Asynchronous I/O in C#: I/O Completion Ports

CreateFile.cs

const uint Flags = 128 | (uint)1 << 30;

var fileHandle = Interop.CreateFile("test.txt", (uint)1 << 31, 0, IntPtr.Zero, 3,
    /*FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED */ Flags,
    IntPtr.Zero);

Interop.CreateIoCompletionPort(
    fileHandle,
    completionPortHandle,
    (uint)fileHandle.ToInt64(), 
    0);

CreatePort.cs

// create completion port
var completionPortHandle = Interop.CreateIoCompletionPort(new IntPtr(-1), IntPtr.Zero, 0,  0);

IOCompletionWorker.cs

public class IOCompletionWorker
{ 
    public unsafe void Start(IntPtr completionPort)
    {
        while (true)
        {
            uint bytesRead;
            uint completionKey;
            NativeOverlapped* nativeOverlapped;

            var result = Interop.GetQueuedCompletionStatus(
                completionPort, 
                out bytesRead,
                out completionKey,
                &nativeOverlapped, 
                uint.MaxValue);

            var overlapped = Overlapped.Unpack(nativeOverlapped);

            if (result)
            {
                var asyncResult = ((FileReadAsyncResult)overlapped.AsyncResult);
                asyncResult.ReadCallback(bytesRead, asyncResult.Buffer);
            }
            else
            {
                ThreadLogger.Log(Interop.GetLastError().ToString());
            }

            Overlapped.Free(nativeOverlapped);
        }
    }
}

Overlapped.cs

var readBuffer = new byte[1024];

uint bytesRead;

var overlapped = new Overlapped 
{
    AsyncResult = new FileReadAsyncResult()
    {
        ReadCallback = (bytesCount, buffer) =>
            {
                var contentRead = Encoding.UTF8.GetString(buffer, 0, (int)bytesCount);
            },
        Buffer = readBuffer
    } 
};

NativeOverlapped* nativeOverlapped = overlapped.UnsafePack(null, readBuffer);

Interop.ReadFile(fileHandle, readBuffer, (uint)readBuffer.Length, out bytesRead, nativeOverlapped);

Thread.cs

var completionPortThread = new Thread(() => new IOCompletionWorker().Start(completionPortHandle))
{
    IsBackground = true
};
completionPortThread.Start();