AsyncTest

using System;
using System.Threading.Tasks;
using System.Threading;
using System.IO;
using System.Collections.Generic;

namespace AsyncTest
{
    class MainClass
    {
        public static void Main(string[] args)
        {            
            AsyncPump.Run(async delegate
            {
                MainClass m = new MainClass();                
                await m.RunTask();
            });                      
        }

        async Task RunTask()
        {
            int originalThreadId = Thread.CurrentThread.ManagedThreadId;
            Console.WriteLine("ThreadId={0}", Thread.CurrentThread.ManagedThreadId);

            var fileName = Path.GetTempFileName();
            File.WriteAllText(fileName, "test");

            //new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
            

            using (Stream stream = File.OpenRead(fileName))
            //using (Stream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read, 1024, true))
            {
                int count = (int)stream.Length;
                byte[] buf = new byte[count];

                // UI thread before.
                await stream.ReadAsync(buf, 0, count);

                // Should continue on UI thread but continues on non-UI thread

                // Using Task.Run instead of above ReadAsync code works.
                //await Task.Run (() => {
                //	Thread.Sleep (400);
                //});
            }

            File.Delete(fileName);

            int newThreadId = Thread.CurrentThread.ManagedThreadId;
            Console.WriteLine("ThreadId={0}", Thread.CurrentThread.ManagedThreadId);

            var val = string.Format("OriginalThreadId={0} After await: ThreadId={1}", originalThreadId, newThreadId);

            Console.WriteLine(val);
        }        
    }
}