[Sensors][proposed patch] sensors.py: Current implementation of bat_get_data very slow

[peacey]

Hello,

The current implementation of bat_get_data is extremely slow. It takes around 2 seconds to even 3 sometimes for the function to return. Consequently, this causes any screenlet that uses this function to stall for 2 or 3 seconds. It even causes the preferences window of the screenlet to stall whenever the battery information gets updated.
Instead, I propose we use dbus to obtain the battery information.

Here are the two functions:

def bat_get_battery_list_from_dbus():
 """Returns battery list"""
 """DBus version"""
 try:
  system_bus = dbus.SystemBus()
         hal_manager = system_bus.get_object('org.freedesktop.Hal', '/org/freedesktop/Hal/Manager')
  batteries = hal_manager.FindDeviceByCapability('battery', dbus_interface='org.freedesktop.Hal.Manager')
  return batteries
 except:
  return[]

def bat_get_data_from_dbus(udi):
 """Returns battery data"""
 """DBus version"""
 try:
  total = 0
  current = 0
  full = 0
  state = ''
  present = True
  system_bus = dbus.SystemBus()
  bat_obj = system_bus.get_object('org.freedesktop.Hal', udi)
  battery = dbus.Interface(bat_obj, dbus_interface='org.freedesktop.Hal.Device')
  present = battery.GetProperty('battery.present')
  total = battery.GetProperty('battery.reporting.design')
  full = battery.GetProperty('battery.reporting.last_full')
  current = battery.GetProperty('battery.reporting.current')
  if (battery.GetProperty('battery.rechargeable.is_charging') == True):
   state = "charging"
  else:
   state = "discharging"
  return total, current, full, state, present
 except:
  return 0, 0, 0, '', False

I have tested this on my machine and there are no more stalls or lags.
There are two proposed patches in the tar file attached: the first one is for sensors.py and the second one is for SysmonitorScreenlet.py for demonstration purposes.
The second patch modifies SysmonitorScreenlet.py to use the new dbus battery functions.
Note: In the SysmonitorScreenlet patch, the last modification was added because in my SysmonitorScreenlet, the Uptime text that is rendered is rendered on top of the processes/top command which makes it hard to read. So I just moved it down a little. Not sure if it happens to others.