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+# 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 keystone.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()
+
+
+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
+
+
+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
+
+ def stop(self):
+ self._running = False
+
+ def wait(self):
+ return self.done.wait()
+
+
+class FixedIntervalLoopingCall(LoopingCallBase):
+ """A fixed interval looping call."""
+
+ 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
+
+
+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.
+ """
+
+ 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