Add restart() method to DecayingTimer

This merely provides a restart() method that passes through to the existing
restart() method on the StopWatch used as the internal for DecayingTimer so
that we can reset it.

Change-Id: Ie6b607ec588db94e2c768bd22ae736a05ab484c1

oslo_messaging/_drivers/common.py

@@ -347,6 +347,9 @@ class DecayingTimer(object):
     def start(self):
         self._watch.start()
 
+    def restart(self):
+        self._watch.restart()
+
     def check_return(self, timeout_callback=None, *args, **kwargs):
         maximum = kwargs.pop('maximum', None)
         left = self._watch.leftover(return_none=True)

oslo_messaging/tests/test_utils.py

@@ -97,3 +97,17 @@ class TimerTestCase(test_utils.BaseTestCase):
         remaining = t.check_return(callback, 1, a='b')
         self.assertEqual(0, remaining)
         callback.assert_called_once_with(1, a='b')
+
+    @mock.patch('oslo_utils.timeutils.now')
+    def test_reset(self, now):
+        now.return_value = 0
+        t = common.DecayingTimer(3)
+        t.start()
+
+        now.return_value = 1
+        remaining = t.check_return()
+        self.assertEqual(2, remaining)
+
+        t.restart()
+        remaining = t.check_return()
+        self.assertEqual(3, remaining)