Source Code for Module sparked.hardware.power

  1  # Copyright (c) 2010 Arjan Scherpenisse 
  2  # See LICENSE for details. 
  3   
  4  """ 
  5  Power monitor: fires events when AC power becomes (un)available; and 
  6  fires an event when the power becomes critically low. 
  7  """ 
  8   
  9  import dbus 
 10   
 11  from twisted.application import service 
 12  from sparked import events 
 13   
 14   
 15 -class PowerService(service.Service): 
 16      """ 
 17      A service which monitors the power state of the computer. It fires 
 18      "available" and "low" events when the power state changes. On the 
 19      startup of the service, these signals get fired once to ensure a 
 20      valid system state. 
 21      """ 
 22   
 23 -    def __init__(self): 
 24          self.manager = None 
 25   
 26   
 27 -    def startService(self): 
 28   
 29          try: 
 30              bus = dbus.Bus() 
 31              hal_interface = 'org.freedesktop.PowerManagement' 
 32              hal_udi = '/org/freedesktop/PowerManagement' 
 33   
 34              managerObj = bus.get_object(hal_interface, hal_udi) 
 35              bus.add_signal_receiver(self.powerEvent, 
 36                                           dbus_interface=hal_interface, 
 37                                           signal_name='OnBatteryChanged') 
 38              bus.add_signal_receiver(self.lowpowerEvent, 
 39                                           dbus_interface=hal_interface, 
 40                                           signal_name='LowBatteryChanged') 
 41              manager    = dbus.Interface(managerObj, hal_interface) 
 42   
 43              self.powerEvent(manager.GetOnBattery()) 
 44              self.lowpowerEvent(manager.GetLowBattery()) 
 45   
 46          except dbus.exceptions.DBusException: 
 47              # not found, try DeviceKit 
 48              try: 
 49                  bus = dbus.SystemBus() 
 50                  dk_interface = 'org.freedesktop.DeviceKit.Power' 
 51                  dk_udi = '/org/freedesktop/DeviceKit/Power' 
 52   
 53                  managerObj = bus.get_object(dk_interface, dk_udi) 
 54                  bus.add_signal_receiver(self.dkPowerChanged, 
 55                                               dbus_interface=dk_interface, 
 56                                               signal_name='Changed') 
 57                  manager    = dbus.Interface(managerObj, dk_interface) 
 58                  self.dk_properties = dbus.Interface(managerObj, 'org.freedesktop.DBus.Properties') 
 59                  self.dkPowerChanged() 
 60   
 61              except dbus.exceptions.DBusException: 
 62                  # finally, try UPower 
 63                  bus = dbus.SystemBus() 
 64                  dk_interface = 'org.freedesktop.UPower' 
 65                  dk_udi = '/org/freedesktop/UPower' 
 66   
 67                  managerObj = bus.get_object(dk_interface, dk_udi) 
 68                  bus.add_signal_receiver(self.upPowerChanged, 
 69                                               dbus_interface=dk_interface, 
 70                                               signal_name='Changed') 
 71                  manager    = dbus.Interface(managerObj, dk_interface) 
 72                  self.up_properties = dbus.Interface(managerObj, 'org.freedesktop.DBus.Properties') 
 73                  self.upPowerChanged() 
 74   
 75   
 76 -    def upPowerChanged(self): 
 77          """ 
 78          Called when UPower signals that something with the power has changed. 
 79          """ 
 80          dk_interface = 'org.freedesktop.UPower' 
 81          self.powerEvent(self.up_properties.Get(dk_interface, "OnBattery")) 
 82          self.lowpowerEvent(self.up_properties.Get(dk_interface, "OnLowBattery")) 
 83   
 84   
 85 -    def dkPowerChanged(self): 
 86          """ 
 87          Called when DeviceKit signals that something with the power has changed. 
 88          """ 
 89          dk_interface = 'org.freedesktop.DeviceKit.Power' 
 90          self.powerEvent(self.dk_properties.Get(dk_interface, "on-battery")) 
 91          self.lowpowerEvent(self.dk_properties.Get(dk_interface, "on-low-battery")) 
 92   
 93   
 94 -    def powerEvent(self, onBattery): 
 95          """ 
 96          Called when the power state switches between running on battery and 
 97          running on mains. The 'available' field contains a flag which is True 
 98          when the computer is running on mains (AC) power. 
 99          """ 
100          powerEvents.dispatch("available", not onBattery) 
101   
102   
103 -    def lowpowerEvent(self, low): 
104          """ 
105          Called when the battery state becomes critically low, or 
106          changes from critical back to normal. When the 'low' field of 
107          the event is True, the power is critically low.  Triggers a 
108          'low' event on this module's dispatcher. 
109          """ 
110          powerEvents.dispatch("low", low) 
111   
112   
113  powerEvents = events.EventDispatcher() 
114