[原创]C#编写的多生产者多消费者同步问题

// 多个生产者和多个消费者，能生产n个产品的情况

using System;
using System.Threading;

public class HoldIntegerSynchronized{

 private int[] buffer;  //缓冲区

 private int occupiedBufferCount = 0;
 
 private int readPosition = 0 , writePosition = 0;
 //下一个读到的位置和写到的位置
 
 public HoldIntegerSynchronized(int capacity){
  buffer = new int[capacity];
 }
 
 public int BufferSize{
  get{
   return buffer.Length;
  }
 }

 public int Buffer{
  get{
   int bufferCopy;
   // 加锁
   lock(this){
    while(occupiedBufferCount == 0){ //多个消费者，所以此处改用while
     Console.WriteLine(Thread.CurrentThread.Name + " tries to read. ");
     DisplayState("Buffer Empty. " + Thread.CurrentThread.Name + " waits.");
     Monitor.Wait(this);
     // 为临界区之外等待的生产者放行，让他来"生产"
     // 一直到生产者生产结束，调用了Monitor.PauseAll()
     // 才能继续执行下去,此时，消费者自动重新获得this的锁
    }

    --occupiedBufferCount;

    bufferCopy = buffer[readPosition];

    readPosition = (readPosition + 1) % buffer.Length;    
    
    DisplayState(Thread.CurrentThread.Name + " reads " + bufferCopy);

    // 通知，让等待的 生产者线程 进入Started状态,如果生产者处于临界区之外，这句话执行完后他仍然在临界区之外
    Monitor.PulseAll(this);

   // 释放锁
   }//lock
   return bufferCopy;
  }

  set{
   // 加锁
   lock(this){
    while(occupiedBufferCount == buffer.Length){
     Console.WriteLine(Thread.CurrentThread.Name + " tries to write. ");
     DisplayState("Buffer Full. " + Thread.CurrentThread.Name + " waits.");
     Monitor.Wait(this); 
     // 为临界区之外等待消费者放行，让他来"消费"
     // 一直到消费者调用了Monitor.Pause()
     // 才能继续执行下去，此时，生产者自动重新获得this的锁
    }

    buffer[writePosition] = value;
    
    ++occupiedBufferCount;
    
    writePosition = (writePosition + 1) % buffer.Length;

    DisplayState(Thread.CurrentThread.Name + " writes " + value);

    // 通知，让Wait状态的 消费者 进入Started状态,如果消费者处于临界区之外，这句话执行完后他仍然在临界区之外
    Monitor.PulseAll(this);

   // 释放锁
   }
  }
 }

 public void DisplayState(string operation){
  Console.Write("{0,-35}",operation);
  for(int i = 0; i < BufferSize; i++ ){
   int a = readPosition;
   int b = writePosition;

   if( a <= i && i < b) {
    Console.Write("{0,-9}",buffer[i]);
   }else if( b < a && !( b <= i && i < a ) ){
    Console.Write("{0,-9}",buffer[i]);
   }else if( occupiedBufferCount == BufferSize){
    Console.Write("{0,-9}",buffer[i]);
   }else{
    Console.Write("{0,-9}","");
   }

  }
  Console.WriteLine("{0}\r\n",occupiedBufferCount);
 }
}

class Producer{
 private HoldIntegerSynchronized sharedLocation;
 private Random randomSleepTime;

 public Producer(HoldIntegerSynchronized shared,Random random){
  sharedLocation = shared;
  randomSleepTime = random;
 }
 
 public void Produce(){
  for (int count=0; count<3; count++) {
   Thread.Sleep(randomSleepTime.Next(1,2000));
   sharedLocation.Buffer = randomSleepTime.Next(5,10);
  }
  Console.WriteLine(Thread.CurrentThread.Name + " done producing.\r\nTerminating " + Thread.CurrentThread.Name + ".\r\n");
 }
}

class Consumer{
 private HoldIntegerSynchronized sharedLocation;
 private Random randomSleepTime;

 public Consumer(HoldIntegerSynchronized shared,Random random){
  sharedLocation = shared;
  randomSleepTime = random;
 }
 
 public void Consume(){
  int sum = 0;
  for (int count=0; count<4; count++) {
   Thread.Sleep(randomSleepTime.Next(1,2000));
   sum += sharedLocation.Buffer;
  }
  Console.WriteLine(Thread.CurrentThread.Name + " read values totaling:" + sum + "\r\nTerminating " + Thread.CurrentThread.Name + ".");
 } 
}

class SharedCell{
 static void Main(string[] args){
  HoldIntegerSynchronized holdInteger = new HoldIntegerSynchronized(5);
  Random random = new Random();
   
  Thread[] producerThreads = new Thread[4];
  Thread[] consumerThreads = new Thread[3];

  Console.Write("{0,-35}","Operation");
  for(int i = 0;i < holdInteger.BufferSize;i++){
   Console.Write("{0,-9}","Elem " + i);
  }
  Console.WriteLine("Occupied Count\r\n");

  for(int i = 0; i < producerThreads.Length;i++){
   Producer producer = new Producer(holdInteger,random);
   producerThreads[i] = new Thread(new ThreadStart(producer.Produce));
   producerThreads[i].Name = "Producer No." + i;
  }

  for(int i = 0; i < consumerThreads.Length;i++){
   Consumer consumer = new Consumer(holdInteger,random);
   consumerThreads[i] = new Thread(new ThreadStart(consumer.Consume));
   consumerThreads[i].Name = "Consumer No." + i;
  }

  for(int i = 0; i < producerThreads.Length;i++){
   producerThreads[i].Start();
  }

  for(int i = 0; i < consumerThreads.Length;i++){
   consumerThreads[i].Start();
  }
 }
}

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