/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* 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 distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.id.uuid;
import java.util.UUID;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.UUIDGenerationStrategy;
import org.hibernate.internal.util.BytesHelper;
/**
* Applies a version 1 (time-based) generation strategy (using ip address rather than mac address) but applies them in a
* different layout. The strategy is very similar to the legacy {@link org.hibernate.id.UUIDHexGenerator} id generator
* but uses a RFC 4122 compliant layout (variant 2).
* <p/>
* NOTE : Can be a bottle neck due to the need to synchronize in order to increment an
* internal count as part of the algorithm.
*
* @author Steve Ebersole
*/
public class CustomVersionOneStrategy implements UUIDGenerationStrategy {
public int getGeneratedVersion() {
return 1;
}
private final long mostSignificantBits;
public CustomVersionOneStrategy() {
// generate the "most significant bits" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
byte[] hiBits = new byte[8];
// use address as first 32 bits (8 * 4 bytes)
System.arraycopy( Helper.getAddressBytes(), 0, hiBits, 0, 4 );
// use the "jvm identifier" as the next 32 bits
System.arraycopy( Helper.getJvmIdentifierBytes(), 0, hiBits, 4, 4 );
// set the version (rfc term) appropriately
hiBits[6] &= 0x0f;
hiBits[6] |= 0x10;
mostSignificantBits = BytesHelper.asLong( hiBits );
}
public UUID generateUUID(SessionImplementor session) {
long leastSignificantBits = generateLeastSignificantBits( System.currentTimeMillis() );
return new UUID( mostSignificantBits, leastSignificantBits );
}
public long getMostSignificantBits() {
return mostSignificantBits;
}
public static long generateLeastSignificantBits(long seed) {
byte[] loBits = new byte[8];
short hiTime = (short) ( seed >>> 32 );
int loTime = (int) seed;
System.arraycopy( BytesHelper.fromShort( hiTime ), 0, loBits, 0, 2 );
System.arraycopy( BytesHelper.fromInt( loTime ), 0, loBits, 2, 4 );
System.arraycopy( Helper.getCountBytes(), 0, loBits, 6, 2 );
loBits[0] &= 0x3f;
loBits[0] |= ((byte)2 << (byte)6);
return BytesHelper.asLong( loBits );
}
public static void main(String[] args) {
CustomVersionOneStrategy strategy = new CustomVersionOneStrategy();
for ( int i = 0; i < 1000; i++ ) {
System.out.println( "Generation # " + i + " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
byte[] loBits = new byte[8];
long sysTime = System.currentTimeMillis();
short hiTime = (short) ( System.currentTimeMillis() >>> 32 );
int loTime = (int) sysTime;
System.arraycopy( BytesHelper.fromShort( hiTime ), 0, loBits, 0, 2 );
System.arraycopy( BytesHelper.fromInt( loTime ), 0, loBits, 2, 4 );
System.arraycopy( Helper.getCountBytes(), 0, loBits, 6, 2 );
System.out.println( " before bit setting ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
System.out.println( " loBits[0] : " + BytesHelper.toBinaryString( loBits[0] ) );
System.out.println( " lsb : " + BytesHelper.toBinaryString( BytesHelper.asLong( loBits ) ) );
System.out.println( " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
loBits[0] &= 0x3f;
loBits[0] |= ((byte)2 << (byte)6);
System.out.println( " after bit setting ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
System.out.println( " loBits[0] : " + BytesHelper.toBinaryString( loBits[0] ) );
long leastSignificantBits = BytesHelper.asLong( loBits );
System.out.println( " lsb : " + BytesHelper.toBinaryString( leastSignificantBits ) );
System.out.println( " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
UUID uuid = new UUID( strategy.mostSignificantBits, leastSignificantBits );
System.out.println( " uuid : " + uuid.toString() );
System.out.println( " variant : " + uuid.variant() );
System.out.println( " version : " + uuid.version() );
if ( uuid.variant() != 2 ) {
throw new RuntimeException( "bad variant" );
}
System.out.println( "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" );
}
}
}