Work Requests

Work Requests

OneTimeWorkRequest and PeriodicWorkRequest

A Worker says what to do in doWork(); a WorkRequest says when: once (OneTimeWorkRequest) or repeatedly (PeriodicWorkRequest). WorkManager 234 stores the request and returns at once:

sync/SyncScheduler.kt: a periodic request with a unique nameKotlin

  fun schedulePeriodic(context: Context) {
    val request = PeriodicWorkRequestBuilder<CatalogSyncWorker>(6, TimeUnit.HOURS)
      .setConstraints(online)
      .setBackoffCriteria(BackoffPolicy.EXPONENTIAL, 30, TimeUnit.SECONDS)
      .addTag("catalog")
      .build()
    WorkManager.getInstance(context)
      .enqueueUniquePeriodicWork("catalog-sync", ExistingPeriodicWorkPolicy.KEEP, request)
  }

The minimum period is 15 minutes (MIN_PERIODIC_INTERVAL_MILLIS), and a run lands anywhere inside its period. Since BookNestApp.onCreate() calls this on every launch, the work is unique: KEEP leaves an existing schedule alone, UPDATE swaps in the new request keeping its timing, CANCEL_AND_REENQUEUE starts over, while a plain enqueue() would stack a copy per launch. The system scheduler then shows:

BookNest's job, as JobScheduler sees itShell

adb -s emulator-5556 shell dumpsys jobscheduler

Output

  JOB androidx.work.systemjobscheduler:u0a216/0: e65e824 @androidx.work.systemjobscheduler@...
    JobInfo:
      Service: com.example.booknest/androidx.work.impl.background.systemjob.SystemJobService
      Requires: charging=false batteryNotLow=true deviceIdle=false
      ...
      Backoff: policy=1 initial=+30s0ms
    Required constraints: BATTERY_NOT_LOW CONNECTIVITY FLEXIBILITY [0x10200002]

It is job 0 in namespace androidx.work.systemjobscheduler. There is no period: WorkManager schedules each run as a one-off job and computes the next itself; the first run started at once.

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