/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-07 The eXist Project
* http://exist-db.org
*
* This program 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
* of the License, or (at your option) any later version.
*
* This program 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 program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* $Id$
*/
package org.exist.indexing.ngram;
import org.apache.log4j.Logger;
import org.exist.backup.RawDataBackup;
import org.exist.indexing.AbstractIndex;
import org.exist.indexing.IndexWorker;
import org.exist.indexing.RawBackupSupport;
import org.exist.storage.BrokerPool;
import org.exist.storage.DBBroker;
import org.exist.storage.btree.BTree;
import org.exist.storage.btree.DBException;
import org.exist.storage.index.BFile;
import org.exist.util.DatabaseConfigurationException;
import org.w3c.dom.Element;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
/**
*/
public class NGramIndex extends AbstractIndex implements RawBackupSupport {
public final static String ID = NGramIndex.class.getName();
private final static Logger LOG = Logger.getLogger(NGramIndex.class);
protected BFile db;
private int gramSize = 3;
private File dataFile = null;
public NGramIndex() {
//Nothing to do
}
@Override
public void configure(BrokerPool pool, String dataDir, Element config) throws DatabaseConfigurationException {
super.configure(pool, dataDir, config);
String fileName = "ngram.dbx";
if (config.hasAttribute("file"))
fileName = config.getAttribute("file");
if (config.hasAttribute("n"))
try {
gramSize = Integer.parseInt(config.getAttribute("n"));
} catch (NumberFormatException e) {
throw new DatabaseConfigurationException("Configuration parameter 'n' should be an integer.");
}
dataFile = new File(dataDir, fileName);
}
@Override
public void open() throws DatabaseConfigurationException {
try {
db = new BFile(pool, (byte) 0, false, dataFile, pool.getCacheManager(), 1.4, 0.01, 0.07);
} catch (DBException e) {
throw new DatabaseConfigurationException("Failed to create index file: " + dataFile.getAbsolutePath() + ": " +
e.getMessage());
}
if (LOG.isDebugEnabled())
LOG.debug("Created NGram index: " + dataFile.getAbsolutePath());
}
@Override
public void close() throws DBException {
LOG.debug("SYNC NGRAM");
db.close();
}
@Override
public void sync() throws DBException {
LOG.debug("SYNC NGRAM");
db.flush();
}
@Override
public void remove() throws DBException {
db.closeAndRemove();
}
@Override
public boolean checkIndex(DBBroker broker) {
return true;
}
@Override
public IndexWorker getWorker(DBBroker broker) {
//TODO : ensure singleton ? a pool ?
return new NGramIndexWorker(broker, this);
}
public int getN() {
return gramSize;
}
public BTree getStorage() {
return db;
}
public void backupToArchive(RawDataBackup backup) throws IOException {
OutputStream os = backup.newEntry(db.getFile().getName());
db.backupToStream(os);
backup.closeEntry();
}
}