private async Task SendTwinRequestAsync()

in iothub/device/src/Transport/Mqtt/MqttTransportHandler.cs [1120:1188]
62 lines of code
9 McCabe index (conditional complexity)

        private async Task<Message> SendTwinRequestAsync(Message request, string rid, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();

            using var responseReceived = new SemaphoreSlim(0);
            Message response = null; ;
            ExceptionDispatchInfo responseException = null;

            void OnTwinResponse(Message possibleResponse)
            {
                try
                {
                    if (ParseResponseTopic(possibleResponse.MqttTopicName, out string receivedRid, out int status))
                    {
                        if (rid == receivedRid)
                        {
                            if (status >= 300)
                            {
                                // The Hub team is refactoring the retriable status codes without breaking changes to the existing ones.
                                // It can be expected that we may bring more retriable codes here in the future.
                                // Retry for Http status code 429 (too many requests)
                                if (status == 429)
                                {
                                    throw new IotHubThrottledException($"Request {rid} was throttled by the server");
                                }
                                else
                                {
                                    throw new IotHubException($"Request {rid} returned status {status}", isTransient: false);
                                }
                            }
                            else
                            {
                                response = possibleResponse;
                                responseReceived.Release();
                            }
                        }
                    }
                }
                catch (Exception e)
                {
                    responseException = ExceptionDispatchInfo.Capture(e);
                    responseReceived.Release();
                }
            }

            try
            {
                _twinResponseEvent += OnTwinResponse;

                await SendEventAsync(request, cancellationToken).ConfigureAwait(false);

                await responseReceived.WaitAsync(TwinTimeout, cancellationToken).ConfigureAwait(false);

                if (responseException != null)
                {
                    responseException.Throw();
                }
                else if (response == null)
                {
                    throw new TimeoutException($"Response for message {rid} not received");
                }

                return response;
            }
            finally
            {
                _twinResponseEvent -= OnTwinResponse;
            }
        }