Add loopingcall from openstack-common

Change-Id: I65a1eb1676f0efb4decb75aa3dfd3af35012bd77

openstack-common.conf

@@ -1,5 +1,5 @@
 [DEFAULT]
 # The list of modules to copy from openstack-common
-modules=cfg,exception,importutils,iniparser,jsonutils,policy,setup,network_utils,notifier,timeutils,log,context,local,rpc,gettextutils,excutils,uuidutils,service
+modules=cfg,exception,importutils,iniparser,jsonutils,policy,setup,network_utils,notifier,timeutils,log,context,local,rpc,gettextutils,excutils,uuidutils,service,loopingcall
 # The base module to hold the copy of openstack.common
 base=quantum

quantum/openstack/common/loopingcall.py

@@ -0,0 +1,88 @@
+# 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 quantum.openstack.common.gettextutils import _
+from quantum.openstack.common import log as logging
+
+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:
+                    self.f(*self.args, **self.kw)
+                    if not self._running:
+                        break
+                    greenthread.sleep(interval)
+            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()