- Android Direct Boot allows alarms and notifications to function even when the device is rebooting or has been idle for a long period of time. It does this through the use of AlarmManager, setAlarmClock(), Direct Boot APIs like createDeviceProtectedStorageContext, and Foreground Services. - The app uses AlarmManager, setAlarmClock(), and intents to set repeating alarms that will trigger even when the device reboots or enters Doze mode. It stores persistent data like alarm settings and schedules using Room SQLite database with a Direct Boot compatible context. A Foreground Service plays alarm audio and vibrates even when the app is in the background.

1. Android Direct Boot
@irgaly
2019/07/11
HealthTech 0.5#3
@TIMESHARING

2. Summary
• About O:SLEEP
• O:SLEEP Alarm
•
• Android AlarmManager
• Android Doze Mode
• Alarm
• Alarm 1 ~ 3
• Android Direct Boot
•
• Foreground Service
• Direct Boot +
• Conclusion: Problems & Solutions

3. About O:SLEEP
•
• Android / iOS
•
•
https://play.google.com/store/apps/details?id=jp.oinc.osleep&hl=ja

4. O:SLEEP Alarm
• 2019/6/24 v1.3.0:
•
•

5. O:SLEEP Alarm
•
•
•
•

6. • AlarmManager Intent
•
AlarmManager
setAlarmClock()
PendingIntent Broadcast Intent
O:SLEEP
Notification
Manager
MediaPlayer
Vibrator

7. AlarmManager
• setExactAndAllowWhileIdle
• API 23 (Android 6.0)~
• “it will not dispatch these alarms more than about every minute (at which
point every such pending alarm is dispatched); when in low-power idle modes
this duration may be significantly longer, such as 15 minutes.”
• Exact 1 ( )
• → Doze Mode ( )
AlarmManagerCompat

8. AlarmManager
• setAlarmClock
• Doze Mode ( )
• API 21 (Android 5.0) ~
•
AlarmManagerCompat

9. Doze Mode
•
• Android 6.0 Doze
•
•
•
•
https://developer.android.com/training/monitoring-device-state/doze-
standby?hl=JA
Alarm Notification
Job

10. Alarm
•
•
•
1
•
•
setAlarmClock() setAlarmClock() setAlarmClock()

11. Alarm 1
•
setAlarmClock() setAlarmClock()
7:00
GMT+09:00 -> 2019/07/11 07:00 +09:00
GMT+08:00 -> 2019/07/11 07:00 +08:00 ←1
( )
<intent-filter>
<action android:name="android.intent.action.TIME_SET"/>
<action android:name=“android.intent.action.TIMEZONE_CHANGED"/>
…

12. Alarm 2
• AlarmManager
•
• System Locked Boot (Direct Boot, )
• System Boot (Locked Boot )
Locked Boot
setAlarmClock()
<intent-filter>
<action android:name="android.intent.action.LOCKED_BOOT_COMPLETED"/>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
…
System Boot
setAlarmClock()

13. Alarm 3
•
• (Broadcast)
•
•
•
setAlarmClock()
<intent-filter>
<action android:name="android.intent.action.MY_PACKAGE_REPLACED"/>
…
setAlarmClock()

14. merge
<intent-filter>
<action android:name="android.intent.action.LOCKED_BOOT_COMPLETED"/>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
<action android:name="android.intent.action.MY_PACKAGE_REPLACED"/>
<action android:name="android.intent.action.PACKAGE_DATA_CLEARED"/>
<action android:name="android.intent.action.TIME_SET"/>
<action android:name="android.intent.action.TIMEZONE_CHANGED"/>
</intent-filter>
Locked Boot System Boot

15. Direct Boot
•
•
https://developer.android.com/training/articles/direct-boot

16. Direct Boot
• Context Context
• createDeviceProtectedStorageContext Context
Direct Boot
•
fun AlarmRoomDatabase(application: Application):
AlarmRoomDatabase {
// Android 7.0 Direct Boot Context
val context = ContextCompat
.createDeviceProtectedStorageContext(application)
?: application
return Room.databaseBuilder(
context,
AlarmRoomDatabase::class.java,
“AlarmRoomDatabase"
).build()
}

17. Direct Boot
• LOCKED_BOOT_COMPLETED BroadcastReceiver
• android:directBootAware=“true”: Direct Boot
BroadcastReceiver Service
<receiver
android:name=".app.receiver.SystemEventBroadcastReceiver"
android:directBootAware="true"
tools:targetApi="n">
<intent-filter>
<action
android:name="android.intent.action.LOCKED_BOOT_COMPLETED"/>
…
</receiver>
<service
android:name=".app.service.AlarmService"
android:directBootAware="true"
tools:targetApi="n"/>

18. Direct Boot
• Context
Preferences Database
Direct Boot
Context
Context OK

19. •
•
AlarmSetting
Room SQLite Database
AlarmSchedule
Room SQLite Database
@Entity
data class AlarmSetting(
@PrimaryKey val id: String,
@Embedded(prefix = "time_") val time:
LocalTime,
val repeatDayOfWeek: Set<DayOfWeek>,
val enabled: Boolean,
…
@Entity
data class AlarmSchedule(
@PrimaryKey val id: String,
val alarmSettingId: String,
val time: DateTimeTz,
…
)

20. Foreground Service
• MediaPlayer
• Android 8.0
• Foreground Service
Android OS
BroadcastReceiverOSLEEP
ForegroundService
ForegroundNotification

21. Foreground Service
• Notification Channel
• ForegroundNotification
@RequiresApi(Build.VERSION_CODES.O)
private fun createNotificationChannel(channel: ChannelType) {
notificationManager.createNotificationChannel(
NotificationChannel(
"alarm",
" ",
NotificationManager.IMPORTANCE_MAX
).apply {
lockscreenVisibility = Notification.VISIBILITY_PUBLIC
}
)
}
class AlarmForegroundService : DaggerService() {
…
override fun onCreate() {
super.onCreate()
startForeground(0, NotificationCompat.Builder(context, "")
.setOngoing(true) //
.setContentTitle(context.getString(R.string.title_alarm_notification))
.setContentText(context.getString(R.string.text_alarm_notification))
.setSmallIcon(R.drawable.ic_notification)
.setCategory(Notification.CATEGORY_ALARM)
.setPriority(PRIORITY_MAX)
.setVisibility(VISIBILITY_PUBLIC)
.setContentIntent(
PendingIntent.getBroadcast(…)
).build())
}
…

22. Foreground Service
• MediaPlayer
private var _player: MediaPlayer? = null
private val player: MediaPlayer get() {
return _player ?: MediaPlayer().apply {
setWakeMode(context, PowerManager.PARTIAL_WAKE_LOCK)
}.also {
_player = it
}
}
override suspend fun playAlarm(soundUrl: String, repeat: Boolean) =
suspendCoroutine<Unit> { continuation ->
player.apply {
reset()
setDataSource(context, Uri.parse(soundUrl))
isLooping = repeat
setAudioAttributes(
AudioAttributes.Builder()
.setUsage(AudioAttributes.USAGE_ALARM)
.setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
.build()
)
prepare()
start()
}
continuation.resume(Unit)
}

23. Foreground Service
• Vibrator
private val vibrator by lazy {
context.getSystemService<Vibrator>() ?: throw
RuntimeException("Vibrator ")
}
override fun vibrateAlarmRepeat(vibrateTime: TimeSpan, pauseTime:
TimeSpan) {
// OFF 0, ON , OFF... list
val pattern = listOf(0L, vibrateTime.millisecondsLong,
pauseTime.millisecondsLong)
if (Build.VERSION_CODES.O <= Build.VERSION.SDK_INT) {
vibrator.vibrate(
VibrationEffect.createWaveform(
pattern.toLongArray(),
0
),
AudioAttributes.Builder()
.setUsage(AudioAttributes.USAGE_ALARM)
.build()
)
} else {
vibrator.vibrate(
pattern.toLongArray(),
0,
AudioAttributes.Builder()
.setUsage(AudioAttributes.USAGE_ALARM)
.build()
)
}
}
TimeSpan https://github.com/korlibs/klock

24. : Direct Boot +
• Direct Boot Media Content Provider
• File Path
• MediaColumns.DATA File Path
private fun getSystemAlarms(): List<AlarmSound> {
return context.contentResolver.query(
MediaStore.Audio.Media.INTERNAL_CONTENT_URI,
null,
"${MediaStore.Audio.Media.IS_ALARM} != 0",
null,
"${MediaStore.Audio.Media.TITLE} ASC"
)?.use { cursor ->
cursor.asSequence().map {
AlarmSound(
it.getString(it.getColumnIndex(MediaStore.Audio.Media.TITLE)),
it.getString(it.getColumnIndex(MediaStore.MediaColumns.DATA))
)
}.toList()
} ?: emptyList()
}
fun Cursor.asSequence(): Sequence<Cursor> {
return generateSequence(seed = takeIf { it.moveToFirst() }) {
takeIf { it.moveToNext() }
}
}

25. Conclusion: Problems & Solutions
• AlarmManager
• →
• Doze Mode
• → setAlarmClock
• Direct Boot
• → createDeviceProtectedStorageContext
•
• → Foreground Service