/*
* Copyright (c) 2001-2007 Sun Microsystems, Inc. All rights reserved.
*
* The Sun Project JXTA(TM) Software License
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The end-user documentation included with the redistribution, if any, must
* include the following acknowledgment: "This product includes software
* developed by Sun Microsystems, Inc. for JXTA(TM) technology."
* Alternately, this acknowledgment may appear in the software itself, if
* and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
* not be used to endorse or promote products derived from this software
* without prior written permission. For written permission, please contact
* Project JXTA at http://www.jxta.org.
*
* 5. Products derived from this software may not be called "JXTA", nor may
* "JXTA" appear in their name, without prior written permission of Sun.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SUN
* MICROSYSTEMS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JXTA is a registered trademark of Sun Microsystems, Inc. in the United
* States and other countries.
*
* Please see the license information page at :
* <http://www.jxta.org/project/www/license.html> for instructions on use of
* the license in source files.
*
* ====================================================================
*
* This software consists of voluntary contributions made by many individuals
* on behalf of Project JXTA. For more information on Project JXTA, please see
* http://www.jxta.org.
*
* This license is based on the BSD license adopted by the Apache Foundation.
*/
package net.jxta.util;
import java.security.SecureRandom;
import java.util.UUID;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
/**
* Utility methods to augment the capabilities of the java.util.UUID class
* as provided in the JDK.
*/
public final class UUIDUtilities {
/**
* The point at which the Gregorian calendar rules are used, measured in
* milliseconds from the standard epoch. Default is October 15, 1582
* (Gregorian) 00:00:00 UTC or -12219292800000L.
*/
private static final long GREGORIAN_MILLIS_OFFSET = 12219292800000L;
/**
* offset of this computer relative to utc
*/
private static long utc_offset = 0L;
/**
* Time at which we last generated a version 1 UUID in relative
* milliseconds from 00:00:00.00, 15 October 1582 UTC.
*/
private static long lastTimeSequence = 0L;
/**
* Count of how many version 1 UUIDs we have generated at this time
* sequence value.
*/
private static long inSequenceCounter = 0L;
/**
* pseudo random value to prevent clock collisions on the same computer.
*/
private static long clock_seq = 0L;
/**
* pseudo random value. If available, this should be seeded with the MAC
* address of a local network interface.
*/
private static long node = 0L;
/**
* Static initializer.
*/
static {
SecureRandom randNum = new SecureRandom();
TimeZone timeZone = TimeZone.getDefault();
Calendar gregorianCalendar = new GregorianCalendar(timeZone);
// FIXME 20031024 bondolo@jxta.org In theory we should be doing this
// EVERY time we generate a UUID. In practice because of we use a random
// clock_seq we don't have to.
utc_offset = gregorianCalendar.get(Calendar.ZONE_OFFSET)
+ gregorianCalendar.get(Calendar.DST_OFFSET);
// Generate a random clock seq
clock_seq = randNum.nextInt() & 0x03FFL;
// Generate a random node ID since we can't get the MAC Address
node = (randNum.nextLong() & 0x0000FFFFFFFFFFFFL);
// mask in the multicast bit since we don't know if its unique.
node |= 0x0000800000000000L;
}
/**
* Prevent construction.
*/
private UUIDUtilities() {
// Empty
}
/**
* Generate a new UUID value. The UUID returned is a version 1 IETF
* variant UUID.
*
* <p/>The node value used is currently a random value rather than the
* normal ethernet MAC address because the MAC address is not directly
* accessible from within java.
*
* @return UUID returns a version 1 IETF variant UUID.
*/
public static UUID newSeqUUID() {
long mostSig = 0L, leastSig = 0L;
long timeSeq = getTimeSequence();
mostSig |= (timeSeq & 0x0FFFFFFFFL) << 32;
mostSig |= ((timeSeq >> 32) & 0x0FFFFL) << 16;
mostSig |= (0x01L) << 12; // version 1;
mostSig |= ((timeSeq >> 48) & 0x00FFFL);
leastSig |= (0x02L) << 62; // ietf variant
leastSig |= ((clock_seq >> 8) & 0x03FL) << 56;
leastSig |= (clock_seq & 0x0FFL) << 48;
leastSig |= node & 0x0FFFFFFFFFFFFL;
return new UUID(mostSig, leastSig);
}
/**
* Returns a formatted time sequence field containing the elapsed time in
* 100 nano units since 00:00:00.00, 15 October 1582. Since the normal
* clock resolution is coarser than 100 nano than this value, the lower
* bits are generated in sequence for each call within the same milli.
*
* @return time sequence value
*/
private static synchronized long getTimeSequence() {
// convert to 100 nano units;
long now = (System.currentTimeMillis()
- GREGORIAN_MILLIS_OFFSET + utc_offset) * 10000L;
if (now > lastTimeSequence) {
lastTimeSequence = now;
// XXX bondolo@jxta.org It might be better to set this to a random
// value and just watch for rollover. The reason is that there may
// be more than one instance running on the same computer which is
// generating UUIDs, but is not excluded by our synchronization.
// A random value would reduce collisions.
inSequenceCounter = 0;
} else {
inSequenceCounter++;
if (inSequenceCounter >= 10000L) {
// we allow the clock to skew forward rather than wait. It's
// really unlikely that anyone will be continuously generating
// more than 10k UUIDs per milli for very long.
lastTimeSequence += 10000L;
inSequenceCounter = 0;
}
}
return (lastTimeSequence + inSequenceCounter);
}
}