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building_battery-conscious_apps [2018/11/01 12:49] – [A review of broadcast receivers] kalaschnikowbuilding_battery-conscious_apps [2020/11/11 08:47] (current) – [Intent to the settings, where you can move your app to the whitelist] kalaschnikow
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 +====== Building Battery-Conscious Apps ======
 +
 +Das ist mein Konspekt von dem Online-Kurs [[https://www.linkedin.com/learning/android-development-building-battery-conscious-apps|Android Development: Building Battery-Conscious Apps]]\\ 
 +
 +===== Introduction =====
 +
 +==== Why be battery conscious? ====
 +...
 +
 +===== 1. Basics of Battery Usage =====
 +
 +==== Principles of battery-concious apps ====
 +
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/principles-of-battery-conscious-apps
 +
 +Wake-Up has costs:
 +  * CPU on
 +  * Screen on
 +  * Data (Wi-Fi or cellular) on
 +
 +Official documentation: http://developer.android.com/topic/performance/power/#lazy
 +
 +Smart Design (aka Lazy First design)
 +  - Reduce (e.g. resolution of photos for upload/download)
 +  - Defer
 +  - Coalesce (combining transactions to a "batch")
 +  - Rethink
 +  
 +
 +===== 2. Battery Drain and Workarounds =====
 +
 +
 +==== Considerations for using AlarmManager ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/considerations-for-using-alarmmanager
 +
 +  * Schedule asynchronous operations
 +  * Time-based
 +  * Single or repetitive
 +  * Perfect for exact time-based scheduling
 +  * Periodic background tasks
 +  * Combined effects cause battery drain
 +  * Wake up has a cost
 +
 +==== Pitfalls of poor AlarmManager usage ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/pitfalls-of-poor-alarmmanager-usage
 +
 +  - Background network operations (AlarmManager does not have intelligent dispatch logic)
 +  - Alarms does not survive reboots (Extra logic required, e.g. BroadcastReceiver)
 +  - Exact Alarm may not be exact
 +    * Since Kitkat
 +    * setExactAndAllowWhileIdle -> is affected by Doze Mode 
 +  - Doze Mode introduces complexity (e.g. ''setExact'' can drift)
 +  
 +Takeaways:
 +  * Avoid network operations
 +  * Doze Mode affects AlarmManager
 +  * Maybe better would be to switch to JobScheduler (because it is not time driven, but event driven)
 +  
 +==== Considerations for using background-started services ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/considerations-for-using-background-started-services
 +  * Background Started Services
 +    * typically long running operations with no UI (e.g. music player)
 +    * started via an API call
 +    * contract:
 +      * client calls **Context.startService()**
 +      * system calls **Service.onStartCommand()**
 +      * Service stops
 +        * service stops itself with **Service.stopSelf()**
 +        * OR: 
 +        * client calls **Service.stopService()**
 +    * System requires service to remain running until stopped explicitly
 +    * Note: in production **IntentService** would be better as simple **Service**
 +  * When to Use Background Started Service
 +    * intense, low-priority tasks not noticed by user
 +    * irregular, user-driven background tasks
 +    * stateless reentrant operations (e.g. refreshing news content)
 +    * work queue processor pattern (IntentService)
 +    * Note: if task is periodic scheduled job may be a better choice
 +==== Pitfalls of poor background-started service usage ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/pitfalls-of-poor-background-started-service-usage
 +
 +  * Pitfall 1: Android
 +    * Google is tightening restrictions
 +  * Pitfall 2: No Rules or Policy Support
 +    * Connectivity checks
 +      * Active connection
 +      * Airplane mode
 +      * Remote server availability
 +    * Appropriateness checks
 +      * Battery level
 +      * Roaming status
 +      * Metered connection  
 +    * Back off and retry policy
 +      * Retry when?
 +      * Retry how often?
 +  * Pitfall 3: No intelligent batching 
 +    * No batching unlike AlarmManager
 +    * Cannot differentiate between services and different apps
 +  * Pitfall 4: Other reasons
 +    * Idle processes are wasteful
 +    * Fragmentation is a problem
 +
 +  * Takeaway
 +    * Use job scheduler for most cases
 +    * Use started services for simple one-shot background tasks
 +
 +==== A review of broadcast receivers ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/a-review-of-broadcast-receivers
 +  * Introduction to Broadcast Receivers
 +    * support event-driven programming
 +    * used for many system events
 +    * Interprocess communication (IPC)
 +    * delivered via Intent
 +    * Intents specify actions and optional extras
 +    * should extend **BroadcastReceiver**
 +    * should implement **onReceive()**
 +
 +==== Registering a broadcast receiver ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/registering-a-broadcast-receiver
 +  * Statically registered (AndroidManifest.xml)
 +  * Dynamically registered (through the Java code)
 +
 +==== Triggering a broadcast receiver ====
 +
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/triggering-a-broadcast-receiver
 +
 +Two posibilities to trigger a broadcast receiver:
 +  - Call implicit trigger
 +    * Candidates matched via filter
 +    * Recipients unknown until match
 +    * Recipients may change 
 +  - Explicit trigger
 +    * Invocation via code
 +    * Recipients known
 +    * Recipients never change
 +  
 +  * Any app can define its own intent
 +
 +Example of triggering explicitly:
 +<code java>
 +Intent i = new Intent("my.action.name")
 +                .setComponent(new ComponentName(context.getPackageName(), className));
 +context.setBroadcast(i);
 +</code> 
 +
 +==== Considerations of static implicit broadcast receivers ====
 +https://www.linkedin.com/learning/android-development-building-battery-conscious-apps/considerations-of-static-implicit-broadcast-receivers
 +
 +===== Post Scriptum =====
 +
 +This post scriptum is not based on the online course, but on other articles.
 +
 +==== Intent to the settings, where you can move your app to the whitelist ====
 +From [[https://proandroiddev.com/android-battery-optimization-for-avoiding-doze-mode-and-app-standby-83cd379ee75b|Android Battery Optimization for Avoiding Doze Mode and App Standby]]
 +<code java>
 +if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
 +    Intent intent = new Intent();
 +    String packageName = getPackageName();
 +    PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
 +    if (!pm.isIgnoringBatteryOptimizations(packageName)) {
 +        intent.setAction(Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS);
 +        intent.setData(Uri.parse("package:" + packageName));
 +        startActivity(intent);
 +    }
 +}
 +</code>