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/*
* Copyright 2018 Fizzed, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.fizzed.crux.util;
import java.util.Objects;
import java.util.UUID;
/**
* Utilities for working with UUIDs, especially time-based UUIDs.
*
* @author jjlauer
*/
public class UUIDs {
static public UUID fromBytes(byte[] bytes) {
if (bytes == null) {
return null;
}
if (bytes.length != 16) {
throw new IllegalArgumentException("must be 16 bytes in length");
}
long msb = 0;
long lsb = 0;
for (int i = 0; i < 8; i++) {
msb = (msb << 8) | (bytes[i] & 0xff);
}
for (int i = 8; i < 16; i++) {
lsb = (lsb << 8) | (bytes[i] & 0xff);
}
return new UUID(msb, lsb);
}
static public byte[] toBytes(String uuid) {
return toBytes(UUID.fromString(uuid));
}
static public byte[] toBytes(UUID uuid) {
if (uuid == null) {
return null;
}
long msb = uuid.getMostSignificantBits();
long lsb = uuid.getLeastSignificantBits();
byte[] bytes = new byte[16];
for (int i = 7; i >= 0; i--) {
bytes[i] = (byte)(msb & 0xFF);
msb >>= 8;
}
for (int i = 15; i >= 8; i--) {
bytes[i] = (byte)(lsb & 0xFF);
lsb >>= 8;
}
return bytes;
}
/**
* Creates a byte array of a time-based UUID that is suitable for sorting
* and lexigraphical ordering. Matches the algorithm in MySQL 8.0's
* uuid_to_bin() method. https://dev.mysql.com/doc/refman/8.0/en/miscellaneous-functions.html#function_uuid-to-bin
* For example, 6ccd780c-babb-1026-9564-5b8c656024db will return a byte
* array as 1026babb-6ccd-780c-9564-5b8c656024db. The embedded timestamp
* is moved to the front.
* @param uuid The time-based UUID
* @return A byte array representation
*/
static public byte[] toTimeBytes(UUID uuid) {
if (uuid == null) {
return null;
}
if (uuid.version() != 1) {
throw new IllegalArgumentException("not a time-based uuid");
}
// move the 6 & 7 octet of msb to front
// move the 4 & 5 octet of msg to next
// then move 0-3 to the back
// in: 6ccd-780c-babb-1026-9564-5b8c-6560-24db
// out: 1026-babb-6ccd-780c-9564-5b8c-6560-24db
long msb = uuid.getMostSignificantBits();
long lsb = uuid.getLeastSignificantBits();
byte[] bytes = new byte[16];
bytes[1] = (byte)(msb & 0xFF); msb >>= 8;
bytes[0] = (byte)(msb & 0xFF); msb >>= 8;
bytes[3] = (byte)(msb & 0xFF); msb >>= 8;
bytes[2] = (byte)(msb & 0xFF); msb >>= 8;
for (int i = 7; i >= 4; i--) {
bytes[i] = (byte)(msb & 0xFF);
msb >>= 8;
}
for (int i = 15; i >= 8; i--) {
bytes[i] = (byte)(lsb & 0xFF);
lsb >>= 8;
}
return bytes;
}
static public UUID fromTimeBytes(byte[] bytes) {
if (bytes == null) {
return null;
}
if (bytes.length != 16) {
throw new IllegalArgumentException("must be 16 bytes in length");
}
// most significant nibble MUST be 1
int version = (bytes[0] >> 4) & 0x0F;
if (version != 1) {
throw new IllegalArgumentException("not a time-based byte array");
}
// in: 1026-babb-6ccd-780c 9564-5b8c-6560-24db
// out: 6ccd-780c-babb-1026 9564-5b8c-6560-24db
long msb = 0;
long lsb = 0;
for (int i = 4; i < 8; i++) {
msb = (msb << 8) | (bytes[i] & 0xff);
}
msb = (msb << 8) | (bytes[2] & 0xff);
msb = (msb << 8) | (bytes[3] & 0xff);
msb = (msb << 8) | (bytes[0] & 0xff);
msb = (msb << 8) | (bytes[1] & 0xff);
for (int i = 8; i < 16; i++) {
lsb = (lsb << 8) | (bytes[i] & 0xff);
}
return new UUID(msb, lsb);
}
// millis at 00:00:00.000 15 Oct 1582
private static final long START_EPOCH = -12219292800000L;
/**
* Extracts the timestamp embedded within a Type 1 time-based UUID and
* converts it to "unix time" as the number of milliseconds that have elapsed
* since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970.
* The same kind of value that System.currentTimeMillis() returns.
* @param uuid The time-based uuid
* @return The number of epoch milliseconds
*/
static public long getEpochMillis(UUID uuid) {
Objects.requireNonNull(uuid, "uuid was null");
if (uuid.version() != 1) {
throw new IllegalArgumentException("not a time-based uuid");
}
return (uuid.timestamp() / 10000L) + START_EPOCH;
}
/**
* Creates a new time-based UUID based on the one provided and sets its
* embedded timestamp to the supplied one. This method does not guarantee
* uniqueness since the caller is supplying a timestamp -- so you should only
* use this method if you will externally verify uniqueness in some other way.
* @param uuid The uuid to use as base
* @param epochMillis The timestamp to use based on "unix time"
* @return A new UUID
*/
static public UUID setEpochMillis(UUID uuid, long epochMillis) {
Objects.requireNonNull(uuid, "uuid was null");
if (uuid.version() != 1) {
throw new IllegalArgumentException("not a time-based uuid");
}
// convert unix time to type 1 timestamp
// note: some granularity will be lost since unix time is less precise
long type1Timestamp = (epochMillis - START_EPOCH) * 10000L;
long msb = buildMSBWithType1Timestamp(type1Timestamp);
return new UUID(msb, uuid.getLeastSignificantBits());
}
/**
* Creates a new time-based UUID based on the one provided and sets its
* embedded timestamp to the supplied one. This method does not guarantee
* uniqueness since the caller is supplying a timestamp -- so you should only
* use this method if you will externally verify uniqueness in some other way.
* @param uuid The uuid to use as a base
* @param type1Timestamp The type-1 timestamp to use. Type 1 timestamps
* are NOT epoch time!
* @return A new UUID
*/
static public UUID setTimestamp(UUID uuid, long type1Timestamp) {
Objects.requireNonNull(uuid, "uuid was null");
if (uuid.version() != 1) {
throw new IllegalArgumentException("not a time-based uuid");
}
long msb = buildMSBWithType1Timestamp(type1Timestamp);
return new UUID(msb, uuid.getLeastSignificantBits());
}
//
// methods below copied from Apache-licensed code here:
// https://github.com/tfredrich/cassandra-java-driver/blob/master/driver-core/src/main/java/com/datastax/driver/core/utils/UUIDs.java
//
static private long buildMSBWithType1Timestamp(long type1Timestamp) {
long msb = 0L;
msb |= (0x00000000ffffffffL & type1Timestamp) << 32;
msb |= (0x0000ffff00000000L & type1Timestamp) >>> 16;
msb |= (0x0fff000000000000L & type1Timestamp) >>> 48;
msb |= 0x0000000000001000L; // sets the version to 1.
return msb;
}
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