[CAY-796] Deserialization of DataContext fails when useSharedCache is false

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.2 branch, 2.0 branch
• Fix Version/s: 3.0M2
• Component/s: Core Library
• Environment: JDK 1.5, Windows XP
• Assignee: Andrus Adamchik
• Reporter: Bob Schellink
• Created: 04/Jun/07 09:55
• Updated: 09/Nov/08 01:07
• Resolved: 15/Sep/07 12:20

Description

Sometimes while developing with Tomcat I get the exception below. This occurs when DataContext is serialized.

Exception in thread "main" org.objectstyle.cayenne.CayenneRuntimeException: [v.1.2.3 May 6 2007] Commit Exception
org.objectstyle.cayenne.access.DataContext.flushToParent(DataContext.java:1290)
org.objectstyle.cayenne.access.DataContext.commitChanges(DataContext.java:1166)
test.SerializeDCTest.main(SerializeDCTest.java:29)

Caused by: java.lang.NullPointerException
org.objectstyle.cayenne.access.DataRowStore.sendUpdateNotification(DataRowStore.java:709)
org.objectstyle.cayenne.access.DataRowStore.processSnapshotChanges(DataRowStore.java:574)
org.objectstyle.cayenne.access.DataDomainFlushAction.postprocess(DataDomainFlushAction.java:278)
org.objectstyle.cayenne.access.DataDomainFlushAction.flush(DataDomainFlushAction.java:178)
org.objectstyle.cayenne.access.DataDomain.onSyncFlush(DataDomain.java:846)
org.objectstyle.cayenne.access.DataDomain$2.transform(DataDomain.java:817)
org.objectstyle.cayenne.access.DataDomain.runInTransaction(DataDomain.java:872)
org.objectstyle.cayenne.access.DataDomain.onSync(DataDomain.java:814)
org.objectstyle.cayenne.access.DataContext.flushToParent(DataContext.java:1262)

Here is a little test to reproduce the error:

package test;

import test.cayenne.Employee;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.List;
import org.objectstyle.cayenne.DataObjectUtils;
import org.objectstyle.cayenne.access.DataContext;
import org.objectstyle.cayenne.query.SelectQuery;

public class SerializeDCTest {

public SerializeDCTest() {
}

public static void main(String[] args)

{ //boolean useSharedCache = true; //works boolean useSharedCache = false; DataContext context = DataContext.createDataContext(useSharedCache); context = serializeDC(context); Employee emp = (Employee) DataObjectUtils.objectForPK(context, Employee.class, 740); emp.setFirstname("test" + Math.random()); context.commitChanges(); }

public static DataContext serializeDC(DataContext dc) {
try

{ ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(dc); ByteArrayInputStream is = new ByteArrayInputStream(bos.toByteArray()); ObjectInputStream ois = new ObjectInputStream(is); DataContext result = (DataContext) ois.readObject(); return result; }

catch (Exception ex)

{ throw new RuntimeException("DataContext serialization failed", ex); }

}
}

Note that if useSharedCache = true, then it works fine.