CancellationToken.IsCancellationRequested Propiedad

Definición

Obtiene si se ha solicitado la cancelación para este token.Gets whether cancellation has been requested for this token.

public:
 property bool IsCancellationRequested { bool get(); };
public bool IsCancellationRequested { get; }
member this.IsCancellationRequested : bool
Public ReadOnly Property IsCancellationRequested As Boolean

Valor de propiedad

true si se solicitó la cancelación de este token; en caso contrario, false.true if cancellation has been requested for this token; otherwise, false.

Ejemplos

A continuación se muestra un ejemplo sencillo en el que se ejecuta un proceso de servidor hasta que la propiedad IsCancellationRequested devuelve true.The following is a simple example that executes a server process until the IsCancellationRequested property returns true.

using System;
using System.Threading;

public class ServerClass
{
   public static void StaticMethod(object obj)
   {
      CancellationToken ct = (CancellationToken)obj;
      Console.WriteLine("ServerClass.StaticMethod is running on another thread.");

      // Simulate work that can be canceled.
      while (!ct.IsCancellationRequested) {
         Thread.SpinWait(50000);
      }
      Console.WriteLine("The worker thread has been canceled. Press any key to exit.");
      Console.ReadKey(true);
   }
}

public class Simple
{
   public static void Main()
   {
      // The Simple class controls access to the token source.
      CancellationTokenSource cts = new CancellationTokenSource();

      Console.WriteLine("Press 'C' to terminate the application...\n");
      // Allow the UI thread to capture the token source, so that it
      // can issue the cancel command.
      Thread t1 = new Thread(() => { if (Console.ReadKey(true).KeyChar.ToString().ToUpperInvariant() == "C")
                                     cts.Cancel(); } );

      // ServerClass sees only the token, not the token source.
      Thread t2 = new Thread(new ParameterizedThreadStart(ServerClass.StaticMethod));
      // Start the UI thread.

      t1.Start();

      // Start the worker thread and pass it the token.
      t2.Start(cts.Token);

      t2.Join();
      cts.Dispose();
   }
}
// The example displays the following output:
//       Press 'C' to terminate the application...
//
//       ServerClass.StaticMethod is running on another thread.
//       The worker thread has been canceled. Press any key to exit.
Imports System.Threading

Public Class ServerClass
   Public Shared Sub StaticMethod(obj As Object)
      Dim ct AS CancellationToken = CType(obj, CancellationToken)
      Console.WriteLine("ServerClass.StaticMethod is running on another thread.")

      ' Simulate work that can be canceled.
      While Not ct.IsCancellationRequested
         Thread.SpinWait(50000)
      End While
      Console.WriteLine("The worker thread has been canceled. Press any key to exit.")
      Console.ReadKey(True)
   End Sub
End Class

Public Class Simple
   Public Shared Sub Main()
      ' The Simple class controls access to the token source.
      Dim cts As New CancellationTokenSource()

      Console.WriteLine("Press 'C' to terminate the application..." + vbCrLf)
      ' Allow the UI thread to capture the token source, so that it
      ' can issue the cancel command.
      Dim t1 As New Thread( Sub()
                               If Console.ReadKey(true).KeyChar.ToString().ToUpperInvariant() = "C" Then
                                  cts.Cancel()
                               End If
                            End Sub)

      ' ServerClass sees only the token, not the token source.
      Dim t2 As New Thread(New ParameterizedThreadStart(AddressOf ServerClass.StaticMethod))

      ' Start the UI thread.
      t1.Start()

      ' Start the worker thread and pass it the token.
      t2.Start(cts.Token)

      t2.Join()
      cts.Dispose()
   End Sub
End Class
' The example displays the following output:
'       Press 'C' to terminate the application...
'
'       ServerClass.StaticMethod is running on another thread.
'       The worker thread has been canceled. Press any key to exit.

En el ejemplo se crea una instancia de un objeto CancellationTokenSource, que controla el acceso al token de cancelación.The example instantiates a CancellationTokenSource object, which controls access to the cancellation token. A continuación, define dos procedimientos de subproceso.It then defines two thread procedures. La primera se define como una expresión lambda que agrupa el teclado y, cuando se presiona la tecla "C", llama a CancellationTokenSource.Cancel para establecer el token de cancelación en el estado cancelado.The first is defined as a lambda expression that pools the keyboard and, when the "C" key is pressed, calls CancellationTokenSource.Cancel to set the cancellation token to the cancelled state. El segundo es un método parametrizado, ServerClass.StaticMethod, que ejecuta un bucle hasta que la propiedad IsCancellationRequested es true.The second is a parameterized method, ServerClass.StaticMethod, that executes a loop until the IsCancellationRequested property is true.

A continuación, el subproceso principal inicia los dos subprocesos y se bloquea hasta que finaliza el subproceso que ejecuta el método ServerClass.StaticMethod.The main thread then starts the two threads and blocks until the thread that executes the ServerClass.StaticMethod method terminates.

Comentarios

Esta propiedad indica si se ha solicitado la cancelación de este token, ya sea a través del token que se está construyendo inicialmente en un estado cancelado o mediante una llamada a Cancel en el @no__t asociado del token.This property indicates whether cancellation has been requested for this token, either through the token initially being constructed in a canceled state, or through calling Cancel on the token's associated CancellationTokenSource.

Si esta propiedad es true, solo garantiza que se ha solicitado la cancelación.If this property is true, it only guarantees that cancellation has been requested. No garantiza que todos los controladores registrados hayan terminado de ejecutarse, ni que las solicitudes de cancelación hayan terminado de propagarse a todos los controladores registrados.It does not guarantee that every registered handler has finished executing, nor that cancellation requests have finished propagating to all registered handlers. Puede ser necesaria una sincronización adicional, especialmente en situaciones en las que los objetos relacionados se cancelan simultáneamente.Additional synchronization may be required, particularly in situations where related objects are being canceled concurrently.

Se aplica a

Consulte también: