Import and convert to oslo loopingcall.

Import the oslo looping call implementation (which is a copy of
nova's), delete nova's local copy, convert all users to the new
location.

It should be noted that the oslo implementation of
FixedIntervalLoopingCall measures time from the start of the
periodic task, not the end, so periodic tasks will run with a
constant frequency instead of the frequency changing depending on
how long the periodic task takes to run.

Change-Id: Ia62ce1988f5373c09146efa6b3b1d1dc094d50c4

1 files changed, 147 insertions, 0 deletions

diff --git a/nova/openstack/common/loopingcall.py b/nova/openstack/common/loopingcall.py
new file mode 100644
index 000000000..f9ca53003
--- /dev/null
+++ b/nova/openstack/common/loopingcall.py
@@ -0,0 +1,147 @@
+# 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 nova.openstack.common.gettextutils import _
+from nova.openstack.common import log as logging
+from nova.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 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 = 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 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
+
+
+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 sleeping for %.02f '
+                                'seconds'), idle)
+                    greenthread.sleep(idle)
+            except LoopingCallDone, 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