Some transaction propagations not working with Spring/Hibernate 4

Question

I'm in the process of upgrading an application to Hibernate 4.2 from 3.3. We're also using Spring 3.1.3 (which we can't/won't update at this time).

Some of my unit tests are now failing with

org.hibernate.HibernateException: No Session found for current thread

in the SpringSessionContext. This is not an issue with the <tx:annotation-driven /> being defined in the wrong context, or a case of missing CGLIB libraries. Most of the tests do work, which means that in most cases, the transaction proxying is working.

The cases where it is now failing seem to be around the use of NOT_SUPPORTED, NEVER, and SUPPORTED propagation types. For whatever reason the SpringSessionContext doesn't create a session in these cases.

Our use cases sometimes require that transactional boundaries don't strictly line up with method boundaries, and that sessions sometimes outlive transactions. In the Spring 3/Hibernate 3 case, the session context was bound to a thread local, and a call to SessionFactory.getCurrentSession() would return a session instance even if a transaction was not started. This is the behavior that I am looking to still have in the Hibernate 4 case.

Does anyone know a workaround for this? It's tough to align Session boundaries with a conversation instead of a transaction if Spring refuses to create a session without a valid transaction. A Session and its persistence context shouldn't be tied to an open transaction.

Answer 1

Worked around this issue by implementing a CurrentSessionContext that is a wrapper around a SpringSessionContext and borrowing some of the code changes that made it into Spring Framwork 4+:

public class ClassLoaderSpringSessionContext implements CurrentSessionContext {

    private final SessionFactoryImplementor sessionFactory;
    private final SpringSessionContext sessionContext;

    public ClassLoaderSpringSessionContext(final SessionFactoryImplementor sessionFactory) {
        this.sessionFactory = sessionFactory;  // This is actually some class loading logic that isn't important to this transaction problem.
        this.sessionContext = new SpringSessionContext(this.sessionFactory);
    }

    @Override
    public Session currentSession() throws HibernateException {
        try {
            return sessionContext.currentSession();
        } catch (HibernateException e) {
            if (TransactionSynchronizationManager.isSynchronizationActive()) {
                Session session = this.sessionFactory.openSession();
                if (TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
                    session.setFlushMode(FlushMode.MANUAL);
                }
                SessionHolder sessionHolder = new SessionHolder(session);
                TransactionSynchronizationManager
                        .registerSynchronization(new SpringSessionSynchronization(sessionHolder,
                            this.sessionFactory));
                TransactionSynchronizationManager.bindResource(this.sessionFactory, sessionHolder);
                sessionHolder.setSynchronizedWithTransaction(true);
                return session;
            } else {
                throw new HibernateException(
                        "Could not obtain transaction-synchronized Session for current thread");
            }
        }
    }
}

SpringSessionSynchronization was a package private class in Spring 4, so I also had to pull a version of that as a private inner class to ClassLoaderSpringSessionContext.

Hope this helps someone else.