[
https://issues.apache.org/jira/browse/NIFI-6420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16878081#comment-16878081
]
Mark Payne commented on NIFI-6420:
----------------------------------
The following integration test can be used to replicate this:
{code:java}
@Test
public void testReferenceCounts() {
final ControllerServiceNode serviceNode =
createControllerServiceNode(LongValidatingControllerService.class.getName());
serviceNode.setProperties(Collections.singletonMap(LongValidatingControllerService.DELAY.getName(),
"250 millis"));
final ProcessorNode counter =
createProcessorNode(ControllerServiceReferencingProcessor.class);
final Map<String, String> properties = new HashMap<>();
properties.put(ControllerServiceReferencingProcessor.OPTIONAL_SERVICE.getName(),
serviceNode.getIdentifier());
counter.setProperties(properties);
assertEquals(1,
serviceNode.getReferences().getReferencingComponents().size());
properties.put(ControllerServiceReferencingProcessor.IGNORED_OPTIONAL_SERVICE.getName(),
serviceNode.getIdentifier());
counter.setProperties(properties);
assertEquals(1,
serviceNode.getReferences().getReferencingComponents().size());
properties.put(ControllerServiceReferencingProcessor.IGNORED_OPTIONAL_SERVICE.getName(),
null);
counter.setProperties(properties);
assertEquals(1,
serviceNode.getReferences().getReferencingComponents().size());
properties.clear();
properties.put(ControllerServiceReferencingProcessor.OPTIONAL_SERVICE.getName(),
null);
counter.setProperties(properties);
assertEquals(0,
serviceNode.getReferences().getReferencingComponents().size());
}{code}
> Controller Service references not properly tracked if multiple references
> from same component
> ---------------------------------------------------------------------------------------------
>
> Key: NIFI-6420
> URL: https://issues.apache.org/jira/browse/NIFI-6420
> Project: Apache NiFi
> Issue Type: Bug
> Components: Core Framework
> Reporter: Mark Payne
> Priority: Major
>
> The StandardControllerServiceNode keeps track of any references to it via
> `addReference` and `removeReference` methods. However, if a Processor (or
> another Controller Service) has two different properties that reference the
> service, then the references can become incorrect.
> This is due to the fact that when Properties are set for a component, we
> determine that Property A previously referenced Service 123 but no longer
> does and call `removeReference` on Service 123. However, if Property B also
> is referencing Service 123, we have a condition where the Processor is
> referencing Service 123, but Service 123 does not know about it, because of
> the call to `removeReference`.
> We should either be storing references as a `List` in
> `StandardControllerServiceNode` or else should determine whether or not all
> references have been removed before calling `removeReference`. I suspect that
> the latter is less error-prone, given that calls to `addReference` currently
> are idempotent and changing the data structure to a `List` would mean that
> the method is no longer idempotent.
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