using System;

using System.Threading.Tasks;

using System.Threading;

​

public class Program

{

    public static void Main(string[] args)

    {

        try

        {       

            CancellationTokenSource source = new CancellationTokenSource();

            CancellationToken token = source.Token;

            var task = LongRunningOperation(100000000, token);

            Console.WriteLine("task started");

            Thread.Sleep(3000);

            Console.WriteLine("task status : {0}", task.Status);

            Console.WriteLine("task is about to cancelled");

            source.Cancel();

            Console.WriteLine("token cancelled");

            Console.WriteLine("task status : {0}", task.Status);

            Console.WriteLine("Press enter to continue");

            Console.ReadLine();

        }

        catch(Exception ex)

        {

            //Console.WriteLine("task exception : {0}", ex);            

        }

        finally

        {

            Console.WriteLine("task completed");    

        }

    }

​

    private static Task<decimal> LongRunningOperation(int loop, CancellationToken canToken)

    {

        Thread th = null;

        // Start a task and return it

        return Task.Run(() =>

                        {

                            th = Thread.CurrentThread;

                            canToken.Register(() => 

                                              {

                                                  Console.WriteLine("cancelled called");

                                                  th.Abort();                    

                                              });

                            decimal result = 0;

​

                            // Loop for a defined number of iterations

                            for (int i = 0; i < loop; i++)

                            {

                                Console.WriteLine("operation {0}",i);

                                // Do something that takes times like a Thread.Sleep in .NET Core 2.

                                Thread.Sleep(10);

                                result += i;

                            }

​

                            return result;

                        }, canToken);

    }

}

​

​