LuceneBackupThread.java

/*
 * This file is part of DrFTPD, Distributed FTP Daemon.
 *
 * DrFTPD 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.
 *
 * DrFTPD 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with DrFTPD; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.drftpd.vfs.index.lucene;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;

import org.apache.log4j.Logger;
import org.apache.lucene.store.FSDirectory;
import org.drftpd.GlobalContext;
import org.drftpd.io.PhysicalFile;

/**
 * Thread that performs backup operations on the index.
 * @author fr0w
 * @version $Id$
 */
public class LuceneBackupThread  extends Thread {
	private static final Logger logger = Logger.getLogger(LuceneBackupThread.class);
	
	private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd-HHmmss");
	private static final String BACKUP_DIRNAME = "index.bkp";
	private static final File BACKUP_HOME = new File(BACKUP_DIRNAME);

	private boolean _stop;
	private boolean _isRunning;
	
	protected int _maxNumberBackup;
	private int _backupInterval;
	private long _lastBackup;
	
	private LuceneEngine _engine;

	protected LuceneBackupThread() {
		setName("LuceneBackupThread");
		_engine = (LuceneEngine) GlobalContext.getGlobalContext().getIndexEngine();
	}

	public void run() {
		String[] backups;
		int x;

		while (true) {
			if (_stop) {
				break;
			}

			// store a limited amount of backups.
			// the code bellow remove older backups.
			backups = BACKUP_HOME.list();
			
			if (backups != null) {
				Arrays.sort(backups, String.CASE_INSENSITIVE_ORDER);
				for (x = 0; x < backups.length; x++) {
					if (BACKUP_HOME.list().length < _maxNumberBackup) {
						break;
					}
					new PhysicalFile(BACKUP_DIRNAME + "/" + backups[x]).deleteRecursive();
				}
			}

			// locking the writer object so that noone can use it.
			// this might be useful.
			synchronized (_engine.getWriter()) {
				setRunning(true);

				String dateTxt = sdf.format(new Date(System.currentTimeMillis()));
				File f = new File(BACKUP_DIRNAME + "/" + dateTxt);

				try {
					if (!f.mkdirs()) {
						throw new IOException("Impossible to create backup directory, not enough permissions.");
					}

					// creating the destination directory.
					FSDirectory bkpDirectory = FSDirectory.open(f);

					for (String file : _engine.getStorage().listAll()) {
						_engine.getStorage().copy(bkpDirectory, file, file);
					}
					
					logger.debug("A backup of the index was created successfully.");
					updateLastBackupTime();
				} catch (IOException e) {
					logger.error(e, e);
				}
			}

			try {
				synchronized (this) {
					setRunning(false);
					wait(_backupInterval);
				}
			} catch (InterruptedException e) {
			}
		}
	}
	
	/**
	 * Will force the backup thread to stop.<br>
	 * If there's an operation already running, it will be finished before the thread is stopped.
	 */
	protected void stopBackup() {
		_stop = true;
	}
	
	/**
	 * Set if the thread is currently performing a backup or not.
	 * @param isRunning
	 */
	protected void setRunning(boolean isRunning) {
		_isRunning = isRunning;
	}
	
	/**
	 * @return true if a backup is being performed or false if not.
	 */
	protected boolean isRunning() {
		return _isRunning;
	}
	
	/**
	 * The last backup will be set to System.currentTimeMillis()
	 */
	protected void updateLastBackupTime() {
		_lastBackup = System.currentTimeMillis();
	}
	
	/**
	 * @return the timestamp from the last backup.
	 */
	protected long getLastBackup() {
		return _lastBackup;
	}
	
	/**
	 * Set the backup interval.
	 * @param interval
	 */
	protected void setBackupInterval(int interval) {
		_backupInterval = interval;
	}
	
	/**
	 * Set the max number of backup that are going to be kept.
	 * @param max
	 */
	protected void setMaximumNumberBackup(int max) {
		_maxNumberBackup = max;
	}
}