CancellationTokenSource.Cancel CancellationTokenSource.Cancel CancellationTokenSource.Cancel CancellationTokenSource.Cancel Method

定義

キャンセル要求を伝えます。Communicates a request for cancellation.

オーバーロード

Cancel() Cancel() Cancel() Cancel()

キャンセル要求を伝えます。Communicates a request for cancellation.

Cancel(Boolean) Cancel(Boolean) Cancel(Boolean) Cancel(Boolean)

キャンセル要求を伝え、例外が発生した場合に残りのコールバックとキャンセル可能な操作を続けるかどうかを指定します。Communicates a request for cancellation, and specifies whether remaining callbacks and cancelable operations should be processed if an exception occurs.

Cancel() Cancel() Cancel() Cancel()

キャンセル要求を伝えます。Communicates a request for cancellation.

public:
 void Cancel();
public void Cancel ();
member this.Cancel : unit -> unit
Public Sub Cancel ()

例外

関連付けられたCancellationToken に登録されたコールバックがスローしたすべての例外を含む集計例外。An aggregate exception containing all the exceptions thrown by the registered callbacks on the associated CancellationToken.

次の例では、乱数ジェネレーターを使用して、11個の異なる音色から10個の整数値を読み取るデータコレクションアプリケーションをエミュレートします。The following example uses a random number generator to emulate a data collection application that reads 10 integral values from eleven different instruments. 値が0の場合は、測定が1つの音色で失敗したことを示します。この場合、操作はキャンセルされ、全体的な平均は計算されません。A value of zero indicates that the measurement has failed for one instrument, in which case the operation should be cancelled and no overall mean should be computed.

この例では、操作の取り消しの可能性を処理するCancellationTokenSourceために、 TaskFactoryオブジェクトに渡されるキャンセルトークンを生成するオブジェクトをインスタンス化します。To handle the possible cancellation of the operation, the example instantiates a CancellationTokenSource object that generates a cancellation token which is passed to a TaskFactory object. そのTaskFactory後、オブジェクトは、特定のインストルメントの読み取りを収集する各タスクにキャンセルトークンを渡します。The TaskFactory object in turn passes the cancellation token to each of the tasks responsible for collecting readings for a particular instrument. このTaskFactory.ContinueWhenAll<TAntecedentResult,TResult>(Task<TAntecedentResult>[], Func<Task<TAntecedentResult>[],TResult>, CancellationToken)メソッドは、すべての読み取りが正常に収集された後にのみ平均が計算されるようにするために呼び出されます。The TaskFactory.ContinueWhenAll<TAntecedentResult,TResult>(Task<TAntecedentResult>[], Func<Task<TAntecedentResult>[],TResult>, CancellationToken) method is called to ensure that the mean is computed only after all readings have been gathered successfully. タスクが取り消されたことが原因でタスクが完了していTaskFactory.ContinueWhenAllない場合、メソッドの呼び出しは例外をスローします。If a task has not because it has been cancelled, the call to the TaskFactory.ContinueWhenAll method throws an exception.

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      // Define the cancellation token.
      CancellationTokenSource source = new CancellationTokenSource();
      CancellationToken token = source.Token;

      Random rnd = new Random();
      Object lockObj = new Object();
      
      List<Task<int[]>> tasks = new List<Task<int[]>>();
      TaskFactory factory = new TaskFactory(token);
      for (int taskCtr = 0; taskCtr <= 10; taskCtr++) {
         int iteration = taskCtr + 1;
         tasks.Add(factory.StartNew( () => {
                                       int value;
                                       int[] values = new int[10];
                                       for (int ctr = 1; ctr <= 10; ctr++) {
                                          lock (lockObj) {
                                             value = rnd.Next(0,101);
                                          }
                                          if (value == 0) { 
                                             source.Cancel();
                                             Console.WriteLine("Cancelling at task {0}", iteration);
                                             break;
                                          }   
                                          values[ctr-1] = value; 
                                       }
                                       return values;
                                    }, token));   
         
      }
      try {
         Task<double> fTask = factory.ContinueWhenAll(tasks.ToArray(), 
                                                      (results) => {
                                                         Console.WriteLine("Calculating overall mean...");
                                                         long sum = 0;
                                                         int n = 0; 
                                                         foreach (var t in results) {
                                                            foreach (var r in t.Result) {
                                                                  sum += r;
                                                                  n++;
                                                               }
                                                         }
                                                         return sum/(double) n;
                                                      } , token);
         Console.WriteLine("The mean is {0}.", fTask.Result);
      }   
      catch (AggregateException ae) {
         foreach (Exception e in ae.InnerExceptions) {
            if (e is TaskCanceledException)
               Console.WriteLine("Unable to compute mean: {0}", 
                                 ((TaskCanceledException) e).Message);
            else
               Console.WriteLine("Exception: " + e.GetType().Name);
         }
      }
      finally {
         source.Dispose();
      }
   }
}
// Repeated execution of the example produces output like the following:
//       Cancelling at task 5
//       Unable to compute mean: A task was canceled.
//       
//       Cancelling at task 10
//       Unable to compute mean: A task was canceled.
//       
//       Calculating overall mean...
//       The mean is 5.29545454545455.
//       
//       Cancelling at task 4
//       Unable to compute mean: A task was canceled.
//       
//       Cancelling at task 5
//       Unable to compute mean: A task was canceled.
//       
//       Cancelling at task 6
//       Unable to compute mean: A task was canceled.
//       
//       Calculating overall mean...
//       The mean is 4.97363636363636.
//       
//       Cancelling at task 4
//       Unable to compute mean: A task was canceled.
//       
//       Cancelling at task 5
//       Unable to compute mean: A task was canceled.
//       
//       Cancelling at task 4
//       Unable to compute mean: A task was canceled.
//       
//       Calculating overall mean...
//       The mean is 4.86545454545455.
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      ' Define the cancellation token.
      Dim source As New CancellationTokenSource()
      Dim token As CancellationToken = source.Token

      Dim lockObj As New Object()
      Dim rnd As New Random

      Dim tasks As New List(Of Task(Of Integer()))
      Dim factory As New TaskFactory(token)
      For taskCtr As Integer = 0 To 10
         Dim iteration As Integer = taskCtr + 1
         tasks.Add(factory.StartNew(Function()
                                       Dim value, values(9) As Integer
                                       For ctr As Integer = 1 To 10
                                          SyncLock lockObj
                                             value = rnd.Next(0,101)
                                          End SyncLock
                                          If value = 0 Then 
                                             source.Cancel
                                             Console.WriteLine("Cancelling at task {0}", iteration)
                                             Exit For
                                          End If   
                                          values(ctr-1) = value 
                                       Next
                                       Return values
                                    End Function, token))   
         
      Next
      Try
         Dim fTask As Task(Of Double) = factory.ContinueWhenAll(tasks.ToArray(), 
                                                         Function(results)
                                                            Console.WriteLine("Calculating overall mean...")
                                                            Dim sum As Long
                                                            Dim n As Integer 
                                                            For Each t In results
                                                               For Each r In t.Result
                                                                  sum += r
                                                                  n+= 1
                                                               Next
                                                            Next
                                                            Return sum/n
                                                         End Function, token)
         Console.WriteLine("The mean is {0}.", fTask.Result)
      Catch ae As AggregateException
         For Each e In ae.InnerExceptions
            If TypeOf e Is TaskCanceledException
               Console.WriteLine("Unable to compute mean: {0}", 
                                 CType(e, TaskCanceledException).Message)
            Else
               Console.WriteLine("Exception: " + e.GetType().Name)
            End If   
         Next
      Finally
         source.Dispose()
      End Try                                                          
   End Sub
End Module
' Repeated execution of the example produces output like the following:
'       Cancelling at task 5
'       Unable to compute mean: A task was canceled.
'       
'       Cancelling at task 10
'       Unable to compute mean: A task was canceled.
'       
'       Calculating overall mean...
'       The mean is 5.29545454545455.
'       
'       Cancelling at task 4
'       Unable to compute mean: A task was canceled.
'       
'       Cancelling at task 5
'       Unable to compute mean: A task was canceled.
'       
'       Cancelling at task 6
'       Unable to compute mean: A task was canceled.
'       
'       Calculating overall mean...
'       The mean is 4.97363636363636.
'       
'       Cancelling at task 4
'       Unable to compute mean: A task was canceled.
'       
'       Cancelling at task 5
'       Unable to compute mean: A task was canceled.
'       
'       Cancelling at task 4
'       Unable to compute mean: A task was canceled.
'       
'       Calculating overall mean...
'       The mean is 4.86545454545455.

注釈

関連付けられてたCancellationTokenにキャンセルを通知し、IsCancellationRequestedがtrueを返す状態に遷移します。The associated CancellationToken will be notified of the cancellation and will transition to a state where IsCancellationRequested returns true.

CancellationTokenに登録されてたすべてのコールバックおよびキャンセル可能な操作が実行されます。Any callbacks or cancelable operations registered with the CancellationToken will be executed.

CancellationTokenに登録されるコールバックおよびキャンセル可能な操作では、例外をスローしないことが推奨されています。We recommend that cancelable operations and callbacks registered with CancellationToken not throw exceptions.

Cancelのこのオーバー ロードでは、スローされた例外がすべてAggregateExceptionに集約されます。1つのコールバックで例外がスローされても、他のコールバックの実行が妨げられることはありません。This overload of Cancel will aggregate any exceptions thrown into an AggregateException, such that one callback throwing an exception will not prevent other registered callbacks from being executed.

こちらもご覧ください

Cancel(Boolean) Cancel(Boolean) Cancel(Boolean) Cancel(Boolean)

キャンセル要求を伝え、例外が発生した場合に残りのコールバックとキャンセル可能な操作を続けるかどうかを指定します。Communicates a request for cancellation, and specifies whether remaining callbacks and cancelable operations should be processed if an exception occurs.

public:
 void Cancel(bool throwOnFirstException);
public void Cancel (bool throwOnFirstException);
member this.Cancel : bool -> unit
Public Sub Cancel (throwOnFirstException As Boolean)

パラメーター

throwOnFirstException
Boolean Boolean Boolean Boolean

例外を直ちに伝達する場合は true 。それ以外の場合は falsetrue if exceptions should immediately propagate; otherwise, false.

例外

関連付けられたCancellationToken に登録されたコールバックがスローしたすべての例外を含む集計例外。An aggregate exception containing all the exceptions thrown by the registered callbacks on the associated CancellationToken.

注釈

関連付けられてたCancellationTokenにキャンセルを通知し、IsCancellationRequestedtrueを返す状態に遷移します。The associated CancellationToken will be notified of the cancellation and will transition to a state where IsCancellationRequested returns true.

CancellationTokenに登録されてたすべてのコールバックおよびキャンセル可能な操作が実行されます。Any callbacks or cancelable operations registered with the CancellationToken will be executed. コールバックは、LIFO の順序で同期的に実行されます。Callbacks will be executed synchronously in LIFO order.

CancellationTokenに登録されるコールバックおよびキャンセル可能な操作では、例外をスローしないことが推奨されています。We recommend that cancelable operations and callbacks registered with CancellationToken not throw exceptions.

throwOnFirstExceptiontrueの場合、例外はCancelの呼び出し外へとすぐに伝達され、残りのコールバックとキャンセル可能な操作は処理されません。If throwOnFirstException is true, an exception will immediately propagate out of the call to Cancel, preventing the remaining callbacks and cancelable operations from being processed.

throwOnFirstExceptionfalseの場合、スローされた例外がすべてAggregateExceptionに集約されます。1つのコールバックで例外がスローされても、他のコールバックの実行が妨げられることはありません。If throwOnFirstException is false, this overload will aggregate any exceptions thrown into an AggregateException, such that one callback throwing an exception will not prevent other registered callbacks from being executed.

こちらもご覧ください

適用対象