关于使用ManualResetEvent的用法c＃？

Question

i am not familiar with the usage of ManualResetEvent ?

is it thread related. what it does and when it is used?

here i got a code where ManualResetEvent is used but i just do not understand what it does?

here is the code

public class Doc : SomeInterfaceFromTheDll
{
  private readonly IVersion version; // An interface from the DLL.
  private readonly ManualResetEvent _complete = new ManualResetEvent(false);

  private bool downloadSuccessful;

  // ...

  public bool Download()
  {
    this.version.DownloadFile(this);
    // Wait for the event to be signalled...
    _complete.WaitOne();
    return this.downloadSuccessful;
  }

  public void Completed(short reason)
  {
    Trace.WriteLine(string.Format("Notify.Completed({0})", reason));
    this.downloadSuccessful = reason == 0;
    // Signal that the download is complete
    _complete.Set();
  }

  // ...
} 

what is the meaning of _complete.WaitOne(); & _complete.Set(); ? _complete.WaitOne(); & _complete.Set(); ?

can anyone give me small sample code where ManualResetEvent class usage will be there.

looking for good discuss and usage of ManualResetEvent ? thanks

Answer 1

I suggest you to read the "remarks" section of the MSDN page of ManualResetEvent which is pretty clear about the usage of this class.

To answer your specific question, the ManualResetEvent is used to simulate a synchronous call to Download even if it's asynchronous. It calls the async method and blocks until the ManualResetEvent is signaled. The ManualResetEvent is signaled within the event handler of the async event-based pattern. So basically it waits until the event is fired and the event handler is executed.

Answer 2

To achieve deep understanding of any subject, I have to read the almost same information in other words. I've read the MSDN documentation about the ManualResetEvent, it was good I almost got to understand it, but this link helped me to understand it well:

http://dotnetpattern.com/threading-manualresetevent

If the current thread calls the method, it will be waiting(so stop doing anything) until any other thread calls the method.

There is another overload for the WaitOne, is the . This is almost the same as the above, but if for eaxample give time to this method, the current thread will be waiting for other thread to call the method for and if no one called , it calls it automatically and contunie the work.

Answer 3

ManualSetEvent是一个类，它可以帮助您管理不同线程之间的通信，当一些线程必须停止并等待完成另一个线程（线程）然后该类非常有用。