Detailed explanation and examples of synchronization using AutoResetEvent in C#

This article mainly introduces the relevant information of C# using AutoResetEvent to achieve synchronization in detail. It has certain reference value. Interested friends can refer to the previous few

Today I encountered a problem with the sequential execution of a thread, which is an asynchronous thread sending a data request to the A interface. Another asynchronous thread sends a data request to the B interface. When both A and B are executed successfully, it sends a request to the C interface. To be honest, I have been working on BS projects and don’t know much about threads. I knew that AutoResetEvent was related to threads and was used to handle thread switching, so I decided to use AutoResetEvent to deal with the above problems.

So I searched for relevant information online:

It turns out that AutoResetEvent is often used in .Net multi-threaded programming. When a thread calls the WaitOne method, the signal is in the sending state, the thread will get the signal, and the program will continue to execute, otherwise it will wait. Moreover, AutoResetEvent.WaitOne() only allows one thread to enter at a time. When a thread gets the signal, AutoResetEvent will automatically set the signal to a non-sending state. Other threads calling WaitOne can only continue to wait. In other words, AutoResetEvent can only When one thread is woken up, other threads are still blocked.

Introduction

AutoResetEvent(bool initialState): Constructor, with an indication whether to set the initial state to terminate Boolean value that initializes a new instance of this class.
false: No signal, the WaitOne method of the sub-thread will not be automatically called
true: There is a signal, the WaitOne method of the sub-thread will be automatically called
Reset (): Set the event status to a non-terminated state , causing the thread to block; if the operation is successful, it returns true; otherwise, it returns false.
Set (): Set the event status to the terminated status, allowing one or more waiting threads to continue; if the operation is successful, return true; otherwise, return false.
WaitOne(): Blocks the current thread until a signal is received.
WaitOne(TimeSpan, Boolean): Blocks the current thread until the current instance receives the signal, uses TimeSpan to measure the time interval and specifies whether to exit the synchronization domain before waiting.​
​ WaitAll(): Wait for all signals.

Implementation

 class Program
 {

  static void Main()
  {
   Request req = new Request();

   //这个人去干三件大事 
   Thread GetCarThread = new Thread(new ThreadStart(req.InterfaceA));
   GetCarThread.Start();

   Thread GetHouseThead = new Thread(new ThreadStart(req.InterfaceB));
   GetHouseThead.Start();

   //等待三件事都干成的喜讯通知信息 
   AutoResetEvent.WaitAll(req.autoEvents);

   //这个人就开心了。 
   req.InterfaceC();

   System.Console.ReadKey();
  }
 }

 public class Request
 {
  //建立事件数组 
  public AutoResetEvent[] autoEvents = null;

  public Request()
  {
   autoEvents = new AutoResetEvent[]
   {
    new AutoResetEvent(false),
    new AutoResetEvent(false)
   };
  }

  public void InterfaceA()
  {
   System.Console.WriteLine("请求A接口");

   Thread.Sleep(1000*2);

   autoEvents[0].Set();

   System.Console.WriteLine("A接口完成");
  }

  public void InterfaceB()
  {
   System.Console.WriteLine("请求B接口");

   Thread.Sleep(1000 * 1);

   autoEvents[1].Set();

   System.Console.WriteLine("B接口完成");
  }

  public void InterfaceC()
  {
   System.Console.WriteLine("两个接口都已经请求完，正在处理C");
  }
 }

Note that it is best to add a timeout to WaitOne or WaitAll. Otherwise, no signal is received and the thread will always be blocked.

Afterword

This is just a simplification of the above scenario, mainly used to solve the problem of the scenario I just mentioned.
The above is a summary of my use of AutoResetEvent. Please give me some pointers on the shortcomings.

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