[jboss-jira] [JBoss JIRA] Resolved: (JBRULES-1034) NullPointerException in a simple test

[Edson Tirelli (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBRULES-1034?page=all ]

Edson Tirelli resolved JBRULES-1034.
------------------------------------

    Resolution: Done

This was a problem in the alpha node hashing feature that was not correctly handling nulls. It only shows up with 3 or more rules because the default value for start hashing nodes is 3.

Committing the fix to be released in 4.0.1.

A workaround if you need that before 4.0.1 is to set a high alpha node threshold, disabling the feature. Do that by either setting the property:

drools.alphaNodeHashingThreshold 

Or by calling the API method:

RuleBaseConfiguration.setAlphaNodeHashingThreshold()

Thanks for reporting and providing the test case.


> NullPointerException in a simple test
> -------------------------------------
>
>                 Key: JBRULES-1034
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-1034
>             Project: JBoss Rules
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions:  4.0.0.GA
>            Reporter: Christian Spurk
>         Assigned To: Edson Tirelli
>            Priority: Blocker
>             Fix For: 4.0.1
>
>
> I have the class and rule files setup listed below and if I run the SimpleTest class, I get the following exception:
> Exception in thread "main" java.lang.NullPointerException
>     at org.drools.reteoo.CompositeObjectSinkAdapter$HashKey.equals(CompositeObjectSinkAdapter.java:608)
>     at org.drools.util.AbstractHashTable$EqualityEquals.equal(AbstractHashTable.java:345)
>     at org.drools.util.ObjectHashMap.get(ObjectHashMap.java:86)
>     at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:295)
>     at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:168)
>     at org.drools.reteoo.Rete.assertObject(Rete.java:168)
>     at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:190)
>     at org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:70)
>     at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:848)
>     at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:822)
>     at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:623)
>     at com.sample.SimpleTest.main(SimpleTest.java:22)
> Following the setup of four files:
> /* SimpleTest.java */
> package com.sample;
> // ... imports removed for brevity
> public class SimpleTest {
>   public static final void main(String[] args) throws Exception {
>     PackageBuilder builder = new PackageBuilder();
>     builder.addPackageFromDrl(new InputStreamReader(SimpleTest.class
>         .getResourceAsStream("/rf1.drl")));
>     builder.addPackageFromDrl(new InputStreamReader(SimpleTest.class
>         .getResourceAsStream("/rf2.drl")));
>     RuleBase rb = RuleBaseFactory.newRuleBase();
>     rb.addPackage(builder.getPackage());
>     WorkingMemory wm = rb.newStatefulSession();
>     wm.insert(new Task()); // <-- crashes here
>     wm.fireAllRules();
>   }
> }
> /* Task.java */
> package com.sample;
> public class Task {
>   private String next = null;
>   public String getNext() {
>     return next;
>   }
>   public void setNext(String next) {
>     this.next = next;
>   }
> }
> // rf1.drl
> package com.sample
> rule "r0"
>   when
>     Task( next == null ); # <-- change to "x"
>   then
>     System.out.println("r0");
> end
> rule "r1"
>   when
>     Task( next == "1" );
>   then
>     System.out.println("r1");
> end
> // rf2.drl
> package com.sample
> rule "r2"
>   when
>     Task( next == "2" );
>   then
>     System.out.println("r1");
> end
> I've marked the position in the source code at which the run crashes.
> Some more strange things relating to this problem:
>  * If I change the 'null' in rf1.drl to '""' (empty string), the problem remains.
>  * If I change the 'null' in rf1.drl to '"x"' (or some other non-empty string), then the exception is gone.
>  * If I remove any of the two rule files, the exception is gone, too.

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