RE: how to get objects locked by a transaction?

[Mahler Thomas]

Hi Jair,


> Hi,
>     Thank you Mahler for your fast reply.
>     I understand that it is not possible to do it with the 
> current OJB API.
>     I am asking you this because I need to remove from OJB 
> cache the objects
> touched by a transaction when it is aborted.
>     Here is what I think could be a good idea to fix this 
> issue: as noted in
> the OJB cache documentation 
> (http://db.apache.org/ojb/objectcache.html), the
> OJB user must manually remove each object touched by the 
> trasaction when
> using ObjectCacheDefaultImpl and the transaction is aborted 
> because the
> objects may be corrupted. So why doesn't the implementation of the
> Transaction.abort method removes the touched objets from the 
> cache? I think
> this should fix this issue, don't you?

That's already implemented!
The ObjectENvelopeTable.rollback() method performs rollback actions for all
registered objects.

    public void rollback()
    {
        PersistenceBroker broker = transaction.getBroker();
        Iterator iter = mvOrderOfIds.iterator();
        while (iter.hasNext())
        {
            ObjectEnvelope mod = (ObjectEnvelope)
mhtObjectEnvelopes.get(iter.next());
            if (log.isDebugEnabled())
                log.debug("rollback: " + mod);
            // if the Object has been modified has been modified by
transaction, mark object as dirty
            if (mod.hasChanged())
            {
 
mod.setModificationState(mod.getModificationState().markDirty());
            }
            mod.getModificationState().rollback(mod, broker);
        }
    }

The ModificationState.rollback(...) calls remove dirty instances from the
cache.
For example the StateOldDirty.rollback method looks like follows:
    public void rollback(ObjectEnvelope mod, PersistenceBroker broker)
    {
        this.removeFromCache(mod.getObject(), broker);
        // Call added to rollback the object itself so it has the previous
values again when it is used further on.
        mod.rollback();
    }

clean Objects (that is Objects not modified during the transaction) will not
be removed from the cache!


>     Well, it's just an idea. In my system I am going to 
> remove the objects
> from cache manually, but as there's no way to get only the 
> objects touched
> by the transaction I'll have to clear the entire cache.

I thinks that's not necessary, given my above explanation.

cheers,
thomas

> Thanks,
> Jair Jr
> 
> ----- Original Message -----
> From: "Mahler Thomas" <[EMAIL PROTECTED]>
> To: "'OJB Users List'" <[EMAIL PROTECTED]>
> Sent: Tuesday, October 28, 2003 1:45 PM
> Subject: RE: how to get objects locked by a transaction?
> 
> 
> > Hello Jair,
> >
> > OJB ODMG stores each registered Objects in an 
> o.a.ojb.odmg.ObjectEnvelope.
> > All ObjectEnvelopes are kept in an o.a.ojb.odmg.ObjectEnvelopeTable.
> > ObjectEnvelopeTable has a public method
> > public Enumeration elements();
> >
> > which returns an Enumeration of all ObjectEnvelopes.
> >
> > The each OJB ODMG TransactionImpl maintains its own 
> ObjectEnvelopeTable:
> >     /**
> >      * the internal table containing all Objects "touched" 
> by this tx and
> > their
> >      * respective transactional state
> >      */
> >     private ObjectEnvelopeTable objectEnvelopeTable = null;
> >
> > Currently TransactionImpl does not provide public access to the
> > ObjectEnvelopeTable.
> > So I don't see a way to perform your task without changing 
> OJB code...
> >
> > cheers,
> > Thomas
> >
> > > -----Original Message-----
> > > From: Jair da Silva Ferreira Júnior [mailto:[EMAIL PROTECTED]
> > > Sent: Tuesday, October 28, 2003 12:25 AM
> > > To: OJB Users List
> > > Subject: how to get objects locked by a transaction?
> > >
> > >
> > > Hello,
> > >     How can I safely get all objects locked by a transaction
> > > using ODMG or broker API?
> > >     I need this because I want to remove all objects locked
> > > by a transaction from the cache. Something like this:
> > >
> > >         .....
> > >         Iterator lockedObjects=getLockedObjects(transaction);
> > >         while(lockedObjects.hasNext()){
> > >             broker.removeFromCache(lockedObjects.next());
> > >         }
> > >         .....
> > >
> > > Thanks,
> > >     Jair Jr
> > >
> >
> >
> > 
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> >
> >
> >
> 
> 
> 
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