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

このトークンに対して取り消しが要求されている場合は true。それ以外の場合は falsetrue if cancellation has been requested for this token; otherwise, false.

IsCancellationRequestedプロパティがを返すtrueまでサーバープロセスを実行する簡単な例を次に示します。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.

この例ではCancellationTokenSource 、キャンセルトークンへのアクセスを制御するオブジェクトをインスタンス化します。The example instantiates a CancellationTokenSource object, which controls access to the cancellation token. 次に、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. 最初のは、キーボードをプールするラムダ式として定義され、"C" キーが押されCancellationTokenSource.Cancelたときに、を呼び出してキャンセルトークンをキャンセル状態に設定します。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つ目のパラメーター化さServerClass.StaticMethodれたメソッドであるは、 IsCancellationRequestedプロパティがtrueになるまでループを実行します。The second is a parameterized method, ServerClass.StaticMethod, that executes a loop until the IsCancellationRequested property is true.

次に、メインスレッドは、2つのスレッドを開始し、 ServerClass.StaticMethodメソッドを実行するスレッドが終了するまでブロックします。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、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。これには、 Cancel最初にキャンセル状態でCancellationTokenSource構築されるトークンを使用するか、関連付けられたトークンのを呼び出します。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.

このプロパティがのtrue場合、キャンセルが要求されただけです。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を保証するわけではなく、すべての登録済みハンドラーにキャンセル要求が反映されたことも保証されません。It does not guarantee that every registered handler has finished executing, nor that cancellation requests have finished propagating to all registered handlers. 特に関連オブジェクトが同時にキャンセルされる場合は、追加の同期が必要になることがあります。Additional synchronization may be required, particularly in situations where related objects are being canceled concurrently.

適用対象

こちらもご覧ください