[jboss-jira] [JBoss JIRA] (DROOLS-236) NPE when ksession is serialized with facts logically inserted

[Toshiya Kobayashi (JIRA)]

Toshiya Kobayashi created DROOLS-236:
----------------------------------------

             Summary: NPE when ksession is serialized with facts logically inserted
                 Key: DROOLS-236
                 URL: https://issues.jboss.org/browse/DROOLS-236
             Project: Drools
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions: 6.0.0.CR1
            Reporter: Toshiya Kobayashi
            Assignee: Mark Proctor


Reproduce steps:

Assuming Employee is a subclass of Person...

1. Insert an Employee (say, 'Alice')
2. InsertLogical a Person (say, 'Bob')
3. Serialize and deserialize ksession
4. Insert an Employee (say, 'Claire')
5. Update 'Claire'

It throws an NEP:

{noformat}
Exception executing consequence for rule "Promote" in defaultpkg: java.lang.NullPointerException
	at org.drools.core.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
	at org.drools.core.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1026)
...
Caused by: java.lang.NullPointerException
	at org.drools.core.common.NamedEntryPoint.update(NamedEntryPoint.java:434)
	at org.drools.core.base.DefaultKnowledgeHelper.update(DefaultKnowledgeHelper.java:367)
	at defaultpkg.Rule_Promote139773612.defaultConsequence(Rule_Promote139773612.java:9)
	at defaultpkg.Rule_Promote139773612DefaultConsequenceInvokerGenerated.evaluate(Unknown Source)
	at defaultpkg.Rule_Promote139773612DefaultConsequenceInvoker.evaluate(Unknown Source)
	at org.drools.core.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1016)
	... 37 more

{noformat}

In the step 2, ClassObjectTypeConf of Person[Bob] enables TMS. But at that time, Employee[Alice] creates its EqualityKey and put it to TMS.

NamedEntryPoint.java:
{code:java}
    private void enableTMS(Object object, ObjectTypeConf conf) {

        
        final Rete source = this.ruleBase.getRete();
        final ClassObjectType cot = new ClassObjectType( object.getClass() );
        final Map<ObjectType, ObjectTypeNode> map = source.getObjectTypeNodes( EntryPointId.DEFAULT );
        final ObjectTypeNode node = map.get( cot );
        final ObjectHashSet memory = ((ObjectTypeNodeMemory) this.wm.getNodeMemory( node )).memory;
      
        // All objects of this type that are already there were certainly stated,
        // since this method call happens at the first logical insert, for any given type.
        org.drools.core.util.Iterator it = memory.iterator();

        for ( Object obj = it.next(); obj != null; obj = it.next() ) {
          
            org.drools.core.util.ObjectHashSet.ObjectEntry holder = (org.drools.core.util.ObjectHashSet.ObjectEntry) obj;
    
            InternalFactHandle handle = (InternalFactHandle) holder.getValue();
            
            if ( handle != null) {
                EqualityKey key = new EqualityKey( handle );
                handle.setEqualityKey( key );
                key.setStatus(EqualityKey.STATED);
                getTruthMaintenanceSystem().put(key);
            }
        }
      
        // Enable TMS for this type.
        conf.enableTMS();
      
    }
{code}

Then during deserialization, ProtobufInputMarshaller enables TMS for ClassObjectTypeConf of Employee[Alice] and ClassObjectTypeConf of Person[Bob]. 

ProtobufInputMarshaller.java:
{code:java}
    public static void readTruthMaintenanceSystem( MarshallerReaderContext context, 
                                                   RuleData _session ) throws IOException {

        TruthMaintenanceSystem tms = context.wm.getTruthMaintenanceSystem();
        ProtobufMessages.TruthMaintenanceSystem _tms = _session.getTms();
        
        for( ProtobufMessages.EqualityKey _key : _tms.getKeyList() ) {
            InternalFactHandle handle = (InternalFactHandle) context.handles.get( _key.getHandleId() );

            // ObjectTypeConf state is not marshalled, so it needs to be re-determined
            ObjectTypeConf typeConf = context.wm.getObjectTypeConfigurationRegistry().getObjectTypeConf( ((NamedEntryPoint)handle.getEntryPoint()).getEntryPoint(),
                                                                                                         handle.getObject() );
            if (!typeConf.isTMSEnabled()) {
                typeConf.enableTMS();
            }
{code}

Finally, Employee(Claire) is updated. ClassObjectTypeConf of Employee is under TMS but Claire doesn't have EqualityKey hence NPE is thrown.


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