操作系統 - 使用google guava庫Monitor 解決消費者問題

1.成員：
生產者、緩衝區、消費者

2.引入jar包
guava-23.0.jar

3.代碼

package monitor;

import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.Monitor;
import com.google.common.util.concurrent.MoreExecutors;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

/*
 * 用google guava庫Monitor 寫消費者問題
 */
 
public class MonitorDemo {
    private LinkedList<Integer> buffer= new LinkedList<>() ;
    private static final int MAX = 10 ;
    //記錄生產的數據編號
    private static AtomicInteger count = new AtomicInteger(0) ;
    //int i ;  i++ ;非原子性操作 ;  i++ 拆分成多行 ；線程安全問題
    private Monitor monitor = new Monitor() ;

    //生產數據
    public void produce(int value){
		//一般方法
		// if(buffer.size()<MAX)
			// notifyALL();  若小於MAX，就喚醒消費者
		// else 
			// wait();
		
        try {
				
            //enterWhen：相當於加鎖
            monitor.enterWhen( monitor.newGuard(  ()->  buffer.size()<MAX        )    ) ;
            buffer.addLast( value);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally{
            monitor.leave();
            System.out.println("生產完畢，緩衝區大小：" + buffer.size());
        }
    }

    //消費數據
    public int consume(){
        try {
            monitor.enterWhen(  monitor.newGuard(  ()-> ! buffer.isEmpty()      )      );
           return  buffer.removeFirst()  ;
        } catch (InterruptedException e) {
            e.printStackTrace();
            throw new RuntimeException(e) ;
        }finally {
            monitor.leave();
            System.out.println("消費完畢，緩衝區大小：" + buffer.size());
        }
    }

    public static void main(String[] args) {
        MonitorDemo demo = new MonitorDemo() ;

		//原生線程池
        ExecutorService executorService = Executors.newFixedThreadPool(6);
        //將線程池包裝
        ListeningExecutorService listeningExecutorService = MoreExecutors.listeningDecorator(executorService);

		//向線程池放入3個生產者
        for(int i=0;i<3;i++){
            listeningExecutorService.submit( () ->{
                while(true){
                  int result =   count.getAndIncrement(); //i++  0  1  2
                  demo.produce( result );
                    System.out.println("生產："+ result);
                }

            }          ) ;
        }
        //向線程池放入3個消費者
        for(int i=0;i<3;i++){
            while(true){
               int result =  demo.consume() ;
                System.out.println("消費" +result);
            }
        }
    }
}