Java并发-同步器CyclicBarrier,Exchanger,Phaser

这篇主要模拟其他三个同步器：循环屏障(CyclicBarrier)、交换器(Exchanger)、Phaser

一、CyclicBarrier同步器

特征：

1. 适用于只有多个线程都到达预定点时才可以继续执行(比如斗地主，需要等齐三个人才开始)

2. CyclicBarrier(int num) :等待线程的数量

3. CyclicBarrier(int num, Runnable action) :等待线程的数量以及所有线程到达后的操作

4. await() : 到达临界点后暂停线程

以下代码模拟该模型：

package com.concurrent.src;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;

/**
* 斗地主：需要等待齐三个玩家游戏才开始
* @author admin
*
*/
public class Cdemo {
public static void main(String[] args) {

// 创建循环屏障，条件满足时就执行runnable
CyclicBarrier cyclicBarrier = new CyclicBarrier(3, new Runnable() {
@Override
public void run() {
System.out.println("Game start...");
}
});

// 有A,B,C三个玩家
new Player(cyclicBarrier, "A").start();
new Player(cyclicBarrier, "B").start();
new Player(cyclicBarrier, "C").start();
}
}

class Player extends Thread {
private CyclicBarrier cyclicBarrier;

public Player(CyclicBarrier cyclicBarrier,String name) {
setName(name);
this.cyclicBarrier = cyclicBarrier;
}

@Override
public void run() {
System.out.println(getName() + " is waiting other player....");
try {
// 屏障处等待
cyclicBarrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}
}

执行结果：

A is waiting other player....
C is waiting other player....
B is waiting other player....
Game start...

二、 交换器(Exchanger)同步器

此处模拟略！暂时没用到！

三、Phaser同步器

特征：

1. 工作方式与CyclicBarrier类似，但是可以定义多个阶段

2. Phaser()/Phaser(int num) : 使用指定0/num个party创建Phaser

3. register() : 注册party

4. arriveAndAdvance() : 到达时等待到所有party到达

5. arriveAndDeregister() : 到达时注销线程自己

以下代码模拟该同步器：

package com.concurrent.src;

import java.util.concurrent.Phaser;

/**
* 一个一个订单处理
* @author admin
*
*/
public class Ddemo {
public static void main(String[] args) {

Phaser phaser = new Phaser(1);
System.out.println("starting...");

// 点餐用餐中会包含多个人员服务
new Worker(phaser, "服务员").start();
new Worker(phaser, "打荷员").start();
new Worker(phaser, "厨师").start();

for (int i = 1; i <= 3; i++) {
phaser.arriveAndAwaitAdvance();
System.out.println("Order " + i + " finished");
}

// 注销
phaser.arriveAndDeregister();

System.out.println("Order all done ");
}
}

class Worker extends Thread {
private Phaser phaser;

public Worker(Phaser phaser,String name) {
setName(name);
this.phaser = phaser;
}

@Override
public void run() {
for (int i = 1; i <= 3; i++) {
System.out.println( "current order is : " + i + " : " + getName());
if (i == 3) {
phaser.arriveAndDeregister();
} else {
phaser.arriveAndAwaitAdvance();
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}

执行结果：

starting...
Order 1 finished
Order 2 finished
Order 3 finished
Order all done
current order is : 1 : 打荷员
current order is : 1 : 服务员
current order is : 1 : 厨师
current order is : 2 : 打荷员
current order is : 2 : 服务员
current order is : 2 : 厨师
current order is : 3 : 打荷员
current order is : 3 : 服务员
current order is : 3 : 厨师