PV操作信号量

PV操作信号量
20090344010 朱凯软（1）
实验目的：模拟哲学家吃通心面和生产者和消费者的问题实验内容：
代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace信号量
{
class Program
{
static void Main(string[] args)
{
Problems p = new Problems();
while (true)
{
Console.WriteLine("Input a problem : \n\t1.哲学家吃心面问题\n\t2.消费者生产者问题");
int n = int.Parse(Console.ReadLine());
p.Play(n);
}
}
}
class Problems
{
#region PV操作
///<summary>
///信号量
///</summary>
class Semaphore
{
///<summary>
///等待句柄，用来协调线程的阻塞和激活
///</summary>
public EventWaitHandle handle;
public Semaphore(int value,string name)
{
Value[0] = value;
Name = name;
handle = new EventWaitHandle(false , EventResetMode.AutoReset);
}
public string Name;
public int[] Value = { 0 };
public Queue<Thread> Threads = new Queue<Thread>();
}
void P(Semaphore s)
{
lock(s.Value) s.Value[0]--;
if (s.Value[0] < 0)
{
Thread t = Thread.CurrentThread;
lock(s.Threads) s.Threads.Enqueue(t);
s.handle.WaitOne();
}
}
void V(Semaphore s)
{
lock(s.Value) s.Value[0]++;
if (s.Value[0] <= 0)
{
Thread t=null;
lock(s.Threads) t= s.Threads.Dequeue();
s.handle.Set();
}
}
#endregion
///<summary>
/// 5位哲学家吃通心面问题
///</summary>
void Pilosopher()
{
Console.WriteLine("5位哲学家吃通心面问题");
Semaphore[] fork = { new Semaphore(1,"1"), new Semaphore(1,"2"), new Semaphore(1,"3"), new Semaphore(1,"4"), new Semaphore(1,"5") };
for (int i = 0; i < 5; i++)
{
int left=i,right=(i+1)%5;
int p=i;
new Thread(delegate()
{
for (int j = 0; j < 4; j++)
{
Console.WriteLine("\t\tThinking ... philosopher:" + p);
Thread.Sleep(2000);
P(fork[left]);
P(fork[right]);
Console.WriteLine("\t\tEating ... philosopher:" + p);
Thread.Sleep(3000);
V(fork[left]);
V(fork[right]);
}
}).Start();
}
}
///<summary>
///单缓冲区生产者消费者问题
///</summary>
void SingleProducerConsumer()
{
Console.WriteLine("单缓冲区生产者消费者问题");
int B = 0;
///可用的空缓冲区数
Semaphore empty;
///缓冲区内空用的产品数
Semaphore full;
///缓冲区内允许放入一件产品
empty = new Semaphore(1,"empty");
///缓冲区内没有产品
full = new Semaphore(0,"empty");
///生产者
new Thread(delegate()
{
= "生产者?";
///生产的产品
int n = 0;
for(int j=0;j<10;j++)
{
n++;//生产一件产品
Console.WriteLine("\t\tProducer ... " + n);
P(empty);
B = n;
V(full);
}
}).Start();
///消费者
new Thread(delegate()
{
= "消费者";
///得到的产品
int n = 0;
for(int j=0;j<10;j++)
{
P(full);
n = B;
V(empty);
Console.WriteLine("\t\tConsume ... " + n);
}
}).Start();
}
public void Play(int n)
{
switch (n)
{
case 1:
Pilosopher();
break;
case 2:
SingleProducerConsumer();
break;
}
}
}
}
实验感受：
PV操作可以解决一些生活中的问题很强悍。