Rename GCR to ACR.
[lgpl/argeo-commons.git] / org.argeo.util / src / org / argeo / util / UuidUtils.java
index d0537a555c87106e9cc4fc6ee1d307a3920e203a..219aef41cedfc9267ba3935ab190f80bc7a442f0 100644 (file)
@@ -1,36 +1,92 @@
 package org.argeo.util;
 
+import static java.lang.System.Logger.Level.DEBUG;
+
+import java.lang.System.Logger;
 import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
 import java.net.UnknownHostException;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.time.Duration;
 import java.time.LocalDateTime;
 import java.time.ZoneOffset;
 import java.util.BitSet;
+import java.util.Objects;
 import java.util.Random;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * Utilities to simplify and extends usage of {@link UUID}. Only variant 1 is
- * supported. Focus is clarity of implementation rather than optimisation.
+ * Static utilities to simplify and extend usage of {@link UUID}. Only the RFC
+ * 4122 variant (also known as Leach–Salz variant) is supported.
+ * 
+ * @see https://datatracker.ietf.org/doc/html/rfc4122
  */
 public class UuidUtils {
        /** Nil UUID (00000000-0000-0000-0000-000000000000). */
        public final static UUID NIL_UUID = UUID.fromString("00000000-0000-0000-0000-000000000000");
+
+       /** Start of the Gregorian time, used by time-based UUID. */
        public final static LocalDateTime GREGORIAN_START = LocalDateTime.of(1582, 10, 15, 0, 0, 0);
 
-       private final static SecureRandom RANDOM;
-       private final static AtomicInteger CLOCK_SEQUENCE;
+       /**
+        * Standard DNS namespace ID for type 3 or 5 UUID (as defined in Appendix C of
+        * RFC4122).
+        */
+       public final static UUID NS_DNS = UUID.fromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8");
+       /**
+        * Standard URL namespace ID for type 3 or 5 UUID (as defined in Appendix C of
+        * RFC4122).
+        */
+       public final static UUID NS_URL = UUID.fromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8");
+       /**
+        * Standard OID namespace ID (typically an LDAP type) for type 3 or 5 UUID (as
+        * defined in Appendix C of RFC4122).
+        */
+       public final static UUID NS_OID = UUID.fromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8");
+       /**
+        * Standard X500 namespace ID (typically an LDAP DN) for type 3 or 5 UUID (as
+        * defined in Appendix C of RFC4122).
+        */
+       public final static UUID NS_X500 = UUID.fromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8");
+
+       /*
+        * INTERNAL STATIC UTILITIES
+        */
+       private final static Logger logger = System.getLogger(UuidUtils.class.getName());
+
+       private final static long MOST_SIG_VERSION1 = (1l << 12);
+       private final static long LEAST_SIG_RFC4122_VARIANT = (1l << 63);
+       private final static int MAX_CLOCKSEQUENCE = 16384;
+
+       private final static SecureRandom SECURE_RANDOM;
+       private final static Random UNSECURE_RANDOM;
        private final static byte[] HARDWARE_ADDRESS;
+
+       private final static AtomicInteger CLOCK_SEQUENCE;
+
+       /** A start timestamp to which {@link System#nanoTime()}/100 can be added. */
+       private final static long START_TIMESTAMP;
+
        static {
-               RANDOM = new SecureRandom();
-               CLOCK_SEQUENCE = new AtomicInteger(RANDOM.nextInt(16384));
+               SECURE_RANDOM = new SecureRandom();
+               UNSECURE_RANDOM = new Random();
+               CLOCK_SEQUENCE = new AtomicInteger(SECURE_RANDOM.nextInt(MAX_CLOCKSEQUENCE));
                HARDWARE_ADDRESS = getHardwareAddress();
+
+               long nowVm = System.nanoTime() / 100;
+               Duration duration = Duration.between(GREGORIAN_START, LocalDateTime.now(ZoneOffset.UTC));
+               START_TIMESTAMP = (duration.getSeconds() * 10000000 + duration.getNano() / 100) - nowVm;
        }
 
+       /*
+        * TIME-BASED (version 1)
+        */
+
        private static byte[] getHardwareAddress() {
                InetAddress localHost;
                try {
@@ -47,121 +103,322 @@ public class UuidUtils {
 
        }
 
-       public static UUID timeBasedUUID() {
-               return timeBasedUUID(LocalDateTime.now(ZoneOffset.UTC));
+       private synchronized static long nextClockSequence() {
+               int i = CLOCK_SEQUENCE.incrementAndGet();
+               while (i < 0 || i >= MAX_CLOCKSEQUENCE) {
+                       CLOCK_SEQUENCE.set(SECURE_RANDOM.nextInt(MAX_CLOCKSEQUENCE));
+                       i = CLOCK_SEQUENCE.incrementAndGet();
+               }
+               return (long) i;
        }
 
-       public static UUID timeBasedRandomUUID() {
-               return timeBasedRandomUUID(LocalDateTime.now(ZoneOffset.UTC), RANDOM);
+       public static UUID timeUUIDwithRandomNode() {
+               long timestamp = START_TIMESTAMP + System.nanoTime() / 100;
+               return timeUUID(timestamp, SECURE_RANDOM);
        }
 
-       public static UUID timeBasedUUID(LocalDateTime time) {
-               if (HARDWARE_ADDRESS == null)
-                       return timeBasedRandomUUID(time, RANDOM);
-               return timeBasedUUID(time, BitSet.valueOf(HARDWARE_ADDRESS));
+       public static UUID timeUUIDwithUnsecureRandomNode() {
+               long timestamp = START_TIMESTAMP + System.nanoTime() / 100;
+               return timeUUID(timestamp, UNSECURE_RANDOM);
        }
 
-       public static UUID timeBasedAddressUUID(LocalDateTime time, NetworkInterface nic) throws SocketException {
-               byte[] nodeBytes = nic.getHardwareAddress();
-               BitSet node = BitSet.valueOf(nodeBytes);
-               return timeBasedUUID(time, node);
+       public static UUID timeUUID(long timestamp, Random random) {
+               byte[] node = new byte[6];
+               random.nextBytes(node);
+               node[0] = (byte) (node[0] | 1);
+               long clockSequence = nextClockSequence();
+               return timeUUID(timestamp, clockSequence, node);
        }
 
-       public static UUID timeBasedRandomUUID(LocalDateTime time, Random random) {
-               byte[] nodeBytes = new byte[6];
-               random.nextBytes(nodeBytes);
-               BitSet node = BitSet.valueOf(nodeBytes);
-               // set random marker
-               node.set(0, true);
-               return timeBasedUUID(time, node);
+       public static UUID timeUUID() {
+               long timestamp = START_TIMESTAMP + System.nanoTime() / 100;
+               return timeUUID(timestamp);
        }
 
-       public static UUID timeBasedUUID(LocalDateTime time, BitSet node) {
-               // most significant
-               Duration duration = Duration.between(GREGORIAN_START, time);
+       public static UUID timeUUID(long timestamp) {
+               if (HARDWARE_ADDRESS == null)
+                       return timeUUID(timestamp, SECURE_RANDOM);
+               long clockSequence = nextClockSequence();
+               return timeUUID(timestamp, clockSequence, HARDWARE_ADDRESS);
+       }
 
-               // Number of 100 ns intervals in one second: 1000000000 / 100 = 10000000
-               long timeNanos = duration.getSeconds() * 10000000 + duration.getNano() / 100;
-               BitSet timeBits = BitSet.valueOf(new long[] { timeNanos });
-               assert timeBits.length() <= 60;
-
-               int clockSequence;
-               synchronized (CLOCK_SEQUENCE) {
-                       clockSequence = CLOCK_SEQUENCE.incrementAndGet();
-                       if (clockSequence > 16384)
-                               CLOCK_SEQUENCE.set(0);
-               }
-               BitSet clockSequenceBits = BitSet.valueOf(new long[] { clockSequence });
-
-               // Build the UUID, bit by bit
-               // see https://tools.ietf.org/html/rfc4122#section-4.2.2
-               // time
-               BitSet time_low = new BitSet(32);
-               BitSet time_mid = new BitSet(16);
-               BitSet time_hi_and_version = new BitSet(16);
-
-               for (int i = 0; i < 60; i++) {
-                       if (i < 32)
-                               time_low.set(i, timeBits.get(i));
-                       else if (i < 48)
-                               time_mid.set(i - 32, timeBits.get(i));
-                       else
-                               time_hi_and_version.set(i - 48, timeBits.get(i));
-               }
-               // version
-               time_hi_and_version.set(12, true);
-               time_hi_and_version.set(13, false);
-               time_hi_and_version.set(14, false);
-               time_hi_and_version.set(15, false);
-
-               // clock sequence
-               BitSet clk_seq_hi_res = new BitSet(8);
-               BitSet clk_seq_low = new BitSet(8);
-               for (int i = 0; i < 8; i++) {
-                       clk_seq_low.set(i, clockSequenceBits.get(i));
-               }
-               for (int i = 8; i < 14; i++) {
-                       clk_seq_hi_res.set(i - 8, clockSequenceBits.get(i));
-               }
-               // variant
-               clk_seq_hi_res.set(6, false);
-               clk_seq_hi_res.set(7, true);
-
-//             String str = toHexString(time_low.toLongArray()[0]) + "-" + toHexString(time_mid.toLongArray()[0]) + "-"
-//                             + toHexString(time_hi_and_version.toLongArray()[0]) + "-"
-//                             + toHexString(clock_seq_hi_and_reserved.toLongArray()[0]) + toHexString(clock_seq_low.toLongArray()[0])
-//                             + "-" + toHexString(node.toLongArray()[0]);
-//             UUID uuid = UUID.fromString(str);
-
-               BitSet uuidBits = new BitSet(128);
-               for (int i = 0; i < 128; i++) {
-                       if (i < 48)
-                               uuidBits.set(i, node.get(i));
-                       else if (i < 56)
-                               uuidBits.set(i, clk_seq_low.get(i - 48));
-                       else if (i < 64)
-                               uuidBits.set(i, clk_seq_hi_res.get(i - 56));
-                       else if (i < 80)
-                               uuidBits.set(i, time_hi_and_version.get(i - 64));
-                       else if (i < 96)
-                               uuidBits.set(i, time_mid.get(i - 80));
-                       else
-                               uuidBits.set(i, time_low.get(i - 96));
+       public static UUID timeUUID(long timestamp, NetworkInterface nic) {
+               byte[] node;
+               try {
+                       node = nic.getHardwareAddress();
+               } catch (SocketException e) {
+                       throw new IllegalStateException("Cannot get hardware address", e);
                }
+               long clockSequence = nextClockSequence();
+               return timeUUID(timestamp, clockSequence, node);
+       }
 
-               long[] uuidLongs = uuidBits.toLongArray();
-               assert uuidLongs.length == 2;
-               UUID uuid = new UUID(uuidLongs[1], uuidLongs[0]);
+       public static UUID timeUUID(LocalDateTime time, long clockSequence, byte[] node) {
+               Duration duration = Duration.between(GREGORIAN_START, time);
+               // Number of 100 ns intervals in one second: 1000000000 / 100 = 10000000
+               long timestamp = duration.getSeconds() * 10000000 + duration.getNano() / 100;
+               return timeUUID(timestamp, clockSequence, node);
+       }
+
+       public static UUID timeUUID(long timestamp, long clockSequence, byte[] node) {
+               Objects.requireNonNull(node, "Node array cannot be null");
+               if (node.length < 6)
+                       throw new IllegalArgumentException("Node array must be at least 6 bytes long");
+
+               long mostSig = MOST_SIG_VERSION1 // base for version 1 UUID
+                               | ((timestamp & 0xFFFFFFFFL) << 32) // time_low
+                               | (((timestamp >> 32) & 0xFFFFL) << 16) // time_mid
+                               | ((timestamp >> 48) & 0x0FFFL);// time_hi_and_version
+
+               long leastSig = LEAST_SIG_RFC4122_VARIANT // base for Leach–Salz UUID
+                               | (((clockSequence & 0x3F00) >> 8) << 56) // clk_seq_hi_res
+                               | ((clockSequence & 0xFF) << 48) // clk_seq_low
+                               | (node[0] & 0xFFL) //
+                               | ((node[1] & 0xFFL) << 8) //
+                               | ((node[2] & 0xFFL) << 16) //
+                               | ((node[3] & 0xFFL) << 24) //
+                               | ((node[4] & 0xFFL) << 32) //
+                               | ((node[5] & 0xFFL) << 40); //
+               UUID uuid = new UUID(mostSig, leastSig);
 
                // tests
-               assert uuid.node() == node.toLongArray()[0];
-               assert uuid.timestamp() == timeNanos;
-               assert uuid.clockSequence() == clockSequence;
+               assert uuid.node() == BitSet.valueOf(node).toLongArray()[0];
+               assert uuid.timestamp() == timestamp;
+               assert uuid.clockSequence() == clockSequence
+                               : "uuid.clockSequence()=" + uuid.clockSequence() + " clockSequence=" + clockSequence;
                assert uuid.version() == 1;
                assert uuid.variant() == 2;
                return uuid;
        }
 
+//     @Deprecated
+//     public static UUID timeBasedUUID() {
+//             return timeBasedUUID(LocalDateTime.now(ZoneOffset.UTC));
+//     }
+//
+//     @Deprecated
+//     public static UUID timeBasedRandomUUID() {
+//             return timeBasedRandomUUID(LocalDateTime.now(ZoneOffset.UTC), RANDOM);
+//     }
+//
+//     @Deprecated
+//     public static UUID timeBasedUUID(LocalDateTime time) {
+//             if (HARDWARE_ADDRESS == null)
+//                     return timeBasedRandomUUID(time, RANDOM);
+//             return timeBasedUUID(time, BitSet.valueOf(HARDWARE_ADDRESS));
+//     }
+//
+//     @Deprecated
+//     public static UUID timeBasedAddressUUID(LocalDateTime time, NetworkInterface nic) throws SocketException {
+//             byte[] nodeBytes = nic.getHardwareAddress();
+//             BitSet node = BitSet.valueOf(nodeBytes);
+//             return timeBasedUUID(time, node);
+//     }
+//
+//     @Deprecated
+//     public static UUID timeBasedRandomUUID(LocalDateTime time, Random random) {
+//             byte[] nodeBytes = new byte[6];
+//             random.nextBytes(nodeBytes);
+//             BitSet node = BitSet.valueOf(nodeBytes);
+//             // set random marker
+//             node.set(0, true);
+//             return timeBasedUUID(time, node);
+//     }
+//
+//     @Deprecated
+//     public static UUID timeBasedUUID(LocalDateTime time, BitSet node) {
+//             // most significant
+//             Duration duration = Duration.between(GREGORIAN_START, time);
+//
+//             // Number of 100 ns intervals in one second: 1000000000 / 100 = 10000000
+//             long timeNanos = duration.getSeconds() * 10000000 + duration.getNano() / 100;
+//             BitSet timeBits = BitSet.valueOf(new long[] { timeNanos });
+//             assert timeBits.length() <= 60;
+//
+//             int clockSequence;
+//             synchronized (CLOCK_SEQUENCE) {
+//                     clockSequence = CLOCK_SEQUENCE.incrementAndGet();
+//                     if (clockSequence > 16384)
+//                             CLOCK_SEQUENCE.set(0);
+//             }
+//             BitSet clockSequenceBits = BitSet.valueOf(new long[] { clockSequence });
+//
+//             // Build the UUID, bit by bit
+//             // see https://tools.ietf.org/html/rfc4122#section-4.2.2
+//             // time
+//             BitSet time_low = new BitSet(32);
+//             BitSet time_mid = new BitSet(16);
+//             BitSet time_hi_and_version = new BitSet(16);
+//
+//             for (int i = 0; i < 60; i++) {
+//                     if (i < 32)
+//                             time_low.set(i, timeBits.get(i));
+//                     else if (i < 48)
+//                             time_mid.set(i - 32, timeBits.get(i));
+//                     else
+//                             time_hi_and_version.set(i - 48, timeBits.get(i));
+//             }
+//             // version
+//             time_hi_and_version.set(12, true);
+//             time_hi_and_version.set(13, false);
+//             time_hi_and_version.set(14, false);
+//             time_hi_and_version.set(15, false);
+//
+//             // clock sequence
+//             BitSet clk_seq_hi_res = new BitSet(8);
+//             BitSet clk_seq_low = new BitSet(8);
+//             for (int i = 0; i < 8; i++) {
+//                     clk_seq_low.set(i, clockSequenceBits.get(i));
+//             }
+//             for (int i = 8; i < 14; i++) {
+//                     clk_seq_hi_res.set(i - 8, clockSequenceBits.get(i));
+//             }
+//             // variant
+//             clk_seq_hi_res.set(6, false);
+//             clk_seq_hi_res.set(7, true);
+//
+////           String str = toHexString(time_low.toLongArray()[0]) + "-" + toHexString(time_mid.toLongArray()[0]) + "-"
+////                           + toHexString(time_hi_and_version.toLongArray()[0]) + "-"
+////                           + toHexString(clock_seq_hi_and_reserved.toLongArray()[0]) + toHexString(clock_seq_low.toLongArray()[0])
+////                           + "-" + toHexString(node.toLongArray()[0]);
+////           UUID uuid = UUID.fromString(str);
+//
+//             BitSet uuidBits = new BitSet(128);
+//             for (int i = 0; i < 128; i++) {
+//                     if (i < 48)
+//                             uuidBits.set(i, node.get(i));
+//                     else if (i < 56)
+//                             uuidBits.set(i, clk_seq_low.get(i - 48));
+//                     else if (i < 64)
+//                             uuidBits.set(i, clk_seq_hi_res.get(i - 56));
+//                     else if (i < 80)
+//                             uuidBits.set(i, time_hi_and_version.get(i - 64));
+//                     else if (i < 96)
+//                             uuidBits.set(i, time_mid.get(i - 80));
+//                     else
+//                             uuidBits.set(i, time_low.get(i - 96));
+//             }
+//
+//             long[] uuidLongs = uuidBits.toLongArray();
+//             assert uuidLongs.length == 2;
+//             UUID uuid = new UUID(uuidLongs[1], uuidLongs[0]);
+//
+//             // tests
+//             assert uuid.node() == node.toLongArray()[0];
+//             assert uuid.timestamp() == timeNanos;
+//             assert uuid.clockSequence() == clockSequence;
+//             assert uuid.version() == 1;
+//             assert uuid.variant() == 2;
+//             return uuid;
+//     }
+
+       /*
+        * NAME BASED (version 3 and 5)
+        */
+
+       public final static String MD5 = "MD5";
+       public final static String SHA1 = "SHA1";
+
+       public static UUID nameUUIDv5(UUID namespace, String name) {
+               Objects.requireNonNull(namespace, "Namespace cannot be null");
+               Objects.requireNonNull(name, "Name cannot be null");
+               return nameUUIDv5(namespace, name.getBytes(StandardCharsets.UTF_8));
+       }
+
+       public static UUID nameUUIDv5(UUID namespace, byte[] name) {
+               byte[] bytes = DigestUtils.sha1(toBytes(namespace), name);
+               bytes[6] &= 0x0f;
+               bytes[6] |= 0x50;// v5
+               bytes[8] &= 0x3f;
+               bytes[8] |= 0x80;// variant 1
+               UUID result = fromBytes(bytes, 0);
+               return result;
+       }
+
+       public static UUID nameUUIDv3(UUID namespace, String name) {
+               Objects.requireNonNull(namespace, "Namespace cannot be null");
+               Objects.requireNonNull(name, "Name cannot be null");
+               return nameUUIDv3(namespace, name.getBytes(StandardCharsets.UTF_8));
+       }
+
+       public static UUID nameUUIDv3(UUID namespace, byte[] name) {
+               byte[] arr = new byte[name.length + 16];
+               copyBytes(namespace, arr, 0);
+               System.arraycopy(name, 0, arr, 16, name.length);
+               return UUID.nameUUIDFromBytes(arr);
+       }
+
+       static byte[] sha1(byte[]... bytes) {
+               try {
+                       MessageDigest digest = MessageDigest.getInstance(SHA1);
+                       for (byte[] arr : bytes)
+                               digest.update(arr);
+                       byte[] checksum = digest.digest();
+                       return checksum;
+               } catch (NoSuchAlgorithmException e) {
+                       throw new UnsupportedOperationException("SHA1 is not avalaible", e);
+               }
+       }
+
+       /*
+        * RANDOM v4
+        */
+       public static UUID unsecureRandomUUID() {
+               byte[] arr = new byte[16];
+               UNSECURE_RANDOM.nextBytes(arr);
+               arr[6] &= 0x0f;
+               arr[6] |= 0x40;// v4
+               arr[8] &= 0x3f;
+               arr[8] |= 0x80;// variant 1
+               return fromBytes(arr);
+       }
+
+       /*
+        * UTILITIES
+        */
+       /**
+        * Convert bytes to an UUID. Byte array must not be null and be exactly of
+        * length 16.
+        */
+       public static UUID fromBytes(byte[] data) {
+               Objects.requireNonNull(data, "Byte array must not be null");
+               if (data.length != 16)
+                       throw new IllegalArgumentException("Byte array as length " + data.length);
+               return fromBytes(data, 0);
+       }
+
+       /**
+        * Convert bytes to an UUID, starting to read the array at this offset.
+        */
+       public static UUID fromBytes(byte[] data, int offset) {
+               Objects.requireNonNull(data, "Byte array cannot be null");
+               long msb = 0;
+               long lsb = 0;
+               for (int i = offset; i < 8 + offset; i++)
+                       msb = (msb << 8) | (data[i] & 0xff);
+               for (int i = 8 + offset; i < 16 + offset; i++)
+                       lsb = (lsb << 8) | (data[i] & 0xff);
+               return new UUID(msb, lsb);
+       }
+
+       public static byte[] toBytes(UUID uuid) {
+               Objects.requireNonNull(uuid, "UUID cannot be null");
+               long msb = uuid.getMostSignificantBits();
+               long lsb = uuid.getLeastSignificantBits();
+               return toBytes(msb, lsb);
+       }
+
+       public static void copyBytes(UUID uuid, byte[] arr, int offset) {
+               Objects.requireNonNull(uuid, "UUID cannot be null");
+               long msb = uuid.getMostSignificantBits();
+               long lsb = uuid.getLeastSignificantBits();
+               copyBytes(msb, lsb, arr, offset);
+       }
+
+       /**
+        * Converts an UUID to a binary string (list of 0 and 1), with a separator to
+        * make it more readable.
+        */
        public static String toBinaryString(UUID uuid, int charsPerSegment, char separator) {
                String binaryString = toBinaryString(uuid);
                StringBuilder sb = new StringBuilder(128 + (128 / charsPerSegment));
@@ -173,6 +430,7 @@ public class UuidUtils {
                return sb.toString();
        }
 
+       /** Converts an UUID to a binary string (list of 0 and 1). */
        public static String toBinaryString(UUID uuid) {
                String most = zeroTo64Chars(Long.toBinaryString(uuid.getMostSignificantBits()));
                String least = zeroTo64Chars(Long.toBinaryString(uuid.getLeastSignificantBits()));
@@ -193,6 +451,10 @@ public class UuidUtils {
                        return str;
        }
 
+       /**
+        * Converts an UUID hex representation without '-' to the standard form (with
+        * '-').
+        */
        public static String compactToStd(String compact) {
                if (compact.length() != 32)
                        throw new IllegalArgumentException(
@@ -209,10 +471,18 @@ public class UuidUtils {
                return std;
        }
 
-       public static UUID compactToUuid(String compact) {
+       /**
+        * Converts an UUID hex representation without '-' to an {@link UUID}.
+        */
+       public static UUID fromCompact(String compact) {
                return UUID.fromString(compactToStd(compact));
        }
 
+       /** To a 32 characters hex string without '-'. */
+       public static String toCompact(UUID uuid) {
+               return toHexString(toBytes(uuid));
+       }
+
        public static boolean isRandom(UUID uuid) {
                return uuid.version() == 4;
        }
@@ -233,41 +503,119 @@ public class UuidUtils {
                return uuid.version() == 3 || uuid.version() == 5;
        }
 
+       final private static char[] hexArray = "0123456789abcdef".toCharArray();
+
+       /** Convert two longs to a byte array with length 16. */
+       public static byte[] toBytes(long long1, long long2) {
+               byte[] result = new byte[16];
+               for (int i = 0; i < 8; i++)
+                       result[i] = (byte) ((long1 >> ((7 - i) * 8)) & 0xff);
+               for (int i = 8; i < 16; i++)
+                       result[i] = (byte) ((long2 >> ((15 - i) * 8)) & 0xff);
+               return result;
+       }
+
+       public static void copyBytes(long long1, long long2, byte[] arr, int offset) {
+               assert arr.length >= 16 + offset;
+               for (int i = offset; i < 8 + offset; i++)
+                       arr[i] = (byte) ((long1 >> ((7 - i) * 8)) & 0xff);
+               for (int i = 8 + offset; i < 16 + offset; i++)
+                       arr[i] = (byte) ((long2 >> ((15 - i) * 8)) & 0xff);
+       }
+
+       /** Converts a byte array to an hex String. */
+       public static String toHexString(byte[] bytes) {
+               char[] hexChars = new char[bytes.length * 2];
+               for (int j = 0; j < bytes.length; j++) {
+                       int v = bytes[j] & 0xFF;
+                       hexChars[j * 2] = hexArray[v >>> 4];
+                       hexChars[j * 2 + 1] = hexArray[v & 0x0F];
+               }
+               return new String(hexChars);
+       }
+
        /** Singleton. */
        private UuidUtils() {
        }
 
-       public final static void main(String[] args) {
-               UUID uuid;
+       /*
+        * SMOKE TESTS
+        */
+
+       static boolean smokeTests() throws AssertionError {
+
+               // warm up a bit before measuring perf and logging it
+               int warmUpCycles = 10;
+               // int warmUpCycles = 10000000;
+               if (logger.isLoggable(DEBUG))
+                       for (int i = 0; i < warmUpCycles; i++) {
+                               UUID.randomUUID();
+                               unsecureRandomUUID();
+                               timeUUID();
+                               timeUUIDwithRandomNode();
+                               nameUUIDv5(NS_DNS, "example.org");
+                               nameUUIDv3(NS_DNS, "example.org");
+                       }
 
-               uuid = compactToUuid("996b1f5122de4b2f94e49168d32f22d1");
-               System.out.println(uuid.toString() + ", isRandom=" + isRandom(uuid));
+               long begin;
 
-               // warm up
-               for (int i = 0; i < 10; i++) {
-                       UUID.randomUUID();
-                       timeBasedRandomUUID();
-                       timeBasedUUID();
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = UUID.randomUUID();
+                       long duration = System.nanoTime() - begin;
+                       assert isRandom(uuid);
+                       logger.log(DEBUG, () -> uuid.toString() + " in " + duration + " ns, isRandom=" + isRandom(uuid));
                }
 
-               long begin;
-               long duration;
-
-               begin = System.nanoTime();
-               uuid = UUID.randomUUID();
-               duration = System.nanoTime() - begin;
-               System.out.println(uuid.toString() + " in " + duration + " ns, isRandom=" + isRandom(uuid));
-
-               begin = System.nanoTime();
-               uuid = timeBasedUUID();
-               duration = System.nanoTime() - begin;
-               System.out.println(uuid.toString() + " in " + duration + " ns, isTimeBasedRandom=" + isTimeBasedRandom(uuid));
-
-               begin = System.nanoTime();
-               uuid = timeBasedRandomUUID();
-               duration = System.nanoTime() - begin;
-               System.out.println(uuid.toString() + " in " + duration + " ns, isTimeBasedRandom=" + isTimeBasedRandom(uuid));
-//             System.out.println(toBinaryString(uuid, 8, ' '));
-//             System.out.println(toBinaryString(uuid, 16, '\n'));
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = unsecureRandomUUID();
+                       long duration = System.nanoTime() - begin;
+                       assert isRandom(uuid);
+                       logger.log(DEBUG, () -> uuid.toString() + " in " + duration + " ns, isRandom=" + isRandom(uuid));
+               }
+
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = timeUUID();
+                       long duration = System.nanoTime() - begin;
+                       assert isTimeBased(uuid);
+                       logger.log(DEBUG,
+                                       () -> uuid.toString() + " in " + duration + " ns, isTimeBasedRandom=" + isTimeBasedRandom(uuid));
+               }
+
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = timeUUIDwithRandomNode();
+                       long duration = System.nanoTime() - begin;
+                       assert isTimeBasedRandom(uuid);
+                       logger.log(DEBUG,
+                                       () -> uuid.toString() + " in " + duration + " ns, isTimeBasedRandom=" + isTimeBasedRandom(uuid));
+               }
+
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = nameUUIDv5(NS_DNS, "example.org");
+                       long duration = System.nanoTime() - begin;
+                       assert isNameBased(uuid);
+                       // uuidgen --sha1 --namespace @dns --name example.org
+                       assert "aad03681-8b63-5304-89e0-8ca8f49461b5".equals(uuid.toString());
+                       logger.log(DEBUG, () -> uuid.toString() + " in " + duration + " ns, isNameBased=" + isNameBased(uuid));
+               }
+
+               {
+                       begin = System.nanoTime();
+                       UUID uuid = nameUUIDv3(NS_DNS, "example.org");
+                       long duration = System.nanoTime() - begin;
+                       assert isNameBased(uuid);
+                       // uuidgen --md5 --namespace @dns --name example.org
+                       assert "04738bdf-b25a-3829-a801-b21a1d25095b".equals(uuid.toString());
+                       logger.log(DEBUG, () -> uuid.toString() + " in " + duration + " ns, isNameBased=" + isNameBased(uuid));
+               }
+               return UuidUtils.class.desiredAssertionStatus();
+       }
+
+       public static void main(String[] args) {
+               smokeTests();
        }
 }