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# 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 openstack.common.gettextutils import _
from openstack.common import log as logging
from openstack.common import timeutils
LOG = logging.getLogger(__name__)
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()
"""
def __init__(self, retvalue=True):
""":param retvalue: Value that LoopingCall.wait() should return."""
self.retvalue = retvalue
class LoopingCall(object):
def __init__(self, f=None, *args, **kw):
self.args = args
self.kw = kw
self.f = f
self._running = False
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, e:
self.stop()
done.send(e.retvalue)
except Exception:
LOG.exception(_('in looping call'))
done.send_exception(*sys.exc_info())
return
else:
done.send(True)
self.done = done
greenthread.spawn_n(_inner)
return self.done
def stop(self):
self._running = False
def wait(self):
return self.done.wait()
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