public async Task SubscribeToDeadLetterAsync(Func <PunchyMessage, Task> onMessageAsync, string groupId, CancellationToken cancellationToken, params string[] topics)
{
topics = topics.Select(topic => TopicNameHelpers.BuildDeadLetterTopicName(topic, groupId)).ToArray();
await SubscribeAsync(onMessageAsync, groupId, cancellationToken, topics);
}
public async Task OnMessageAsync(IMessage message)
{
if (message == null)
{
throw new ArgumentNullException(nameof(message));
}
var badMessageNextLevel = TopicNameHelpers.ExtractBadMessageNextLevel(message.Topic);
string badMessageNextLevelTopicName;
if (badMessageNextLevel == badMessageMaxLevels)
{
badMessageNextLevelTopicName = TopicNameHelpers.BuildDeadLetterTopicName(message.Topic, groupId);
}
else
{
badMessageNextLevelTopicName = TopicNameHelpers.BuildBadMessageTopicName(message.Topic, badMessageNextLevel, groupId);
}
var attempts = new List <Attempt>();
var badMessageCandidate = message;
message = GetSourceMessage(badMessageCandidate, attempts);
// If message is null, retry time not ellapsed so will ignore this message for now.
// It will be read again latter
if (message != null)
{
try
{
await onMessageAsync.Invoke(new PunchyMessage()
{
MessageAddress = message.MessageAddress,
MessageBytes = message.MessageBytes,
Timestamp = message.Timestamp,
Topic = message.Topic,
Attempts = attempts
});
}
catch (Exception exception)
{
if (badMessageNextLevel < badMessageMaxLevels)
{
logger.LogWarning(exception, "Action failed for message, moving to bad message level '{BadMessageNextLevel}'. " +
"Will try again in {RetrySeconds}. Topic: {Topic}; Original message address: {@MessageAddress}",
badMessageNextLevel, configuration.LevelDelaysInSeconds[badMessageNextLevel],
message.Topic, message.MessageAddress);
}
else // is final level
{
logger.LogError(exception, "Action failed for message, will NOT try again. Topic: {Topic}; Original message address: {@MessageAddress}",
message.Topic, message.MessageAddress);
}
var badMessageContents = new BadMessageContents()
{
Exception = exception,
SourceMessageAddress = badMessageCandidate.MessageAddress
};
await pubSub.PublishAsync(badMessageNextLevelTopicName,
Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(badMessageContents)));
}
await badMessageCandidate.CommitAsync();
}
}
