Cache and PersistenceBroker optimization

[Alessandro Colantoni <ac...@brujulatelecom.com>]

-----Mensaje original-----
De: Alessandro Colantoni [mailto:acolantoni@brujulatelecom.com] 
Enviado el: jueves, 16 de diciembre de 2004 14:23
Para: 'OJB Users List'
Asunto: Cache and per



Hi all!!
I'm doing a very large use of caching.
I have to do thousands of small queries that look for a small number of
entries.

I'm using the connection pool of OC4J.
The application consumes rapidly a large number of connections.

I implemented the queries in DAOs that have methods like this one

 
public ValueObject findByPrimaryKey(Integer parCodigo)throws
DataAccessException{
        PersistenceBroker broker = null;
        ParametroVO parametroVO = null;
        try{   
            broker =
PersistenceBrokerFactoryFactory.instance().defaultPersistenceBroker();
            parametroVO = new  ParametroVO();
            parametroVO.setParCodigo(parCodigo);
            
            Identity oid = new Identity(parametroVO,broker);
            ObjectCache cache = broker.serviceObjectCache();
            parametroVO = (ParametroVO)cache.lookup(oid);
            if (parametroVO==null){
                Criteria criteria = new Criteria();
                criteria.addEqualTo("parCodigo",parCodigo);
                Query query = new QueryByCriteria(ParametroVO.class,
criteria);
                parametroVO =
(ParametroVO)broker.getObjectByQuery(query);
            }else {
                log.info("************parametroVO in
cache***************");
            }
        } catch (ServiceLocatorException e) {
            log.error("ServiceLocatorException thrown in
ParametroDAO.findByPrimaryKey(Integer parCodigo): " + e.toString());
            throw new DataAccessException("Error in
ParametroDAO.findByPrimaryKey(Integer parCodigo): " + e.toString(),e);
        } catch (ClassNotPersistenceCapableException e) {
            log.error("ClassNotPersistenceCapableException thrown in
ParametroDAO.findByPrimaryKey(Integer parCodigo): " + e.toString());
            throw new DataAccessException("Error in
ParametroDAO.findByPrimaryKey(Integer parCodigo): " + e.toString(),e);
        } finally {
                  if (broker != null) broker.close();
        }
        return parametroVO;
    }

My question is:
The DB connection is opened when I do
broker =
PersistenceBrokerFactoryFactory.instance().defaultPersistenceBroker();

and is released when I do broker.close()?;

As I told quite always the ValueObject is found in cache.
Is there any way to check if it is in cache without opening a broker?

I saw in documentation the constructor
public Identity(java.lang.Class realClass,
                java.lang.Class topLevel,
                java.lang.Object[] pkValues)

But I don't understand how to use it.
What's the difference between realClass and topLevel?
Does this constructor could be useful for me?

Hoping someone can help me
Thanks in advance 



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