问题
In the book Pro Android 4 By Satya Komatineni , Dave MacLean I've found:
Android acquires a partial wake lock when invoking a broadcast service and releases it when it returns from the service in the main thread
Does it mean that the Android OS ensures that the device will wake up for the time of going through onReceive of BroadcastReceiver? In my case the BroadcastReceiver should get an intent from Google Play Services (GoogleLocationServices and to be precise Geofences api).
Where is it documented?
EDIT: I've also found it here:
because it is guaranteed that the BroadcastReceiver.onReceive() will be always fully executed before the CPU goes to sleep
回答1:
There is no such thing as a "broadcast service".
Also, you need to read the entire post containing your second quote, as that is only for a broadcast triggered by AlarmManager. It is AlarmManager, not the broadcast Intent mechanism, that holds the WakeLock. Also, as noted in that blog post, Dianne Hackborn had confirmed this behavior, and she's a core Android engineer.
Does it mean that Adnroid OS ensures that the device will wake up for the time of going thru onReceive of BroadcastReceiver?
Not generally.
In my case the BroadcastReceiver should get intent from Google Play Services (GoogleLocationServices and to be precise Geofences api).
If the Google Play Services documentation does not make any claims regarding the behavior of your receiver with respect to wakefulness, you should assume that you are not inside of a WakeLock. If the work is something that will take 1-2ms, and therefore is probably safe to do in onReceive() anyway, you're welcome to take the risk and skip a WakeLock and hope for the best.
But usually a broadcast like this triggers more work, involving disk I/O and/or network I/O, and you need to get that work off of the main application thread. Frequently, you do that by delegating to an IntentService, as it gives you a background thread with a marker service to let the OS know that you're still doing some work here. And, to ensure that the device will stay awake for that work to complete, use WakefulBroadcastReceiver or my WakefulIntentService, to hold a WakeLock from early in onReceive() until the completion of the work in onHandleIntent().
Where is it documented?
AFAIK, it isn't. Get used to it, as for complex systems, usually only a tiny fraction of the system's behavior winds up being documented.
来源：https://stackoverflow.com/questions/27396766/do-i-need-to-acquire-wake-lock-when-invoking-a-broadcastreceiver