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manager.py
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manager.py
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright (c) 2013 TrilioData, Inc.
# 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.
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 raksha.db import base
from raksha import flags
from raksha.openstack.common import log as logging
from raksha.openstack.common.rpc import dispatcher as rpc_dispatcher
from raksha.scheduler import rpcapi as scheduler_rpcapi
from raksha import version
FLAGS = flags.FLAGS
LOG = logging.getLogger(__name__)
def periodic_task(*args, **kwargs):
"""Decorator to indicate that a method is a periodic task.
This decorator can be used in two ways:
1. Without arguments '@periodic_task', this will be run on every tick
of the periodic scheduler.
2. With arguments, @periodic_task(ticks_between_runs=N), this will be
run on every N ticks of the periodic scheduler.
"""
def decorator(f):
f._periodic_task = True
f._ticks_between_runs = kwargs.pop('ticks_between_runs', 0)
return f
class ManagerMeta(type):
def __init__(cls, names, bases, dict_):
"""Metaclass that allows us to collect decorated periodic tasks."""
super(ManagerMeta, cls).__init__(names, bases, dict_)
try:
cls._periodic_tasks = cls._periodic_tasks[:]
except AttributeError:
cls._periodic_tasks = []
try:
cls._ticks_to_skip = cls._ticks_to_skip.copy()
except AttributeError:
cls._ticks_to_skip = {}
for value in cls.__dict__.values():
if getattr(value, '_periodic_task', False):
task = value
name = task.__name__
cls._periodic_tasks.append((name, task))
cls._ticks_to_skip[name] = task._ticks_between_runs
class Manager(base.Base):
__metaclass__ = ManagerMeta
# Set RPC API version to 1.0 by default.
RPC_API_VERSION = '1.0'
def __init__(self, host=None, db_driver=None):
if not host:
host = FLAGS.host
self.host = host
super(Manager, self).__init__(db_driver)
def create_rpc_dispatcher(self):
'''Get the rpc dispatcher for this manager.
If a manager would like to set an rpc API version, or support more than
one class as the target of rpc messages, override this method.
'''
return rpc_dispatcher.RpcDispatcher([self])
def periodic_tasks(self, context, raise_on_error=False):
"""Tasks to be run at a periodic interval."""
for task_name, task in self._periodic_tasks:
full_task_name = '.'.join([self.__class__.__name__, task_name])
ticks_to_skip = self._ticks_to_skip[task_name]
if ticks_to_skip > 0:
LOG.debug(_("Skipping %(full_task_name)s, %(ticks_to_skip)s"
" ticks left until next run"), locals())
self._ticks_to_skip[task_name] -= 1
continue
self._ticks_to_skip[task_name] = task._ticks_between_runs
LOG.debug(_("Running periodic task %(full_task_name)s"), locals())
try:
task(self, context)
except Exception as e:
if raise_on_error:
raise
LOG.exception(_("Error during %(full_task_name)s: %(e)s"),
locals())
def init_host(self):
"""Handle initialization if this is a standalone service.
Child classes should override this method.
"""
pass
def service_version(self, context):
return version.version_string()
def service_config(self, context):
config = {}
for key in FLAGS:
config[key] = FLAGS.get(key, None)
return config
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
self.scheduler_rpcapi = scheduler_rpcapi.SchedulerAPI()
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
@periodic_task
def _publish_service_capabilities(self, context):
"""Pass data back to the scheduler at a periodic interval."""
if self.last_capabilities:
LOG.debug(_('Notifying Schedulers of capabilities ...'))
self.scheduler_rpcapi.update_service_capabilities(
context,
self.service_name,
self.host,
self.last_capabilities)