/// <summary>
/// Checks the loaded saga data to see if the message currently being handled is a duplicate of a message that has previously been handled.
/// If that is the case, message dispatch is skipped, but any messages stored as outgoing messages from previously handling the incoming message will be sent.
/// </summary>
public async Task Process(IncomingStepContext context, Func <Task> next)
{
var message = context.Load <Message>();
var messageId = message.GetMessageId();
var transactionContext = context.Load <ITransactionContext>();
object temp;
if (transactionContext.Items.TryGetValue(Keys.MessageData, out temp))
{
_log.Info($"Checking if message with ID {messageId} has already been processed before.");
var messageData = (MessageData)temp;
if (messageData.HasAlreadyHandled(messageId))
{
_log.Info($"Message with ID {messageId} has already been handled");
var outgoingMessages = messageData
.GetOutgoingMessages()
.ToList();
if (outgoingMessages.Any())
{
_log.Info("Found {0} outgoing messages to be (re-)sent... will do that now",
outgoingMessages.Count);
foreach (var messageToResend in outgoingMessages)
{
foreach (var destinationAddress in messageToResend.DestinationAddresses)
{
await
_transport.Send(destinationAddress, messageToResend.TransportMessage,
transactionContext);
}
}
}
else
{
_log.Info("Found no outgoing messages to be (re-)sent...");
}
}
else
{
_log.Info($"Message with ID {messageId} has not been handled yet.");
if (await _msgStorage.IsProcessing(messageId)) // does the message have an assigned thread id?
{
_log.Info($"Message with ID {messageId} is ignored as it already is being processed.");
// ignore the message or maybe return as in 'Assigned' state
// todo: should we retry once a message has been assigned for too long? What is too long? By default 5m?
return;
}
var threadId = Thread.CurrentThread.ManagedThreadId;
_log.Info($"Updating message storage for the message with ID {messageId} as being processed by thread {threadId}");
// insert the message or update it with the current input queue address, the current thread id and the current date
messageData.InputQueueAddress = _transport.Address;
messageData.ProcessingThreadId = threadId;
messageData.TimeThreadIdAssigned = DateTime.UtcNow;
await _msgStorage.InsertOrUpdate(messageData);
// hand the message of to the next pipeline step
await next();
_log.Info($"Marking the message with ID {messageId} as been handled.");
messageData.MarkMessageAsHandled();
}
}
else
{
// The LoadMessageDataStep was not triggered
await next();
}
}
