我要让我们的进程同步，因为我是浪漫的程序员！

wait(S){
    while(S<=0);
    S--;
}

signal(S){
    S++；
}

typedef struct{
    int value;
    struct process_control_block *list;
}semaphore;

wait(semaphore *S){
    S->value--;
    if(S->value<0)  block(S->list);
}

signal(semaphore *S){
    s->value++;
    if(S->value<=0)
      wakeup(S->list);
}

wait(S1,S2,...,Sn)
{
    while(true)
    {
        if(Si>=1&&...&&Sn>=1)
        {
            for(i=1;i<n;i++)
            Si--;
            break;
        }
        else
        {
            place the process in the waiting queue associated with.....
            //如果没有申请到资源的话就挂到相应的阻塞队列里去
        }
    }
}

Ssignal(S1,S2,...Sn)
{
    while(true)
    {
        for(i=1;i<=n;i++)
        {
            Si++;
            remove all the process waiting in the queue associated with Si into the ready queue;
            //去后备队列里唤醒或移除因Si资源阻塞的进程
        }
    }
}

semaphore mutex=1;
PA(){
    while(1){
        wait(mutex);
        临界区
        signal(mutex);
        剩余区
    }
}

PB(){
    while(1){
        wait(mutex);
        临界区
        signal(mutex);
        剩余区
    }
}

package com.common;

/**
 * 定义缓冲器余量，生产者和消费者执行的方法
 */
public class BaoZi {
    Integer count = 0;      //记录包子总数

    /**
     * 生产包子（产生资源）
     *
     * @param name 厨师名
     */
    public synchronized void makeBaoZi(String name) {
//        判断包子数是否大于3达到上限
        while (count >= 3) {
            System.out.println(name + "：包子已经达到上限了！");
            try {
                wait();     //包子容量达到3，超出上限，生产者进入等待
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        count++;    //如果没有达到3就做一个包子
        System.out.println(name + "：做了一个包子，还剩【" + count + "】个！");
        notifyAll();    //有包子资源了，唤醒消费者购买包子
    }

    /**
     * 购买包子（使用资源）
     *
     * @param name
     */
    public synchronized void buyBaoZi(String name) {
//        判断包子资源数是否等于0，
        while (count == 0) {
            System.out.println(name + "：没有包子资源了！");
            try {
                wait();     //没有包子资源，消费者进程进入等待状态
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        count--;    //包子资源数量减一
        System.out.println(name + "：购买了一个包子，包子资源剩余【" + count + "】个！");
        notifyAll();    //包子数未达到上限，让生产者厨师做包子，（唤醒所有等待该资源的进程），
    }
}

package com.producer;

import com.common.BaoZi;

/**
 * 生产者进程
 */
public class BaoZiPu extends Thread {
    private String name;    //厨师名字
    private BaoZi baoZi;    //缓冲区包子资源

    public BaoZiPu() {
    }

    public BaoZiPu(BaoZi baoZi, String name) {
        this.baoZi = baoZi;
        this.name = name;
    }

    @Override
    public void run() {
        while (true) {
            try {
                Thread.sleep(2000);     //休眠两秒钟
                baoZi.makeBaoZi(name);  //生产一个包子资源
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }
}

package com.consumer;

import com.common.BaoZi;

/**
 * 消费者进程，消耗包子资源
 */
public class Customer extends Thread {

    private String name;
    private BaoZi baoZi;

    public Customer() {
    }

    public Customer(BaoZi baoZi, String name) {
        this.baoZi = baoZi;
        this.name = name;
    }

    @Override
    public void run() {
        while (true){
            try {
                Thread.sleep(2000); //休眠两秒钟
                baoZi.buyBaoZi(name);   //消耗一个包子资源
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }
}

import com.common.BaoZi;
import com.consumer.Customer;
import com.producer.BaoZiPu;

public class TestMain {

    public static void main(String[] args) {
        System.out.println("==========进程同步测试==========");
        BaoZi baoZi = new BaoZi();
        Thread rouBaoZi = new Thread(new BaoZiPu(baoZi, "肉包子厨师"));
        Thread suBaoZi = new Thread(new BaoZiPu(baoZi, "素包子厨师"));
        Thread customerZS = new Thread(new Customer(baoZi, "顾客张三"));
        Thread customerLS = new Thread(new Customer(baoZi, "顾客李四"));
        customerZS.start();
        rouBaoZi.start();
        suBaoZi.start();
        customerLS.start();

    }
}