From 22eef9618b7e84a4dea7bb143f36ed7e0fc11924 Mon Sep 17 00:00:00 2001
From: Joshua Harlow <harlowja@yahoo-inc.com>
Date: Thu, 15 Jan 2015 11:29:33 -0800
Subject: [PATCH] Provide the stopwatch elapsed method a maximum

To anticipate moving this code over to oslo.utils so that
it can be shared by taskflow, oslo.messaging (and others) add
a maximum elapsed value to the elapsed method which will
limit the maximum value it returns.

Change-Id: Ica85cbd39b34211ac04cd58dcbdc499a778487b0
---
 taskflow/tests/unit/test_types.py | 17 +++++++++++++++++
 taskflow/types/timing.py          | 19 +++++++++++--------
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/taskflow/tests/unit/test_types.py b/taskflow/tests/unit/test_types.py
index 85d6e557..d13124ac 100644
--- a/taskflow/tests/unit/test_types.py
+++ b/taskflow/tests/unit/test_types.py
@@ -217,6 +217,23 @@ class StopWatchTest(test.TestCase):
         watch.start()
         self.assertEqual(0, len(watch.splits))
 
+    def test_elapsed_maximum(self):
+        watch = tt.StopWatch()
+        watch.start()
+
+        timeutils.advance_time_seconds(1)
+        self.assertEqual(1, watch.elapsed())
+
+        timeutils.advance_time_seconds(10)
+        self.assertEqual(11, watch.elapsed())
+        self.assertEqual(1, watch.elapsed(maximum=1))
+
+        watch.stop()
+        self.assertEqual(11, watch.elapsed())
+        timeutils.advance_time_seconds(10)
+        self.assertEqual(11, watch.elapsed())
+        self.assertEqual(0, watch.elapsed(maximum=-1))
+
 
 class TableTest(test.TestCase):
     def test_create_valid_no_rows(self):
diff --git a/taskflow/types/timing.py b/taskflow/types/timing.py
index 2cbeee9b..5001762f 100644
--- a/taskflow/types/timing.py
+++ b/taskflow/types/timing.py
@@ -136,17 +136,20 @@ class StopWatch(object):
         self.start()
         return self
 
-    def elapsed(self):
+    def elapsed(self, maximum=None):
         """Returns how many seconds have elapsed."""
-        if self._state == self._STOPPED:
-            return max(0.0, float(timeutils.delta_seconds(self._started_at,
-                                                          self._stopped_at)))
-        elif self._state == self._STARTED:
-            return max(0.0, float(timeutils.delta_seconds(self._started_at,
-                                                          timeutils.utcnow())))
-        else:
+        if self._state not in (self._STOPPED, self._STARTED):
             raise RuntimeError("Can not get the elapsed time of a stopwatch"
                                " if it has not been started/stopped")
+        if self._state == self._STOPPED:
+            elapsed = max(0.0, float(timeutils.delta_seconds(
+                self._started_at, self._stopped_at)))
+        else:
+            elapsed = max(0.0, float(timeutils.delta_seconds(
+                self._started_at, timeutils.utcnow())))
+        if maximum is not None and elapsed > maximum:
+            elapsed = max(0.0, maximum)
+        return elapsed
 
     def __enter__(self):
         """Starts the watch."""