/// <summary>
/// Acknowledge the message arrival and processing, so that RabbitMq can remove it from the queue.
/// </summary>
/// <param name="msg">The message instance</param>
public void Ack(RabbitWorkMessage msg)
{
if (ConsumerChannel.IsOpen)
{
ConsumerChannel.BasicAck(msg.DeliveryTag, false);
}
}
private bool CheckRetryLimit(long retryLimit, RabbitWorkMessage msg)
{
IBasicProperties properties = msg.BasicProperties;
if (retryLimit <= 0)
{
return(true);
}
// check dead-letter counter (number of times the message was dlx)
long count = msg.GetRetryCount();
// check dlx count against our threshold
if (count >= retryLimit)
{
// move message to dead-letter queue
if (String.IsNullOrEmpty(deadLetterQueue))
{
// create dead letter queue
lock (QueueName)
{
deadLetterQueue = QueueName + ".dead-letter";
deadLetterQueue = EnsureQueueExists(deadLetterQueue, Mode);
}
}
// publish message to the deadletter queue
PublishChannel.BasicPublish("", deadLetterQueue, (IBasicProperties)properties.Clone(), msg.Body);
// delete message
Ack(msg);
return(false);
}
return(true);
}
/// <summary>
/// Get messages from the queue.
/// </summary>
/// <param name="millisecondsTimeout">The wait timeout in milliseconds for a message to arrive. -1 for infinite timeout</param>
/// <param name="noAck">If the acknowledgement will be manual (noAck == false) or automatic (true).</param>
public IEnumerable <RabbitWorkMessage> Get(int millisecondsTimeout, bool noAck = false)
{
RabbitMQ.Client.Events.BasicDeliverEventArgs item;
bool done = false;
while (!done)
{
done = true;
using (var sub = new RabbitMQ.Client.MessagePatterns.Subscription(ConsumerChannel, QueueName, noAck))
{
while (sub.Next(millisecondsTimeout, out item))
{
if (item == null)
{
// in case of a connection close, the item will be null and we should re-subscribe
done = false;
break;
}
// if the message is within the retry threshold, proceed...
var msg = new RabbitWorkMessage(this, item);
if (CheckRetryLimit(_maxRetry, msg))
{
yield return(msg);
}
}
}
}
}
/// <summary>
/// Negative acknowledge the message, the message will be returned to the queue or send to dead letter exchange.
/// </summary>
/// <param name="msg">The message instance</param>
/// <param name="requeue">False will send to dead letter exchange, true will send back to the queue.</param>
private void Nack(RabbitWorkMessage msg, bool requeue = false)
{
if (ConsumerChannel.IsOpen)
{
// check max retry limit
if (!requeue && !CheckRetryLimit(_maxRetry - 1, msg))
{
return;
}
ConsumerChannel.BasicNack(msg.DeliveryTag, false, requeue);
}
}
/// <summary>
/// Rejects the message and returns it to the queue. This does not count against the maxRetry counter.
/// </summary>
/// <param name="msg">The message instance</param>
public void Requeue(RabbitWorkMessage msg)
{
Nack(msg, true);
}
/// <summary>
/// Negative acknowledge the message, the message will be marked as a try and send to dead letter exchange according to the maxRetry threshold.
/// </summary>
/// <param name="msg">The message instance</param>
public void Nack(RabbitWorkMessage msg)
{
Nack(msg, false);
}