public async Task Start(CancellationToken cancellationToken)
{
_logger.Info($"Consumer-{_settings.Id}: Starting");
while (!cancellationToken.IsCancellationRequested)
{
try
{
IMessage <T> currentMessage;
while (true)
{
currentMessage = await _queue.GetAsync(cancellationToken);
if (currentMessage != null)
{
_queuePolingPolicy.NextDelay(true);
break;
}
await Task.Delay(_queuePolingPolicy.NextDelay(false), cancellationToken);
}
try
{
//attempt to process the message
_logger.Debug($"Consumer-{_settings.Id}: Handling Message: {currentMessage.MessageId}");
var handlerSuccess = await _messageHandler.Handle(currentMessage, cancellationToken);
if (handlerSuccess ||
_failedMessageHandler == null)
{
//if the handler is successful or if we don't a failed handler to fall back on
//then consider the message "handled" and remove the message
await _queue.DeleteAsync(currentMessage, cancellationToken);
}
else
{
_logger.Debug($"Consumer-{_settings.Id}: Executing failed handler on message: {currentMessage.MessageId}");
await _failedMessageHandler.Handle(currentMessage, cancellationToken);
await _queue.DeleteAsync(currentMessage, cancellationToken);
}
}
catch (Exception ex)
{
_logger.Error(ex, $"Consumer-{_settings.Id}: Exception occured while processing {currentMessage}");
try
{
if (_exceptionHandler != null)
{
_logger.Debug($"Consumer-{_settings.Id}: Executing exception handler on message: {currentMessage.MessageId}");
await _exceptionHandler.Handle(currentMessage, ex, cancellationToken);
}
}
catch (Exception nex)
{
_logger.Error(nex, $"Consumer-{_settings.Id}: Exception occured while attempt to handle outer exception for {currentMessage}");
}
}
}
catch (Exception ex)
{
if (_settings.Behavior == By.Exiting)
{
_logger.Fatal(ex, $"Consumer-{_settings.Id}: An exception occurred which FATALLY terminated the consumer.");
throw;
}
else if (_settings.Behavior == By.Continuing)
{
_logger.Error(ex, $"Consumer-{_settings.Id}: An exception occurred and the consumer continued iterating. A message may have been lost");
}
}
}
_logger.Info($"Consumer-{_settings.Id}: Stopping");
}
