并发-Exchanger

Exchanger

• Exchanger是两个任务之间交换对象的栅栏。当这些任务进入栅栏时，各自拥有一个对象，当它们离开时，它们都拥有之前由对象持有的对象。
• Exchanger的典型应用场景是：一个任务在创建对象，这些对象的生产代价很高昂，而另一个任务在消费这些对象。通过这种方式，可以有更多的对象在被创建的同时被消费。

package com21concurrent;
import com15.BasicGenerator;
import com15.Generator;

import java.util.List;
import java.util.concurrent.*;

/**
 * Created by Panda on 2018/6/2.
 */
class ExchangerProducer implements Runnable{
    private Generator generator;
    private Exchanger> exchanger;
    private List holder;

    public ExchangerProducer(Generator generator, Exchanger> exchanger, List holder) {
        this.generator = generator;
        this.exchanger = exchanger;
        this.holder = holder;
    }

    @Override
    public void run() {
        try{
            while (!Thread.interrupted()){
                for (int i = 0; i catch (InterruptedException e){

        }
    }
}

class ExchangeConsumer implements Runnable{
    private Exchanger> exchanger;
    private List holder;
    private volatile T value;

    public ExchangeConsumer(Exchanger> exchanger, List holder) {
        this.exchanger = exchanger;
        this.holder = holder;
    }


    @Override
    public void run() {
        try{
            while (!Thread.interrupted()){
                holder=exchanger.exchange(holder);
                for(T x:holder){
                    value=x;
                    holder.remove(x);
                }
            }
        }catch (InterruptedException e){

        }
        System.out.println("Final value: "+value);
    }
}

public class ExchangerDemo {
    static int size=10;
    static int delay=5;

    public static void main(String[] args) throws Exception{
        if(args.length>0) size=new Integer(args[0]);
        if(args.length>1) delay=new Integer(args[1]);
        ExecutorService executorService = Executors.newCachedThreadPool();
        Exchanger> listExchanger=new Exchanger<>();
        List producerList=new CopyOnWriteArrayList<>();
        List consumerList=new CopyOnWriteArrayList<>();

        executorService.execute(new ExchangerProducer<>(BasicGenerator.create(Fat.class),listExchanger ,producerList));
        executorService.execute(new ExchangeConsumer<>(listExchanger,consumerList));
        TimeUnit.SECONDS.sleep(delay);
        executorService.shutdownNow();

    }
}