WaitOrTimerCallback Delegado

Definición

Representa un método al que se debe llamar cuando un WaitHandle está señalado o se agota su tiempo de espera.Represents a method to be called when a WaitHandle is signaled or times out.

public delegate void WaitOrTimerCallback(System::Object ^ state, bool timedOut);
public delegate void WaitOrTimerCallback(object? state, bool timedOut);
public delegate void WaitOrTimerCallback(object state, bool timedOut);
[System.Runtime.InteropServices.ComVisible(true)]
public delegate void WaitOrTimerCallback(object state, bool timedOut);
type WaitOrTimerCallback = delegate of obj * bool -> unit
[<System.Runtime.InteropServices.ComVisible(true)>]
type WaitOrTimerCallback = delegate of obj * bool -> unit
Public Delegate Sub WaitOrTimerCallback(state As Object, timedOut As Boolean)

Parámetros

state
Object

Objeto que contiene la información que va a utilizar el método de devolución de llamadas cada vez que se ejecute.An object containing information to be used by the callback method each time it executes.

timedOut
Boolean

true si WaitHandle ha agotado el tiempo de espera; false si estaba señalado.true if the WaitHandle timed out; false if it was signaled.

Atributos

Ejemplos

En el ejemplo siguiente se muestra cómo utilizar el WaitOrTimerCallback delegado para representar un método de devolución de llamada que se ejecuta cuando se señala un identificador de espera.The following example shows how to use the WaitOrTimerCallback delegate to represent a callback method that is executed when a wait handle is signaled.

En el ejemplo también se muestra cómo usar el RegisterWaitForSingleObject método para ejecutar un método de devolución de llamada especificado cuando se señala un identificador de espera especificado.The example also shows how to use the RegisterWaitForSingleObject method to execute a specified callback method when a specified wait handle is signaled. En este ejemplo, el método de devolución de llamada es WaitProc y el identificador de espera es AutoResetEvent .In this example, the callback method is WaitProc and the wait handle is an AutoResetEvent.

En el ejemplo se define una TaskInfo clase que contiene la información que se pasa a la devolución de llamada cuando se ejecuta.The example defines a TaskInfo class to hold the information that is passed to the callback when it executes. En el ejemplo se crea un TaskInfo objeto y se le asignan algunos datos de cadena.The example creates a TaskInfo object and assigns it some string data. El RegisteredWaitHandle devuelto por el RegisterWaitForSingleObject método se asigna al Handle campo del TaskInfo objeto, por lo que el método de devolución de llamada tiene acceso a RegisteredWaitHandle .The RegisteredWaitHandle that is returned by the RegisterWaitForSingleObject method is assigned to the Handle field of the TaskInfo object, so that the callback method has access to the RegisteredWaitHandle.

Además del TaskInfo objeto, la llamada al RegisterWaitForSingleObject método especifica la AutoResetEvent tarea que espera, un WaitOrTimerCallback delegado que representa el WaitProc método de devolución de llamada, un intervalo de tiempo de espera de un segundo y varias devoluciones de llamada.In addition to the TaskInfo object, the call to the RegisterWaitForSingleObject method specifies the AutoResetEvent the task waits on, a WaitOrTimerCallback delegate that represents the WaitProc callback method, a one-second timeout interval, and multiple callbacks.

Cuando el subproceso principal señala a AutoResetEvent llamando a su Set método, WaitOrTimerCallback se invoca al delegado.When the main thread signals the AutoResetEvent by calling its Set method, the WaitOrTimerCallback delegate is invoked. El WaitProc método prueba RegisteredWaitHandle para determinar si se ha agotado el tiempo de espera.The WaitProc method tests RegisteredWaitHandle to determine whether a timeout occurred. Si se invocó la devolución de llamada porque se señaló el identificador de espera, el WaitProc método anula el registro de RegisteredWaitHandle y detiene las devoluciones de llamada.If the callback was invoked because the wait handle was signaled, the WaitProc method unregisters the RegisteredWaitHandle, stopping further callbacks. En el caso de un tiempo de espera, la tarea continúa esperando.In the case of a timeout, the task continues waiting. El WaitProc método finaliza mediante la impresión de un mensaje en la consola.The WaitProc method ends by printing a message to the console.

using namespace System;
using namespace System::Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public ref class TaskInfo
{
public:
   TaskInfo()
   {
      Handle = nullptr;
      OtherInfo = "default";
   }

   RegisteredWaitHandle^ Handle;
   String^ OtherInfo;
};

ref class Example
{
public:

   // The callback method executes when the registered wait times out,
   // or when the WaitHandle (in this case AutoResetEvent) is signaled.
   // WaitProc unregisters the WaitHandle the first time the event is 
   // signaled.
   static void WaitProc( Object^ state, bool timedOut )
   {
      
      // The state Object must be cast to the correct type, because the
      // signature of the WaitOrTimerCallback delegate specifies type
      // Object.
      TaskInfo^ ti = static_cast<TaskInfo^>(state);
      String^ cause = "TIMED OUT";
      if (  !timedOut )
      {
         cause = "SIGNALED";
         
         // If the callback method executes because the WaitHandle is
         // signaled, stop future execution of the callback method
         // by unregistering the WaitHandle.
         if ( ti->Handle != nullptr )
                  ti->Handle->Unregister( nullptr );
      }

      Console::WriteLine( "WaitProc( {0}) executes on thread {1}; cause = {2}.", ti->OtherInfo, Thread::CurrentThread->GetHashCode(), cause );
   }

};

int main()
{
   
   // The main thread uses AutoResetEvent to signal the
   // registered wait handle, which executes the callback
   // method.
   AutoResetEvent^ ev = gcnew AutoResetEvent( false );
   TaskInfo^ ti = gcnew TaskInfo;
   ti->OtherInfo = "First task";
   
   // The TaskInfo for the task includes the registered wait
   // handle returned by RegisterWaitForSingleObject.  This
   // allows the wait to be terminated when the object has
   // been signaled once (see WaitProc).
   ti->Handle = ThreadPool::RegisterWaitForSingleObject( ev, gcnew WaitOrTimerCallback( Example::WaitProc ), ti, 1000, false );
   
   // The main thread waits three seconds, to demonstrate the
   // time-outs on the queued thread, and then signals.
   Thread::Sleep( 3100 );
   Console::WriteLine( "Main thread signals." );
   ev->Set();
   
   // The main thread sleeps, which should give the callback
   // method time to execute.  If you comment out this line, the
   // program usually ends before the ThreadPool thread can execute.
   Thread::Sleep( 1000 );
   
   // If you start a thread yourself, you can wait for it to end
   // by calling Thread::Join.  This option is not available with 
   // thread pool threads.
   return 0;
}

using System;
using System.Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public class TaskInfo {
    public RegisteredWaitHandle Handle = null;
    public string OtherInfo = "default";
}

public class Example {
    public static void Main(string[] args) {
        // The main thread uses AutoResetEvent to signal the
        // registered wait handle, which executes the callback
        // method.
        AutoResetEvent ev = new AutoResetEvent(false);

        TaskInfo ti = new TaskInfo();
        ti.OtherInfo = "First task";
        // The TaskInfo for the task includes the registered wait
        // handle returned by RegisterWaitForSingleObject.  This
        // allows the wait to be terminated when the object has
        // been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject(
            ev,
            new WaitOrTimerCallback(WaitProc),
            ti,
            1000,
            false
        );

        // The main thread waits three seconds, to demonstrate the
        // time-outs on the queued thread, and then signals.
        Thread.Sleep(3100);
        Console.WriteLine("Main thread signals.");
        ev.Set();

        // The main thread sleeps, which should give the callback
        // method time to execute.  If you comment out this line, the
        // program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000);
        // If you start a thread yourself, you can wait for it to end
        // by calling Thread.Join.  This option is not available with 
        // thread pool threads.
    }
   
    // The callback method executes when the registered wait times out,
    // or when the WaitHandle (in this case AutoResetEvent) is signaled.
    // WaitProc unregisters the WaitHandle the first time the event is 
    // signaled.
    public static void WaitProc(object state, bool timedOut) {
        // The state object must be cast to the correct type, because the
        // signature of the WaitOrTimerCallback delegate specifies type
        // Object.
        TaskInfo ti = (TaskInfo) state;

        string cause = "TIMED OUT";
        if (!timedOut) {
            cause = "SIGNALED";
            // If the callback method executes because the WaitHandle is
            // signaled, stop future execution of the callback method
            // by unregistering the WaitHandle.
            if (ti.Handle != null)
                ti.Handle.Unregister(null);
        } 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.",
            ti.OtherInfo, 
            Thread.CurrentThread.GetHashCode().ToString(), 
            cause
        );
    }
}
Imports System.Threading

' TaskInfo contains data that will be passed to the callback
' method.
Public Class TaskInfo
    public Handle As RegisteredWaitHandle = Nothing
    public OtherInfo As String = "default"
End Class

Public Class Example

    <MTAThread> _
    Public Shared Sub Main()
        ' The main thread uses AutoResetEvent to signal the
        ' registered wait handle, which executes the callback
        ' method.
        Dim ev As New AutoResetEvent(false)

        Dim ti As New TaskInfo()
        ti.OtherInfo = "First task"
        ' The TaskInfo for the task includes the registered wait
        ' handle returned by RegisterWaitForSingleObject.  This
        ' allows the wait to be terminated when the object has
        ' been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject( _
            ev, _
            New WaitOrTimerCallback(AddressOf WaitProc), _
            ti, _
            1000, _
            false _
        )

        ' The main thread waits about three seconds, to demonstrate 
        ' the time-outs on the queued task, and then signals.
        Thread.Sleep(3100)
        Console.WriteLine("Main thread signals.")
        ev.Set()

        ' The main thread sleeps, which should give the callback
        ' method time to execute.  If you comment out this line, the
        ' program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000)
        ' If you start a thread yourself, you can wait for it to end
        ' by calling Thread.Join.  This option is not available with 
        ' thread pool threads.
    End Sub
   
    ' The callback method executes when the registered wait times out,
    ' or when the WaitHandle (in this case AutoResetEvent) is signaled.
    ' WaitProc unregisters the WaitHandle the first time the event is 
    ' signaled.
    Public Shared Sub WaitProc(state As Object, timedOut As Boolean)
        ' The state object must be cast to the correct type, because the
        ' signature of the WaitOrTimerCallback delegate specifies type
        ' Object.
        Dim ti As TaskInfo = CType(state, TaskInfo)

        Dim cause As String = "TIMED OUT"
        If Not timedOut Then
            cause = "SIGNALED"
            ' If the callback method executes because the WaitHandle is
            ' signaled, stop future execution of the callback method
            ' by unregistering the WaitHandle.
            If Not ti.Handle Is Nothing Then
                ti.Handle.Unregister(Nothing)
            End If
        End If 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.", _
            ti.OtherInfo, _
            Thread.CurrentThread.GetHashCode().ToString(), _
            cause _
        )
    End Sub
End Class

Comentarios

WaitOrTimerCallback representa un método de devolución de llamada que se desea ejecutar cuando un identificador de espera registrado agota el tiempo de espera o se señala.WaitOrTimerCallback represents a callback method that you want to execute when a registered wait handle times out or is signaled. Cree el delegado pasando el método de devolución de llamada al WaitOrTimerCallback constructor.Create the delegate by passing your callback method to the WaitOrTimerCallback constructor. El método debe tener la firma que se muestra aquí.Your method must have the signature shown here.

Cree el identificador de espera registrado pasando el WaitOrTimerCallback delegado y un WaitHandle a ThreadPool.RegisterWaitForSingleObject .Create the registered wait handle by passing the WaitOrTimerCallback delegate and a WaitHandle to ThreadPool.RegisterWaitForSingleObject. El método de devolución de llamada se ejecuta cada vez que se agota el WaitHandle tiempo de espera o se señala.Your callback method executes each time the WaitHandle times out or is signaled.

Nota

Visual Basic usuarios pueden omitir el WaitOrTimerCallback constructor y simplemente usar el AddressOf operador al pasar el método de devolución de llamada a RegisterWaitForSingleObject .Visual Basic users can omit the WaitOrTimerCallback constructor, and simply use the AddressOf operator when passing the callback method to RegisterWaitForSingleObject. Visual Basic llama automáticamente al constructor de delegado correcto.Visual Basic automatically calls the correct delegate constructor.

Si desea pasar información al método de devolución de llamada, cree un objeto que contenga la información necesaria y páselo a RegisterWaitForSingleObject cuando cree el identificador de espera registrado.If you want to pass information to your callback method, create an object that contains the necessary information and pass it to RegisterWaitForSingleObject when you create the registered wait handle. Cada vez que se ejecuta el método de devolución de llamada, el state parámetro contiene este objeto.Each time your callback method executes, the state parameter contains this object.

Para obtener más información sobre el uso de métodos de devolución de llamada para sincronizar subprocesos del grupo de subprocesos, vea el grupo de subprocesoFor more information about using callback methods to synchronize thread pool threads, see The managed thread pool.

Métodos de extensión

GetMethodInfo(Delegate)

Obtiene un objeto que representa el método representado por el delegado especificado.Gets an object that represents the method represented by the specified delegate.

Se aplica a