CancellationToken Yapı

Tanım

İşlemlerin iptal edilmesi gereken bildirimi yayar.Propagates notification that operations should be canceled.

public value class CancellationToken
public struct CancellationToken
[System.Runtime.InteropServices.ComVisible(false)]
public struct CancellationToken
type CancellationToken = struct
[<System.Runtime.InteropServices.ComVisible(false)>]
type CancellationToken = struct
Public Structure CancellationToken
Devralma
CancellationToken
Öznitelikler

Örnekler

Aşağıdaki örnek, on iki farklı gereçden 10 integral değeri okuyan bir veri toplama uygulamasına öykünmek için rastgele bir sayı Oluşturucu kullanır.The following example uses a random number generator to emulate a data collection application that reads 10 integral values from eleven different instruments. Sıfır değeri, ölçümün bir gereç için başarısız olduğunu gösterir, bu durumda işlem iptal edilmelidir ve genel bir ortalama hesaplanmamalıdır.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.

İşlemin olası iptalinin işlenmesi için, örnek bir CancellationTokenSource nesneye iletilen bir iptal belirteci üreten bir nesne oluşturur TaskFactory .To handle the possible cancellation of the operation, the example instantiates a CancellationTokenSource object that generates a cancellation token that's passed to a TaskFactory object. Buna karşılık, TaskFactory nesnesi, belirli bir gereç için readusing 'leri toplamaktan sorumlu görevlerin her birine iptal belirtecini geçirir.In turn, the TaskFactory object passes the cancellation token to each of the tasks responsible for collecting readings for a particular instrument. TaskFactory.ContinueWhenAll<TAntecedentResult,TResult>(Task<TAntecedentResult>[], Func<Task<TAntecedentResult>[],TResult>, CancellationToken)Yöntemi, ortalaması yalnızca tüm kullanımlar başarıyla toplandıktan sonra hesaplandığından emin olmak için çağrılır.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. Bir görev iptal edilmiyorsa, TaskFactory.ContinueWhenAll Yöntem bir özel durum oluşturur.If a task has not completed because it was cancelled, 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.

Açıklamalar

CancellationToken, İş parçacıkları, iş parçacığı havuzu iş öğeleri veya nesneler arasında birlikte çalışılma iptali sunar Task .A CancellationToken enables cooperative cancellation between threads, thread pool work items, or Task objects. CancellationTokenSourceÖzelliğinden alınan iptal belirteçlerini yöneten bir nesneyi örnekleyerek bir iptal belirteci oluşturursunuz CancellationTokenSource.Token .You create a cancellation token by instantiating a CancellationTokenSource object, which manages cancellation tokens retrieved from its CancellationTokenSource.Token property. Ardından iptal belirtecini, iptal bildirimi alması gereken herhangi bir sayıda iş parçacığı, görev veya işlem için geçitirsiniz.You then pass the cancellation token to any number of threads, tasks, or operations that should receive notice of cancellation. Belirteç iptal işlemini başlatmak için kullanılamaz.The token cannot be used to initiate cancellation. Sahip nesne çağırdığında CancellationTokenSource.Cancel , IsCancellationRequested iptal belirtecinin her kopyasının özelliği olarak ayarlanır true .When the owning object calls CancellationTokenSource.Cancel, the IsCancellationRequested property on every copy of the cancellation token is set to true. Bildirimi alan nesneler, uygun olan her türlü şekilde yanıt verebilir.The objects that receive the notification can respond in whatever manner is appropriate.

Daha fazla bilgi ve kod örnekleri için bkz. yönetilen Iş parçacıklarında iptal.For more information and code examples see Cancellation in Managed Threads.

Oluşturucular

CancellationToken(Boolean)

Öğesini başlatır CancellationToken .Initializes the CancellationToken.

Özellikler

CanBeCanceled

Bu belirtecin iptal edilme durumunda olup olmadığını alır.Gets whether this token is capable of being in the canceled state.

IsCancellationRequested

Bu belirteç için İptalin istenip istenmediğini alır.Gets whether cancellation has been requested for this token.

None

Boş bir CancellationToken değer döndürür.Returns an empty CancellationToken value.

WaitHandle

WaitHandleBelirteç iptal edildiğinde sinyal alır.Gets a WaitHandle that is signaled when the token is canceled.

Yöntemler

Equals(CancellationToken)

Geçerli CancellationToken Örneğin belirtilen belirtece eşit olup olmadığını belirler.Determines whether the current CancellationToken instance is equal to the specified token.

Equals(Object)

Geçerli CancellationToken Örneğin belirtilen değere eşit olup olmadığını belirler Object .Determines whether the current CancellationToken instance is equal to the specified Object.

GetHashCode()

, İçin bir karma işlev işlevi görür CancellationToken .Serves as a hash function for a CancellationToken.

Register(Action)

Bu iptal edildiğinde çağrılacak bir temsilciyi kaydeder CancellationToken .Registers a delegate that will be called when this CancellationToken is canceled.

Register(Action, Boolean)

Bu iptal edildiğinde çağrılacak bir temsilciyi kaydeder CancellationToken .Registers a delegate that will be called when this CancellationToken is canceled.

Register(Action<Object>, Object)

Bu iptal edildiğinde çağrılacak bir temsilciyi kaydeder CancellationToken .Registers a delegate that will be called when this CancellationToken is canceled.

Register(Action<Object>, Object, Boolean)

Bu iptal edildiğinde çağrılacak bir temsilciyi kaydeder CancellationToken .Registers a delegate that will be called when this CancellationToken is canceled.

ThrowIfCancellationRequested()

OperationCanceledExceptionBu belirteçte iptal isteğinde bulunulmışsa bir oluşturur.Throws a OperationCanceledException if this token has had cancellation requested.

UnsafeRegister(Action<Object>, Object)

Bu iptal edildiğinde çağrılan bir temsilciyi kaydeder CancellationToken .Registers a delegate that is called when this CancellationToken is canceled.

İşleçler

Equality(CancellationToken, CancellationToken)

İki örneğinin eşit olup olmadığını belirler CancellationToken .Determines whether two CancellationToken instances are equal.

Inequality(CancellationToken, CancellationToken)

İki örnek eşit olup olmadığını belirler CancellationToken .Determines whether two CancellationToken instances are not equal.

Şunlara uygulanır

İş Parçacığı Güvenliği

Tüm ortak ve korumalı üyeleri CancellationToken iş parçacığı açısından güvenlidir ve birden çok iş parçacığından aynı anda kullanılabilir.All public and protected members of CancellationToken are thread-safe and may be used concurrently from multiple threads.