Threading in CoroutineWorker

For Kotlin users, WorkManager provides first-class support for coroutines. To get started, include work-runtime-ktx in your gradle file. Instead of extending Worker, you should extend CoroutineWorker, which has a suspending version of doWork(). For example, if you wanted to build a simple CoroutineWorker to perform some network operations, you would do the following:

class CoroutineDownloadWorker(
    context: Context,
    params: WorkerParameters
) : CoroutineWorker(context, params) {

    override suspend fun doWork(): Result {
        val data = downloadSynchronously("https://www.google.com")
        saveData(data)
        return Result.success()
    }
}

Note that CoroutineWorker.doWork() is a suspending function. Unlike Worker, this code does not run on the Executor specified in your Configuration. Instead, it defaults to Dispatchers.Default. You can customize this by providing your own CoroutineContext. In the above example, you would probably want to do this work on Dispatchers.IO, as follows:

class CoroutineDownloadWorker(
    context: Context,
    params: WorkerParameters
) : CoroutineWorker(context, params) {

    override suspend fun doWork(): Result {
        withContext(Dispatchers.IO) {
            val data = downloadSynchronously("https://www.google.com")
            saveData(data)
            return Result.success()
        }
    }
}

CoroutineWorker handles stoppages automatically by cancelling the coroutine and propagating the cancellation signals. You don't need to do anything special to handle work stoppages.

Running a CoroutineWorker in a different process

You can also bind a worker to a specific process by using RemoteCoroutineWorker, an implementation of ListenableWorker.

RemoteCoroutineWorker binds to a specific process with two extra arguments that you provide as part of the input data when building the work request: ARGUMENT_CLASS_NAME and ARGUMENT_PACKAGE_NAME.

The following example demonstrates building a work request that is bound to a specific process:

val PACKAGE_NAME = "com.example.background.multiprocess"

val serviceName = RemoteWorkerService::class.java.name
val componentName = ComponentName(PACKAGE_NAME, serviceName)

val data: Data = Data.Builder()
   .putString(ARGUMENT_PACKAGE_NAME, componentName.packageName)
   .putString(ARGUMENT_CLASS_NAME, componentName.className)
   .build()

return OneTimeWorkRequest.Builder(ExampleRemoteCoroutineWorker::class.java)
   .setInputData(data)
   .build()

String PACKAGE_NAME = "com.example.background.multiprocess";

String serviceName = RemoteWorkerService.class.getName();
ComponentName componentName = new ComponentName(PACKAGE_NAME, serviceName);

Data data = new Data.Builder()
        .putString(ARGUMENT_PACKAGE_NAME, componentName.getPackageName())
        .putString(ARGUMENT_CLASS_NAME, componentName.getClassName())
        .build();

return new OneTimeWorkRequest.Builder(ExampleRemoteCoroutineWorker.class)
        .setInputData(data)
        .build();

For each RemoteWorkerService, you also need to add a service definition in your AndroidManifest.xml file:

<manifest ... >
    <service
            android:name="androidx.work.multiprocess.RemoteWorkerService"
            android:exported="false"
            android:process=":worker1" />

        <service
            android:name=".RemoteWorkerService2"
            android:exported="false"
            android:process=":worker2" />
    ...
</manifest>