private static IEnumerable <EventBase> DoWork(
ILogger logger,
IConsumer <Ignore, string> consumer,
CancellationToken token)
{
while (!token.IsCancellationRequested)
{
ConsumeResult <Ignore, string> consumeResult;
try
{
consumeResult = consumer.Consume(token);
}
catch (OperationCanceledException)
{
// ignore
yield break;
}
catch (ConsumeException e)
{
logger.LogError(e, "Unable to consume event(s).");
throw;
}
EventBase @event;
try
{
@event = KafkaEventListener.TranslateJson(consumeResult.Message.Value);
}
catch (JsonException)
{
logger.LogError($"Failed to deserialize event: \"{consumeResult.Message.Value}\".");
throw;
}
yield return(@event);
}
}
public void StartListening()
{
if (this.token != null && !this.token.IsCancellationRequested)
{
throw new InvalidOperationException("Already listening.");
}
this.token = new CancellationTokenSource();
this.task = Task.Run(
() =>
{
foreach (var eventBase in KafkaEventListener.DoWork(this.logger, this.consumer, this.token.Token))
{
this.subject.OnNext(eventBase);
}
},
this.token.Token)
.ContinueWith(
prevTask =>
{
this.consumer.Unsubscribe();
if (prevTask.IsFaulted)
{
this.subject.OnError(prevTask.Exception);
}
else
{
this.subject.OnCompleted();
}
this.task = null;
});
this.consumer.Subscribe(this.configuration.Topics.Select(x => x.Value));
}
