/*
* 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.ResultSet;
import java.sql.SQLException;
import org.hibernate.JDBCException;
import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.StaleObjectStateException;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.sql.SimpleSelect;
/**
* A locking strategy where the locks are obtained through select statements.
* <p/>
* For non-read locks, this is achieved through the Dialect's specific
* SELECT ... FOR UPDATE syntax.
*
* @see org.hibernate.dialect.Dialect#getForUpdateString(org.hibernate.LockMode)
* @see org.hibernate.dialect.Dialect#appendLockHint(org.hibernate.LockMode, String)
* @since 3.2
*
* @author Steve Ebersole
*/
public class SelectLockingStrategy extends AbstractSelectLockingStrategy {
/**
* Construct a locking strategy based on SQL SELECT statements.
*
* @param lockable The metadata for the entity to be locked.
* @param lockMode Indictates the type of lock to be acquired.
*/
public SelectLockingStrategy(Lockable lockable, LockMode lockMode) {
super( lockable, lockMode );
}
/**
* @see LockingStrategy#lock
*/
public void lock(
Serializable id,
Object version,
Object object,
int timeout,
SessionImplementor session) throws StaleObjectStateException, JDBCException {
final String sql = determineSql( timeout );
SessionFactoryImplementor factory = session.getFactory();
try {
PreparedStatement st = session.getTransactionCoordinator().getJdbcCoordinator().getStatementPreparer().prepareStatement( sql );
try {
getLockable().getIdentifierType().nullSafeSet( st, id, 1, session );
if ( getLockable().isVersioned() ) {
getLockable().getVersionType().nullSafeSet(
st,
version,
getLockable().getIdentifierType().getColumnSpan( factory ) + 1,
session
);
}
ResultSet rs = st.executeQuery();
try {
if ( !rs.next() ) {
if ( factory.getStatistics().isStatisticsEnabled() ) {
factory.getStatisticsImplementor()
.optimisticFailure( getLockable().getEntityName() );
}
throw new StaleObjectStateException( getLockable().getEntityName(), id );
}
}
finally {
rs.close();
}
}
finally {
st.close();
}
}
catch ( SQLException sqle ) {
throw session.getFactory().getSQLExceptionHelper().convert(
sqle,
"could not lock: " + MessageHelper.infoString( getLockable(), id, session.getFactory() ),
sql
);
}
}
protected String generateLockString(int timeout) {
SessionFactoryImplementor factory = getLockable().getFactory();
LockOptions lockOptions = new LockOptions( getLockMode() );
lockOptions.setTimeOut( timeout );
SimpleSelect select = new SimpleSelect( factory.getDialect() )
.setLockOptions( lockOptions )
.setTableName( getLockable().getRootTableName() )
.addColumn( getLockable().getRootTableIdentifierColumnNames()[0] )
.addCondition( getLockable().getRootTableIdentifierColumnNames(), "=?" );
if ( getLockable().isVersioned() ) {
select.addCondition( getLockable().getVersionColumnName(), "=?" );
}
if ( factory.getSettings().isCommentsEnabled() ) {
select.setComment( getLockMode() + " lock " + getLockable().getEntityName() );
}
return select.toStatementString();
}
}