1. Introduction

The tasks plugin provides the means to schedule and manage tasks. Tasks will always be executed off the UI thread. In many respects task execution follows the same rules as JDK’s SwingWorker.

This plugin contains code written by Eike Kettner (swing-tasks).

1.1. Creating Tasks

Tasks must implement the Task interface. There is a helper class (AbstractTask) which can be subclassed, for which the execute() method must be implemented as a minimum. This method should contain the long running code.

The following example depicts a Task used to find the first N prime numbers

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import griffon.plugins.tasks.Tracker;
import org.codehaus.griffon.runtime.tasks.AbstractTask;

public class PrimeNumbersTask extends AbstractTask<List<Integer>, Integer> {
    public PrimeNumbersTask(int numbersToFind) {
        //initialize
    }

    @Override
    public Integer execute(Tracker<Integer> tracker) throws Exception {
        while (!enough && !isCancelled()) {
            int number = nextPrimeNumber();
            tracker.publish(number);
            tracker.setProgress(100 * numbers.size() / numbersToFind);
        }
        return 0;
    }
}

1.2. TaskManager

The TaskManager is the entry point for scheduling tasks. It is used to create TaskControl instances, register listeners and find currently running tasks.

You can provide your own implementation by binding it inside a Module.

1.3. Executing and controlling Tasks

Use the TaskManager to create a TaskControl object and invoke its execute() method.

TaskControl taskControl = taskManager.create(new PrimeNumbersTask(10));
taskControl.execute();

The execute() method will return immediately and submit the task for execution. Now the TaskControl can be used to cancel the execution of the task. The method waitFor() can be invoked to wait for the task to finish.

1.4. Listeners

You can register TaskListeners to receive notifications on tasks. There are 3 different ways to register listeners concerning the scope of events received:

  • register on TaskManager (use taskManager.getTaskListenerSupport()) to receive events for all tasks

  • register on TaskManager using a taskId to receive events for tasks of the given taskId

  • register on a TaskControl (use taskControl.getTaskContext()) to receive events solely for one execution

Griffon version: 2.11.0

2. Build Configuration

2.1. Gradle

You have two options for configuring this plugin: automatic and manual.

2.1.1. Automatic

As long as the project has the org.codehaus.griffon.griffon plugin applied to it you may include the following snippet in build.gradle

dependencies {
    griffon 'org.codehaus.griffon.plugins:griffon-tasks-plugin:2.0.0'
}

The griffon plugin will take care of the rest given its configuration.

2.1.2. Manual

You will need to configure any of the following blocks depending on your setup

dependencies {
    compile 'org.codehaus.griffon.plugins:griffon-tasks-core:2.0.0'
}

2.2. Maven

First configure the griffon-tasks-plugin BOM in your POM file, by placing the following snippet before the <build> element

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.codehaus.griffon.plugins</groupId>
            <artifactId>griffon-tasks-plugin</artifactId>
            <version>2.0.0</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

Next configure dependencies as required by your particular setup

<dependency>
    <groupId>org.codehaus.griffon.plugins</groupId>
    <artifactId>griffon-tasks-core</artifactId>
</dependency>

3. Modules

The following sections display all bindings per module. Use this information to successfully override a binding on your own modules or to troubleshoot a module binding if the wrong type has been applied by the Griffon runtime.

3.1. Theme

Module name: tasks

bind(TaskManager.class)
    .to(NonBlockingTaskManager.class)
    .asSingleton();