/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.dialect.lock;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.JDBCException;
import org.hibernate.LockMode;
import org.hibernate.StaleObjectStateException;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.sql.Update;

import org.jboss.logging.Logger;

A locking strategy where the locks are obtained through update statements.

This strategy is not valid for read style locks.
Author:Steve Ebersole
Since:3.2
/** * A locking strategy where the locks are obtained through update statements. * <p/> * This strategy is not valid for read style locks. * * @author Steve Ebersole * @since 3.2 */
public class UpdateLockingStrategy implements LockingStrategy { private static final CoreMessageLogger LOG = Logger.getMessageLogger( CoreMessageLogger.class, UpdateLockingStrategy.class.getName() ); private final Lockable lockable; private final LockMode lockMode; private final String sql;
Construct a locking strategy based on SQL UPDATE statements.
Params:
  • lockable – The metadata for the entity to be locked.
  • lockMode – Indictates the type of lock to be acquired. Note that read-locks are not valid for this strategy.
/** * 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 UpdateLockingStrategy(Lockable lockable, LockMode lockMode) { this.lockable = lockable; this.lockMode = lockMode; if ( lockMode.lessThan( LockMode.UPGRADE ) ) { throw new HibernateException( "[" + lockMode + "] not valid for update statement" ); } if ( !lockable.isVersioned() ) { LOG.writeLocksNotSupported( lockable.getEntityName() ); this.sql = null; } else { this.sql = generateLockString(); } } @Override public void lock( Serializable id, Object version, Object object, int timeout, SharedSessionContractImplementor session) throws StaleObjectStateException, JDBCException { if ( !lockable.isVersioned() ) { throw new HibernateException( "write locks via update not supported for non-versioned entities [" + lockable.getEntityName() + "]" ); } // todo : should we additionally check the current isolation mode explicitly? final SessionFactoryImplementor factory = session.getFactory(); try { final PreparedStatement st = session.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 ); } final int affected = session.getJdbcCoordinator().getResultSetReturn().executeUpdate( st ); if ( affected < 0 ) { if (factory.getStatistics().isStatisticsEnabled()) { factory.getStatistics().optimisticFailure( lockable.getEntityName() ); } throw new StaleObjectStateException( lockable.getEntityName(), id ); } } finally { session.getJdbcCoordinator().getLogicalConnection().getResourceRegistry().release( st ); session.getJdbcCoordinator().afterStatementExecution(); } } catch ( SQLException sqle ) { throw session.getJdbcServices().getSqlExceptionHelper().convert( sqle, "could not lock: " + MessageHelper.infoString( lockable, id, session.getFactory() ), sql ); } } protected String generateLockString() { final SessionFactoryImplementor factory = lockable.getFactory(); final Update update = new Update( factory.getDialect() ); update.setTableName( lockable.getRootTableName() ); update.addPrimaryKeyColumns( lockable.getRootTableIdentifierColumnNames() ); update.setVersionColumnName( lockable.getVersionColumnName() ); update.addColumn( lockable.getVersionColumnName() ); if ( factory.getSessionFactoryOptions().isCommentsEnabled() ) { update.setComment( lockMode + " lock " + lockable.getEntityName() ); } return update.toStatementString(); } protected LockMode getLockMode() { return lockMode; } }