Is it possible to list all dirty objects in a session?

nick.hynes · **Posted:** Mon Jan 10, 2005 10:05 pm

Is it possible to query the second level cache for a list of all objects updated (including inserts and deletes) which have not yet been committed?

We're using optimistic locking (3.0 beta 1), and in some cases we know there will be a clash. Rather than just doing a...

Code:

transaction.rollback();

... or similar, we'd like to get a list of objects which have been updated, and then - in certain cases - apply some logic which looks like this:

Code:

    session.evict( oldVersion );
    session.save( newVersion );

We know we can safely do this in some cases, and it would save our users a lot of headaches if we can get it working. Any suggestions on how this might be achieved?

henri · **Posted:** Tue Jan 11, 2005 6:21 am

From what I understood, you in fact want to know the objects in level 1 cache.

At one time I was wanting to print all objects in the cache and I did something dirty to do so. It's absolutly dependent of hibernate implementation. Hibernate doesn't allow to be the cache contain in a clean way. So I did that:

Code:

   public void printHibernateEntities(RootContext ctx) throws Exception {      
      SessionImpl s = (SessionImpl) ctx.getFlowContext().getFlowManager().getHibSession();
      Map entities = (Map) getField(s, "entityEntries");
      List result = new ArrayList(entities.size());
      for(Iterator it = entities.values().iterator(); it.hasNext();) {
         Object o = it.next();
         String className = (String) getField(o, "className");
         Long id = (Long) getField(o, "id");
         result.add(className + ": " + id);
      }
      
      Collections.sort(result);
      
      for(Iterator it = result.iterator(); it.hasNext();) {
         System.out.println(it.next());         
      }
      
   }
   
   private Object getField(Object instance, String name) throws Exception {
      Field f = instance.getClass().getDeclaredField(name);
      f.setAccessible(true);      
      return f.get(instance);
   }

You can do the same kind of thing to solve your issue. However, I'm not sure I should tell you that since I'm pretty sure there is a much prettier solution to your problem.

nick.hynes · **Posted:** Tue Jan 11, 2005 4:18 pm

Thanks Henri,

Quote:

From what I understood, you in fact want to know the objects in level 1 cache.

Yes, that's exactly what I'm after. I couldn't see anything in the 'public' interface (i.e. in the hibernate.org package) which did this.

I understand that it might not be version resilient, since it relies on the implementation classes, but it should be good enough for now.

Perhaps we could get a function like this put in the public interface? (perhaps session.getDirtyObjectSet()??) Comments... expressions of interest welcome...

emmanuel · **Posted:** Wed Jan 12, 2005 7:07 am

can interceptors help?

nick.hynes · **Posted:** Thu Jan 13, 2005 11:03 pm

Yeah, thanks Emmanuel, that's what I'm looking for.

The only thing I'm not sure on is how to determine which objects are dirty.

I thought this would be obvious from , but that doesn't always seem to be called. For example in the following scenario, the Cat (momo) has a reference to its Vet (sarah). If you save the Cat first, onFlushDirty() is never called on the Vet.

Is this the expected behaviour? Is there some other way to determine which objects are dirty?

Code:

    sarah = Vet.create( "sarah", null );
    momo = Cat.create( "momo", 'm', 8.5F, sarah );
    // i.e. momo.setVet( sarah );
    session.save( momo );

Quote:

onSave( [Cat 'momo'])
isTransient called on [Vet 'sarah']

Code:

session.save( sarah );

Quote:

onSave( [Vet 'sarah'])

Code:

session.flush();

Quote:

preFlush( [ [Cat 'momo'], [Vet 'sarah'] ] )
findDirty( [Cat 'momo'] )
onFlushDirty( [Cat 'momo'])
findDirty( [Vet 'sarah'] )
Hibernate: insert into CAT (version, NAME, sex, weight, vet, CAT_ID) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into VET (version, NAME, certificationDate, VET_ID) values (?, ?, ?, ?)
Hibernate: update CAT set version=?, NAME=?, sex=?, weight=?, vet=? where CAT_ID=? and version=?
postFlush()

nick.hynes · **Posted:** Thu Jan 13, 2005 11:06 pm

Quote:

I thought this would be obvious from , but that doesn't always seem to be called.

Correction, I meant to say:

Quote:

I thought this would be obvious from onFlushDirty(), but that doesn't always seem to be called.