001    /**
002     * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
003     *
004     * This library is free software; you can redistribute it and/or modify it under
005     * the terms of the GNU Lesser General Public License as published by the Free
006     * Software Foundation; either version 2.1 of the License, or (at your option)
007     * any later version.
008     *
009     * This library is distributed in the hope that it will be useful, but WITHOUT
010     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
011     * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
012     * details.
013     */
014    
015    package com.liferay.portal.kernel.dao.db;
016    
017    import com.liferay.portal.kernel.util.StringPool;
018    import com.liferay.portal.kernel.util.StringUtil;
019    
020    import java.util.concurrent.ConcurrentHashMap;
021    import java.util.concurrent.ConcurrentMap;
022    
023    /**
024     * @author Shuyang Zhou
025     */
026    public abstract class BaseDBFactory implements DBFactory {
027    
028            @Override
029            public DB create(int dbMajorVersion, int dbMinorVersion) {
030                    String majorVersion = StringUtil.toHexString(dbMajorVersion);
031                    String minorVersion = StringUtil.toHexString(dbMinorVersion);
032    
033                    String version = majorVersion.concat(StringPool.POUND).concat(
034                            minorVersion);
035    
036                    DB db = _dbs.get(version);
037    
038                    if (db == null) {
039                            db = doCreate(dbMajorVersion, dbMinorVersion);
040    
041                            DB previousDB = _dbs.putIfAbsent(version, db);
042    
043                            if (previousDB != null) {
044                                    db = previousDB;
045                            }
046                    }
047    
048                    return db;
049            }
050    
051            protected abstract DB doCreate(int dbMajorVersion, int dbMinorVersion);
052    
053            private final ConcurrentMap<String, DB> _dbs = new ConcurrentHashMap<>();
054    
055    }