timeutils: avoid passing leap second to datetime

Python datetime module does not support leap seconds [1]. The best thing
we can do without switching API to using another time module is to
avoid passing leap seconds to underlying python module.

Note: next leap second is scheduled for June 30 [2].

[1]: http://bugs.python.org/issue23574
[2]: http://www.usatoday.com/story/tech/2015/01/08/computer-chaos-feares/21433363/

Closes-Bug: #1427212
Change-Id: I7ffd8121cb20f3742e8e9cd7d4b8f0f15fa6ca9a

oslo_utils/tests/test_timeutils.py

@@ -191,6 +191,18 @@ class TimeUtilsTest(test_base.BaseTestCase):
         backagain = timeutils.unmarshall_time(binary)
         self.assertEqual(now, backagain)
 
+    def test_unmarshall_time_leap_second(self):
+        leap_dict = dict(day=30, month=6, year=2015,
+                         hour=23, minute=59,
+                         second=timeutils._MAX_DATETIME_SEC + 1,
+                         microsecond=0)
+        leap_time = timeutils.unmarshall_time(leap_dict)
+
+        leap_dict.update(second=timeutils._MAX_DATETIME_SEC)
+        expected = timeutils.unmarshall_time(leap_dict)
+
+        self.assertEqual(expected, leap_time)
+
     def test_delta_seconds(self):
         before = timeutils.utcnow()
         after = before + datetime.timedelta(days=7, seconds=59,

oslo_utils/timeutils.py

@@ -31,6 +31,8 @@ _ISO8601_TIME_FORMAT_SUBSECOND = '%Y-%m-%dT%H:%M:%S.%f'
 _ISO8601_TIME_FORMAT = '%Y-%m-%dT%H:%M:%S'
 PERFECT_TIME_FORMAT = _ISO8601_TIME_FORMAT_SUBSECOND
 
+_MAX_DATETIME_SEC = 59
+
 # Use monotonic time in stopwatches if we can get at it...
 #
 # PEP @ https://www.python.org/dev/peps/pep-0418/
@@ -211,12 +213,17 @@ def marshall_now(now=None):
 
 def unmarshall_time(tyme):
     """Unmarshall a datetime dict."""
+
+    # NOTE(ihrachys): datetime does not support leap seconds,
+    # so the best thing we can do for now is dropping them
+    # http://bugs.python.org/issue23574
+    second = min(tyme['second'], _MAX_DATETIME_SEC)
     return datetime.datetime(day=tyme['day'],
                              month=tyme['month'],
                              year=tyme['year'],
                              hour=tyme['hour'],
                              minute=tyme['minute'],
-                             second=tyme['second'],
+                             second=second,
                              microsecond=tyme['microsecond'])