Source code for ceilometer.openstack.common.loopingcall

# 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 logging
import sys
import time

from eventlet import event
from eventlet import greenthread

from ceilometer.openstack.common._i18n import _LE, _LW

LOG = logging.getLogger(__name__)

# NOTE(zyluo): This lambda function was declared to avoid mocking collisions
#              with time.time() called in the standard logging module
#              during unittests.
_ts = lambda: time.time()


[docs]class LoopingCallDone(Exception): """Exception to break out and stop a LoopingCallBase. The poll-function passed to LoopingCallBase 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 LoopingCallBase.wait() """ def __init__(self, retvalue=True): """:param retvalue: Value that LoopingCallBase.wait() should return.""" self.retvalue = retvalue
[docs]class LoopingCallBase(object): def __init__(self, f=None, *args, **kw): self.args = args self.kw = kw self.f = f self._running = False self.done = None
[docs] def stop(self): self._running = False
[docs] def wait(self): return self.done.wait()
[docs]class FixedIntervalLoopingCall(LoopingCallBase): """A fixed interval looping call."""
[docs] 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 = _ts() self.f(*self.args, **self.kw) end = _ts() if not self._running: break delay = end - start - interval if delay > 0: LOG.warn(_LW('task %(func_name)r run outlasted ' 'interval by %(delay).2f sec'), {'func_name': self.f, 'delay': delay}) greenthread.sleep(-delay if delay < 0 else 0) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_LE('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
[docs]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. """
[docs] 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 %(func_name)r sleeping ' 'for %(idle).02f seconds', {'func_name': self.f, 'idle': idle}) greenthread.sleep(idle) except LoopingCallDone as e: self.stop() done.send(e.retvalue) except Exception: LOG.exception(_LE('in dynamic looping call')) done.send_exception(*sys.exc_info()) return else: done.send(True) self.done = done greenthread.spawn(_inner) return self.done