[jboss-jira] [JBoss JIRA] Created: (JBRULES-2904) KnowledgeAgent unsubscribes monitors, doesn't resubscribe them

[Laird Nelson (JIRA)]

KnowledgeAgent unsubscribes monitors, doesn't resubscribe them
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                 Key: JBRULES-2904
                 URL: https://issues.jboss.org/browse/JBRULES-2904
             Project: Drools
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: drools-core
    Affects Versions: 5.1.1.FINAL
            Reporter: Laird Nelson
            Assignee: Mark Proctor


A KnowledgeAgent set up to monitor a .drl file, and set to perform incremental builds, will correctly monitor that file for changes.

When a change to that file, however, results in a DRL syntax exception (or any other KnowledgeBuilder errors), the KnowledgeAgent no longer monitors the resource for changes.

This means that a typo in the file effectively stops the KnowledgeAgent from ever seeing that file again.  Consequently, an error in the DRL file requires a restart to whatever server is using the KnowledgeAgent.

Esteban and I have found that the error is related to lines 337 and following of KnowledgeAgentImpl.java.  Here is a snippet from one of his emails to me:

"The problem seems to be related to the lines you mentioned. When a resource is modified,  all its knowledgeDefinition->resource are cleared and reconstructed later. I don't see any reason to unsubscribe the listener though. So the call to  Set<KnowledgeDefinition> definitions = this.removeResourceMapping(resource, true); should be Set<KnowledgeDefinition> definitions = this.removeResourceMapping(resource, false); 

"That means: remove all the mappings but don't unsubscribe me (the kagent) as a listener."

Further background can be found at http://drools-java-rules-engine.46999.n3.nabble.com/Drools-5-1-What-happens-when-an-incremental-KA-rebuild-fails-td2258083.html

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