Android: allow a --single-step for test_runner.py perf.

build/android/test_runner.py

 #!/usr/bin/env python
 #
 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Runs all types of tests from one unified interface."""
 
 import collections
 import logging
@@ skipping 416 matching lines @@
       options.throttle,
       options.seed,
       options.extra_args)
 
 
 def AddPerfTestOptions(option_parser):
   """Adds perf test options to |option_parser|."""
 
   option_parser.usage = '%prog perf [options]'
   option_parser.commands_dict = {}
-  option_parser.example = ('%prog perf --steps perf_steps.json')
+  option_parser.example = ('%prog perf '
+                           '[--single-step command] or '
+                           '[--steps perf_steps.json] or '
+                           '[--print-step  step]')
 
   option_parser.add_option(
+      '--single-step',
+      help='Execute the given command with retries, but only print the result '
+           'for the "most successful" round.')
+  option_parser.add_option(
       '--steps',
-      help='JSON file containing the list of perf steps to run.')
+      help='JSON file containing the list of commands to run.')
   option_parser.add_option(
       '--flaky-steps',
       help=('A JSON file containing steps that are flaky '
             'and will have its exit code ignored.'))
   option_parser.add_option(
       '--print-step',
       help='The name of a previously executed perf step to print.')
   option_parser.add_option(
       '--no-timeout', action='store_true',
       help=('Do not impose a timeout. Each perf step is responsible for '
@@ skipping 12 matching lines @@
   """Processes all perf test options.
 
   Args:
     options: optparse.Options object.
     error_func: Function to call with the error message in case of an error.
 
   Returns:
     A PerfOptions named tuple which contains all options relevant to
     perf tests.
   """
-  if not options.steps and not options.print_step:
-    error_func('Please specify --steps or --print-step')
+  # Only one of steps, print_step or single_step must be provided.
+  count = len(filter(None,
+                     [options.steps, options.print_step, options.single_step]))
+  if count != 1:
+    error_func('Please specify one of: --steps, --print-step, --single-step.')
   return perf_test_options.PerfOptions(
       options.steps, options.flaky_steps, options.print_step,
-      options.no_timeout, options.test_filter, options.dry_run)
+      options.no_timeout, options.test_filter, options.dry_run,
+      options.single_step)
 
 
 def _RunGTests(options, error_func, devices):
   """Subcommand of RunTestsCommands which runs gtests."""
   ProcessGTestOptions(options)
 
   exit_code = 0
   for suite_name in options.suite_name:
     # TODO(gkanwar): Move this into ProcessGTestOptions once we require -s for
     # the gtest command.
@@ skipping 137 matching lines @@
   runner_factory, tests = perf_setup.Setup(perf_options)
 
   results, _ = test_dispatcher.RunTests(
       tests, runner_factory, devices, shard=True, test_timeout=None,
       num_retries=options.num_retries)
 
   report_results.LogFull(
       results=results,
       test_type='Perf',
       test_package='Perf')
+
+  if perf_options.single_step:
+    return perf_test_runner.PrintTestOutput('single_step')
+
   # Always return 0 on the sharding stage. Individual tests exit_code
   # will be returned on the print_step stage.
   return 0
 
 
 def _GetAttachedDevices(test_device=None):
   """Get all attached devices.
 
   Args:
     test_device: Name of a specific device to use.
@@ skipping 121 matching lines @@
 
 
 def main(argv):
   option_parser = command_option_parser.CommandOptionParser(
       commands_dict=VALID_COMMANDS)
   return command_option_parser.ParseAndExecute(option_parser)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))