AutoResetEvent(Boolean) Construtor

public:
 AutoResetEvent(bool initialState);

public AutoResetEvent (bool initialState);

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

Public Sub New (initialState As Boolean)

Parâmetros

Exemplos

O exemplo a seguir usa um AutoResetEvent para sincronizar as atividades de dois threads. O primeiro thread, que é o thread do aplicativo, é Mainexecutado. Ele grava valores no recurso protegido, que é um static campo (Shared em Visual Basic) chamado number. O segundo thread executa o método estático ThreadProc , que lê os valores gravados por Main.

O ThreadProc método aguarda o AutoResetEvent. Quando Main chama o Set método no AutoResetEvent, o ThreadProc método lê um valor. A AutoResetEvent redefinição imediata, portanto, o ThreadProc método aguarda novamente.

A lógica do programa garante que o ThreadProc método nunca lerá o mesmo valor duas vezes. Ele não garante que o ThreadProc método leia todos os valores escritos por Main. Essa garantia exigiria um segundo AutoResetEvent bloqueio.

Após cada operação de gravação, Main produz chamando o Thread.Sleep método para dar ao segundo thread a chance de executar. Caso contrário, em um computador Main de processador único escreveria muitos valores entre as duas operações de leitura.

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

Aplica-se a

Confira também

• WaitHandle
• Threading gerenciado
• Visão geral dos primitivos de sincronização