/*
* JBoss, Home of Professional Open Source.
* Copyright 2011, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.cmp.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.Iterator;
import javax.ejb.EJBException;
import javax.sql.DataSource;
import org.jboss.as.cmp.CmpMessages;
import org.jboss.as.cmp.jdbc.bridge.JDBCCMPFieldBridge;
import org.jboss.as.cmp.jdbc.bridge.JDBCCMRFieldBridge;
import org.jboss.logging.Logger;
/**
* Deletes relations from a relation table.
*
* @author <a href="mailto:dain@daingroup.com">Dain Sundstrom</a>
* @author <a href="mailto:alex@jboss.org">Alex Loubyansky</a>
* @version $Revision: 81030 $
*/
public final class JDBCDeleteRelationsCommand {
private final Logger log;
private int maxKeysInDelete;
private String maxKeysStatement;
public JDBCDeleteRelationsCommand(JDBCStoreManager manager) {
// Create the Log
log = Logger.getLogger(this.getClass().getName() +
"." +
manager.getMetaData().getName()
);
maxKeysInDelete = manager.getJDBCTypeFactory().getTypeMapping().getMaxKeysInDelete();
}
//
// This command needs to be changed to chunk delete commands, because
// some database have a limit on the number of parameters in a statement.
//
public void execute(RelationData relationData) {
if (relationData.removedRelations.size() == 0) {
return;
}
Iterator pairs = relationData.removedRelations.iterator();
int i = 0;
while (i < relationData.removedRelations.size()) {
String sql = getSQL(relationData, relationData.removedRelations.size() - i);
Connection con = null;
PreparedStatement ps = null;
JDBCCMRFieldBridge cmrField = relationData.getLeftCMRField();
try {
// create the statement
if (log.isDebugEnabled()) {
log.debug("Executing SQL: " + sql);
}
// get the connection
DataSource dataSource = cmrField.getDataSource();
con = dataSource.getConnection();
ps = con.prepareStatement(sql);
// set the parameters
setParameters(ps, relationData, pairs);
// execute statement
int rowsAffected = ps.executeUpdate();
if (log.isDebugEnabled()) {
log.debug("Rows affected = " + rowsAffected);
}
i += (maxKeysInDelete > 0 ? maxKeysInDelete : relationData.removedRelations.size());
} catch (Exception e) {
throw CmpMessages.MESSAGES.couldNotDeleteRelations(cmrField.getQualifiedTableName(), e);
} finally {
JDBCUtil.safeClose(ps);
JDBCUtil.safeClose(con);
}
}
}
private String getSQL(RelationData relationData, int keys) {
if (maxKeysInDelete > 0 && keys >= maxKeysInDelete) {
if (maxKeysStatement == null) {
maxKeysStatement = createSQL(relationData, maxKeysInDelete);
}
return maxKeysStatement;
}
return createSQL(relationData, keys);
}
private static String createSQL(RelationData relationData, int keysInDelete) {
JDBCCMRFieldBridge left = relationData.getLeftCMRField();
JDBCCMRFieldBridge right = relationData.getRightCMRField();
StringBuffer sql = new StringBuffer(300);
sql.append(SQLUtil.DELETE_FROM)
.append(left.getQualifiedTableName())
.append(SQLUtil.WHERE);
StringBuffer whereClause = new StringBuffer(20);
whereClause.append('(');
// left keys
SQLUtil.getWhereClause(left.getTableKeyFields(), whereClause)
.append(SQLUtil.AND);
// right keys
SQLUtil.getWhereClause(right.getTableKeyFields(), whereClause)
.append(')');
String whereClauseStr = whereClause.toString();
sql.append(whereClauseStr);
for (int i = 1; i < keysInDelete; ++i) {
sql.append(SQLUtil.OR).append(whereClauseStr);
}
return sql.toString();
}
private void setParameters(PreparedStatement ps, RelationData relationData, Iterator pairs)
throws Exception {
int index = 1;
JDBCCMPFieldBridge[] leftFields = (JDBCCMPFieldBridge[]) relationData.getLeftCMRField().getTableKeyFields();
JDBCCMPFieldBridge[] rightFields = (JDBCCMPFieldBridge[]) relationData.getRightCMRField().getTableKeyFields();
int keyIndex = 0;
while (pairs.hasNext()) {
RelationPair pair = (RelationPair) pairs.next();
// left keys
Object leftId = pair.getLeftId();
for (int i = 0; i < leftFields.length; ++i) {
index = leftFields[i].setPrimaryKeyParameters(ps, index, leftId);
}
// right keys
Object rightId = pair.getRightId();
for (int i = 0; i < rightFields.length; ++i) {
index = rightFields[i].setPrimaryKeyParameters(ps, index, rightId);
}
if (maxKeysInDelete > 0) {
++keyIndex;
if (keyIndex == maxKeysInDelete) {
break;
}
}
}
}
}