Add elapsed-time sorting option to build summary

post_build_ninja_summary.py normally sorts its output by weighted time,
which is elapsed time divided by how many steps are running. Sometimes
it is more appropriate to sort by elapsed (wall clock) time instead.
This adds a -e/--elapsed_time_sorting option to do this.

Change-Id: I13a1b094f8fd7f6795a871bee91932ce0ddab79d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4285697
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>

post_build_ninja_summary.py

@@ -206,7 +206,7 @@ def GetExtension(target, extra_patterns):
   return extension
 
 
-def SummarizeEntries(entries, extra_step_types):
+def SummarizeEntries(entries, extra_step_types, elapsed_time_sorting):
     """Print a summary of the passed in list of Target objects."""
 
     # Create a list that is in order by time stamp and has entries for the
@@ -271,9 +271,12 @@ def SummarizeEntries(entries, extra_step_types):
             'untrustworthy. Length = %.3f, weighted total = %.3f' % (
             length, weighted_total))
 
-    # Print the slowest build steps (by weighted time).
+    # Print the slowest build steps:
     print('    Longest build steps:')
-    entries.sort(key=lambda x: x.WeightedDuration())
+    if elapsed_time_sorting:
+      entries.sort(key=lambda x: x.Duration())
+    else:
+      entries.sort(key=lambda x: x.WeightedDuration())
     for target in entries[-long_count:]:
       print('      %8.1f weighted s to build %s (%.1f s elapsed time)' % (
             target.WeightedDuration(),
@@ -293,9 +296,13 @@ def SummarizeEntries(entries, extra_step_types):
 
     print('    Time by build-step type:')
     # Copy to a list with extension name and total time swapped, to (time, ext)
-    weighted_time_by_ext_sorted = sorted((y, x) for (x, y) in
-                                          weighted_time_by_ext.items())
-    # Print the slowest build target types (by weighted time):
+    if elapsed_time_sorting:
+      weighted_time_by_ext_sorted = sorted((y, x) for (x, y) in
+                                            time_by_ext.items())
+    else:
+      weighted_time_by_ext_sorted = sorted((y, x) for (x, y) in
+                                            weighted_time_by_ext.items())
+    # Print the slowest build target types:
     for time, extension in weighted_time_by_ext_sorted[-long_ext_count:]:
         print('      %8.1f s weighted time to generate %d %s files '
                '(%1.1f s elapsed time sum)' % (time, count_by_ext[extension],
@@ -317,6 +324,12 @@ def main():
         '-s',
         '--step-types',
         help='semicolon separated fnmatch patterns for build-step grouping')
+    parser.add_argument(
+        '-e',
+        '--elapsed_time_sorting',
+        default=False,
+        action='store_true',
+        help='Sort output by elapsed time instead of weighted time')
     parser.add_argument('--log-file',
                         help="specific ninja log file to analyze.")
     args, _extra_args = parser.parse_known_args()
@@ -337,7 +350,7 @@ def main():
     try:
       with open(log_file, 'r') as log:
         entries = ReadTargets(log, False)
-        SummarizeEntries(entries, args.step_types)
+        SummarizeEntries(entries, args.step_types, args.elapsed_time_sorting)
     except IOError:
       print('Log file %r not found, no build summary created.' % log_file)
       return errno.ENOENT