package com.spell.threads;

import java.util.concurrent.CountDownLatch;

public class CountDownLatchTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// 构造参数为1，可以作为开始开关，只有等他countDown后才开始处理所有的线程
		CountDownLatch start = new CountDownLatch(1);
		CountDownLatch done = new CountDownLatch(5);
		Worker wk = new Worker(start, done);
		for (int i = 0; i < 5; i++) {
			new Thread(wk).start();
		}
		System.out
				.println(System.currentTimeMillis() + " all thread has start");
		// 发送开始信号，通知所有线程该工作了
		start.countDown();
		try {
			// 等待所有的线程工作完成
			done.await();
			System.out.println(System.currentTimeMillis()
					+ " all thread has done");
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

}

class Worker implements Runnable {
	private final CountDownLatch start;
	private final CountDownLatch done;

	Worker(CountDownLatch start, CountDownLatch done) {
		this.start = start;
		this.done = done;
	}

	public void run() {
		try {
			// 阻塞，等待开始信号
			start.await();
			doWork();
			// 发送线程完成信号
			done.countDown();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}

	}

	// 工作的任务就睡打个盹
	public void doWork() {
		// 产生个随机数
		Double d = Math.random() * 1000L;
		Long sleepTime = d.longValue();
		try {
			// 睡觉
			Thread.sleep(sleepTime);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		// 睡晚了报告时间
		System.out.println(Thread.currentThread().getName() + " sleep "
				+ sleepTime + " seconds");
	}
}