C# ManualResetEvent用法詳解

2020-01-24 00:01:17

字體：大中小

來源：轉載

供稿：網友

ManualResetEvent表示線程同步事件，可以對所有進行等待的線程進行統一管理（收到信號時必須手動重置該事件）

其構造函數為：

public ManualResetEvent (bool initialState);

參數 initialState 表示是否初始化，如果為 true，則將初始狀態設置為終止（不阻塞）；如果為 false，則將初始狀態設置為非終止（阻塞）。

注意：如果其參數設置為true，則ManualResetEvent等待的線程不會阻塞。如果初始狀態為false, 則在Set調用方法之前, 將阻止線程。

它只有兩個方法

//將事件狀態設置為終止狀態，從而允許繼續執行一個或多個等待線程。public bool Set ();//將事件狀態設置為非終止，從而導致線程受阻。public bool Reset ();//返回值：操作成功返回true，否則false

講了這么多，看個例子理解一下

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(); //開始線程    }    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(); //阻塞線程，直到調用Set方法才能繼續執行    Console.WriteLine(name + " ends.");  }}

結果如下