internal void Rollback()

in src/main/csharp/MessageConsumer.cs [810:874]
51 lines of code
9 McCabe index (conditional complexity)

        internal void Rollback()
        {
            lock(this.unconsumedMessages.SyncRoot)
            {
                lock(this.dispatchedMessages)
                {
                    Tracer.DebugFormat("Rollback started, rolling back {0} message",
                                       dispatchedMessages.Count);

                    if(this.dispatchedMessages.Count == 0)
                    {
                        return;
                    }

                    // Only increase the redelivery delay after the first redelivery..
                    MessageDispatch lastMd = this.dispatchedMessages.First.Value;
                    int currentRedeliveryCount = lastMd.Message.RedeliveryCounter;

                    redeliveryDelay = this.redeliveryPolicy.RedeliveryDelay(currentRedeliveryCount);

                    foreach(MessageDispatch dispatch in this.dispatchedMessages)
                    {
                        // Allow the message to update its internal to reflect a Rollback.
                        dispatch.Message.OnMessageRollback();
                    }

                    if(this.redeliveryPolicy.MaximumRedeliveries >= 0 &&
                       lastMd.Message.RedeliveryCounter > this.redeliveryPolicy.MaximumRedeliveries)
                    {
                        this.redeliveryDelay = 0;
                    }
                    else
                    {
                        // stop the delivery of messages.
                        this.unconsumedMessages.Stop();

                        foreach(MessageDispatch dispatch in this.dispatchedMessages)
                        {
                            this.unconsumedMessages.EnqueueFirst(dispatch);
                        }

                        if(redeliveryDelay > 0 && !this.unconsumedMessages.Closed)
                        {
                            Tracer.DebugFormat("Rollback delayed for {0} seconds", redeliveryDelay);
                            DateTime deadline = DateTime.Now.AddMilliseconds(redeliveryDelay);
                            ThreadPool.QueueUserWorkItem(this.RollbackHelper, deadline);
                        }
                        else
                        {
                            Start();
                        }
                    }

                    this.deliveredCounter -= this.dispatchedMessages.Count;
                    this.dispatchedMessages.Clear();
                }
            }

            // Only redispatch if there's an async listener otherwise a synchronous
            // consumer will pull them from the local queue.
            if(this.listener != null)
            {
                this.session.Redispatch(this.unconsumedMessages);
            }
        }