PauseableThread.java

/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * 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://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License 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.badlogic.gdx.utils;

/**
 * A pausable thread. The runnable must not execute an inifite loop but should
 * return control to the thread as often as possible so that the thread can
 * actually pause.
 * 
 * @author mzechner
 */
public class PauseableThread extends Thread {
    final Runnable runnable;
    boolean paused = false;
    boolean exit = false;

    /**
     * Constructs a new thread setting the runnable which will be called
     * repeatedly in a loop.
     * 
     * @param runnable
     *            the runnable.
     */
    public PauseableThread(Runnable runnable) {
        this.runnable = runnable;
    }

    public void run() {
        while (true) {
            synchronized (this) {
                try {
                    while (paused)
                        wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            if (exit)
                return;

            runnable.run();
        }
    }

    /** Pauses the thread. This call is non-blocking */
    public void onPause() {
        paused = true;
    }

    /** Resumes the thread. This call is non-blocking */
    public void onResume() {
        synchronized (this) {
            paused = false;
            this.notifyAll();
        }
    }

    /**
     * @return whether this thread is paused or not
     */
    public boolean isPaused() {
        return paused;
    }

    /** Stops this thread */
    public void stopThread() {
        exit = true;
        if (paused)
            onResume();
    }
}