[jira] [Created] (KAFKA-4791) Kafka Streams - unable to add state stores when using wildcard topics on the source

["Bart Vercammen (JIRA)" <ji...@apache.org>]

Bart Vercammen created KAFKA-4791:
-------------------------------------

             Summary: Kafka Streams - unable to add state stores when using wildcard topics on the source
                 Key: KAFKA-4791
                 URL: https://issues.apache.org/jira/browse/KAFKA-4791
             Project: Kafka
          Issue Type: Bug
          Components: streams
    Affects Versions: 0.10.1.1
         Environment: Java 8
            Reporter: Bart Vercammen


I'm trying to build up a topology (using TopologyBuilder) with following components :
{code}
new TopologyBuilder()
  .addSource("ingest", Pattern.compile( ... ))
  .addProcessor("myprocessor", ..., "ingest")
  .addStateStore(dataStore, "myprocessor")
{code}

Somehow this does not seem to work.
When creating the topology with exact topic names, all works fine, but it seems not possible to attach state stores when using wildcard topics on the sources.

Inside {{addStateStore}}, the processor gets connected to the state store with {{connectProcessorAndStateStore}}, and there it will try to connect the state store with the source topics from the processor: {{connectStateStoreNameToSourceTopics}}  
Here lies the problem: 
{code}
    private Set<String> findSourceTopicsForProcessorParents(String [] parents) {
        final Set<String> sourceTopics = new HashSet<>();
        for (String parent : parents) {
            NodeFactory nodeFactory = nodeFactories.get(parent);
            if (nodeFactory instanceof SourceNodeFactory) {
                sourceTopics.addAll(Arrays.asList(((SourceNodeFactory) nodeFactory).getTopics()));
            } else if (nodeFactory instanceof ProcessorNodeFactory) {
                sourceTopics.addAll(findSourceTopicsForProcessorParents(((ProcessorNodeFactory) nodeFactory).parents));
            }
        }
        return sourceTopics;
    }
{code}

The call to {{sourceTopics.addAll(Arrays.asList(((SourceNodeFactory) nodeFactory).getTopics()))}} will fail as there are no topics inside the {{SourceNodeFactory}} object, only a pattern ({{.getTopics}} returns null)

I also tried to search for some unit tests inside the Kafka Streams project that cover this scenario, but alas, I was not able to find any.
Only some tests on state stores with exact topic names, and some tests on wildcard topics, but no combination of both ...





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