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

This is the src/ part of trying to make android up and downstream run more or
less the same stack for perf tests.
Instead of requiring all steps listed (which allows sharding), this instead
allows running a single step, with retries and other niceties such as adb
restarting, device fail over, etc..

BUG=

Review URL: https://codereview.chromium.org/66373004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234493 0039d316-1c4b-4281-b951-d872f2087c98

build/android/pylib/perf/setup.py

@@ -66,8 +66,13 @@ def Setup(test_options):
   # Before running the tests, kill any leftover server.
   _KillPendingServers()
 
-  with file(test_options.steps, 'r') as f:
-    tests = json.load(f)
+  if test_options.single_step:
+    # Running a single command, build the tests structure.
+    tests = [['single_step', test_options.single_step]]
+
+  if test_options.steps:
+    with file(test_options.steps, 'r') as f:
+      tests = json.load(f)
 
   # The list is necessary to keep the steps order, but internally
   # the format is squashed from a list of lists into a single dict:

build/android/pylib/perf/test_options.py

@@ -13,4 +13,5 @@
     'no_timeout',
     'test_filter',
     'dry_run',
+    'single_step',
 ])

build/android/pylib/perf/test_runner.py

@@ -141,9 +141,12 @@ def _LaunchPerfTest(self, test_name):
     if self._options.dry_run:
       full_cmd = 'echo %s' % cmd
 
+    logfile = sys.stdout
+    if self._options.single_step:
+      logfile = None
     output, exit_code = pexpect.run(
         full_cmd, cwd=os.path.abspath(constants.DIR_SOURCE_ROOT),
-        withexitstatus=True, logfile=sys.stdout, timeout=timeout,
+        withexitstatus=True, logfile=logfile, timeout=timeout,
         env=os.environ)
     end_time = datetime.datetime.now()
     if exit_code is None:

build/android/test_runner.py

@@ -435,11 +435,18 @@ def AddPerfTestOptions(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 '
@@ -472,11 +479,15 @@ def ProcessPerfTestOptions(options, error_func):
     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):
@@ -634,6 +645,10 @@ def _RunPerfTests(options, error_func, devices):
       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