Mono-async-EndRequest

Global.asax.cs

namespace WebApplication2
{
    using System;
    using System.Threading.Tasks;
    using System.Web;

    public class MvcApplication : HttpApplication
    {
        public MvcApplication()
        {
            AuthenticateRequest += OnAuthenticateRequest ; 
            AddOnEndRequestAsync(OnBeginEndRequest, OnEndEndRequest);
        }

        private volatile bool isEnding = false;

        private void OnAuthenticateRequest(object sender, EventArgs e)
        {
            if (isEnding)
            {
                throw new Exception("OnAuthenticateRequest: isEnding: expected false, got true");
            }
        }

        private IAsyncResult OnBeginEndRequest(object sender, EventArgs e, AsyncCallback cb, object extradata)
        {
            Func<Task<object>> InnerFn = async () =>
            {
                await Task.Delay(TimeSpan.FromMilliseconds(1000));
                isEnding = false;
                return null;
            };

            isEnding = true;

            return InnerFn().AsApm(cb, extradata);
        }

        private void OnEndEndRequest(IAsyncResult ar)
        {
            var r = ((Task<object>) ar).Result;
        }
    }
    
    public static class Util
    {
        public static IAsyncResult AsApm<T>(this Task<T> task, 
            AsyncCallback callback, 
            object state)
        {
            if (task == null) 
                throw new ArgumentNullException("task");
    
            var tcs = new TaskCompletionSource<T>(state);
            task.ContinueWith(t => 
            {
                if (t.IsFaulted) 
                    tcs.TrySetException(t.Exception.InnerExceptions);
                else if (t.IsCanceled)    
                    tcs.TrySetCanceled();
                else 
                    tcs.TrySetResult(t.Result);

                if (callback != null) 
                    callback(tcs.Task);
            }, TaskScheduler.Default);
            return tcs.Task;
        }
    }
}