private Task ContinueTaskQueue(Task task, BasicMessage message, TKey key, TValue item)
{
return(task.ContinueWith(async t =>
{
if (!t.IsCompletedSuccessfully)
{
message.Nack();
throw new Exception($"Processing chain aborted for {key}");
}
try
{
await ProcessAsync(item);
message.Ack();
}
catch (Exception e)
{
_logger.LogError(e, $"Couldn't process: {e.Message} key: {key} tag: ({message.DeliveryTag})");
if (e is AggregateException agg)
{
foreach (var ex in agg.InnerExceptions)
{
_logger.LogError(ex, ex.Message);
}
}
message.ErrorAction();
throw;
}
}).Unwrap());
}
/// <summary>
/// This method is run sequentially. The number of tasks will be dependent on the prefetch setting in Rabbit.
/// </summary>
/// <param name="message"></param>
/// <returns></returns>
public bool Process(BasicMessage message)
{
CleanUpTasks();
try
{
var item = Get(message);
var key = GetKey(item);
_logger.LogDebug($"Processing message for {key}");
if (key == null)
{
_logger.LogInformation($"Message ignored {message.Properties?.MessageId} -> {message.Body}, no key");
return(true);
}
if (!_tasks.TryGetValue(key, out var task))
{
task = Task.CompletedTask;
}
// save the task at the end of the queues.
var tailTask = ContinueTaskQueue(task, message, key, item);
_tasks[key] = tailTask; // add completed task to the to be used.
return(false);
}
catch (Exception e)
{
_logger.LogError(e, $"Error Processing message {message.Body}, {e.Message}");
throw;
}
}
private void ReceiveEvent(object sender, BasicDeliverEventArgs args)
{
var channel = (sender as EventingBasicConsumer)?.Model;
if (channel == null)
{
throw new ArgumentNullException(nameof(sender), "Model null in received consumer event.");
}
var message = new BasicMessage(args, channel, _queueServiceParams.QueueName,
() => OnError(sender, args));
try
{
if (_handler.Process(message))
{
message.Ack();
}
_retryCount = 0;
}
catch (Exception ex)
{
// error processing message
_logger.LogError(ex, $"{ex.Message} -> {args.DeliveryTag}: {args.BasicProperties.MessageId}");
message?.ErrorAction?.Invoke();
}
}
/// <summary> /// Must be provided to decompose the message to a TValue e.g. perform any deserialisation or object creation. /// </summary> /// <param name="message"></param> /// <returns>The decomposed message</returns> protected abstract TValue Get(BasicMessage message);
