jtatransaction.java

一个Java持久层类库

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.transaction;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.transaction.Status;
import javax.transaction.Synchronization;
import javax.transaction.SystemException;
import javax.transaction.TransactionManager;
import javax.transaction.UserTransaction;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.hibernate.AssertionFailure;
import org.hibernate.HibernateException;
import org.hibernate.Transaction;
import org.hibernate.TransactionException;
import org.hibernate.jdbc.JDBCContext;
import org.hibernate.util.JTAHelper;

/**
 * {@link Transaction} implementation based on transaction management through
 * a JTA {@link UserTransaction}.  Similar to {@link CMTTransaction}, except
 * here we are actually managing the transactions through the Hibernate
 * transaction mechanism.
 * <p/>
 * Instances check to see if there is an existing JTA transaction.  If none
 * exists, a new transaction is started; if one exists, all work is done in the
 * existing context. The following properties are used to locate the underlying
 * {@link UserTransaction}:<ul>
 * <li><tt>hibernate.jndi.url</tt> : JNDI initial context URL</li>
 * <li><tt>hibernate.jndi.class</tt> : JNDI provider class</li>
 * <li><tt>jta.UserTransaction</tt> : JNDI namespace</li>
 * </ul>
 *
 * @author Gavin King
 */
public class JTATransaction implements Transaction {

	private static final Logger log = LoggerFactory.getLogger(JTATransaction.class);

	private final JDBCContext jdbcContext;
	private final TransactionFactory.Context transactionContext;

	private UserTransaction ut;
	private boolean newTransaction;
	private boolean begun;
	private boolean commitFailed;
	private boolean commitSucceeded;
	private boolean callback;
	
	public JTATransaction(
			InitialContext context, 
			String utName, 
			JDBCContext jdbcContext, 
			TransactionFactory.Context transactionContext
	) {
		this.jdbcContext = jdbcContext;
		this.transactionContext = transactionContext;

		log.debug("Looking for UserTransaction under: " + utName);
		
		try {
			ut = (UserTransaction) context.lookup(utName);
		}
		catch (NamingException ne) {
			log.error("Could not find UserTransaction in JNDI", ne);
			throw new TransactionException("Could not find UserTransaction in JNDI: ", ne);
		}
		if (ut==null) {
			throw new AssertionFailure("A naming service lookup returned null");
		}

		log.debug("Obtained UserTransaction");
	}

	/**
	 * {@inheritDoc}
	 */
	public void begin() throws HibernateException {
		if (begun) {
			return;
		}
		if (commitFailed) {
			throw new TransactionException("cannot re-start transaction after failed commit");
		}
		
		log.debug("begin");

		try {
			newTransaction = ut.getStatus() == Status.STATUS_NO_TRANSACTION;
			if (newTransaction) {
				ut.begin();
				log.debug("Began a new JTA transaction");
			}
		}
		catch (Exception e) {
			log.error("JTA transaction begin failed", e);
			throw new TransactionException("JTA transaction begin failed", e);
		}

		/*if (newTransaction) {
			// don't need a synchronization since we are committing
			// or rolling back the transaction ourselves - assuming
			// that we do no work in beforeTransactionCompletion()
			synchronization = false;
		}*/

		boolean synchronization = jdbcContext.registerSynchronizationIfPossible();

		if ( !newTransaction && !synchronization ) {
			log.warn("You should set hibernate.transaction.manager_lookup_class if cache is enabled");
		}

		if (!synchronization) {
			//if we could not register a synchronization,
			//do the before/after completion callbacks
			//ourself (but we need to let jdbcContext
			//know that this is what we are going to
			//do, so it doesn't keep trying to register
			//synchronizations)
			callback = jdbcContext.registerCallbackIfNecessary();
		}

		begun = true;
		commitSucceeded = false;
		
		jdbcContext.afterTransactionBegin(this);
	}

	/**
	 * {@inheritDoc}
	 */
	public void commit() throws HibernateException {
		if (!begun) {
			throw new TransactionException("Transaction not successfully started");
		}

		log.debug("commit");

		boolean flush = !transactionContext.isFlushModeNever()
		        && ( callback || !transactionContext.isFlushBeforeCompletionEnabled() );

		if (flush) {
			transactionContext.managedFlush(); //if an exception occurs during flush, user must call rollback()
		}

		if (callback && newTransaction) {
			jdbcContext.beforeTransactionCompletion(this);
		}

		closeIfRequired();

		if (newTransaction) {
			try {
				ut.commit();
				commitSucceeded = true;
				log.debug("Committed JTA UserTransaction");
			}
			catch (Exception e) {
				commitFailed = true; // so the transaction is already rolled back, by JTA spec
				log.error("JTA commit failed", e);
				throw new TransactionException("JTA commit failed: ", e);
			}
			finally {
				afterCommitRollback();
			}
		}
		else {
			// this one only really needed for badly-behaved applications!
			// (if the TransactionManager has a Sychronization registered,
			// its a noop)
			// (actually we do need it for downgrading locks)
			afterCommitRollback();
		}

	}

	/**
	 * {@inheritDoc}
	 */
	public void rollback() throws HibernateException {
		if (!begun && !commitFailed) {
			throw new TransactionException("Transaction not successfully started");
		}

		log.debug("rollback");

		/*if (!synchronization && newTransaction && !commitFailed) {
			jdbcContext.beforeTransactionCompletion(this);
		}*/

		try {
			closeIfRequired();
		}
		catch (Exception e) {
			log.error("could not close session during rollback", e);
			//swallow it, and continue to roll back JTA transaction
		}

		try {
			if (newTransaction) {
				if (!commitFailed) {
					ut.rollback();
					log.debug("Rolled back JTA UserTransaction");
				}
			}
			else {
				ut.setRollbackOnly();
				log.debug("set JTA UserTransaction to rollback only");
			}
		}
		catch (Exception e) {
			log.error("JTA rollback failed", e);
			throw new TransactionException("JTA rollback failed", e);
		}
		finally {
			afterCommitRollback();
		}
	}

	private static final int NULL = Integer.MIN_VALUE;

	private void afterCommitRollback() throws TransactionException {
		
		begun = false;

		if (callback) { // this method is a noop if there is a Synchronization!

			if (!newTransaction) {
				log.warn("You should set hibernate.transaction.manager_lookup_class if cache is enabled");
			}
			int status=NULL;
			try {
				status = ut.getStatus();
			}
			catch (Exception e) {
				log.error("Could not determine transaction status after commit", e);
				throw new TransactionException("Could not determine transaction status after commit", e);
			}
			finally {
				/*if (status!=Status.STATUS_COMMITTED && status!=Status.STATUS_ROLLEDBACK) {
					log.warn("Transaction not complete - you should set hibernate.transaction.manager_lookup_class if cache is enabled");
					//throw exception??
				}*/
				jdbcContext.afterTransactionCompletion(status==Status.STATUS_COMMITTED, this);
			}

		}
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean wasRolledBack() throws TransactionException {

		//if (!begun) return false;
		//if (commitFailed) return true;

		final int status;
		try {
			status = ut.getStatus();
		}
		catch (SystemException se) {
			log.error("Could not determine transaction status", se);
			throw new TransactionException("Could not determine transaction status", se);
		}
		if (status==Status.STATUS_UNKNOWN) {
			throw new TransactionException("Could not determine transaction status");
		}
		else {
			return JTAHelper.isRollback(status);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public boolean wasCommitted() throws TransactionException {

		//if (!begun || commitFailed) return false;

		final int status;
		try {
			status = ut.getStatus();
		}
		catch (SystemException se) {
			log.error("Could not determine transaction status", se);
			throw new TransactionException("Could not determine transaction status: ", se);
		}
		if (status==Status.STATUS_UNKNOWN) {
			throw new TransactionException("Could not determine transaction status");
		}
		else {
			return status==Status.STATUS_COMMITTED;
		}
	}
	
	/**
	 * {@inheritDoc}
	 */
	public boolean isActive() throws TransactionException {

		if (!begun || commitFailed || commitSucceeded) return false;

		final int status;
		try {
			status = ut.getStatus();
		}
		catch (SystemException se) {
			log.error("Could not determine transaction status", se);
			throw new TransactionException("Could not determine transaction status: ", se);
		}
		if (status==Status.STATUS_UNKNOWN) {
			throw new TransactionException("Could not determine transaction status");
		}
		else {
			return status==Status.STATUS_ACTIVE;
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public void registerSynchronization(Synchronization sync) throws HibernateException {
		if (getTransactionManager()==null) {
			throw new IllegalStateException("JTA TransactionManager not available");
		}
		else {
			try {
				getTransactionManager().getTransaction().registerSynchronization(sync);
			}
			catch (Exception e) {
				throw new TransactionException("could not register synchronization", e);
			}
		}
	}

	/**
	 * Getter for property 'transactionManager'.
	 *
	 * @return Value for property 'transactionManager'.
	 */
	private TransactionManager getTransactionManager() {
		return transactionContext.getFactory().getTransactionManager();
	}

	private void closeIfRequired() throws HibernateException {
		boolean close = callback && 
				transactionContext.shouldAutoClose() && 
				!transactionContext.isClosed();
		if ( close ) {
			transactionContext.managedClose();
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public void setTimeout(int seconds) {
		try {
			ut.setTransactionTimeout(seconds);
		}
		catch (SystemException se) {
			throw new TransactionException("could not set transaction timeout", se);
		}
	}

	/**
	 * Getter for property 'userTransaction'.
	 *
	 * @return Value for property 'userTransaction'.
	 */
	protected UserTransaction getUserTransaction() {
		return ut;
	}
}