Add Stopwatch.start_stop_seconds(), don't use timedelta.total_seconds().

This function is only available in Python >= 2.7. On

  http://docs.python.org/library/datetime.html#timedelta-objects

it says total_seconds() is equal to

  (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6

with true division enabled. We are using

  td.days * 24 * 3600 +
  td.seconds +
  operator.truediv(td.microseconds, 10**6)

now in Stopwatch.start_stop_seconds(), which I find more readable.

3 files changed, 11 insertions, 4 deletions

diff --git a/morphlib/builder.py b/morphlib/builder.py
index 416216d3..31fc617f 100644
--- a/morphlib/builder.py
+++ b/morphlib/builder.py
@@ -93,11 +93,10 @@ class BinaryBlob(object):
             'build-times': {}
         }
         for stage in self.build_watch.ticks.iterkeys():
-            delta = self.build_watch.start_stop_delta(stage)
             meta['build-times'][stage] = {
                 'start': '%s' % self.build_watch.start_time(stage),
                 'stop': '%s' % self.build_watch.stop_time(stage),
-                'delta': delta.total_seconds()
+                'delta': self.build_watch.start_stop_seconds(stage)
             }
         self.write_cache_metadata(meta)
 
diff --git a/morphlib/stopwatch.py b/morphlib/stopwatch.py
index bcdc9291..492738d5 100644
--- a/morphlib/stopwatch.py
+++ b/morphlib/stopwatch.py
@@ -14,6 +14,8 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 
+import operator
+
 from datetime import datetime
 
 
@@ -48,3 +50,9 @@ class Stopwatch(object):
     def start_stop_delta(self, reference_object):
         return (self.stop_time(reference_object) - 
                 self.start_time(reference_object))
+
+    def start_stop_seconds(self, reference_object):
+        delta = self.start_stop_delta(reference_object)
+        return (delta.days * 24 * 3600 +
+                delta.seconds +
+                operator.truediv(delta.microseconds, 10**6))
diff --git a/morphlib/stopwatch_tests.py b/morphlib/stopwatch_tests.py
index 7441eac3..1a899f41 100644
--- a/morphlib/stopwatch_tests.py
+++ b/morphlib/stopwatch_tests.py
@@ -53,6 +53,6 @@ class StopwatchTests(unittest.TestCase):
 
         our_delta = stop - start
         watch_delta = self.stopwatch.start_stop_delta('start-stop')
-
-        assert our_delta.total_seconds() > 0
         self.assertEqual(our_delta, watch_delta)
+
+        assert self.stopwatch.start_stop_seconds('start-stop') > 0