java.lang.ClassCastException: on rule removal for shared LeftInputAdapterNodes

When removing packages from a knowledge base, the following intermittent error is encountered:

java.lang.ClassCastException: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.RuleTerminalNode$TerminalNodeMemory
at org.drools.reteoo.RuleTerminalNode.doRemove(RuleTerminalNode.java:357)
at org.drools.common.BaseNode.remove(BaseNode.java:95)
at org.drools.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:237)
at org.drools.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:366)
at org.drools.common.AbstractRuleBase.removeRule(AbstractRuleBase.java:712)
at org.drools.common.AbstractRuleBase.removePackage(AbstractRuleBase.java:640)
at org.drools.impl.KnowledgeBaseImpl.removeKnowledgePackage(KnowledgeBaseImpl.java:166)

The following JUnit code, which reads a dril file, adds packages to a knowledge base and then serialises/deserialises the knowledge packages before removing them, whilst not reproducing the issue, could be a useful starting point.

It is currently considered that it is some combination of serialise and then add/remove package from a knowledge base that is causing the issue.

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Logger;
import org.drools.KnowledgeBase;
import org.drools.KnowledgeBaseConfiguration;
import org.drools.KnowledgeBaseFactory;
import org.drools.builder.KnowledgeBuilder;
import org.drools.builder.KnowledgeBuilderConfiguration;
import org.drools.builder.KnowledgeBuilderError;
import org.drools.builder.KnowledgeBuilderErrors;
import org.drools.builder.KnowledgeBuilderFactory;
import org.drools.builder.ResourceType;
import org.drools.compiler.PackageBuilderConfiguration;
import org.drools.definition.KnowledgePackage;
import org.drools.io.Resource;
import org.drools.io.ResourceFactory;
import org.drools.rule.builder.dialect.java.JavaDialectConfiguration;
import org.junit.Assert;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

/**

• test for a classcastexception issue when removing a knowledge package
  *
  */
  public class DroolsJiraIssues {

private static String filename = "ENTER DRL FILENAME HERE";

private static Logger log = Logger.getLogger(DroolsJiraIssues.class);

private KnowledgeBaseConfiguration knowledgeBaseConfiguration = KnowledgeBaseFactory
.newKnowledgeBaseConfiguration();

private KnowledgeBuilderConfiguration knowledgeBuilderConfiguration;

@BeforeClass
public static void beforeClass()

{ BasicConfigurator.configure(); }

@Before
public void setUp()

{ knowledgeBuilderConfiguration = KnowledgeBuilderFactory.newKnowledgeBuilderConfiguration(); JavaDialectConfiguration conf = (JavaDialectConfiguration) ((PackageBuilderConfiguration)knowledgeBuilderConfiguration).getDialectConfiguration("java"); conf.setCompiler(JavaDialectConfiguration.JANINO); }

/**

• remove knowledge packages sometimes throws the following error:
• java.lang.ClassCastException: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.RuleTerminalNode$TerminalNodeMemory
• at org.drools.reteoo.RuleTerminalNode.doRemove(RuleTerminalNode.java:357)
• at org.drools.common.BaseNode.remove(BaseNode.java:95)
• at org.drools.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:237)
• at org.drools.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:366)
• at org.drools.common.AbstractRuleBase.removeRule(AbstractRuleBase.java:712)
• at org.drools.common.AbstractRuleBase.removePackage(AbstractRuleBase.java:640)
• at org.drools.impl.KnowledgeBaseImpl.removeKnowledgePackage(KnowledgeBaseImpl.java:166)
  *
  */
  @Test
  public void testRemoveKnowledgePackages() throws IOException {
  // create a knowledge base
  KnowledgeBase knowledgeBase = createKnowlegeBase();

// create knowledge packages from a .drl file
Collection<KnowledgePackage> packages = readKnowledgePackagesFromFile(filename);
log.info("packages.size() = " + packages.size());

// add all knowledge packages
knowledgeBase.addKnowledgePackages(packages);
log.info("added knowledge packages");

// remove all knowledge packages
try

{ removePackagesForKnowledgeBase(knowledgeBase); } catch (ClassCastException e) { Assert.assertTrue(false); }
log.info("removed knowledge packages");

// serialise and deserialise the knowledge packages
Collection<KnowledgePackage> packages2 = null;
try { packages2 = serialiseDeserialiseKnowledgePackages(packages); } catch (ClassNotFoundException e) { Assert.assertTrue(false); }
Assert.assertTrue(packages2.size() == packages.size());
knowledgeBase.addKnowledgePackages(packages2);
log.info("added serialised/deserialised knowledge packages");

// remove all knowledge packages
try { removePackagesForKnowledgeBase(knowledgeBase); }

catch (ClassCastException e)

{ Assert.assertTrue(false); }

}

private Collection<KnowledgePackage> serialiseDeserialiseKnowledgePackages(Collection<KnowledgePackage> packages) throws ClassNotFoundException, IOException {
Collection<KnowledgePackage> packages2 = new ArrayList<KnowledgePackage>();

List<byte[]> serialisedPackageList = new ArrayList<byte[]>();

// serialize and deserialise knowledge packages by using a bytearrayoutputstream
for (Iterator<KnowledgePackage> iter = packages.iterator(); iter.hasNext()

{ KnowledgePackage kbPackage = iter.next(); ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(kbPackage); log.info("wrote package name " + kbPackage.getName()); serialisedPackageList.add(bos.toByteArray()); }

for (byte[] byteArray : serialisedPackageList)

{ ByteArrayInputStream bis = new ByteArrayInputStream(byteArray); ObjectInputStream ois = new ObjectInputStream(bis); KnowledgePackage kbPackage = (KnowledgePackage) ois.readObject(); log.info("read package name " + kbPackage.getName()); packages2.add(kbPackage); }

return packages2;
}

/**

• create a new knowledge base
• @return KnowledgeBase
  */
  private KnowledgeBase createKnowlegeBase() { KnowledgeBase knowledgeBase = KnowledgeBaseFactory .newKnowledgeBase(knowledgeBaseConfiguration); return knowledgeBase; }

/**

• remove existing packages from a given knowledge base
• @param knowledgeBase
  */
  private void removePackagesForKnowledgeBase(KnowledgeBase knowledgeBase) {
  Collection<KnowledgePackage> packages = knowledgeBase
  .getKnowledgePackages();

for (Iterator<KnowledgePackage> iter = packages.iterator(); iter
.hasNext()

{ KnowledgePackage kbPackage = iter.next(); String packageName = kbPackage.getName(); knowledgeBase.removeKnowledgePackage(packageName); log.info("removed packageName = " + packageName); }

}

private Collection<KnowledgePackage> readKnowledgePackagesFromFile(
String filename) {

Collection<KnowledgePackage> knowledgePackageList = new ArrayList<KnowledgePackage>();

URL fileUrl = TestTopologyServerImpl.class.getResource(filename);
try {
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory
.newKnowledgeBuilder();
Resource resource = ResourceFactory.newUrlResource(fileUrl);
kbuilder.add(resource, ResourceType.DRL);
if (kbuilder.hasErrors()) {
KnowledgeBuilderErrors errors = kbuilder.getErrors();
Iterator<KnowledgeBuilderError> it = errors.iterator();
while (it.hasNext())

{ KnowledgeBuilderError error = it.next(); log.error(error.getMessage()); }

}
Assert.assertTrue(!kbuilder.hasErrors());
knowledgePackageList = kbuilder.getKnowledgePackages();
} catch (Exception e)

{ log.error("error: " + e.getMessage()); }

return knowledgePackageList;
}

/**

• load a file
• @param file
• @return
• @throws IOException
  */
  protected final String loadFileAsString(final File file) throws IOException { return new String(getFileAsBytes(file)); }

/**

• get the bytes of a file
• @param file
• @return
• @throws IOException
  */
  private final byte[] getFileAsBytes(final File file) throws IOException { final BufferedInputStream bis = new BufferedInputStream( new FileInputStream(file)); final byte[] bytes = new byte[(int) file.length()]; bis.read(bytes); bis.close(); return bytes; }

  }