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'),
   },
 ]
 
-
 @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 29 matching lines @@
       command = self._cache['charging_config']['enable_command']
     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)
 
+  # TODO(rnephew): Make private when all use cases can use the context manager.
+  @decorators.WithTimeoutAndRetriesFromInstance()
+  def DisableBatteryUpdates(self, timeout=None, retries=None):
+    """ Resets battery data and makes device appear like it is not
+    charging so that it will collect power data since last charge.
+
+    Args:
+      timeout: timeout in seconds
+      retries: number of retries
+    """
+    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)

[jbudorick, 2015/03/17 20:03:51]

nit: formatting. Can --checkin fit on the line above?

[rnephew (Wrong account), 2015/03/17 20:37:58]

Done.

+    for line in battery_data:
+      l = line.split(',')
+      if l[3] == 'pwi' and l[1] != 0:

[jbudorick, 2015/03/17 20:03:51]

This should check the length of the list returned by l.split before using the
indices.

The expected format should also be better documented here.

[rnephew (Wrong account), 2015/03/17 20:37:58]

Done.

+        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)
+
+  # TODO(rnephew): Make private when all use cases can use the context manager.
+  @decorators.WithTimeoutAndRetriesFromInstance()
+  def EnableBatteryUpdates(self, timeout=None, retries=None):
+    """ Restarts device charging so that dumpsys no longer collects power data.
+
+    Args:
+      timeout: timeout in seconds
+      retries: number of retries
+    """
+    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. It makes
+    the device appear to stop charging so that dumpsys will start collecting
+    power data since last charge. Once the with block is exited, charging is
+    resumed and power data since last charge is no longer collected.
+
+    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
+
+    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.
 
@@ skipping 41 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)