8cc9813e19
This refactors the looping call subclasses to share a common '_run_loop' function, this avoids duplicating that code and taking advanage of the commonality of both of these subclasses. This also moves this code closer to not being dependent on eventlet. Change-Id: I61c0bbd6a7cda11f96374fd7c453ac5fa89ed613
142 lines
4.6 KiB
Python
142 lines
4.6 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# Copyright 2011 Justin Santa Barbara
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# All Rights Reserved.
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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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import logging
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import sys
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from eventlet import event
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from eventlet import greenthread
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from oslo_utils import timeutils
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from oslo_service._i18n import _LE, _LW, _
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LOG = logging.getLogger(__name__)
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class LoopingCallDone(Exception):
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"""Exception to break out and stop a LoopingCallBase.
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The poll-function passed to LoopingCallBase can raise this exception to
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break out of the loop normally. This is somewhat analogous to
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StopIteration.
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An optional return-value can be included as the argument to the exception;
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this return-value will be returned by LoopingCallBase.wait()
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"""
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def __init__(self, retvalue=True):
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""":param retvalue: Value that LoopingCallBase.wait() should return."""
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self.retvalue = retvalue
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class LoopingCallBase(object):
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def __init__(self, f=None, *args, **kw):
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self.args = args
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self.kw = kw
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self.f = f
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self._running = False
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self.done = None
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def stop(self):
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self._running = False
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def wait(self):
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return self.done.wait()
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def _run_loop(self, kind, event, idle_for_func,
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initial_delay=None):
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if initial_delay:
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greenthread.sleep(initial_delay)
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try:
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watch = timeutils.StopWatch()
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while self._running:
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watch.restart()
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result = self.f(*self.args, **self.kw)
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watch.stop()
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if not self._running:
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break
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idle = idle_for_func(result, watch.elapsed())
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LOG.debug('%(kind)s %(func_name)r sleeping '
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'for %(idle).02f seconds',
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{'func_name': self.f, 'idle': idle,
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'kind': kind})
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greenthread.sleep(idle)
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except LoopingCallDone as e:
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self.stop()
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event.send(e.retvalue)
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except Exception:
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exc_info = sys.exc_info()
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try:
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LOG.error(_LE('%(kind)s %(func_name)r failed'),
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{'kind': kind, 'func_name': self.f},
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exc_info=exc_info)
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event.send_exception(*exc_info)
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finally:
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del exc_info
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return
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else:
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event.send(True)
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class FixedIntervalLoopingCall(LoopingCallBase):
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"""A fixed interval looping call."""
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_KIND = _('Fixed interval looping call')
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def start(self, interval, initial_delay=None):
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def _idle_for(result, elapsed):
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delay = elapsed - interval
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if delay > 0:
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LOG.warning(_LW('Function %(func_name)r run outlasted '
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'interval by %(delay).2f sec'),
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{'func_name': self.f, 'delay': delay})
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return -delay if delay < 0 else 0
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self._running = True
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self.done = event.Event()
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greenthread.spawn_n(self._run_loop,
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self._KIND, self.done, _idle_for,
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initial_delay=initial_delay)
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return self.done
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class DynamicLoopingCall(LoopingCallBase):
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"""A looping call which sleeps until the next known event.
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The function called should return how long to sleep for before being
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called again.
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"""
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_KIND = _('Dynamic interval looping call')
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def start(self, initial_delay=None, periodic_interval_max=None):
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def _idle_for(suggested_delay, elapsed):
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delay = suggested_delay
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if periodic_interval_max is not None:
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delay = min(delay, periodic_interval_max)
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return delay
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self._running = True
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self.done = event.Event()
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greenthread.spawn_n(self._run_loop,
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self._KIND, self.done, _idle_for,
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initial_delay=initial_delay)
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return self.done
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