Add option to output device status to a JSON file.

build/android/buildbot/bb_device_status_check.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.
 
 """A class to keep track of devices across builds and report state."""
+import json
 import logging
 import optparse
 import os
 import psutil
 import re
 import signal
 import smtplib
 import subprocess
 import sys
 import time
@@ skipping 250 matching lines @@
   parser = optparse.OptionParser()
   parser.add_option('', '--out-dir',
                     help='Directory where the device path is stored',
                     default=os.path.join(constants.DIR_SOURCE_ROOT, 'out'))
   parser.add_option('--no-provisioning-check', action='store_true',
                     help='Will not check if devices are provisioned properly.')
   parser.add_option('--device-status-dashboard', action='store_true',
                     help='Output device status data for dashboard.')
   parser.add_option('--restart-usb', action='store_true',
                     help='Restart USB ports before running device check.')
+  parser.add_option('--json-output',
+                    help='Output JSON information into a specified file.')

[tonyg, 2014/07/11 02:19:15]

We should document the format somewhere.

 
   options, args = parser.parse_args()
   if args:
     parser.error('Unknown options %s' % args)
 
   # Remove the last build's "bad devices" before checking device statuses.
   device_blacklist.ResetBlacklist()
 
   try:
     expected_devices = device_list.GetPersistentDeviceList(
@@ skipping 64 matching lines @@
     perf_tests_results_helper.PrintPerfResult('BotDevices', 'OnlineDevices',
                                               [len(devices)], 'devices')
     perf_tests_results_helper.PrintPerfResult('BotDevices', 'OfflineDevices',
                                               [len(offline_devices)], 'devices',
                                               'unimportant')
     for serial, battery in zip(devices, batteries):
       perf_tests_results_helper.PrintPerfResult('DeviceBattery', serial,
                                                 [battery], '%',
                                                 'unimportant')
 
+  if options.json_output:
+    with open(options.json_output, 'wb') as f:
+      f.write(json.dumps({
+        'online_devices': devices,

[tonyg, 2014/07/11 02:19:15]

Let's add expected_devices too.

Also, prior to recipes we got some other helpful info in the build step such as
the android version and device type.

"Online devices: 1. Device types ['mako'], builds ['KOT49H']"
http://chromegw/i/chromium.perf/builders/Android%20Nexus4%20Perf/builds/983

Should we add more info to this json so that could be restored?

[zty, 2014/07/11 18:58:30]

Acknowledged.

+        'offline_devices': offline_devices
+      }))
+
   if False in fail_step_lst:
     # TODO(navabi): Build fails on device status check step if there exists any
     # devices with critically low battery. Remove those devices from testing,
     # allowing build to continue with good devices.
     return 2
 
   if not devices:
     return 1
 
 
 if __name__ == '__main__':
   sys.exit(main())