PeriodicWorkRequest with WorkManager

Question

Well as WorkManager is newly introduce in Google I/O, I'm trying to use workmanager to perform task periodically,

What I'm doing is, Scheduling the work using PeriodicWorkRequest as following :

Constraints constraints = new Constraints.Builder().setRequiredNetworkType(NetworkType.CONNECTED).build();
PeriodicWorkRequest build = new PeriodicWorkRequest.Builder(SyncJobWorker.class, MY_SCHEDULE_TIME, TimeUnit.MILLISECONDS)
           .addTag(TAG)
           .setConstraints(constraints)
           .build();

WorkManager instance = WorkManager.getInstance();
if (instance != null) {
          instance.enqueueUniquePeriodicWork(TAG, ExistingPeriodicWorkPolicy.REPLACE, build);
}

Problem I'm having is when i'm requesting PeriodicWorkRequest then also it will start work immediately,

• Does anybody know how to stop that immediate work execution? while using PeriodicWorkRequest.
• Also want to know how we can Rechedule the work? What if i want to change the time of already scheduled work ?

I'm using : implementation "android.arch.work:work-runtime:1.0.0-alpha04"

Any help will be appreciated.

Answer 1

You can achieve this by using flex period in PeriodicWorkRequest.Builder. As example, if you want run your Worker within 15 minutes at the end of repeat interval (let's say 8 hours), code will look like this:

val periodicRefreshRequest = PeriodicWorkRequest.Builder(
            RefreshWorker::class.java, // Your worker class
            8, // repeating interval
            TimeUnit.HOURS,
            15, // flex interval - worker will run somewhen within this period of time, but at the end of repeating interval
            TimeUnit.MINUTES
    )

Visual ilustration

Answer 2

you need to add initialDelay to the builder

fun scheduleRecurringFetchWeatherSyncUsingWorker() {
    val constraints: Constraints = Constraints.Builder().apply {
        setRequiredNetworkType(NetworkType.CONNECTED)
        setRequiresBatteryNotLow(true)
    }.build()

    val request: PeriodicWorkRequest = PeriodicWorkRequest.Builder(
        MySimpleWorker::class.java, 3, TimeUnit.HOURS, 1, TimeUnit.HOURS)
        .setConstraints(constraints)
        .setInitialDelay(2, TimeUnit.HOURS)
        .setBackoffCriteria(BackoffPolicy.LINEAR, 1, TimeUnit.HOURS)
        .build()
    mWorkManager.enqueueUniquePeriodicWork(
        TAG_WORK_NAME,
        ExistingPeriodicWorkPolicy.KEEP,
        request
    )
}