System.Net.WebSockets.WebSocketHttpListenerDuplexStream.HttpListenerAsyncEventArgs.StartOperationCommon C# (CSharp) Method

            internal void StartOperationCommon(WebSocketHttpListenerDuplexStream currentStream, ThreadPoolBoundHandle boundHandle)
            {
                // Change status to "in-use".
                if (Interlocked.CompareExchange(ref _operating, InProgress, Free) != Free)
                {
                    // If it was already "in-use" check if Dispose was called.
                    if (_disposeCalled)
                    {
                        // Dispose was called - throw ObjectDisposed.
                        throw new ObjectDisposedException(GetType().FullName);
                    }

                    Debug.Assert(false, "Only one outstanding async operation is allowed per HttpListenerAsyncEventArgs instance.");
                    // Only one at a time.
                    throw new InvalidOperationException();
                }

                // HttpSendResponseEntityBody can return ERROR_INVALID_PARAMETER if the InternalHigh field of the overlapped
                // is not IntPtr.Zero, so we have to reset this field because we are reusing the Overlapped.
                // When using the IAsyncResult based approach of HttpListenerResponseStream the Overlapped is reinitialized
                // for each operation by the CLR when returned from the OverlappedDataCache.

                InitializeOverlapped(boundHandle);

                _exception = null;
                _bytesTransferred = 0;
            }