Question

so I am looking into PowerManager to prevent phone from going to sleep.

Two questions:

1) My phone is currently set to turn the display off after X seconds, will the PowerManager.Wakelock functions override this?

2) My phone has a top button which can be used to turn off the display, or shut the phone off. Will PowerManager.WakeLock override this functionality as well?

insight appreciated

Answer 1

1. I’m not sure but I think so. And it’s hard to me to find this
   functionality in the sources.

2. There is a function in PowerManager.java goToSleep(time). This
   function simply calls method of PowerManagerService goToSleepLocked:

   private void goToSleepLocked(long time, int reason) {
   
   if (mLastEventTime <= time) {
   mLastEventTime = time;
   // cancel all of the wake locks
   mWakeLockState = SCREEN_OFF;
   int N = mLocks.size();
   int numCleared = 0;
   boolean proxLock = false;
   
   for (int i=0; i<N; i++) {
       WakeLock wl = mLocks.get(i);
       if (isScreenLock(wl.flags)) {
           if (((wl.flags & LOCK_MASK) == PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK)
                && reason == WindowManagerPolicy.OFF_BECAUSE_OF_PROX_SENSOR) {
           proxLock = true;
           } else {
               mLocks.get(i).activated = false;
               numCleared++;
           }
       }
   }
   if (!proxLock) {
       mProxIgnoredBecauseScreenTurnedOff = true;
       if (mDebugProximitySensor) {
           Slog.d(TAG, "setting mProxIgnoredBecauseScreenTurnedOff");
       }
   }
   EventLog.writeEvent(EventLogTags.POWER_SLEEP_REQUESTED, numCleared);
   mStillNeedSleepNotification = true;
   mUserState = SCREEN_OFF;
   setPowerState(SCREEN_OFF, false, reason);
   cancelTimerLocked();
   }
   }
   

So you can see that all wakelocks are shutdowned in this method.

The method goToSleep can be called only by system components (protected with signature permission). And I think that it is called during the press of your power button. So it rewrites all the wakelocks.