PausableThreadPoolExecutor.java

package se.unlogic.standardutils.threads;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class PausableThreadPoolExecutor extends ThreadPoolExecutor {

	private boolean isPaused;
	private final ReentrantLock pauseLock = new ReentrantLock();
	private final Condition unpaused = pauseLock.newCondition();

	public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,	BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
		super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
	}

	public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,	BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory,	RejectedExecutionHandler handler) {
		super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
	}

	public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,	BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {
		super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
	}

	public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
		super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
	}

	@Override
	protected void beforeExecute(Thread t, Runnable r) {
		super.beforeExecute(t, r);
		pauseLock.lock();
		try {
			while (isPaused) {
				unpaused.await();
			}
		} catch (InterruptedException ie) {
			t.interrupt();
		} finally {
			pauseLock.unlock();
		}
	}

	public void pause() {
		pauseLock.lock();
		try {
			isPaused = true;
		} finally {
			pauseLock.unlock();
		}
	}

	public void resume() {
		pauseLock.lock();
		try {
			isPaused = false;
			unpaused.signalAll();
		} finally {
			pauseLock.unlock();
		}
	}
}