/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. 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 Inc.
*
* 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.dialect.lock;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.jboss.logging.Logger;
import org.hibernate.HibernateException;
import org.hibernate.JDBCException;
import org.hibernate.LockMode;
import org.hibernate.PessimisticLockException;
import org.hibernate.StaleObjectStateException;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.sql.Update;
/**
* A pessimistic locking strategy where the locks are obtained through update statements.
* <p/>
* This strategy is valid for LockMode.PESSIMISTIC_READ
*
* This class is a clone of UpdateLockingStrategy.
*
* @since 3.5
*
* @author Steve Ebersole
* @author Scott Marlow
*/
public class PessimisticReadUpdateLockingStrategy implements LockingStrategy {
private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class,
PessimisticReadUpdateLockingStrategy.class.getName());
private final Lockable lockable;
private final LockMode lockMode;
private final String sql;
/**
* Construct a locking strategy based on SQL UPDATE statements.
*
* @param lockable The metadata for the entity to be locked.
* @param lockMode Indictates the type of lock to be acquired. Note that
* read-locks are not valid for this strategy.
*/
public PessimisticReadUpdateLockingStrategy(Lockable lockable, LockMode lockMode) {
this.lockable = lockable;
this.lockMode = lockMode;
if ( lockMode.lessThan( LockMode.PESSIMISTIC_READ ) ) {
throw new HibernateException( "[" + lockMode + "] not valid for update statement" );
}
if ( !lockable.isVersioned() ) {
LOG.writeLocksNotSupported( lockable.getEntityName() );
this.sql = null;
}
else {
this.sql = generateLockString();
}
}
/**
* @see org.hibernate.dialect.lock.LockingStrategy#lock
*/
public void lock(
Serializable id,
Object version,
Object object,
int timeout, SessionImplementor session) throws StaleObjectStateException, JDBCException {
if ( !lockable.isVersioned() ) {
throw new HibernateException( "write locks via update not supported for non-versioned entities [" + lockable.getEntityName() + "]" );
}
SessionFactoryImplementor factory = session.getFactory();
try {
PreparedStatement st = session.getTransactionCoordinator().getJdbcCoordinator().getStatementPreparer().prepareStatement( sql );
try {
lockable.getVersionType().nullSafeSet( st, version, 1, session );
int offset = 2;
lockable.getIdentifierType().nullSafeSet( st, id, offset, session );
offset += lockable.getIdentifierType().getColumnSpan( factory );
if ( lockable.isVersioned() ) {
lockable.getVersionType().nullSafeSet( st, version, offset, session );
}
int affected = st.executeUpdate();
if ( affected < 0 ) { // todo: should this instead check for exactly one row modified?
factory.getStatisticsImplementor().optimisticFailure( lockable.getEntityName() );
throw new StaleObjectStateException( lockable.getEntityName(), id );
}
}
finally {
st.close();
}
}
catch ( SQLException sqle ) {
JDBCException e = session.getFactory().getSQLExceptionHelper().convert(
sqle,
"could not lock: " + MessageHelper.infoString( lockable, id, session.getFactory() ),
sql
);
throw new PessimisticLockException("could not obtain pessimistic lock", e, object);
}
}
protected String generateLockString() {
SessionFactoryImplementor factory = lockable.getFactory();
Update update = new Update( factory.getDialect() );
update.setTableName( lockable.getRootTableName() );
update.addPrimaryKeyColumns( lockable.getRootTableIdentifierColumnNames() );
update.setVersionColumnName( lockable.getVersionColumnName() );
update.addColumn( lockable.getVersionColumnName() );
if ( factory.getSettings().isCommentsEnabled() ) {
update.setComment( lockMode + " lock " + lockable.getEntityName() );
}
return update.toStatementString();
}
protected LockMode getLockMode() {
return lockMode;
}
}