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# vim: tabstop=4 shiftwidth=4 softtabstop=4
#
# 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.
import datetime
import time
from oslo.config import cfg
from openstack.common.gettextutils import _
from openstack.common import log as logging
from openstack.common import timeutils
periodic_opts = [
cfg.BoolOpt('run_external_periodic_tasks',
default=True,
help=('Some periodic tasks can be run in a separate process. '
'Should we run them here?')),
]
CONF = cfg.CONF
CONF.register_opts(periodic_opts)
LOG = logging.getLogger(__name__)
DEFAULT_INTERVAL = 60.0
class InvalidPeriodicTaskArg(Exception):
message = _("Unexpected argument for periodic task creation: %(arg)s.")
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 cycle
of the periodic scheduler.
2. With arguments:
@periodic_task(spacing=N [, run_immediately=[True|False]])
this will be run on approximately every N seconds. If this number is
negative the periodic task will be disabled. If the run_immediately
argument is provided and has a value of 'True', the first run of the
task will be shortly after task scheduler starts. If
run_immediately is omitted or set to 'False', the first time the
task runs will be approximately N seconds after the task scheduler
starts.
"""
def decorator(f):
# Test for old style invocation
if 'ticks_between_runs' in kwargs:
raise InvalidPeriodicTaskArg(arg='ticks_between_runs')
# Control if run at all
f._periodic_task = True
f._periodic_external_ok = kwargs.pop('external_process_ok', False)
if f._periodic_external_ok and not CONF.run_external_periodic_tasks:
f._periodic_enabled = False
else:
f._periodic_enabled = kwargs.pop('enabled', True)
# Control frequency
f._periodic_spacing = kwargs.pop('spacing', 0)
f._periodic_immediate = kwargs.pop('run_immediately', False)
if f._periodic_immediate:
f._periodic_last_run = None
else:
f._periodic_last_run = timeutils.utcnow()
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 _PeriodicTasksMeta(type):
def __init__(cls, names, bases, dict_):
"""Metaclass that allows us to collect decorated periodic tasks."""
super(_PeriodicTasksMeta, 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._periodic_last_run = cls._periodic_last_run.copy()
except AttributeError:
cls._periodic_last_run = {}
try:
cls._periodic_spacing = cls._periodic_spacing.copy()
except AttributeError:
cls._periodic_spacing = {}
for value in cls.__dict__.values():
if getattr(value, '_periodic_task', False):
task = value
name = task.__name__
if task._periodic_spacing < 0:
LOG.info(_('Skipping periodic task %(task)s because '
'its interval is negative'),
{'task': name})
continue
if not task._periodic_enabled:
LOG.info(_('Skipping periodic task %(task)s because '
'it is disabled'),
{'task': name})
continue
# A periodic spacing of zero indicates that this task should
# be run every pass
if task._periodic_spacing == 0:
task._periodic_spacing = None
cls._periodic_tasks.append((name, task))
cls._periodic_spacing[name] = task._periodic_spacing
cls._periodic_last_run[name] = task._periodic_last_run
class PeriodicTasks(object):
__metaclass__ = _PeriodicTasksMeta
def run_periodic_tasks(self, context, raise_on_error=False):
"""Tasks to be run at a periodic interval."""
idle_for = DEFAULT_INTERVAL
for task_name, task in self._periodic_tasks:
full_task_name = '.'.join([self.__class__.__name__, task_name])
now = timeutils.utcnow()
spacing = self._periodic_spacing[task_name]
last_run = self._periodic_last_run[task_name]
# If a periodic task is _nearly_ due, then we'll run it early
if spacing is not None and last_run is not None:
due = last_run + datetime.timedelta(seconds=spacing)
if not timeutils.is_soon(due, 0.2):
idle_for = min(idle_for, timeutils.delta_seconds(now, due))
continue
if spacing is not None:
idle_for = min(idle_for, spacing)
LOG.debug(_("Running periodic task %(full_task_name)s"), locals())
self._periodic_last_run[task_name] = timeutils.utcnow()
try:
task(self, context)
except Exception as e:
if raise_on_error:
raise
LOG.exception(_("Error during %(full_task_name)s: %(e)s"),
locals())
time.sleep(0)
return idle_for
|
