/*
* Copyright (C) 2006 http://www.chaidb.org
*
* 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.
*
* 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 General Public License for more details.
*
*/
package org.chaidb.db.helper;
import org.apache.log4j.Logger;
import org.apache.xerces.parsers.DOMParser;
import org.chaidb.db.exception.ChaiDBException;
import org.chaidb.db.exception.ErrorCode;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import java.io.*;
import java.util.Random;
/**
* This class is used for Backup/Archive/Restore/DataRep. It implements most
* common function like backupFile, lockDir, and synchronization.
*/
public class SafeUpdateUtils {
private static final String DEFAULT_TEMP_EXT = "ibk";
public static final Object bmObj = new Object();
private boolean restoreBackuped = false;
private String tempFileExt = DEFAULT_TEMP_EXT;
private String[] nameList = new String[0];
private static final Logger logger = Logger.getLogger(SafeUpdateUtils.class);
public void backupFiles(String[] nameList, String tmpExt) throws IOException {
tempFileExt = tmpExt;
backupFiles(nameList);
}
private void backupFiles(String[] nameList) throws IOException {
if (nameList == null) {
return;
}
restoreBackuped = false;
this.nameList = new String[nameList.length];
System.arraycopy(nameList, 0, this.nameList, 0, nameList.length);
try {
for (int i = 0; i < nameList.length; i++) {
FileUtil.backupFile(nameList[i], tempFileExt);
}
} catch (IOException e) {
this.nameList = new String[0];
throw e;
}
restoreBackuped = true;
}
public void restoreFiles() {
if (nameList == null) {
return;
}
if (!restoreBackuped) {
return;
}
for (int i = 0; i < nameList.length; i++) {
try {
FileUtil.restoreFile(nameList[i], tempFileExt);
} catch (IOException e) {
logger.error(e);
System.err.println(e.getMessage());
}
}
restoreBackuped = false;
}
public void clearFiles() {
if (nameList == null) {
return;
}
if (!restoreBackuped) {
return;
}
for (int i = 0; i < nameList.length; i++) {
FileUtil.clearBackupFile(nameList[i], tempFileExt);
}
nameList = new String[0];
restoreBackuped = false;
}
static Document parse(InputSource input) throws IOException, org.xml.sax.SAXException {
DOMParser parser = new DOMParser();
parser.parse(input);
return parser.getDocument();
}
public static synchronized void writeToDisk(Object obj, String filename, boolean writeToTempFile) throws IOException {
String diskfile = filename;
if (writeToTempFile) {
diskfile = filename + ".tmp";
}
FileOutputStream fo = null;
try {
fo = new FileOutputStream(diskfile);
fo.write(getUTFBytes(obj.toString()));
fo.flush();
} catch (UnsupportedEncodingException e) {
logger.error(e);
} finally {
if (fo != null) {
fo.close();
}
}
}
public static synchronized void commitWrite(String filename) throws ChaiDBException {
String tmpFilename = filename + "." + DEFAULT_TEMP_EXT;
File tmpFile = new File(tmpFilename);
File orgFile = new File(filename);
if (orgFile.exists()) {
orgFile.delete();
}
if (!tmpFile.renameTo(orgFile)) {
throw new ChaiDBException(ErrorCode.BACKUP_FILE_COPY_ERROR, "Can't rename a temp file. The File is " + tmpFilename + ". You should rename it to " + filename + " manually.");
}
}
public static synchronized void rollbackWrite(String filename) {
String tmpFilename = filename + "." + DEFAULT_TEMP_EXT;
File tmpFile = new File(tmpFilename);
tmpFile.delete();
}
public static synchronized long genGUID() {
Random rnd = new Random();
return rnd.nextLong();
}
/**
* lock a directory such as archive dir
*
* @param path - the dir which need lock
* @param share
* @return lock Object of lock, need for release, null if can't get lock
*/
public static DirLock lockDir(String path, boolean share) {
if (!path.endsWith(File.separator)) {
path += File.separator;
}
File file = new File(path);
if (!file.exists() || !file.isDirectory()) {
return null;
}
synchronized (path) {
while (true) {
RandomAccessFile lockfile = null;
try {
/* If share is true, it called by read-only process
* if share is false, it called by main process, we
* should create the file if it does not exist in
* main process.
*/
String mode = "rw";
if (share) {
mode = "r";
}
lockfile = new RandomAccessFile(path + DirLock.LOCK_FILE, mode);
//lockfile.getChannel().lock(0L, Long.MAX_VALUE, true);
if (lockfile.getChannel().tryLock(0L, Long.MAX_VALUE, share) != null) {
return new DirLock(lockfile, path);
} else {
lockfile.close();
}
} catch (IOException e) {
if (lockfile != null) {
try {
lockfile.close();
} catch (IOException e1) {
e1.printStackTrace();
}
lockfile = null;
}
return null;
}
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
return null;
}
}
}
}
private static byte[] getUTFBytes(String s) throws UnsupportedEncodingException {
return s.getBytes("UTF-8");
}
public static class DirLock {
public static final String LOCK_FILE = "~lockfile";
String path;
RandomAccessFile lock;
public DirLock(RandomAccessFile lock, String path) {
this.lock = lock;
this.path = path;
}
public void release() {
try {
lock.close();
// new File(path + LOCK_FILE).delete();
} catch (IOException e) {
;
}
}
}
}