private void EndConnectImpl(IAsyncResult ar, ConnectionMultiplexer multiplexer, TextWriter log, Tuple<Socket, ISocketCallback> tuple)
        {
            try
            {
                bool ignoreConnect = false;
                ShouldIgnoreConnect(tuple.Item2, ref ignoreConnect);
                if (ignoreConnect) return;
                var socket = tuple.Item1;
                var callback = tuple.Item2;
#if CORE_CLR
                multiplexer.Wait((Task)ar); // make it explode if invalid (note: already complete at this point)
#else
                socket.EndConnect(ar);
#endif
                var netStream = new NetworkStream(socket, false);
                var socketMode = callback == null ? SocketMode.Abort : callback.Connected(netStream, log);
                switch (socketMode)
                {
                    case SocketMode.Poll:
                        multiplexer.LogLocked(log, "Starting poll");
                        OnAddRead(socket, callback);
                        break;
                    case SocketMode.Async:
                        multiplexer.LogLocked(log, "Starting read");
                        try
                        { callback.StartReading(); }
                        catch (Exception ex)
                        {
                            ConnectionMultiplexer.TraceWithoutContext(ex.Message);
                            Shutdown(socket);
                        }
                        break;
                    default:
                        ConnectionMultiplexer.TraceWithoutContext("Aborting socket");
                        Shutdown(socket);
                        break;
                }
            }
            catch (ObjectDisposedException)
            {
                multiplexer.LogLocked(log, "(socket shutdown)");
                if (tuple != null)
                {
                    try
                    { tuple.Item2.Error(); }
                    catch (Exception inner)
                    {
                        ConnectionMultiplexer.TraceWithoutContext(inner.Message);
                    }
                }
            }
            catch(Exception outer)
            {
                ConnectionMultiplexer.TraceWithoutContext(outer.Message);
                if (tuple != null)
                {
                    try
                    { tuple.Item2.Error(); }
                    catch (Exception inner)
                    {
                        ConnectionMultiplexer.TraceWithoutContext(inner.Message);
                    }
                }
            }
        }