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OpenStack Study: loopingcall.py**** CubicPower OpenStack Study ****
# 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 2011 Justin Santa Barbara # 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. import sys from eventlet import event from eventlet import greenthread from glance.openstack.common.gettextutils import _ from glance.openstack.common import log as logging from glance.openstack.common import timeutils LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class LoopingCallDone(Exception): """Exception to break out and stop a LoopingCall. The poll-function passed to LoopingCall can raise this exception to break out of the loop normally. This is somewhat analogous to StopIteration. An optional return-value can be included as the argument to the exception; this return-value will be returned by LoopingCall.wait() """
**** CubicPower OpenStack Study **** def __init__(self, retvalue=True): """:param retvalue: Value that LoopingCall.wait() should return.""" self.retvalue = retvalue
**** CubicPower OpenStack Study **** class LoopingCallBase(object):
**** CubicPower OpenStack Study **** def __init__(self, f=None, *args, **kw): self.args = args self.kw = kw self.f = f self._running = False self.done = None
**** CubicPower OpenStack Study **** def stop(self): self._running = False
**** CubicPower OpenStack Study **** def wait(self): return self.done.wait()
**** CubicPower OpenStack Study **** class FixedIntervalLoopingCall(LoopingCallBase): """A fixed interval looping call."""
**** CubicPower OpenStack Study **** def start(self, interval, initial_delay=None): self._running = True done = event.Event() def _inner(): if initial_delay: greenthread.sleep(initial_delay) try: while self._running: start = timeutils.utcnow() self.f(*self.args, **self.kw) end = timeutils.utcnow() if not self._running: break delay = interval - timeutils.delta_seconds(start, end) if delay <= 0: LOG.warn(_('task run outlasted interval by %s sec') % -delay) greenthread.sleep(delay if delay > 0 else 0) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_('in fixed duration looping call')) done.send_exception(*sys.exc_info()) return else: done.send(True) self.done = done greenthread.spawn_n(_inner) return self.done # TODO(mikal): this class name is deprecated in Havana and should be removed # in the I release LoopingCall = FixedIntervalLoopingCall
**** CubicPower OpenStack Study **** def _inner(): if initial_delay: greenthread.sleep(initial_delay) try: while self._running: start = timeutils.utcnow() self.f(*self.args, **self.kw) end = timeutils.utcnow() if not self._running: break delay = interval - timeutils.delta_seconds(start, end) if delay <= 0: LOG.warn(_('task run outlasted interval by %s sec') % -delay) greenthread.sleep(delay if delay > 0 else 0) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_('in fixed duration looping call')) done.send_exception(*sys.exc_info()) return else: done.send(True) self.done = done greenthread.spawn_n(_inner) return self.done # TODO(mikal): this class name is deprecated in Havana and should be removed # in the I release LoopingCall = FixedIntervalLoopingCall
**** CubicPower OpenStack Study **** class DynamicLoopingCall(LoopingCallBase): """A looping call which sleeps until the next known event. The function called should return how long to sleep for before being called again. """
**** CubicPower OpenStack Study **** def start(self, initial_delay=None, periodic_interval_max=None): self._running = True done = event.Event() def _inner(): if initial_delay: greenthread.sleep(initial_delay) try: while self._running: idle = self.f(*self.args, **self.kw) if not self._running: break if periodic_interval_max is not None: idle = min(idle, periodic_interval_max) LOG.debug(_('Dynamic looping call sleeping for %.02f ' 'seconds'), idle) greenthread.sleep(idle) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_('in dynamic looping call')) done.send_exception(*sys.exc_info()) return else: done.send(True) self.done = done greenthread.spawn(_inner) return self.done
**** CubicPower OpenStack Study **** def _inner(): if initial_delay: greenthread.sleep(initial_delay) try: while self._running: idle = self.f(*self.args, **self.kw) if not self._running: break if periodic_interval_max is not None: idle = min(idle, periodic_interval_max) LOG.debug(_('Dynamic looping call sleeping for %.02f ' 'seconds'), idle) greenthread.sleep(idle) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_('in dynamic looping call')) done.send_exception(*sys.exc_info()) return else: done.send(True) self.done = done greenthread.spawn(_inner) return self.done
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