ManualResetEvent类的用法

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#作用

一个线程通知其他一个或多个线程正在发送的事件。

ManualResetEvent manualResetEvent = new ManualResetEvent(false);

参数表示调用WaitOne（）方法的线程是继续执行（true）还是阻塞(false)。

WaitOne()：调用WaitOne()方法的线程会阻塞，等待主控线程的manualResetEvent.Set()信号。

Set()：将事件状态设为true,调用WaitOne()的线程继续执行。
Reset()：将事件状态设为false,调用WaitOne()的线程阻塞。

Set() Reset()：只针对WaitOne()方法，不影响WaitOne()方法之前的程序执行。若没有信号，调用WaitOne()方法的线程一直阻塞。

1.事件初始状态设为false，task线程在第一个WaitOne()处阻塞。

using System;
using System.Threading;
using System.Threading.Tasks;
namespace ManualResetEvent测试
{ 
   
    class Program
    { 
   
        static ManualResetEvent manualResetEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        { 
   
            //Task线程和主线程同时执行
            Task task = Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(1);
            });
            Console.ReadLine();
        }

        static void GetDataFromServer(int serverNumber)
        { 
   
            Console.WriteLine("I get first data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("I get second data from server" + serverNumber);
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine("I get third data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("All the data collected from server" + serverNumber);
        }
    }
}

输出：
I get first data from server1

2.manualResetEvent.Set()事件状态设为true，task线程在每一个WaitOne()处都不阻塞。

namespace ManualResetEvent测试
{ 
   
    class Program
    { 
   
        static ManualResetEvent manualResetEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        { 
   
            //两个Task线程和主线程同时执行
            Task task = Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(1);
            });
            
            //主线程执行，将信号set为true,调用WaitOne()的线程被释放
            manualResetEvent.Set();
 
            Console.ReadLine();

        }

        static void GetDataFromServer(int serverNumber)
        { 
   
            Console.WriteLine("I get first data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("I get second data from server" + serverNumber);
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine("I get third data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("All the data collected from server" + serverNumber);
        }
    }
}

输出：
I get first data from server1
I get second data from server1
I get third data from server1
All the data collected from server1

3.manualResetEvent调用Set()再调用Reset(),task线程在第一个WaitOne()处阻塞。

namespace ManualResetEvent测试
{ 
   
    class Program
    { 
   
        static ManualResetEvent manualResetEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        { 
   
            //两个Task线程和主线程同时执行
            Task task = Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(1);
            });
            
            //主线程执行，调用WaitOne()的线程被释放再马上阻塞
            manualResetEvent.Set();
 			manualResetEvent.Reset();
            Console.ReadLine();

        }

        static void GetDataFromServer(int serverNumber)
        { 
   
            Console.WriteLine("I get first data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("I get second data from server" + serverNumber);
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine("I get third data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("All the data collected from server" + serverNumber);
        }
    }
}

输出：
I get first data from server1

4.manualResetEvent.Set()事件状态设为true，task线程在第一个WaitOne()处阻塞然后被释放。

namespace ManualResetEvent测试
{ 
   
    class Program
    { 
   
        static ManualResetEvent manualResetEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        { 
   
            //Task线程和主线程同时执行
            Task task = Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(1);
            });

			setEvent.Set();
            manualResetEvent.Reset();

            Thread.Sleep(TimeSpan.FromSeconds(8));
            manualResetEvent.Set();

            Console.ReadLine();
        }

        static void GetDataFromServer(int serverNumber)
        { 
   
            Console.WriteLine("I get first data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("I get second data from server" + serverNumber);
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine("I get third data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("All the data collected from server" + serverNumber);
        }
    }
}

输出：
先输出 I get first data from server1
然后task被阻塞，8秒后task获得Set()信号，再输出 I get second data from server1
再间隔2秒输出，第二个WaitOne()不会被阻塞
I get third data from server1
All the data collected from server1

5.三个线程异步执行，set()释放所有线程

namespace ManualResetEvent测试
{ 
   
    class Program
    { 
   
        static ManualResetEvent manualResetEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        { 
   
            //两个Task线程和主线程同时执行
            Task task = Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(1);
            });

            Task.Factory.StartNew(() =>
            { 
   
                GetDataFromServer(2);
            });

            manualResetEvent.Set();
            manualResetEvent.Reset();

            Thread.Sleep(TimeSpan.FromSeconds(8));
            manualResetEvent.Set();
            
            Console.ReadLine();

        }

        static void GetDataFromServer(int serverNumber)
        { 
   
            Console.WriteLine("I get first data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("I get second data from server" + serverNumber);
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine("I get third data from server" + serverNumber);
            manualResetEvent.WaitOne();
            Console.WriteLine("All the data collected from server" + serverNumber);
        }
    }
}

输出：
先输出
I get first data from server1
I get first data from server2
然后task被阻塞，8秒后task获得Set()信号，再输出
I get second data from server2
I get second data from server1
再间隔2秒输出，第二个WaitOne()不会被阻塞
I get third data from server2
All the data collected from server2
I get third data from server1
All the data collected from server1