using System.Linq;

using System.Threading;

using System.Threading.Tasks;

using System;

using System.Collections.Generic;

using System.IO;

using System.Runtime.InteropServices;

​

namespace ConsoleApplication

{

    public class Program

    {

        public static void TaskCancellationTest()

        {

            try

            {

                Console.WriteLine("TaskCancellationTest started.");

                var cts = new CancellationTokenSource();

                var t = Task.Run(() =>

                {

                    if (cts.Token.IsCancellationRequested)

                        return;

                    Console.WriteLine("1");

                    Task.Delay(2000).Wait();

                    Console.WriteLine("2");

                }

​

                ).ContinueWith(task =>

                {

                    if (cts.Token.IsCancellationRequested)

                        return;

                    Console.WriteLine("3");

                    Task.Delay(2000).Wait();

                    Console.WriteLine("4");

                }

​

                );

                Task.Run(() =>

                {

                    Task.Delay(1000).Wait();

                    Console.WriteLine("Cancelling...");

                    cts.Cancel();

                }

​

                );

                try

                {

                    t.Wait();

                    cts.Token.ThrowIfCancellationRequested();

                }

                catch (OperationCanceledException)

                {

                    Console.WriteLine("Gracefully canceled.");

                }

​

                Console.WriteLine("TaskCancellationTest completed.");

            }

            catch (Exception ex)

            {

                Console.WriteLine("TaskCancellationTest... Failure: " + ex);

            }

        }

​

        public static void TaskCancellationTest2()

        {

            try

            {

                Console.WriteLine("TaskCancellationTest2 started.");

                var cts = new CancellationTokenSource();

                var t1 = Task.Run(() =>

                {

                    Console.WriteLine("1");

                    Task.Delay(2000).Wait();

                    Console.WriteLine("2");

                }

​

                , cts.Token);

                var t2 = t1.ContinueWith(task =>

                {

                    Console.WriteLine("3");

                    Task.Delay(2000).Wait();

                    cts.Token.ThrowIfCancellationRequested();

                    Console.WriteLine("4");

                }

​

                , cts.Token);

                Task.Run(() =>

                {

                    Task.Delay(1000).Wait();

                    Console.WriteLine("Cancelling...");

                    cts.Cancel();

                }

​

                );

                try

                {

                    try

                    {

                        Task.WaitAll(t1, t2);

                    }

                    catch (AggregateException ae)

                    {

                        if (ae.InnerExceptions.Count == 1 && ae.InnerExceptions.Single() is OperationCanceledException)

                        {

                            throw ae.InnerExceptions.Single();

                        }

​

                        throw;

                    }

                }

                catch (OperationCanceledException)

                {

                    Console.WriteLine("Gracefully canceled.");

                }

​

                Console.WriteLine("TaskCancellationTest2 completed.");

            }

            catch (Exception ex)

            {

                Console.WriteLine("TaskCancellationTest2... Failure: " + ex);

            }

        }

​

        public static void Main(string[] args)

        {

            TaskCancellationTest();

            TaskCancellationTest2();

            Console.WriteLine("Enter to exit...");

            Console.ReadLine();

        }

    }

}