games.stendhal.server.core.engine.db.StendhalSearchIndexDAO.java Source code

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Here is the source code for games.stendhal.server.core.engine.db.StendhalSearchIndexDAO.java

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/***************************************************************************
 *                    (C) Copyright 2014 - Faiumoni e. V.                  *
 ***************************************************************************
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
package games.stendhal.server.core.engine.db;

import games.stendhal.server.core.rp.searchindex.SearchIndexEntry;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Set;

import marauroa.server.db.DBTransaction;

import com.google.common.collect.Sets;

/**
 * database base access for the searchindex used on the website
 *
 * @author hendrik
 */
public class StendhalSearchIndexDAO {

    /**
     * reads existing search index entries from the database
     *
     * @param transaction DBTransaction
     * @return set of existing search index entries
     * @throws SQLException in case a database error is thrown.
     */
    private Set<SearchIndexEntry> readExistingEntries(DBTransaction transaction) throws SQLException {
        Set<SearchIndexEntry> res = Sets.newHashSet();
        String query = "SELECT id, searchterm, entitytype, entityname, searchscore FROM searchindex";
        ResultSet resultSet = transaction.query(query, null);
        while (resultSet.next()) {
            res.add(new SearchIndexEntry(resultSet.getString(2), resultSet.getString(3).charAt(0),
                    resultSet.getString(4), resultSet.getInt(5), resultSet.getInt(1)));
        }
        return res;
    }

    /**
     * writes an entry to the search index table
     *
     * @param stmt PreparedStatement in batch mode
     * @param entry SearchEntry
     * @throws SQLException in case a database error is thrown.
     */
    private void writeEntry(PreparedStatement stmt, SearchIndexEntry entry) throws SQLException {
        stmt.setString(1, entry.getSearchTerm());
        stmt.setString(2, String.valueOf(entry.getEntityType()));
        stmt.setString(3, entry.getEntityName());
        stmt.setInt(4, entry.getSearchScore());
        stmt.addBatch();
    }

    /**
     * deletes obsolte entries
     *
     * @param transaction DBTransactions
     * @param toDelete entries to delete
     * @throws SQLException
     */
    private void deleteObsoleteEntries(DBTransaction transaction, Set<SearchIndexEntry> toDelete)
            throws SQLException {
        StringBuilder sql = new StringBuilder();
        sql.append("DELETE FROM searchindex WHERE id IN (");
        boolean first = true;
        for (SearchIndexEntry entry : toDelete) {
            if (first) {
                first = false;
            } else {
                sql.append(",");
            }
            sql.append(String.valueOf(entry.getDbId()));
        }
        sql.append(")");

        // if there is at least one entry to delete
        if (!first) {
            transaction.execute(sql.toString(), null);
        }
    }

    /**
     * insert new entries
     *
     * @param transaction DBTransactions
     * @param toAdd entries to add
     * @throws SQLException
     */
    private void addNewEntries(DBTransaction transaction, Set<SearchIndexEntry> toAdd) throws SQLException {
        PreparedStatement stmt = transaction.prepareStatement("INSERT INTO searchindex"
                + " (searchterm, entitytype, entityname, searchscore)" + " VALUES (?, ?, ?, ?)", null);
        for (SearchIndexEntry entry : toAdd) {
            writeEntry(stmt, entry);
        }
        stmt.executeBatch();
    }

    /**
     * dumps the search index
     *
     * @param transaction DBTransaction
     * @param entries required entries
     * @throws SQLException in case of an database error
     */
    public void updateSearchIndex(DBTransaction transaction, Set<SearchIndexEntry> entries) throws SQLException {
        Set<SearchIndexEntry> oldEntries = readExistingEntries(transaction);

        Set<SearchIndexEntry> toDelete = Sets.difference(oldEntries, entries);
        Set<SearchIndexEntry> toAdd = Sets.difference(entries, oldEntries);

        deleteObsoleteEntries(transaction, toDelete);
        addNewEntries(transaction, toAdd);
    }

}