using System;

using System.Reactive.Linq;

using System.Threading;

using System.Threading.Tasks;

using System.Reflection;

​

public class Program

{

    public static void Main()

    {

        CancellationToken capturedToken = default(CancellationToken);

        var subscription = Observable.FromAsync(async token =>

        {

            capturedToken = token;

            token.Register(() => Console.WriteLine("Token canceled"));

            await Task.Delay(Timeout.Infinite, token);

        })

        .TakeUntil(Observable.Timer(TimeSpan.FromMilliseconds(500)))

        .Finally(() => Console.WriteLine("The observable was terminated"))

        .Subscribe();

​

        Thread.Sleep(1000);

​

        var cts = (CancellationTokenSource)(typeof(CancellationToken)

            .GetField("m_source", BindingFlags.NonPublic | BindingFlags.Instance)

            .GetValue(capturedToken));

        bool disposed = (bool)(typeof(CancellationTokenSource)

            .GetField("m_disposed", BindingFlags.NonPublic | BindingFlags.Instance)

            .GetValue(cts));

        Console.WriteLine("IsCancellationRequested: {0}", cts.IsCancellationRequested);

        Console.WriteLine("IsDisposed: {0}", disposed);

    }

}