deb-manila/manila/manager.py
Doug Hellmann bb69046db5 Drop use of 'oslo' namespace package
The Oslo libraries have moved all of their code out of the 'oslo'
namespace package into per-library packages. The namespace package was
retained during kilo for backwards compatibility, but will be removed by
the liberty-2 milestone. This change removes the use of the namespace
package, replacing it with the new package names.

The patches in the libraries will be put on hold until application
patches have landed, or L2, whichever comes first. At that point, new
versions of the libraries without namespace packages will be released as
a major version update.

Please merge this patch, or an equivalent, before L2 to avoid problems
with those library releases.

Blueprint: remove-namespace-packages
https://blueprints.launchpad.net/oslo-incubator/+spec/remove-namespace-packages

Change-Id: I75e6e15d50ef9830d0581efd4cbcceb3e626f7b7
2015-04-29 16:51:33 +03:00

228 lines
8.2 KiB
Python

# 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 oslo_log import log
import six
from manila.db import base
from manila.i18n import _LE
from manila.scheduler import rpcapi as scheduler_rpcapi
from manila import version
CONF = cfg.CONF
LOG = log.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
# NOTE(sirp): The `if` is necessary to allow the decorator to be used with
# and without parens.
#
# In the 'with-parens' case (with kwargs present), this function needs to
# return a decorator function since the interpreter will invoke it like:
#
# periodic_task(*args, **kwargs)(f)
#
# In the 'without-parens' case, the original function will be passed
# in as the first argument, like:
#
# periodic_task(f)
if kwargs:
return decorator
else:
return decorator(args[0])
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_)
# NOTE(sirp): if the attribute is not present then we must be the base
# class, so, go ahead an initialize it. If the attribute is present,
# then we're a subclass so make a copy of it so we don't step on our
# parent's toes.
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
@six.add_metaclass(ManagerMeta)
class Manager(base.Base):
@property
def RPC_API_VERSION(self):
"""Redefine this in child classes."""
raise NotImplementedError
@property
def target(self):
"""This property is used by oslo_messaging.
https://wiki.openstack.org/wiki/Oslo/Messaging#API_Version_Negotiation
"""
if not hasattr(self, '_target'):
import oslo_messaging as messaging
self._target = messaging.Target(version=self.RPC_API_VERSION)
return self._target
def __init__(self, host=None, db_driver=None):
if not host:
host = CONF.host
self.host = host
self.additional_endpoints = []
super(Manager, self).__init__(db_driver)
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",
{'full_task_name': full_task_name,
'ticks_to_skip': ticks_to_skip})
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",
{'full_task_name': full_task_name})
try:
task(self, context)
except Exception as e:
if raise_on_error:
raise
LOG.exception(_LE("Error during %(full_task_name)s: %(e)s"),
{'full_task_name': full_task_name, 'e': e})
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 CONF:
config[key] = CONF.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)