实现一个简单的 CountDownLatch Demo

现在很多框架或者中间件由于多次迭代、优化和兼容、扩展处理，最核心的设计思想和原理很容易就被覆盖，导致我们想学习的时候就不太容易抓住主干。

先不看各种原理，就基与 ​​CountDownLatch​​​ 提供的功能使用最简单的方式去实现 ​​CountDownLatch​​:

package dongguabai.concurrent;

/**
 * @author Dongguabai
 * @description
 * @date 2022-04-25 12:38
 */
public class MyCountDownLatch {

    private volatile int count;

    public MyCountDownLatch(int count) {
        this.count = count;
    }

    public synchronized void countDown() {
        count--;
    }

    public void await() {
        while (count > 0) {
        }
    }

    public static void main(String[] args) {
        //CountDownLatch cl
    }
}

使用​​JUC之AQS之CountDownLatch​​中的例子测试一下：

package dongguabai.concurrent;

import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author Dongguabai
 * @date 2018/9/24 11:46
 */
public class CountDownLaunthDemo implements Runnable{
 
    static int count = 10;
 
    static MyCountDownLatch end = new MyCountDownLatch(count);
    static CountDownLaunthDemo demo = new CountDownLaunthDemo();
 
    @Override
    public void run() {
        try {
            Thread.sleep(new Random().nextInt(10)*1000);
            System.out.println("check complete");
            end.countDown();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
 
    public static void main(String[] args) throws InterruptedException {
        ExecutorService exec = Executors.newFixedThreadPool(count);
        for (int i = 0; i < count; i++) {
            exec.submit(demo);
        }
        end.await();
        System.out.println("-------------Fire");
        exec.shutdownNow();
    }
}

输出：

check complete
check complete
check complete
check complete
check complete
check complete
check complete
check complete
check complete
check complete
-------------Fire

References

• javascript:void(0)