public async Task DoConsumeAsync(CancellationToken cancellationToken)
{
//Iterate while thread hasn't been canceled
while (!cancellationToken.IsCancellationRequested)
{
//Create BasicDeliverEventArgs object and start trying to get the next message on the queue
BasicDeliverEventArgs lastResult;
var messageReceived = _subscription.Next(Convert.ToInt32(CheckAliveFrequency.TotalMilliseconds),
out lastResult);
//If a message hasn't been succesfully fetched from the queue
if (!messageReceived)
{
//If the model has been closed
if (!_model.IsOpen)
{
//Dispose ConsumerWorker
Dispose();
//Throw AlreadyClosedException (model is already closed)
throw new global::RabbitMQ.Client.Exceptions.AlreadyClosedException(_model.CloseReason);
}
}
//If something was in fact returned from the queue
if (lastResult != null)
{
//Get message body
var messageBody = GetBody(lastResult);
//Create empty messageObject instance
var messageObject = default(T);
try
{
//Try to deserialize message body into messageObject
messageObject = _serializer.Deserialize <T>(messageBody);
}
catch (Exception exception)
{
//Create DeserializationException to pass to RejectionHandler
var deserializationException = new DeserializationException("Unable to deserialize data.", exception)
{
SerializedDataString = messageBody,
SerializedDataBinary = lastResult.Body,
QueueName = _subscription.QueueName
};
//Pass DeserializationException to RejectionHandler
_messageRejectionHandler.OnRejection(deserializationException);
//Remove message from queue after RejectionHandler dealt with it
Nack(lastResult.DeliveryTag, false);
}
//If message has been successfully deserialized and messageObject is populated
if (messageObject != null)
{
//Create messageFeedbackSender instance with corresponding model and deliveryTag
IMessageFeedbackSender messageFeedbackSender = new RabbitMQMessageFeedbackSender(_model, lastResult.DeliveryTag);
try
{
//Call given messageProcessingWorker's OnMessage method to proceed with message processing
await _messageProcessingWorker.OnMessageAsync(messageObject, messageFeedbackSender,
cancellationToken).ConfigureAwait(false);
//If message has been processed with no errors but no Acknoledgement has been given
if (!messageFeedbackSender.MessageAcknoledged)
{
//Acknoledge message
_subscription.Ack();
}
}
catch (Exception)
{
//If something went wrong with message processing and message hasn't been acknoledged yet
if (!messageFeedbackSender.MessageAcknoledged)
{
//Negatively Acknoledge message, asking for requeue
Nack(lastResult.DeliveryTag, true);
}
//Rethrow catched Exception
throw;
}
}
}
//In the end of the consumption loop, check if scaleDown has been requested
if (_scaleCallbackFunc())
{
//If so, break consumption loop to let the thread end gracefully
break;
}
}
//Loop ended, dispose ConsumerWorker
Dispose();
}
public async Task DoConsumeAsync(CancellationToken cancellationToken)
{
_modelConsumer.BasicQos(0, _prefetchCount, false);
using (var subscription = new RabbitMQSubscription(_modelConsumer, _queueName, false))
{
//Iterate while thread hasn't been canceled
while (!cancellationToken.IsCancellationRequested)
{
//Create BasicDeliverEventArgs object and start trying to get the next message on the queue
var messageReceived = subscription.Next(Convert.ToInt32(CheckAliveFrequency.TotalMilliseconds),
out var lastResult);
if (messageReceived)
{
if (lastResult != null)
{
//Get message body
var messageBody = GetBody(lastResult);
try
{
//Try to deserialize message body into messageObject
var messageObject = _serializer.Deserialize <T>(messageBody);
//Create messageFeedbackSender instance with corresponding model and deliveryTag
IFeedbackSender feedbackSender = new RabbitMQMessageFeedbackSender(subscription, lastResult);
try
{
//Call given messageProcessingWorker's OnMessage method to proceed with message processing
var context = new RabbitMQConsumerContext(_queueClient, _modelPublisher);
await _messageProcessingWorker.OnMessageAsync(messageObject, context, feedbackSender,
cancellationToken).ConfigureAwait(false);
//If message has been processed with no errors but no Acknoledgement has been given
if (!feedbackSender.HasAcknoledged)
{
//Acknoledge message
feedbackSender.Ack();
}
}
catch (Exception e)
{
//If something went wrong with message processing and message hasn't been acknoledged yet
if (!feedbackSender.HasAcknoledged)
{
//Negatively Acknoledge message, asking for requeue
feedbackSender.Nack(true);
}
//Rethrow caught Exception
throw;
}
}
catch (Exception exception)
{
//Create DeserializationException to pass to RejectionHandler
var deserializationException = new DeserializationException("Unable to deserialize data.", exception)
{
SerializedDataString = messageBody,
SerializedDataBinary = lastResult.Body,
QueueName = subscription.QueueName
};
//Pass DeserializationException to RejectionHandler
await _messageRejectionHandler.OnRejectionAsync(deserializationException).ConfigureAwait(false);
//Remove message from queue after RejectionHandler dealt with it
subscription.Nack(lastResult, false, false);
}
}
}
else
{
if (subscription.Model.IsClosed)
{
throw new Exception(
$"Model is already closed for RabbitMQConsumerWorker. Queue: {_queueName}");
}
}
subscription.Nack(true);
}
}
}
