Add new method to disable android device charging.

build/android/pylib/device/device_utils.py

 # Copyright 2014 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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=unused-argument
 
 import collections
+import contextlib
 import itertools
 import logging
 import multiprocessing
 import os
 import re
 import sys
 import tempfile
 import time
 import zipfile
 
@@ skipping 40 matching lines @@
     'enable_command': (
         'echo 0x4A > /sys/kernel/debug/bq24192/INPUT_SRC_CONT && '
         'echo 1 > /sys/class/power_supply/usb/online'),
     'disable_command': (
         'echo 0xCA > /sys/kernel/debug/bq24192/INPUT_SRC_CONT && '
         'chmod 644 /sys/class/power_supply/usb/online && '
         'echo 0 > /sys/class/power_supply/usb/online'),
   },
 ]
 
-

[perezju, 2015/03/17 12:52:19]

nit: this line went missing

 @decorators.WithExplicitTimeoutAndRetries(
     _DEFAULT_TIMEOUT, _DEFAULT_RETRIES)
 def GetAVDs():
   """Returns a list of Android Virtual Devices.
 
   Returns:
     A list containing the configured AVDs.
   """
   lines = cmd_helper.GetCmdOutput([
       os.path.join(constants.ANDROID_SDK_ROOT, 'tools', 'android'),
@@ skipping 1324 matching lines @@
       timeout: timeout in seconds
       retries: number of retries
     Returns:
       A dict containing various battery information as reported by dumpsys
       battery.
     """
     result = {}
     # Skip the first line, which is just a header.
     for line in self.RunShellCommand(
         ['dumpsys', 'battery'], check_return=True)[1:]:
-      k, v = line.split(': ', 1)
-      result[k.strip()] = v.strip()
+      # If usb charging has been disabled, an extra line of header exists.
+      if 'UPDATES STOPPED' in line:
+        logging.warning('Dumpsys battery not receiving updates. '
+                        'Run dumpsys battery reset if this is in error.')
+      elif ':' not in line:
+        logging.warning('Unknown line found in dumpsys battery.')
+        logging.warning(line)
+      else:
+        k, v = line.split(': ', 1)
+        result[k.strip()] = v.strip()
     return result
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def GetCharging(self, timeout=None, retries=None):
     """Gets the charging state of the device.
 
     Args:
       timeout: timeout in seconds
       retries: number of retries
     Returns:
@@ skipping 30 matching lines @@
     else:
       command = self._cache['charging_config']['disable_command']
 
     def set_and_verify_charging():
       self.RunShellCommand(command, check_return=True)
       return self.GetCharging() == enabled
 
     timeout_retry.WaitFor(set_and_verify_charging, wait_period=1)
 
   @decorators.WithTimeoutAndRetriesFromInstance()
+  def _DisableBatteryUpdates(self, timeout=None, retries=None):
+    def battery_updates_disabled():
+      return self.GetCharging() is False
+
+    self.RunShellCommand(
+        ['dumpsys', 'batterystats', '--reset'], check_return=True)
+    battery_data = self.RunShellCommand(
+        ['dumpsys', 'batterystats', '--charged',
+        '--checkin'], check_return=True)
+    for line in battery_data:
+      l = line.split(',')
+      if l[3] == 'pwi' and l[1] != 0:
+        raise device_errors.CommandFailedError(
+            'Non-zero pmi value found after reset.')
+    self.RunShellCommand(['dumpsys', 'battery', 'set', 'usb', '0'],
+                         check_return=True)
+    timeout_retry.WaitFor(battery_updates_disabled, wait_period=1)
+
+  @decorators.WithTimeoutAndRetriesFromInstance()
+  def _EnableBatteryUpdates(self, timeout=None, retries=None):
+    def battery_updates_enabled():
+      return self.GetCharging() is True
+
+    self.RunShellCommand(['dumpsys', 'battery', 'reset'], check_return=True)
+    timeout_retry.WaitFor(battery_updates_enabled, wait_period=1)
+
+  @contextlib.contextmanager
+  def BatteryMeasurement(self, timeout=None, retries=None):
+    """Context manager that enables battery data collection when in.
+    Only for devices L and higher.
+
+    Example usage:
+      with BatteryMeasurement():
+        browser_actions()
+        get_power_data() # report usage within this block
+      after_measurements() # Anything that runs after power
+                           # measurements are collected

[perezju, 2015/03/17 12:52:19]

nit: I think these comments could be improved a bit. I understand that battery
measurements within the context manager block will report usage relative to the
start of the block ("as if" the device had stopped charging then); while battery
measurements taken after exiting the block will revert to report live usage (and
do not aggregate data that would otherwise be collected "since last charge").

Is this more or less accurate? Could you update the comments to better reflect
the intended behavior?

[rnephew (Wrong account), 2015/03/17 19:58:42]

Done.

+
+    Args:
+      timeout: timeout in seconds
+      retries: number of retries
+    """
+    if self.build_version_sdk < constants.ANDROID_SDK_VERSION_CODES.LOLLIPOP:
+      raise device_errors.CommandFailedError('Device must be L or higher.')
+    try:
+      self._DisableBatteryUpdates(timeout=timeout, retries=retries)
+      yield
+    finally:
+      self._EnableBatteryUpdates(timeout=timeout, retries=retries)
+
+  @decorators.WithTimeoutAndRetriesFromInstance()
   def GetDevicePieWrapper(self, timeout=None, retries=None):
     """Gets the absolute path to the run_pie wrapper on the device.
 
     We have to build our device executables to be PIE, but they need to be able
     to run on versions of android that don't support PIE (i.e. ICS and below).
     To do so, we push a wrapper to the device that lets older android versions
     run PIE executables. This method pushes that wrapper to the device if
     necessary and returns the path to it.
 
     This is exposed publicly to allow clients to write scripts using run_pie
@@ skipping 40 matching lines @@
     """
     if not devices:
       devices = adb_wrapper.AdbWrapper.GetDevices()
       if not devices:
         raise device_errors.NoDevicesError()
     devices = [d if isinstance(d, cls) else cls(d) for d in devices]
     if async:
       return parallelizer.Parallelizer(devices)
     else:
       return parallelizer.SyncParallelizer(devices)