/// <summary>
/// consumes a single message
/// </summary>
/// <returns>false if consumer loop should be stopped</returns>
private async Task <bool> ConsumeMessageAsync(CancellationToken stoppingToken)
{
try
{
var result = _consumer.Consume((int)_config.ConsumeTimeout.TotalMilliseconds);
// task might have been canceled during the call to Consume()
if (stoppingToken.IsCancellationRequested)
{
return(false);
}
var canProcess = (result is not null && !result.IsPartitionEOF);
if (canProcess)
{
await _messageHandler.HandleAsync(result, _queueReferences, stoppingToken);
}
return(true);
}
catch (ConsumeException ex) when(ex.Error?.Code == ErrorCode.UnknownTopicOrPart)
{
// noop. seems to be a known issue in the c# Kafka driver
// occurring when consumers are started before producers.
_logger.LogWarning(ex, "Topic '{Topic}' still not available : {Exception}",
_queueReferences.TopicName, ex.Message);
await Task.Delay(_config.ConsumeDelay, stoppingToken);
return(true);
}
catch (ObjectDisposedException ex)
{
_logger.LogWarning(ex, "consumer closed on Topic '{Topic}', probably during Dispose() call",
_queueReferences.TopicName);
return(false);
}
catch (TaskCanceledException ex)
{
_logger.LogInformation(ex, "requested consumer cancellation on Topic '{Topic}'",
_queueReferences.TopicName);
return(false);
}
catch (OperationCanceledException ex)
{
_logger.LogInformation(ex, "requested consumer cancellation on Topic '{Topic}'",
_queueReferences.TopicName);
return(false);
}
catch (Exception ex)
{
_logger.LogError(ex, "an error has occurred while consuming messages from Topic '{Topic}': {Exception}",
_queueReferences.TopicName, ex.Message);
}
return(false);
}
