CancellationToken.IsCancellationRequested CancellationToken.IsCancellationRequested CancellationToken.IsCancellationRequested CancellationToken.IsCancellationRequested Property

定義

このトークンに対して取り消しが要求されたかどうかを取得します。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

プロパティ値

true キャンセルがある場合は、このトークンに対して要求されています。それ以外の場合、falseします。if cancellation has been requested for this token; otherwise, false.

までのサーバー プロセスを実行する単純な例を次に、IsCancellationRequestedプロパティが返すtrueします。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.

例では、インスタンス化、CancellationTokenSourceオブジェクトで、キャンセル トークンへのアクセスを制御します。The example instantiates a CancellationTokenSource object, which controls access to the cancellation token. 2 つのスレッド プロシージャを定義します。It then defines two thread procedures. 1 つ目は、キーボードをプールし、"C"キーが押されたときに呼び出すラムダ式として定義CancellationTokenSource.Cancelキャンセル トークンを取り消された状態に設定します。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. 2 つ目は、パラメーター化されたメソッドでは、 ServerClass.StaticMethod、まで、ループを実行する、IsCancellationRequestedプロパティはtrueします。The second is a parameterized method, ServerClass.StaticMethod, that executes a loop until the IsCancellationRequested property is true.

メイン スレッドは、2 つのスレッドとブロックを開始すると、スレッドを実行するまで、ServerClass.StaticMethodメソッドを終了します。The main thread then starts the two threads and blocks until the thread that executes the ServerClass.StaticMethod method terminates.

注釈

このプロパティは、トークンが取り消された状態の場合は、最初に構築される、または呼び出しを通じて、このトークンに対して取り消しが要求されているかどうかを示しますCancelでトークンに関連付けられたCancellationTokenSourceします。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.

このプロパティは、する場合true取り消しが要求されていることのみ保証します。If this property is true, it only guarantees that cancellation has been requested. すべての登録済みハンドラーの実行が完了したことも、キャンセル要求のすべての登録済みハンドラーへの伝達が完了したことは保証されません。It does not guarantee that every registered handler has finished executing, nor that cancellation requests have finished propagating to all registered handlers. 追加の同期は、特に関連するオブジェクトを同時にキャンセルされている状況で必要になる可能性があります。Additional synchronization may be required, particularly in situations where related objects are being canceled concurrently.

適用対象

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