/*
* Copyright 2008 Oleg Nitz, Bruce Snyder, Ralf Joachim
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.castor.cpa.persistence.sql.keygen;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.castor.core.util.Messages;
import org.castor.cpa.persistence.sql.keygen.typehandler.KeyGeneratorTypeHandlerBigDecimal;
import org.castor.cpa.persistence.sql.keygen.typehandler.KeyGeneratorTypeHandlerInteger;
import org.castor.cpa.persistence.sql.keygen.typehandler.KeyGeneratorTypeHandlerLong;
import org.exolab.castor.jdo.PersistenceException;
import org.exolab.castor.jdo.engine.JDBCSyntax;
import org.exolab.castor.mapping.MappingException;
import org.exolab.castor.persist.spi.PersistenceFactory;
import org.exolab.castor.persist.spi.QueryExpression;
/**
* HIGH-LOW key generators.
*
* @see HighLowKeyGeneratorFactory
* @author <a href="mailto:on AT ibis DOT odessa DOT ua">Oleg Nitz</a>
* @author <a href="mailto:bruce DOT snyder AT gmail DOT com">Bruce Snyder</a>
* @author <a href="mailto:ralf DOT joachim AT syscon DOT eu">Ralf Joachim</a>
* @version $Revision$ $Date: 2006-04-10 16:39:24 -0600 (Mon, 10 Apr 2006) $
*/
public final class HighLowKeyGenerator extends AbstractBeforeKeyGenerator {
//-----------------------------------------------------------------------------------
/** The <a href="http://jakarta.apache.org/commons/logging/">Jakarta
* Commons Logging</a> instance used for all logging. */
private static final Log LOG = LogFactory.getLog(HighLowKeyGenerator.class);
/** String constant for table. */
private static final String SEQ_TABLE = "table";
/** String constant for key-column. */
private static final String SEQ_KEY = "key-column";
/** String constant for value-column. */
private static final String SEQ_VALUE = "value-column";
/** String constant for grab-size. */
private static final String GRAB_SIZE = "grab-size";
/** String constant for same-connection. */
private static final String SAME_CONNECTION = "same-connection";
/** String constant for global. */
private static final String GLOBAL = "global";
/** Int constant. */
private static final int UPDATE_PARAM_MAX = 1;
/** Int constant. */
private static final int UPDATE_PARAM_TABLE = 2;
/** Int constant. */
private static final int UPDATE_PARAM_LAST = 3;
/** Int constant. */
private static final int INSERT_PARAM_TABLE = 1;
/** Int constant. */
private static final int INSERT_PARAM_MAX = 2;
/** Int constant. */
private static final int LOCK_TRIALS = 7;
/** Map to store value handler. */
private final Map<String, HighLowValueHandler<? extends Object>> _handlers =
new HashMap<String, HighLowValueHandler<? extends Object>>();
/** Persistence factory for the database engine the entity is persisted in.
* Used to format the SQL statement. */
private final PersistenceFactory _factory;
/** Databse engine type. */
private final int _sqlType;
/** Sequence table name. */
private String _seqTable;
/** Sequence table key column name. */
private String _seqKey;
/** Sequence table value column name. */
private String _seqValue;
/** Grab size. */
private int _grabSize;
/** Shell the same connection be used?
* <br/>
* Note: This is less efficient, but in EJB envirinment we have no choice for now. */
private boolean _sameConnection;
/** Shell globally unique identities be generated? */
private boolean _global;
//-----------------------------------------------------------------------------------
/**
* Initialize the HIGH-LOW key generator.
*
* @param factory A PersistenceFactory instance.
* @param params Database engine specific parameters.
* @param sqlType A SQLTypidentifier.
* @throws MappingException if this key generator is not compatible with the
* persistance factory.
*/
public HighLowKeyGenerator(final PersistenceFactory factory, final Properties params,
final int sqlType) throws MappingException {
super(factory);
_factory = factory;
_sqlType = sqlType;
if ((sqlType != Types.INTEGER) && (sqlType != Types.BIGINT)
&& (sqlType != Types.NUMERIC) && (sqlType != Types.DECIMAL)) {
String msg = Messages.format("mapping.keyGenSQLType",
getClass().getName(), new Integer(sqlType));
throw new MappingException(msg);
}
initFromParameters(params);
}
/** Method to init some class variables.
*
* @param params Database engine specific parameters.
* @throws MappingException if this key generator is not compatible with the
* persistance factory.
*/
public void initFromParameters(final Properties params) throws MappingException {
_seqTable = params.getProperty(SEQ_TABLE);
if (_seqTable == null) {
throw new MappingException(Messages.format(
"mapping.KeyGenParamNotSet", SEQ_TABLE, getClass().getName()));
}
_seqKey = params.getProperty(SEQ_KEY);
if (_seqKey == null) {
throw new MappingException(Messages.format(
"mapping.KeyGenParamNotSet", SEQ_KEY, getClass().getName()));
}
_seqValue = params.getProperty(SEQ_VALUE);
if (_seqValue == null) {
throw new MappingException(Messages.format(
"mapping.KeyGenParamNotSet", SEQ_VALUE, getClass().getName()));
}
String grabSize = params.getProperty(GRAB_SIZE, "10");
try {
_grabSize = Integer.parseInt(grabSize);
} catch (NumberFormatException except) {
_grabSize = 0;
}
if (_grabSize <= 0) {
throw new MappingException(Messages.format(
"mapping.wrongKeyGenParam", grabSize, GRAB_SIZE, getClass().getName()));
}
_sameConnection = "true".equals(params.getProperty(SAME_CONNECTION));
_global = "true".equals(params.getProperty(GLOBAL));
}
//-----------------------------------------------------------------------------------
/**
* {@inheritDoc}
*/
public synchronized Object generateKey(final Connection conn, final String tableName,
final String primKeyName) throws PersistenceException {
String intTableName = tableName;
if (_global) { intTableName = "<GLOBAL>"; }
HighLowValueHandler<? extends Object> handler = _handlers.get(intTableName);
if (handler == null) {
if (_sqlType == Types.INTEGER) {
KeyGeneratorTypeHandlerInteger typeHandler =
new KeyGeneratorTypeHandlerInteger(false);
handler = new HighLowValueHandler<Integer>(intTableName, _grabSize, typeHandler);
} else if (_sqlType == Types.BIGINT) {
KeyGeneratorTypeHandlerLong typeHandler =
new KeyGeneratorTypeHandlerLong(false);
handler = new HighLowValueHandler<Long>(intTableName, _grabSize, typeHandler);
} else {
KeyGeneratorTypeHandlerBigDecimal typeHandler =
new KeyGeneratorTypeHandlerBigDecimal(false);
handler = new HighLowValueHandler<BigDecimal>(intTableName, _grabSize, typeHandler);
}
_handlers.put(intTableName, handler);
}
if (!handler.hasNext()) {
// Create "SELECT seq_val FROM seq_table WHERE seq_key='table'"
// with database-dependent keyword for lock
// Note: Some databases (InstantDB, HypersonicSQL) don't support such locks.
QueryExpression query = _factory.getQueryExpression();
query.addColumn(_seqTable, _seqValue);
query.addCondition(_seqTable, _seqKey, QueryExpression.OP_EQUALS, JDBCSyntax.PARAMETER);
String lockSQL = query.getStatement(true);
// For the case that "SELECT FOR UPDATE" is not supported, perform dirty checking
String updateSQL = "UPDATE " + _seqTable
+ " SET " + _seqValue + "=" + JDBCSyntax.PARAMETER
+ JDBCSyntax.WHERE + _seqKey + QueryExpression.OP_EQUALS + JDBCSyntax.PARAMETER
+ JDBCSyntax.AND + _seqValue + QueryExpression.OP_EQUALS + JDBCSyntax.PARAMETER;
String maxSQL = JDBCSyntax.SELECT + "MAX(" + primKeyName + ") "
+ "FROM " + intTableName;
String insertSQL = "INSERT INTO " + _seqTable
+ " (" + _seqKey + "," + _seqValue + ") VALUES (?, ?)";
PreparedStatement stmt = null;
try {
// Separate connection should be committed/rolled back at this point
if (!_sameConnection) { conn.rollback(); }
// Retry 7 times (lucky number)
boolean success = false;
for (int i = 0; !success && (i < LOCK_TRIALS); i++) {
stmt = conn.prepareStatement(lockSQL);
handler.bindTable(stmt, 1);
ResultSet rs = stmt.executeQuery();
handler.init(rs);
boolean found = rs.isFirst();
stmt.close();
if (found) {
stmt = conn.prepareStatement(updateSQL);
handler.bindMax(stmt, UPDATE_PARAM_MAX);
handler.bindTable(stmt, UPDATE_PARAM_TABLE);
handler.bindLast(stmt, UPDATE_PARAM_LAST);
success = (stmt.executeUpdate() == 1);
stmt.close();
} else {
if (!_global) {
stmt = conn.prepareStatement(maxSQL);
rs = stmt.executeQuery();
handler.init(rs);
stmt.close();
}
stmt = conn.prepareStatement(insertSQL);
handler.bindTable(stmt, INSERT_PARAM_TABLE);
handler.bindMax(stmt, INSERT_PARAM_MAX);
success = (stmt.executeUpdate() == 1);
stmt.close();
}
}
if (success) {
if (!_sameConnection) { conn.commit(); }
} else {
if (!_sameConnection) { conn.rollback(); }
throw new PersistenceException(Messages.format(
"persist.keyGenFailed", getClass().getName()));
}
} catch (SQLException ex) {
try {
if (!_sameConnection) { conn.rollback(); }
} catch (SQLException ex2) {
LOG.warn ("Problem rolling back JDBC transaction.", ex2);
}
throw new PersistenceException(Messages.format(
"persist.keyGenSQL", getClass().getName(), ex.toString()), ex);
} finally {
try {
if (stmt != null) { stmt.close(); }
} catch (SQLException ex) {
LOG.warn (Messages.message("persist.stClosingFailed"), ex);
}
}
}
return handler.next();
}
/**
* {@inheritDoc}
*/
public boolean isInSameConnection() {
return _sameConnection;
}
//-----------------------------------------------------------------------------------
}