AutoResetEvent(Boolean) 建構函式

定義

命名空間:

System.Threading

組件:

System.Threading.dll

Source:

AutoResetEvent.cs

使用布林值 (Boolean) 來初始化 AutoResetEvent 類別的新執行個體，指出初始狀態是否設定為信號狀態。

public:
 AutoResetEvent(bool initialState);

public AutoResetEvent (bool initialState);

new System.Threading.AutoResetEvent : bool -> System.Threading.AutoResetEvent

Public Sub New (initialState As Boolean)

參數

initialState

Boolean

true 表示初始狀態設定為已收到信號，false 表示初始狀態設定為未收到信號。

範例

下列範例會使用 AutoResetEvent 來同步處理兩個執行緒的活動。 第一個執行緒是應用程式執行緒，會 Main 執行 。 它會將值寫入受保護的資源，這是 static 名為 的 Visual Basic) 欄位中 number 的 (Shared 。 第二個執行緒會執行靜態 ThreadProc 方法，以讀取 所 Main 寫入的值。

方法 ThreadProc 會 AutoResetEvent 等候 。 在 上 AutoResetEvent 呼叫 Set 方法時 Main ， ThreadProc 方法會讀取一個值。 AutoResetEvent會立即重設，因此方法 ThreadProc 會再次等候。

程式邏輯保證 ThreadProc 方法永遠不會讀取相同的值兩次。 不保證 ThreadProc 方法會讀取 所 Main 寫入的每個值。 該保證需要第二 AutoResetEvent 個鎖定。

在每個寫入作業之後， Main 呼叫 Thread.Sleep 方法會產生 ，讓第二個執行緒有機會執行。 否則，在單處理器電腦上 Main ，會在任兩個讀取作業之間寫入許多值。

using namespace System;
using namespace System::Threading;
ref class MyMainClass
{
public:
   static void MyReadThreadProc()
   {
      while ( true )
      {
         
         //The value will not be read until the writer has written
         // at least once since the last read.
         myResetEvent->WaitOne();
         Console::WriteLine( " {0} reading value: {1}", Thread::CurrentThread->Name, number );
      }
   }


   //Initially not signaled.
   static AutoResetEvent^ myResetEvent = gcnew AutoResetEvent( false );
   static int number;
   literal int numIterations = 100;
};

int main()
{
   
   //Create and start the reader thread.
   Thread^ myReaderThread = gcnew Thread( gcnew ThreadStart( MyMainClass::MyReadThreadProc ) );
   myReaderThread->Name = "ReaderThread";
   myReaderThread->Start();
   for ( int i = 1; i <= MyMainClass::numIterations; i++ )
   {
      Console::WriteLine( "Writer thread writing value: {0}", i );
      MyMainClass::number = i;
      
      //Signal that a value has been written.
      MyMainClass::myResetEvent->Set();
      
      //Give the Reader thread an opportunity to act.
      Thread::Sleep( 1 );

   }
   
   //Terminate the reader thread.
   myReaderThread->Abort();
}

using System;
using System.Threading;

namespace AutoResetEvent_Examples
{
    class MyMainClass
    {
        //Initially not signaled.
      const int numIterations = 100;
      static AutoResetEvent myResetEvent = new AutoResetEvent(false);
      static int number;
      
      static void Main()
        {
         //Create and start the reader thread.
         Thread myReaderThread = new Thread(new ThreadStart(MyReadThreadProc));
         myReaderThread.Name = "ReaderThread";
         myReaderThread.Start();

         for(int i = 1; i <= numIterations; i++)
         {
            Console.WriteLine("Writer thread writing value: {0}", i);
            number = i;
            
            //Signal that a value has been written.
            myResetEvent.Set();
            
            //Give the Reader thread an opportunity to act.
            Thread.Sleep(1);
         }

         //Terminate the reader thread.
         myReaderThread.Abort();
      }

      static void MyReadThreadProc()
      {
         while(true)
         {
            //The value will not be read until the writer has written
            // at least once since the last read.
            myResetEvent.WaitOne();
            Console.WriteLine("{0} reading value: {1}", Thread.CurrentThread.Name, number);
         }
      }
    }
}

Imports System.Threading

Namespace AutoResetEvent_Examples
    Class MyMainClass
        'Initially not signaled.
        Private Const numIterations As Integer = 100
        Private Shared myResetEvent As New AutoResetEvent(False)
        Private Shared number As Integer

        <MTAThread> _
        Shared Sub Main()
            'Create and start the reader thread.
            Dim myReaderThread As New Thread(AddressOf MyReadThreadProc)
            myReaderThread.Name = "ReaderThread"
            myReaderThread.Start()

            Dim i As Integer
            For i = 1 To numIterations
                Console.WriteLine("Writer thread writing value: {0}", i)
                number = i

                'Signal that a value has been written.
                myResetEvent.Set()

                'Give the Reader thread an opportunity to act.
                Thread.Sleep(1)
            Next i

            'Terminate the reader thread.
            myReaderThread.Abort()
        End Sub

        Shared Sub MyReadThreadProc()
            While True
                'The value will not be read until the writer has written
                ' at least once since the last read.
                myResetEvent.WaitOne()
                Console.WriteLine("{0} reading value: {1}", Thread.CurrentThread.Name, number)
            End While
        End Sub
    End Class
End Namespace 'AutoResetEvent_Examples

另請參閱

• WaitHandle
• Managed 執行緒處理
• 同步處理原始物件概觀