UseSharedCache follow up

[bob <sa...@gmail.com>]

Hi all

Using Cayenne 1.2.2, jdk5.

In my previous post when the "use shared cache" is false in the modeler 
and one were to programmatically set it to true, a nullpointer would be 
thrown. This was fixed in the meantime, thanks Andrus!

In my playing around with Cayenne options I ran into another exception 
awhile back. In the modeler under cache configuration the "use shared 
cache" is now enabled.

If one were to programmatically set the useSharedCache to false, AND the 
datacontext is somehow serialized which might happen in say a servlet 
container, the exception below is thrown. Here is the code to reproduce 
this exception.

public static void main(String[] args) {
    //boolean useSharedCache = true; //still works even after serializing
    boolean useSharedCache = false;
    DataContext context = DataContext.createDataContext(useSharedCache);
    context = serializeDC(context); //serialize and deserialize the dc
    Employee emp = (Employee) DataObjectUtils.objectForPK(context, 
Employee.class, 200);
    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);
   }
}

Here is the stacktrace:

Exception in thread "main" 
org.objectstyle.cayenne.CayenneRuntimeException: Commit Exception
org.objectstyle.cayenne.access.DataContext.flushToParent(DataContext.java:1290)
org.objectstyle.cayenne.access.DataContext.commitChanges(DataContext.java:1166)
test.SerializeDC.main(SerializeDCTest.java:27)


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)

PS: I have tried for awhile now to reproduce the above error for a easy 
test case, but did not realize the above problem came about only after a 
serialization of the datacontext. This was until Marc Gabriel-Willem 
mentioned he had problems after serialization.

kind regards

bob