A suspending function is a function that can be paused and resumed later. A suspending function can execute a long running operation and wait for it to complete without blocking the main thread. The doWork method inside the Worker class is called on a background thread.
The method performs work synchronously, and should return a ListenableWorker. Result object. The Android system gives a Worker a maximum of 10 minutes to finish its execution and return a ListenableWorker. After this time has expired, the system forcefully stops the Worker. To create a ListenableWorker. Result object, call one of the following static methods to indicate the completion status of the background work:.
In this task, you implement the doWork method to fetch the DevBytes video playlist from the network. You can reuse the existing methods in the VideosRepository class to retrieve the data from the network. A Worker defines a unit of work, and the WorkRequest defines how and when work should be run. There are two concrete implementations of the WorkRequest class:. Tasks can be one-off or periodic, so choose the class accordingly.
For more information on scheduling recurring work, see the recurring work documentation. In this task, you define and schedule a WorkRequest to run the worker that you created in the previous task.
Within an Android app, the Application class is the base class that contains all other components, such as activities and services. When the process for your application or package is created, the Application class or any subclass of Application is instantiated before any other class.
In this sample app, the DevByteApplication class is a subclass of the Application class. This method allows you to add a uniquely named PeriodicWorkRequest to the queue, where only one PeriodicWorkRequest of a particular name can be active at a time. For example, you might only want one sync operation to be active. If one sync operation is pending, you can choose to let it run or replace it with your new work, using an ExistingPeriodicWorkPolicy.
Pass in repeatingRequest as the PeriodicWorkRequest parameter. If pending uncompleted work exists with the same name, the ExistingPeriodicWorkPolicy. KEEP parameter makes the WorkManager keep the previous periodic work and discard the new work request. In the Logcat pane, notice the log statements that show that the work request is scheduled, then runs successfully. In this step, you decrease the time interval from 1 day to 15 minutes. You do this so you can see the logs for a periodic work request in action.
To clear the previous logs, click the Clear logcat icon. Run the app, and the WorkManager schedules your recurring work immediately. In the Logcat pane, notice the logs—the work request is run once every 15 minutes. Wait 15 minutes to see another set of work request logs. You can leave the app running or close it; the work manager should still run.
Notice that the interval is sometimes less than 15 minutes, and sometimes more than 15 minutes. The exact timing is subject to OS battery optimizations.
You created a worker and scheduled the work request with WorkManager. WorkManager will schedule the work once a day, even if the device is low on battery, sleeping, or has no network connection. This will affect the device battery and performance and could result in a poor user experience. In the previous task, you used WorkManager to schedule a work request.
In this task, you add criteria for when to execute the work. When defining the WorkRequest, you can specify constraints for when the Worker should run. For example, you might want to specify that the work should only run when the device is idle, or only when the device is plugged in and connected to Wi-Fi. You can also specify a backoff policy for retrying work. The supported constraints are the set methods in Constraints.
To learn more, see Defining your Work Requests. A WorkRequest for repeating work, for example PeriodicWorkRequest, executes multiple times until it is cancelled. The first execution happens immediately, or as soon as the given constraints are met.
The next execution happens during the next period interval. In technical terms, Wi-Fi access points or connections with unlimited data access are termed unmetered connections, while those that come with data caps are termed metred connections. Smartphones or Android devices automatically restrict heavy data usage like online backup, updates download etc.
But most Android devices automatically set Wi-Fi connections as unmetered, which means it can carry out all heavy data usage activities on it. Though most smartphones can automatically find out metred or unmetered Wi-Fi connections, you might need to change it depending upon your actual subscription plan. The way to set a Wi-Fi connection to metered or unmetered will vary depending upon the user interface. I will discuss explain this tutorial for stock Android running Android 9.
Not all handsets come with this provision, and thus, you should be careful while choosing a Wi-Fi network on such devices, as you might end up losing your costly mobile data if it is being shared through a Wi-Fi hotspot.
So if user not connected to wifi file will be uploaded after every 1 hr, If connected to wifi unmetered file will be uploaded after every 30 min and if connected to metered wifi then file will be uploaded after every 45 min. Is above logic make sense to create 3 sepearte task to upload file. Any suggestion will be appreciated. Thanks in advance. If all you care about is a presence of a network connection just use NetworkType.
If the file is very big, and could cost the user as they will end up using an expensive data connection you should use NetworkType. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 3 years, 3 months ago. Active 2 years, 6 months ago. It's easy to run a task in a thread and wait for its result.
But it gets complex when you need to interact with a thread immediately and move on to the next task in a queue of tasks that are batched. For example, a file might be downloading in a background thread but the user might want to pause or delete it. Changes on statuses from background threads to the main thread and back can happen extremely fast.
You have to be very careful with the flow of your states and how those statuses might change in the middle of an execution. Storing statuses in memory is faster than using disk persistence, but we had to consider what happens if the client app is suddenly shutting down. Testing is hard and the real world is harsh. By now we are true pros at it! Some of them might have a considerable impact on your implementation.
If you find that something is fundamentally wrong, you might have to go back to the drawing board, sketch all your system again and think a better way out. Recovery is tricky. There will be many different reasons for which a download might fail.
0コメント