CancelableThread.java

/*
 * Copyright 2010-2012 Amazon Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *    http://aws.amazon.com/apache2.0
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
 * OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and
 * limitations under the License.
 */
package com.amazonaws.eclipse.core.ui;

/**
 * Thread with running and canceled information, meant for background tasks
 * where the work will often be discarded and restarted. Subclasses should make
 * sure to set isRunning to false when their work is done, and to not do any
 * potentially conflicting work if isCanceled is true.
 */
public abstract class CancelableThread extends Thread {

    protected boolean running = true;
    protected boolean canceled = false;

    public synchronized final boolean isRunning() {
        return running;
    }

    public synchronized final void setRunning(boolean running) {
        this.running = running;
    }

    /**
     * Subclasses shouldn't do any potentially conflicting UI work before
     * checking to see if the thread has been canceled.
     */
    public synchronized final boolean isCanceled() {
        return canceled;
    }

    public synchronized final void cancel() {
        this.canceled = true;
    }

    /**
     * Cancels the thread given if it's running.
     */
    public static void cancelThread(CancelableThread thread) {
        if ( thread != null ) {
            synchronized ( thread ) {
                if ( thread.isRunning() ) {
                    thread.cancel();
                }
            }
        }
    }

}