src/tools/telemetry/telemetry/core/platform/power_monitor/power_monitor_controller.py

   1 # Copyright 2014 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import telemetry.core.platform.power_monitor as power_monitor
   6
   7
   8 class PowerMonitorController(power_monitor.PowerMonitor):
   9   """
  10   PowerMonitor that acts as facade for a list of PowerMonitor objects and uses
  11   the first available one.
  12   """
  13   def __init__(self, power_monitors):
  14     super(PowerMonitorController, self).__init__()
  15     self._cascading_power_monitors = power_monitors
  16     self._active_monitor = None
  17
  18   def _AsyncPowerMonitor(self):
  19     return next(
  20         (x for x in self._cascading_power_monitors if x.CanMonitorPowerAsync()),
  21         None)
  22
  23   def CanMonitorPowerAsync(self):
  24     return bool(self._AsyncPowerMonitor())
  25
  26   def StartMonitoringPowerAsync(self):
  27     self._active_monitor = self._AsyncPowerMonitor()
  28     assert self._active_monitor, 'No available monitor.'
  29     self._active_monitor.StartMonitoringPowerAsync()
  30
  31   def StopMonitoringPowerAsync(self):
  32     assert self._active_monitor, 'StartMonitoringPowerAsync() not called.'
  33     try:
  34       return self._active_monitor.StopMonitoringPowerAsync()
  35     finally:
  36       self._active_monitor = None