Bug 1153852

Created attachment 947771 [details]
BZ1153852-reproducer.zip

I've attached a reproducer that could demonstrate the issue.

The reproducer zip file contains two maven projects bpms.test.01256902.sample.kjar and bpms.test.01256902.

The first one is to build the kjar and second one is the test client which uses junit.

Steps to reproduce the issue:

1) unzip the reproduce and go to project bpms.test.01256902.sample.kjar, run command 
     mvn clean install
This should install the kjar in your local maven repo.

2) go to project bpms.test.01256902 and run command
    mvn clean package 
or 
    mvn clean test
This should build the test client and start the junit test. 
From console you should see some printouts that shows something like:
   Firing Second Rule XXX 0
   Firing Second Rule XXX 1
   Firing Second Rule XXX 2
   Firing Second Rule XXX 3
   Firing Second Rule XXX 4

This shows the rule "SecondRule" gets fired without issue.

3) keep the test client running, and make a change to the "SecondRule". 
for example:
  change
    System.out.println("Firing Second Rule XXX " + $s);
  to 
    System.out.println("Firing Second Rule XXXxxx " + $s);

and run command
   mvn clean install

After the maven command finish successfully, you can see the rule stop firing. It doesn't show on the console any more.

4) make further change, say, removing the function call from the rule.
   for example,
       change 
           eval(doSomething($s))
       to
           //eval(doSomething($s))
and run command
   mvn clean install
After it finishes successfully, you should see NPE error:

Exception in thread "Timer-0" java.lang.NullPointerException
	at org.drools.core.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:156)
	at org.drools.core.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:1415)
	at org.drools.core.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:1406)
	at org.drools.compiler.compiler.PackageBuilder.preProcessRules(PackageBuilder.java:1146)
	at org.drools.compiler.compiler.PackageBuilder.compileRules(PackageBuilder.java:1089)
	at org.drools.compiler.compiler.PackageBuilder.compileAllRules(PackageBuilder.java:973)
	at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildRules(CompositeKnowledgeBuilderImpl.java:266)
	at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:98)
	at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:87)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.rebuildAll(KieContainerImpl.java:302)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.update(KieContainerImpl.java:178)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateDependencyToVersion(KieContainerImpl.java:114)
	at org.kie.scanner.KieRepositoryScannerImpl.updateKieModule(KieRepositoryScannerImpl.java:231)
	at org.kie.scanner.KieRepositoryScannerImpl.scanNow(KieRepositoryScannerImpl.java:218)
	at org.kie.scanner.KieRepositoryScannerImpl$ScanTask.run(KieRepositoryScannerImpl.java:198)
	at java.util.TimerThread.mainLoop(Timer.java:555)
	at java.util.TimerThread.run(Timer.java:505)

I couldn't reproduce any NPE on master. Nevertheless using the attached reproducer I found that incremental compilation doesn't work correctly when a rule uses a function. 

I fixed this problem with this commit: https://github.com/droolsjbpm/drools/commit/d905672bf

I also checked 6.0.x branch and found that it suffers of exactly the same problem I found on master. Moreover the fix I pushed on master also solved this issue on 6.0.x

Backported to 6.0.x with https://github.com/droolsjbpm/drools/commit/f044ef89c

Hi Mario,

I've created a "patch" for BPMS 6.0.3 based on your fix in https://github.com/droolsjbpm/drools/commit/f044ef89c. 

After some more tests, we can verify that it fixes the following scenarios: 

1) A new version of the kjar includes a modification to a rule that calls an existing function
2) A new version of the kjar includes the removal of a function entirely from the DRL and modifications to any rules that previously called removed function.

However, the patched jar does not fix the following kie module update scenario: 

3) A new version of the kjar includes the addition of a new function to the DRL file as well as a modification to a rule in the same DRL to call the new function.

Are you able to look into the issue again to see if we can get the 3) issue fixed?

I just tested the scenario 3) mentioned in your previous post:

3) A new version of the kjar includes the addition of a new function to the DRL file as well as a modification to a rule in the same DRL to call the new function.


I added one new function in the test drl rule. 
for example:
   function boolean doSomething2(String name) {
    System.out.println("Function Called YYYYY");
    return true ;
   }

And I changed the rule
 from
    System.out.println("Firing Second Rule XXX " + $s);
 to
    System.out.println("Firing Second Rule XXXxxx " + $s);


What happened in my test is that I received the following error:

Exception in thread "Timer-0" java.lang.NoSuchMethodError: org.drools.core.reteoo.ReteooRuleBase.removeObjectsGeneratedFromResource(Lorg/kie/api/io/Resource;)Z
	at org.drools.compiler.compiler.PackageBuilder.removeObjectsGeneratedFromResource(PackageBuilder.java:4181)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateResourcesIncrementally(KieContainerImpl.java:260)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.update(KieContainerImpl.java:161)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateDependencyToVersion(KieContainerImpl.java:114)
	at org.kie.scanner.KieRepositoryScannerImpl.updateKieModule(KieRepositoryScannerImpl.java:231)
	at org.kie.scanner.KieRepositoryScannerImpl.scanNow(KieRepositoryScannerImpl.java:218)
	at org.kie.scanner.KieRepositoryScannerImpl$ScanTask.run(KieRepositoryScannerImpl.java:198)
	at java.util.TimerThread.mainLoop(Timer.java:555)
	at java.util.TimerThread.run(Timer.java:505)


In the meanwhile, the client application continue to fire the old rule. Any changes to the rule are not applied.

I also fixed scenario 3) with this commit on master https://github.com/droolsjbpm/drools/commit/e4b1bff10 and backported the fix on 6.0.x branch https://github.com/droolsjbpm/drools/commit/dd4901a29

Verified on BRMS 6.1.0 ER3.

I have encountered unexpected behaviour with LATEST versions - it has been filed as BZ 1174836.