如何在C＃中停止运行任务

Question

I have a running task and need to make a feature that user can stop the running task anytime. I tried to token.Cancel(); but still didn't work.

here is my code:

var task = new Task(new Action(Method), tokenSource2.Token);
 var cToken = tokenSource2.Token;
cToken.Register(() => cancelNotification());

// code to stop the running task .. button click event

 if (tokenSource2 != null)
            {

                tokenSource2.Cancel();


            }

Answer 1

I believe for cancellation tokens to work, the method being called as the body of the task needs to accept a cancellation token and constantly check if it has been cancelled between each step of logic. See here for more details .

This example is an excerpt from that document and outlines how to check the status of a cancellation token.

using System;
using System.Threading;

public class Example
{
   public static void Main()
   {
      // Create the token source.
      CancellationTokenSource cts = new CancellationTokenSource();

      // Pass the token to the cancelable operation.
      ThreadPool.QueueUserWorkItem(new WaitCallback(DoSomeWork), cts.Token);
      Thread.Sleep(2500);

      // Request cancellation.
      cts.Cancel();
      Console.WriteLine("Cancellation set in token source...");
      Thread.Sleep(2500);
      // Cancellation should have happened, so call Dispose.
      cts.Dispose();
   }

   // Thread 2: The listener
   static void DoSomeWork(object obj)
   {
      CancellationToken token = (CancellationToken)obj;

      for (int i = 0; i < 100000; i++) {
         if (token.IsCancellationRequested)
         {
            Console.WriteLine("In iteration {0}, cancellation has been requested...",
                              i + 1);
            // Perform cleanup if necessary.
            //...
            // Terminate the operation.
            break;
         }
         // Simulate some work.
         Thread.SpinWait(500000);
      }
   }
}
// The example displays output like the following:
//       Cancellation set in token source...
//       In iteration 1430, cancellation has been requested...