Kuangcp/JavaBase

package com.github.kuangcp.list;

import com.github.kuangcp.old.BuildFactory;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.locks.ReentrantLock;

/**
 * Created by https://github.com/kuangcp on 17-8-15  下午8:55
 * 展示写时复制的特性，使用上锁存器 CountDownLatch 严格控制事件的顺序
 * 虽然线程的启动1在前， 但是锁存器控制了 2 在 1 之前，且很清楚的表明了写时复制的特性，
 * 第一个线程添加了一个元素，然后就得到了复制数组，就被挂起了，然后第二个线程又添加一个，运行结束后将1唤醒，运行结束
 */
public class ShowCopyOnWrite {

  public static void main(String[] a) {
    final CountDownLatch firstLatch = new CountDownLatch(1);
    final CountDownLatch secondLatch = new CountDownLatch(1);
    // 使用不可变对象
    final BuildFactory.Builder builder = new BuildFactory.Builder();

    CopyOnWriteArrayList<BuildFactory> elements = new CopyOnWriteArrayList<>();
    elements.add(builder.name("myth").addr("local").build());
    elements.add(builder.name("roll").addr("remote").build());
    ReentrantLock lock = new ReentrantLock();

    ElementList<BuildFactory> list = new ElementList<>(elements, lock, "list1 > ");
    ElementList<BuildFactory> list2 = new ElementList<>(elements, lock, "list2 > ");

    Thread thread1 = new Thread(() -> {
      System.out.println("进入 线程 1");
      elements.add(builder.name("dyn 1").addr("89").build());
      list.prep();
      // 将计数器减一，也就是减成了0
      firstLatch.countDown();
//                System.out.println(firstLatch.toString());
      try {
        secondLatch.await();
      } catch (InterruptedException e) {
        System.out.println("first inter error");
      }
      list.listElement("first ");
    });
    Thread thread2 = new Thread(() -> {
      System.out.println("进入 线程 2");
      try {
        Thread.sleep(2000);
        firstLatch.await();
        elements.add(builder.name("dyn 2").addr("00").build());
        list2.prep();
        // 唤醒 线程1
        secondLatch.countDown();
      } catch (InterruptedException e) {
        System.out.println("second inter error");
      }
      list2.listElement("second");
    });

    thread1.start();
    thread2.start();
  }
}