116 lines
4.2 KiB
Python
116 lines
4.2 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
|
|
|
|
# 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 sytem. 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
|
|
tasksto a wrapping service.
|
|
|
|
This module provides Manager, a base class for managers.
|
|
|
|
"""
|
|
|
|
from nova import flags
|
|
from nova import log as logging
|
|
from nova import utils
|
|
from nova.db import base
|
|
from nova.scheduler import api
|
|
|
|
|
|
FLAGS = flags.FLAGS
|
|
|
|
|
|
LOG = logging.getLogger('nova.manager')
|
|
|
|
|
|
class Manager(base.Base):
|
|
def __init__(self, host=None, db_driver=None):
|
|
if not host:
|
|
host = FLAGS.host
|
|
self.host = host
|
|
super(Manager, self).__init__(db_driver)
|
|
|
|
def periodic_tasks(self, context=None):
|
|
"""Tasks to be run at a periodic interval."""
|
|
pass
|
|
|
|
def init_host(self):
|
|
"""Handle initialization if this is a standalone service.
|
|
|
|
Child classes should override this method.
|
|
|
|
"""
|
|
pass
|
|
|
|
|
|
class SchedulerDependentManager(Manager):
|
|
"""Periodically send capability updates to the Scheduler services.
|
|
|
|
Services that need to update the Scheduler of their capabilities
|
|
should derive from this class. Otherwise they can derive from
|
|
manager.Manager directly. Updates are only sent after
|
|
update_service_capabilities is called with non-None values.
|
|
|
|
"""
|
|
|
|
def __init__(self, host=None, db_driver=None, service_name='undefined'):
|
|
self.last_capabilities = None
|
|
self.service_name = service_name
|
|
super(SchedulerDependentManager, self).__init__(host, db_driver)
|
|
|
|
def update_service_capabilities(self, capabilities):
|
|
"""Remember these capabilities to send on next periodic update."""
|
|
self.last_capabilities = capabilities
|
|
|
|
def periodic_tasks(self, context=None):
|
|
"""Pass data back to the scheduler at a periodic interval."""
|
|
if self.last_capabilities:
|
|
LOG.debug(_('Notifying Schedulers of capabilities ...'))
|
|
api.update_service_capabilities(context, self.service_name,
|
|
self.host, self.last_capabilities)
|
|
|
|
super(SchedulerDependentManager, self).periodic_tasks(context)
|