public async Task SubscribeAsync(Func <PunchyMessage, Task> onMessageAsync, string groupId, CancellationToken cancellationToken, params string[] topics)
{
if (onMessageAsync == null)
{
throw new ArgumentNullException(nameof(onMessageAsync));
}
if (groupId == null)
{
throw new ArgumentNullException(nameof(groupId));
}
if (!TopicNameHelpers.IsValid(groupId))
{
throw new ArgumentException(
$"The groupId must match regex pattern: '{TopicNameHelpers.TopicOrGroupIdValidationRegexPattern}'", nameof(groupId));
}
var messageHandler = new MessageHandler(onMessageAsync, pubSub, logger, configuration, groupId);
var retryerTopics = new List <string>();
foreach (var topic in topics)
{
if (!TopicNameHelpers.IsValid(topic))
{
throw new ArgumentException(
$"The topic name must match regex pattern: '{TopicNameHelpers.TopicOrGroupIdValidationRegexPattern}'. " +
$"Validation failed for '{topic}'.", nameof(topics));
}
if (!TopicNameHelpers.IsBadMessageTopic(topic))
{
for (int i = 0; i < configuration.LevelDelaysInSeconds.Length; i++)
{
retryerTopics.Add(TopicNameHelpers.BuildBadMessageTopicName(topic, i, groupId));
}
}
}
var subscription = pubSub.Subscribe(messageHandler, groupId, topics.Union(retryerTopics).ToArray());
messageHandler.Subscription = subscription;
await subscription.StartAsync(cancellationToken);
}
private IMessage GetSourceMessage(IMessage message, List <Attempt> attempts)
{
var badMessageCurrentLevel = TopicNameHelpers.ExtractBadMessageLevel(message.Topic);
while (message != null && badMessageCurrentLevel >= 0)
{
var badMessageContents = JsonConvert.DeserializeObject <BadMessageContents>(
Encoding.UTF8.GetString(message.MessageBytes));
var attemp = new Attempt()
{
BadMessageContents = badMessageContents,
MessageAddress = message.MessageAddress,
Topic = message.Topic,
Timestamp = message.Timestamp
};
attempts.Insert(0, attemp);
// retrying
var messageTimestamp = message.Timestamp;
var messageAgeMilliseconds = (int)Math.Round((DateTimeOffset.Now - messageTimestamp).TotalMilliseconds);
var delayMilliseconds = configuration.LevelDelaysInSeconds[badMessageCurrentLevel] * 1000;
if (messageAgeMilliseconds >= delayMilliseconds)
{
// the message is being replaced here with the original message
message = pubSub.ReadSingle(badMessageContents.SourceMessageAddress);
badMessageCurrentLevel = TopicNameHelpers.ExtractBadMessageLevel(message.Topic);
}
else
{
var reloadAt = DateTimeOffset.Now.AddMilliseconds(delayMilliseconds - messageAgeMilliseconds);
logger.LogDebug("Retrying message but delay time did not ellapse yet, so ignoring it for now. Will reload PubSub at {ReloadAt}", reloadAt);
Subscription?.ReloadAt(reloadAt);
message = null; // retry time not ellapsed
}
}
return(message);
}
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();
}
}