PowerManager和PARTIAL_WAKE_LOCK

Question

My app works fine when the device is plugged in the power supply whereas it fails (time to time) when the device is unplugged. I think that the piece of code responsible of this issue is as follows:

    PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
    PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "foo");
    wl.acquire();
foo();
    wl.release();

foo() is a function that invokes a Camera.takePicture() that, as you know, results in a parallel task that takes a couple of seconds to complete. Thus, wl.release() is actually called when the picture has not yet taken. The above code is executed by an alarm which wakeup the device from its standby mode. My question is, is there the risk that the device returns in its standby mode before the picture has been taken due to the fact that wl.release might be called before the picture is taken? Does wl.release() release instantaneously the PARTIAL_WAKE_LOCK or the device remains in its run mode for a while?

Many thanks in advance for any comment.

Answer 1

My question is, is there the risk that the device returns in its standby mode before the picture has been taken due to the fact that wl.release might be called before the picture is taken?

Yes.

Does wl.release() release instantaneously the PARTIAL_WAKE_LOCK

Yes.

or the device remains in its run mode for a while?

That depends on what else might be holding a WakeLock .