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Background Tasks

To provide cluster related tasks in the background we use a system to run tasks in the background. If all tabs for a cluster are closed this tasks will be removed from the background task system. The most common use case is to watch the cluster for changes of resources.

Only one instance of a background task is running for a cluster. Use Background Tasks only if it makes sense to have a singleton instance for a cluster. The job will live as long as the cluster is open in the UI.

How to implement a background task​

To register a new Background Task you need to call the getBackgroundJob method of the Core class and provide a creator lambda. The creator lambda will be called if the background task is not running for the cluster.

core.getBackgroundJob(clusterConfig.name(), ClusterNodeWatch.class, () -> new ClusterNodeWatch())

Best practice is to use backgroundJobInstance() method to get the instance of the background task.

var job = core.backgroundJobInstance(cluster, ClusterNodeWatch.class);

The Background Task class must extend from abstract ClusterBackgroundJob but in the most cases from AbstractClusterWatch is a better choice. The AbstractClusterWatch class simplifies the implementation of a background task.

public abstract class AbstractClusterWatch<V1Namespace> {

}

How to use background jobs​

Background job is a special kind of background task and is managed by the BackgroundJobDialogRegistry class. A background job is always a graphical progress dialog. You can create it by using the BackgroundJobDialog.

If you allow canceling you should check the isCanceled() method to stop the job properly.

var dialog = new BackgroundJobDialog(core, cluster, true);
dialog.setHeaderTitle("My Background Job");
dialog.open();

Thread.startVirtualThread(() ->{
        while(!dialog.isCanceled()){
        // do something
        }
        context.getUi().access(()->dialog.close());
});