Problem with custom operator where standard operator works

[Florian Braun]

Hello Drools community,

I am running into a bit of a problem with a custom operator I have created (it works exactly like matches does for strings but caches the regex). For some very specific reasons I am working with 5.4.0. When I tested the new operator on small scale I got no errors and it all seemed to work fine. But when implementing it in our entire system and running tests on it we received a large number of errors of this type:

java.lang.ArrayIndexOutOfBoundsException: 0  at org.drools.base.mvel.MVELCompilationUnit.getFactHandle(MVELCompilationUnit.java:416)    
at org.drools.base.mvel.MVELCompilationUnit.updateFactory(MVELCompilationUnit.java:332)     at
org.drools.base.mvel.MVELCompilationUnit.updateFactory(MVELCompilationUnit.java:289)    
at org.drools.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:59)      at org.drools.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:49)      at org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:200) at org.drools.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:157)    
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:137)  at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59)      
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:141)  at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497)      
at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:372)       at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:141)      at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497)       at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382)       at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:141)      at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497)       at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382)       at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235)  at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240)    
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:350)   at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:311)  
at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:903)    at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:847)

I was able to trace the error to a single rule with this format before changing operators (I know it is a horribly written rule, I still need to find whoever came up with this logic and hit them over the head with it, but it works):

when

        code:   Fact( type not in ( <<types>> ),

                      documentType == <<doc_type>>,

                      (code not matches <<regex>> || code matches <<regex>> || code matches <<regex>>))

then

        retract( code );

end

When I went through I just replaced matches with the new operator like this:

when

        code:   Fact( type not in ( <<types>> ),

                      documentType == <<doc_type>>,

                      (code not cmatches <<regex>> || code cmatches <<regex>> || code cmatches <<regex>>))

then

        retract( code );

end

And all of a sudden I get the above error.

I was hoping someone would be able to help me figure out why this would be happening. I can easily fix the problem and have the same results by rewriting the rule but I would expect it to work the same.

-Florian

[Mario Fusco]

Hi Florian,

at a first sight what you did looks correct, but it's very hard if not impossible for us to provide support on a so old version of Drools.
Please consider trying 6.x and if the error persist feel free to send a reproducer so we could investigate it.

Regards,

Mario

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[Florian Braun]

Hi Mario,

Thanks for getting back to me on this. I wish I could upgrade, sadly I am stuck right now. I did however do two more things to figure out where the error lives.

I went back and looked at the way we implemented our version of the operator and I realized some things were missing when looking at the drools implementation of 'matches' so I literally took the drools implementation and just added caching to it.

I have also figured out it is any use of the operator and a disjunction ( || ). The only thing I could think of is some issue with the fact that all evaluators use the same serializationID so I messed with those and it still did not work.

import java.io.IOException;

import java.io.ObjectInput;

import java.io.ObjectOutput;

import java.util.HashMap;

import java.util.Map;

import java.util.regex.Pattern;

import org.drools.base.BaseEvaluator;

import org.drools.base.ValueType;

import org.drools.common.InternalWorkingMemory;

import org.drools.rule.VariableRestriction.ObjectVariableContextEntry;

import org.drools.rule.VariableRestriction.VariableContextEntry;

import org.drools.spi.Evaluator;

import org.drools.spi.FieldValue;

import org.drools.spi.InternalReadAccessor;

import org.drools.base.evaluators.EvaluatorCache;

import org.drools.base.evaluators.EvaluatorDefinition;

import org.drools.base.evaluators.Operator;

/**

* This class defines the matches evaluator

*/

public class CacheMatchDefinition implements EvaluatorDefinition {

public static final Operator CMATCHES = Operator.addOperatorToRegistry( "cmatches", false );

public static final Operator NOT_CMATCHES = Operator.addOperatorToRegistry( "cmatches", true );

protected static final Map<String, Pattern> CACHE = new HashMap<String, Pattern>();

protected static final Map<String, Integer> COUNTS = new HashMap<String,Integer>();

private static final String[] SUPPORTED_IDS = { CMATCHES.getOperatorString() };

private EvaluatorCache evaluators = new EvaluatorCache() {

private static final long serialVersionUID = 510;

{

addEvaluator( ValueType.STRING_TYPE, CMATCHES, StringCMatchesEvaluator.INSTANCE );

addEvaluator( ValueType.OBJECT_TYPE, CMATCHES, StringCMatchesEvaluator.INSTANCE );

addEvaluator( ValueType.STRING_TYPE, NOT_CMATCHES, StringNotCMatchesEvaluator.INSTANCE );

addEvaluator( ValueType.OBJECT_TYPE, NOT_CMATCHES, StringNotCMatchesEvaluator.INSTANCE );

}

};

protected static boolean isMatch(String s, String regex){

if(s == null){

return false;

} else {

Pattern p = CACHE.get(regex);

if(p == null){

p = Pattern.compile(regex);

CACHE.put(regex, p);

COUNTS.put(regex, 1);

} else {

COUNTS.put(regex, COUNTS.get(regex) + 1);

}

return p.matcher(s).matches();

}

}

static public int getCacheSize() { return CACHE.size();}

static public Map<String, Integer> getCacheCounter() { return COUNTS;}

public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {

evaluators = (EvaluatorCache)in.readObject();

}

public void writeExternal(ObjectOutput out) throws IOException {

out.writeObject(evaluators);

}

/**

* @inheridDoc

*/

public Evaluator getEvaluator(ValueType type, Operator operator) {

return this.evaluators.getEvaluator( type, operator );

}

/**

* @inheridDoc

*/

public Evaluator getEvaluator(ValueType type, Operator operator, String parameterText) {

return this.evaluators.getEvaluator( type, operator );

}

　

public Evaluator getEvaluator(final ValueType type, final String operatorId, final boolean isNegated, final String parameterText) {

return this.getEvaluator( type, operatorId, isNegated, parameterText, Target.FACT, Target.FACT );

}

/**

* @inheritDoc

*/

public Evaluator getEvaluator(final ValueType type, final String operatorId, final boolean isNegated, final String parameterText, final Target left, final Target right ) {

return this.evaluators.getEvaluator( type, Operator.determineOperator( operatorId, isNegated ) );

}

public String[] getEvaluatorIds() {

return SUPPORTED_IDS;

}

public boolean isNegatable() {

return true;

}

public Target getTarget() {

return Target.FACT;

}

public boolean supportsType(ValueType type) {

return this.evaluators.supportsType( type );

}

/* *********************************************************

* Evaluator Implementations

* *********************************************************

*/

public static class StringCMatchesEvaluator extends BaseEvaluator {

private static final long serialVersionUID = 400l;

public final static Evaluator INSTANCE = new StringCMatchesEvaluator();

　

public StringCMatchesEvaluator() {

super( ValueType.STRING_TYPE, CMATCHES );

}

public boolean evaluate(InternalWorkingMemory workingMemory, final InternalReadAccessor extractor, final Object object1, final FieldValue object2) {

final String value1 = (String) extractor.getValue( workingMemory, object1 );

final String value2 = (String) object2.getValue();

return isMatch(value1, value2);

}

public boolean evaluateCachedRight(InternalWorkingMemory workingMemory, final VariableContextEntry context, final Object left) {

final String value = (String) ((ObjectVariableContextEntry) context).right;

return isMatch(value, (String) context.declaration.getExtractor().getValue( workingMemory, left ) );

}

public boolean evaluateCachedLeft(InternalWorkingMemory workingMemory, final VariableContextEntry context, final Object right) {

final String value = (String) context.extractor.getValue( workingMemory, right );

return isMatch(value, (String) ((ObjectVariableContextEntry) context).left );

}

public boolean evaluate(InternalWorkingMemory workingMemory, final InternalReadAccessor extractor1, final Object object1, final InternalReadAccessor extractor2, final Object object2) {

final Object value1 = extractor1.getValue( workingMemory, object1 );

final Object value2 = extractor2.getValue( workingMemory, object2 );

return isMatch( (String) value1, (String) value2 );

}

public String toString() {

return "String cmatches";

}

}

public static class StringNotCMatchesEvaluator extends BaseEvaluator {

private static final long serialVersionUID = 400L;

public final static Evaluator INSTANCE = new StringNotCMatchesEvaluator();

public StringNotCMatchesEvaluator() {

super( ValueType.STRING_TYPE, NOT_CMATCHES );

}

public boolean evaluate(InternalWorkingMemory workingMemory, final InternalReadAccessor extractor, final Object object1, final FieldValue object2) {

final String value1 = (String) extractor.getValue( workingMemory, object1 );

final String value2 = (String) object2.getValue();

return !isMatch(value1, value2);

}

public boolean evaluateCachedRight(InternalWorkingMemory workingMemory, final VariableContextEntry context, final Object left) {

final String value = (String) ((ObjectVariableContextEntry) context).right;

return !isMatch(value, (String) context.declaration.getExtractor().getValue( workingMemory, left ) );

}

public boolean evaluateCachedLeft(InternalWorkingMemory workingMemory, final VariableContextEntry context, final Object right) {

final String value = (String) context.extractor.getValue( workingMemory, right );

return !isMatch(value, (String) ((ObjectVariableContextEntry) context).left );

}

public boolean evaluate(InternalWorkingMemory workingMemory, final InternalReadAccessor extractor1, final Object object1, final InternalReadAccessor extractor2, final Object object2) {

final Object value1 = extractor1.getValue( workingMemory, object1 );

final Object value2 = extractor2.getValue( workingMemory, object2 );

return !isMatch( (String) value1, (String) value2 );

}

public String toString() {

return "String not cmatches";

}

}

}

I don't really expect any help, I know I am stuck at an older drools version, but maybe someone has run into this before.

-Florian