What is the definition of asleep for an android device?

Question

I'm using

alarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME, 0, DURATION, broadcast);

To schedule an repeating task that should only be executed if the device is not asleep. As I understand the API on the AlarmManager the intent will be called once the device wakes up from sleep.

Now when is an Android device asleep? For testing I set the duration to two minutes and connected the device to my machine. Now I'm watching logcat and every two minutes it will spit out my debug message.

I always thought that an deactivated screen means that the devices starts sleeping. Or is my looking at the debug output preventing the device from sleeping? I also disconnected the USB connection and looked at the log after half an hour and I could see a call to my timer code even if the display was dark for more then 15 minutes.

How can I verify from which time the command is not executed anymore and what asleep refers to in the AlarmManager documentation? Is there a way to see from the logcat output when the device started sleeping?

Answer 1

A screen that is off, does not necessarily indicate a sleeping device. Applications can request wake locks that will keep the device awake while the screen is off. If another app has a timer that does not use inexact repeating, then the device will wake up for that as well.

Depending on the version of Android on your device, you can find a chart of your awake time in Settings - > About Phone -> Battery Use -> Then clicking on the graph up top. More information on wake locks can be found at http://developer.android.com/reference/android/os/PowerManager.html