public async Task <PullResult> Pull(ChannelClient client, TmqMessage request)
{
QueueMessage message = null;
await _queue.RunInListSync(() =>
{
//pull from prefential messages
if (_queue.HighPriorityLinkedList.Count > 0)
{
message = _queue.HighPriorityLinkedList.First.Value;
_queue.HighPriorityLinkedList.RemoveFirst();
if (message != null)
{
message.IsInQueue = false;
}
}
//if there is no prefential message, pull from standard messages
if (message == null && _queue.RegularLinkedList.Count > 0)
{
message = _queue.RegularLinkedList.First.Value;
_queue.RegularLinkedList.RemoveFirst();
if (message != null)
{
message.IsInQueue = false;
}
}
});
//there is no pullable message
if (message == null)
{
await client.Client.SendAsync(MessageBuilder.ResponseStatus(request, KnownContentTypes.NotFound));
return(PullResult.Empty);
}
try
{
await ProcessPull(client, request, message);
}
catch (Exception ex)
{
_queue.Info.AddError();
try
{
Decision decision = await _queue.DeliveryHandler.ExceptionThrown(_queue, message, ex);
await _queue.ApplyDecision(decision, message);
if (decision.KeepMessage && !message.IsInQueue)
{
_queue.AddMessage(message, false);
}
}
catch //if developer does wrong operation, we should not stop
{
}
}
return(PullResult.Success);
}
