schedulers of capabilities ...')
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self.scheduler_rpcapi.update_service_capabilities(
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context,
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self.service_name,
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self.host,
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self.last_capabilities)
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