/*
* ====================================================================
* Copyright (c) 2004-2009 TMate Software Ltd. All rights reserved.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://svnkit.com/license.html
* If newer versions of this license are posted there, you may use a
* newer version instead, at your option.
* ====================================================================
*/
package org.tmatesoft.svn.core.internal.util;
import java.rmi.server.UID;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.MessageFormat;
import java.util.Arrays;
import java.util.Random;
import org.tmatesoft.svn.core.SVNErrorCode;
import org.tmatesoft.svn.core.SVNErrorMessage;
import org.tmatesoft.svn.core.SVNException;
import org.tmatesoft.svn.core.internal.wc.SVNErrorManager;
import org.tmatesoft.svn.util.SVNLogType;
/**
* @version 1.3
* @author TMate Software Ltd.
*/
public class SVNUUIDGenerator {
private static final int NODE_LENGTH = 6;
private static byte[] ourUUIDStateNode = new byte[NODE_LENGTH];
private static long ourUUIDStateSeqNum;
private static long ourLastGeneratedTime;
private static long ourFudgeFactor;
/*
* We must be sure we don't use the same time values for generating 'random'
* UUIDs
*/
private static long getCurrentTime() {
long currentTime = System.currentTimeMillis();
/* if clock reading changed since last UUID generated... */
if (ourLastGeneratedTime != currentTime) {
/*
* The clock reading has changed since the last UUID was generated.
* Reset the fudge factor. if we are generating them too fast, then
* the fudge may need to be reset to something greater than zero.
*/
if (ourLastGeneratedTime + ourFudgeFactor > currentTime) {
ourFudgeFactor = ourLastGeneratedTime + ourFudgeFactor - currentTime + 1;
} else {
ourFudgeFactor = 0;
}
ourLastGeneratedTime = currentTime;
} else {
/* We generated two really fast. Bump the fudge factor. */
++ourFudgeFactor;
}
return currentTime + ourFudgeFactor;
}
public static String generateUUIDString() throws SVNException {
return formatUUID(generateUUID());
}
public static synchronized byte[] generateUUID() throws SVNException {
if (ourUUIDStateNode[0] == 0) {
initState();
}
long timestamp = getCurrentTime();
byte[] uuidData = new byte[16];
uuidData[0] = (byte) timestamp;
uuidData[1] = (byte) (timestamp >> 8);
uuidData[2] = (byte) (timestamp >> 16);
uuidData[3] = (byte) (timestamp >> 24);
uuidData[4] = (byte) (timestamp >> 32);
uuidData[5] = (byte) (timestamp >> 40);
uuidData[6] = (byte) (timestamp >> 48);
uuidData[7] = (byte) (((timestamp >> 56) & 0x0F) | 0x10);
uuidData[8] = (byte) (((ourUUIDStateSeqNum >> 8) & 0x3F) | 0x80);
uuidData[9] = (byte) ourUUIDStateSeqNum;
System.arraycopy(ourUUIDStateNode, 0, uuidData, 10, NODE_LENGTH);
return uuidData;
}
public static String formatUUID(byte[] uuid) {
if (uuid.length < 16) {
byte[] tmpBuf = new byte[16];
Arrays.fill(tmpBuf, (byte) 0);
System.arraycopy(uuid, 0, tmpBuf, 0, uuid.length);
uuid = tmpBuf;
}
String[] hexNumbers = new String[16];
for (int i = 0; i < 16; i++) {
hexNumbers[i] = SVNFormatUtil.getHexNumberFromByte(uuid[i]);
}
String formatString = "{0}{1}{2}{3}-{4}{5}-{6}{7}-{8}{9}-{10}{11}{12}{13}{14}{15}";
Object args = hexNumbers;
return MessageFormat.format(formatString, (Object[]) args);
}
private static void initState() throws SVNException {
/*
* Offset between UUID formatted times and System.currentTimeMillis()
* formatted times. UUID UTC base time is October 15, 1582.
* System.currentTimeMillis() base time is January 1, 1970.
*/
long currentTime = System.currentTimeMillis() * 10 + 0x01B21DD213814000L;
Random randomGen = new Random();
randomGen.setSeed(((currentTime >> 32) ^ currentTime) & 0xffffffffL);
ourUUIDStateSeqNum = randomGen.nextLong() & 0x0FFFFL;
getRandomInfo(ourUUIDStateNode);
}
private static void getRandomInfo(byte[] node) throws SVNException {
UID uid = new UID();
MessageDigest digest = null;
try {
digest = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
SVNErrorMessage err = SVNErrorMessage.create(SVNErrorCode.IO_ERROR, "MD5 implementation not found: {0}", e.getLocalizedMessage());
SVNErrorManager.error(err, e, SVNLogType.DEFAULT);
}
digest.update(uid.toString().getBytes());
byte[] seed = digest.digest();
int numToCopy = node.length < seed.length ? node.length : seed.length;
System.arraycopy(seed, 0, node, 0, numToCopy);
node[0] |= 0x01;
}
}