116 lines
4.3 KiB
Python
116 lines
4.3 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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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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from quantum.openstack.common.gettextutils import _
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from quantum.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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def periodic_task(*args, **kwargs):
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"""Decorator to indicate that a method is a periodic task.
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This decorator can be used in two ways:
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1. Without arguments '@periodic_task', this will be run on every tick
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of the periodic scheduler.
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2. With arguments, @periodic_task(ticks_between_runs=N), this will be
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run on every N ticks of the periodic scheduler.
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"""
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def decorator(f):
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f._periodic_task = True
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f._ticks_between_runs = kwargs.pop('ticks_between_runs', 0)
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return f
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# NOTE(sirp): The `if` is necessary to allow the decorator to be used with
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# and without parens.
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#
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# In the 'with-parens' case (with kwargs present), this function needs to
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# return a decorator function since the interpreter will invoke it like:
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#
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# periodic_task(*args, **kwargs)(f)
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#
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# In the 'without-parens' case, the original function will be passed
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# in as the first argument, like:
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#
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# periodic_task(f)
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if kwargs:
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return decorator
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else:
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return decorator(args[0])
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class _PeriodicTasksMeta(type):
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def __init__(cls, names, bases, dict_):
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"""Metaclass that allows us to collect decorated periodic tasks."""
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super(_PeriodicTasksMeta, cls).__init__(names, bases, dict_)
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# NOTE(sirp): if the attribute is not present then we must be the base
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# class, so, go ahead and initialize it. If the attribute is present,
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# then we're a subclass so make a copy of it so we don't step on our
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# parent's toes.
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try:
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cls._periodic_tasks = cls._periodic_tasks[:]
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except AttributeError:
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cls._periodic_tasks = []
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try:
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cls._ticks_to_skip = cls._ticks_to_skip.copy()
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except AttributeError:
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cls._ticks_to_skip = {}
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# This uses __dict__ instead of
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# inspect.getmembers(cls, inspect.ismethod) so only the methods of the
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# current class are added when this class is scanned, and base classes
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# are not added redundantly.
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for value in cls.__dict__.values():
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if getattr(value, '_periodic_task', False):
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task = value
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name = task.__name__
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cls._periodic_tasks.append((name, task))
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cls._ticks_to_skip[name] = task._ticks_between_runs
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class PeriodicTasks(object):
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__metaclass__ = _PeriodicTasksMeta
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def run_periodic_tasks(self, context, raise_on_error=False):
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"""Tasks to be run at a periodic interval."""
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for task_name, task in self._periodic_tasks:
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full_task_name = '.'.join([self.__class__.__name__, task_name])
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ticks_to_skip = self._ticks_to_skip[task_name]
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if ticks_to_skip > 0:
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LOG.debug(_("Skipping %(full_task_name)s, %(ticks_to_skip)s"
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" ticks left until next run"),
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dict(full_task_name=full_task_name,
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ticks_to_skip=ticks_to_skip))
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self._ticks_to_skip[task_name] -= 1
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continue
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self._ticks_to_skip[task_name] = task._ticks_between_runs
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LOG.debug(_("Running periodic task %(full_task_name)s"),
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dict(full_task_name=full_task_name))
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try:
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task(self, context)
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except Exception as e:
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if raise_on_error:
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raise
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LOG.exception(_("Error during %(full_task_name)s:"
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" %(e)s"),
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dict(e=e, full_task_name=full_task_name))
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