The problem of alarm in dormant state after Android4.4

The problem of alarm in Android4.4 and after sleep condition

To reduce power consumption, extend battery life. Android 4.4and the subsequent version number adopts the non-precision alarm clock mechanism. And the wakeup type of hibernation will alarm not wake the device in real time, but will wait until the machine is physically awakened alarm . Android 6.0provides a new API: setExactAndAllowWhileIdle() partially solves the problem, but still cannot wake up accurately in hibernation.

alarm apifor support and use please refer to:

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In addition, the application layer should not wakelock be used instead of being held BroadcastReceiver WakefulBroadcastReceiver .

In order to fix this problem. In the case of version 5.0.2, the alarm-dev.c under the kernel and the Alarmmanagerservice under the framework need to be changed.

• Kernel ALARM-DEV.C: The reason for this is that it uses generic static struct wakeup_source alarm_wake_lock; rather than WAKE_LOCK_SUSPEND categorical information and struct wake_lock needs to use android_ a prefix- wakeup lock related function.

  That

  android_wake_lock_initandroid_wake_lock_destroyandroid_wake_lockandroid_wake_lock_timeoutandroid_wake_unlock

  Rather than the normal wake lock operation function:

  wake_lock_initwake_lock_destroywake_lockwake_lock_timeoutwake_unlock

• Framework Alarmmanagerservice.java: wakeup Special handling of types is required alarm : precise alarms. setImplAdd the following code in the example:

   Public Boolean Iswakeup(intType) {return(Type & type_nonwakeup_mask) = =0;}voidSetimpl (intTypeLongTriggerattime,LongWindowlength,LongInterval, pendingintent operation,BooleanIsstandalone, WorkSource WorkSource, Alarmmanager.alarmclockinfo alarmclock) {if(Operation = =NULL) {SLOG.W (TAG,"Set/setrepeating ignored because there is no intent");return; }if(Iswakeup (type))        {windowlength = alarmmanager.window_exact; Isstandalone =true; }

  And alarm when triggered, more than a few satisfying conditions to batch do the processing:

  BooleanTriggeralarmslocked (arraylist<alarm> triggerlist,Final LongNowelapsed,Final LongNOWRTC) {BooleanHaswakeup =false;//Batches is temporally sorted, so we need    //start of the list until we either empty it or hit a batch    // that's not yet deliverableArraylist<alarm> repeatlist =NewArraylist<alarm> (); Listiterator<batch> it = Malarmbatches.listiterator (); while(It.hasnext ()) {Batch Batch = It.next ();if(Batch.start > nowelapsed) {//Everything else is scheduled             Break; }//We'll (re) schedule some alarms now; don ' t let that interfere        //With delivery of this current batchIt.remove ();Final intN = Batch.size (); for(inti =0; i < N;            i++) {Alarm Alarm = Batch.get (i); Alarm.Count=1; Triggerlist.add (alarm);//Recurring alarms may has passed several alarm intervals while the            //Phone is asleep or off, so pass a trigger count when sending them.            if(Alarm.repeatinterval >0) {//This adjustment'll be the zero if we ' re late by                //Less than one full repeat intervalAlarm.Count+ = (nowelapsed-alarm.whenelapsed)/alarm.repeatinterval;//Also schedule its next recurrenceRepeatlist.add (alarm); }if(alarm.wakeup) {haswakeup =true; Mnextwakeup =0; }//We removed an alarm clock. Let the caller recompute the next alarm clock.            if(Alarm.alarmclock! =NULL) {Mnextalarmclockmaychange =true; }        }    }if(Repeatlist.size () >0) { for(Alarm alarm:repeatlist) {Final LongDelta = alarm.Count* ALARM.REPEATINTERVAL;Final Longnextelapsed = alarm.whenelapsed + Delta; Setimpllocked (Alarm.type, Alarm.when + Delta, nextelapsed, Alarm.windowlength, Maxtriggertime (NowELAPSE D, nextelapsed, Alarm.repeatinterval), Alarm.repeatinterval, alarm.operation, alarm.windowlength = Ala Rmmanager.window_exact,true, Alarm.worksource, Alarm.alarmclock, Alarm.userid); }    }//This is a new alarm delivery set, bump the sequence number to indicate    //All apps ' alarm delivery classes should is recalculated.mcurrentseq++;    Calculatedeliverypriorities (triggerlist); Collections.sort (Triggerlist, malarmdispatchcomparator);returnHaswakeup;}

• Application-level use WakefulBroadcastReceiver :

  ImportAndroid.support.v4.content.WakefulBroadcastReceiver; Public  class autoupdatealarmreceiver extends wakefulbroadcastreceiver {    @Override     Public void OnReceive(context context, Intent Intent) {//Start the service, keeping the device awake while the service is        //Launching. The Intent to deliver to the service.Intent Service =NewIntent (context, autoupdateintentservice.class);        Service.setaction (Intent.getaction ());    Startwakefulservice (context, service); }}

  The corresponding IntentService example of the following is seen:

   Public  class autoupdateintentservice extends intentservice {     Public Autoupdateintentservice() {Super("Autoupdateintentservice"); }@Override    protected void onhandleintent(Intent Intent) {String action = intent.getaction ();//Do your work here.        // ...        //Release The wake Lock provided by the Wakefulbroadcastreceiver.Autoupdatealarmreceiver.completewakefulintent (Intent); }}

The problem of alarm in dormant state after Android4.4