C# ManualResetEvent用法详解

程序员文章站 2023-09-07 15:11:26

manualresetevent表示线程同步事件，可以对所有进行等待的线程进行统一管理（收到信号时必须手动重置该事件）其构造函数为： public manualreset...

manualresetevent表示线程同步事件，可以对所有进行等待的线程进行统一管理（收到信号时必须手动重置该事件）

其构造函数为：

public manualresetevent (bool initialstate);

参数 initialstate 表示是否初始化，如果为 true，则将初始状态设置为终止（不阻塞）；如果为 false，则将初始状态设置为非终止（阻塞）。

注意：如果其参数设置为true，则manualresetevent等待的线程不会阻塞。如果初始状态为false, 则在set调用方法之前, 将阻止线程。

它只有两个方法

//将事件状态设置为终止状态，从而允许继续执行一个或多个等待线程。
public bool set ();

//将事件状态设置为非终止，从而导致线程受阻。
public bool reset ();

//返回值：操作成功返回true，否则false

讲了这么多，看个例子理解一下

using system;
using system.threading;

public class example
{
  // mre is used to block and release threads manually. it is
  // created in the unsignaled state.
  private static manualresetevent mre = new manualresetevent(false);

  static void main()
  {
    console.writeline("\nstart 3 named threads that block on a manualresetevent:\n");

    for (int i = 0; i <= 2; i++)
    {
      thread t = new thread(threadproc);
      t.name = "thread_" + i;
      t.start(); //开始线程
    }

    thread.sleep(500);
    console.writeline("\nwhen all three threads have started, press enter to call set()" +
             "\nto release all the threads.\n");
    console.readline();

    mre.set();

    thread.sleep(500);
    console.writeline("\nwhen a manualresetevent is signaled, threads that call waitone()" +
             "\ndo not block. press enter to show this.\n");
    console.readline();

    for (int i = 3; i <= 4; i++)
    {
      thread t = new thread(threadproc);
      t.name = "thread_" + i;
      t.start();
    }

    thread.sleep(500);
    console.writeline("\npress enter to call reset(), so that threads once again block" +
             "\nwhen they call waitone().\n");
    console.readline();

    mre.reset();

    // start a thread that waits on the manualresetevent.
    thread t5 = new thread(threadproc);
    t5.name = "thread_5";
    t5.start();

    thread.sleep(500);
    console.writeline("\npress enter to call set() and conclude the demo.");
    console.readline();

    mre.set();

    // if you run this example in visual studio, uncomment the following line:
    //console.readline();
  }


  private static void threadproc()
  {
    string name = thread.currentthread.name;

    console.writeline(name + " starts and calls mre.waitone()");

    mre.waitone(); //阻塞线程，直到调用set方法才能继续执行

    console.writeline(name + " ends.");
  }
}

结果如下

C# ManualResetEvent用法详解