9. Repository and workManager - WorkManager

Setup and starter code walkthrough

Step 1: 스타터 앱 다운로드받고 실행하기

github.com/google-developer-training/android-kotlin-fundamentals-apps/tree/master/DevBytesRepository

google-developer-training/android-kotlin-fundamentals-apps

 

Step 2: 코드 살펴보기

 

 

 

Concept: WorkManager

developer.android.com/codelabs/kotlin-android-training-work-manager?continue=https%3A%2F%2Fdeveloper.android.com%2Fcourses%2Fpathways%2Fkotlin-fundamentals-nine%23codelab-%2Fcodelabs%2Fkotlin-android-training-work-manager#3

Android Kotlin Fundamentals: WorkManager  |  Android 개발자

 

 

 

Add the WorkManager dependency

build.gradle (Module:app)

dependencies {
    ...

    // WorkManager dependency
    def work_version = "1.0.1"
    implementation "android.arch.work:work-runtime-ktx:$work_version"
}

 

 

 

Create a background worker

Step 1: worker 생성하기

work/RefreshDataWorker.kt

class RefreshDataWorker(appContext: Context, params: WorkerParameters) :
        CoroutineWorker(appContext, params) {
    override suspend fun doWork(): Result {
        return Result.success()
    }
}

suspending function은 나중에 중단되고 재개될 수 있는 함수이다. suspending function은 오랫동안 실행되는 작업을 수행할 수 있고 메인 스레드가 블락되지 않고 완료되기를 기다릴 수 있다.

 

Step 2: doWork() 구현하기

RefreshDataWorker.kt

class RefreshDataWorker(appContext: Context, params: WorkerParameters) :
        CoroutineWorker(appContext, params) {
    override suspend fun doWork(): Result {
        val database = getDatabase(applicationContext)
        val repository = VideosRepository(database)
        try {
            repository.refreshVideos( )
            Timber.d("Work request for sync is run")
        } catch (e: HttpException) {
            return Result.retry()
        }
        return Result.success()
    }
}

 

 

 

Define a periodic WorkRequest

Note: periodic work의 최소 간격은 15분이다. periodic work의 제약 중 하나로 periodic work은 초기 delay를 가질 수 없다.

 

Step 1: 반복적인 작업 설정하기

DevByteApplication.kt

    /**
     * Setup WorkManager background job to 'fetch' new network data daily.
     */
    private fun setupRecurringWork() {
        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(1, TimeUnit.DAYS)
                .build()
    }

 

Step 2: WorkManager로 WorkRequest 스케줄링하기

RefreshDataWorker.kt

    companion object {
        const val WORK_NAME = "com.example.android.devbyteviewer.work.RefreshDataWorker"
    }

 

DevByteApplication.kt

class DevByteApplication : Application() {
    private val applicationScope = CoroutineScope(Dispatchers.Default)

    /**
     * onCreate is called before the first screen is shown to the user.
     *
     * Use it to setup any background tasks, running expensive setup operations in a background
     * thread to avoid delaying app start.
     */
    override fun onCreate() {
        super.onCreate()
        delayedInit()
    }

    /**
     * Setup WorkManager background job to 'fetch' new network data daily.
     */
    private fun setupRecurringWork() {
        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(1, TimeUnit.DAYS)
                .build()

        WorkManager.getInstance().enqueueUniquePeriodicWork(
                RefreshDataWorker.WORK_NAME,
                ExistingPeriodicWorkPolicy.KEEP,
                repeatingRequest)
    }

    private fun delayedInit() {
        applicationScope.launch {
            Timber.plant(Timber.DebugTree())
            setupRecurringWork()
        }
    }
}

같은 이름의 보류된(끝나지 않은) 작업이 존재하면 ExistingPeriodicWorkPolicy.KEEP 매개변수가 WorkManager가 이전의 periodic work를 유지하고 요청된 새로운 작업을 폐기하도록 한다.

Best Practice: onCreate() 메서드는 메인 스레드에서 실행된다. onCreate()에서 long-running operation을 수행한느 것은 UI 스레드를 블락할 수 있고 앱 로딩 딜레이를 발생시킬 수 있다. 이 문제를 피하기 위해 메인 스레드에서 벗어나 코루틴 안에서 Timber 초기화와 WorkManager 스케줄링 같은 task를 수행한다.

 

Step 3: (Optional) 최소 간격으로 WorkRequest 스케줄링하기

//        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(1, TimeUnit.DAYS)
//                .build()
        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(15, TimeUnit.MINUTES)
                .build()

 

 

 

Add constraints

developer.android.com/codelabs/kotlin-android-training-work-manager?continue=https%3A%2F%2Fdeveloper.android.com%2Fcourses%2Fpathways%2Fkotlin-fundamentals-nine%23codelab-%2Fcodelabs%2Fkotlin-android-training-work-manager#7

Android Kotlin Fundamentals: WorkManager  |  Android 개발자

 

Step 1: Constraint 객체를 추가하고 제약 하나를 설정하기

DevByteApplication.kt

    private fun setupRecurringWork() {
        val constraints = Constraints.Builder()
                .setRequiredNetworkType(NetworkType.UNMETERED)
                .build()

//        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(1, TimeUnit.DAYS)
//                .build()
        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(15, TimeUnit.MINUTES)
                .setConstraints(constraints)
                .build()

        ...
    }

 

Step 2: 앱을 실행하고 로그 확인하기

 

Step 3: 더 많은 제약 추가하기

DevByteApplication.kt

    private fun setupRecurringWork() {

        val constraints = Constraints.Builder()
                .setRequiredNetworkType(NetworkType.UNMETERED)
                .setRequiresBatteryNotLow(true)
                .setRequiresCharging(true)
                .apply {
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        setRequiresDeviceIdle(true)
                    }
                }
                .build()
        val repeatingRequest = PeriodicWorkRequestBuilder<RefreshDataWorker>(1, TimeUnit.DAYS)
                .setConstraints(constraints)
                .build()

        Timber.d("Periodic Work request for sync is scheduled")
        WorkManager.getInstance().enqueueUniquePeriodicWork(
                RefreshDataWorker.WORK_NAME,
                ExistingPeriodicWorkPolicy.KEEP,
                repeatingRequest)
    }

 

 

 

Homework

Q1. 2 / Q2. 1 / Q3. 1

 

 

 

Quiz

1. 3 / 2. 1 / 3. 2 / 4. 1 / 5. 2, 3 / 6. 1 / 7. 1