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/*
* Licensed to Elastic Search and Shay Banon under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Elastic Search licenses this
* file to you 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 org.elasticsearch.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
/**
* A UUID taken from java UUID that simply holds less data.
*
* @author kimchy (Shay Banon)
*/
public class UUID implements Comparable {
/*
* The most significant 64 bits of this UUID.
*
* @serial
*/
private final long mostSigBits;
/*
* The least significant 64 bits of this UUID.
*
* @serial
*/
private final long leastSigBits;
/*
* The random number generator used by this class to create random
* based UUIDs.
*/
private static volatile SecureRandom numberGenerator = null;
// Constructors and Factories
/*
* Private constructor which uses a byte array to construct the new UUID.
*/
private UUID(byte[] data) {
long msb = 0;
long lsb = 0;
assert data.length == 16;
for (int i = 0; i < 8; i++)
msb = (msb << 8) | (data[i] & 0xff);
for (int i = 8; i < 16; i++)
lsb = (lsb << 8) | (data[i] & 0xff);
this.mostSigBits = msb;
this.leastSigBits = lsb;
}
/**
* Constructs a new UUID using the specified data.
* mostSigBits is used for the most significant 64 bits
* of the UUID and leastSigBits becomes the
* least significant 64 bits of the UUID.
*
* @param mostSigBits
* @param leastSigBits
*/
public UUID(long mostSigBits, long leastSigBits) {
this.mostSigBits = mostSigBits;
this.leastSigBits = leastSigBits;
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
*
* The UUID is generated using a cryptographically strong
* pseudo random number generator.
*
* @return a randomly generated UUID.
*/
public static UUID randomUUID() {
SecureRandom ng = numberGenerator;
if (ng == null) {
numberGenerator = ng = new SecureRandom();
}
byte[] randomBytes = new byte[16];
ng.nextBytes(randomBytes);
randomBytes[6] &= 0x0f; /* clear version */
randomBytes[6] |= 0x40; /* set to version 4 */
randomBytes[8] &= 0x3f; /* clear variant */
randomBytes[8] |= 0x80; /* set to IETF variant */
return new UUID(randomBytes);
}
/**
* Static factory to retrieve a type 3 (name based) UUID based on
* the specified byte array.
*
* @param name a byte array to be used to construct a UUID.
* @return a UUID generated from the specified array.
*/
public static UUID nameUUIDFromBytes(byte[] name) {
MessageDigest md;
try {
md = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException nsae) {
throw new InternalError("MD5 not supported");
}
byte[] md5Bytes = md.digest(name);
md5Bytes[6] &= 0x0f; /* clear version */
md5Bytes[6] |= 0x30; /* set to version 3 */
md5Bytes[8] &= 0x3f; /* clear variant */
md5Bytes[8] |= 0x80; /* set to IETF variant */
return new UUID(md5Bytes);
}
/**
* Creates a UUID from the string standard representation as
* described in the {@link #toString} method.
*
* @param name a string that specifies a UUID.
* @return a UUID with the specified value.
* @throws IllegalArgumentException if name does not conform to the
* string representation as described in {@link #toString}.
*/
public static UUID fromString(String name) {
String[] components = name.split("-");
if (components.length != 5)
throw new IllegalArgumentException("Invalid UUID string: " + name);
for (int i = 0; i < 5; i++)
components[i] = "0x" + components[i];
long mostSigBits = Long.decode(components[0]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[1]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[2]).longValue();
long leastSigBits = Long.decode(components[3]).longValue();
leastSigBits <<= 48;
leastSigBits |= Long.decode(components[4]).longValue();
return new UUID(mostSigBits, leastSigBits);
}
// Field Accessor Methods
/**
* Returns the least significant 64 bits of this UUID's 128 bit value.
*
* @return the least significant 64 bits of this UUID's 128 bit value.
*/
public long getLeastSignificantBits() {
return leastSigBits;
}
/**
* Returns the most significant 64 bits of this UUID's 128 bit value.
*
* @return the most significant 64 bits of this UUID's 128 bit value.
*/
public long getMostSignificantBits() {
return mostSigBits;
}
// Object Inherited Methods
/**
* Returns a String object representing this
* UUID.
*
* The UUID string representation is as described by this BNF :
*
* {@code
* UUID = "-" "-"
* "-"
* "-"
*
* time_low = 4*
* time_mid = 2*
* time_high_and_version = 2*
* variant_and_sequence = 2*
* node = 6*
* hexOctet =
* hexDigit =
* "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
* | "a" | "b" | "c" | "d" | "e" | "f"
* | "A" | "B" | "C" | "D" | "E" | "F"
* }
*
* @return a string representation of this UUID.
*/
public String toString() {
return (digits(mostSigBits >> 32, 8) + "-" +
digits(mostSigBits >> 16, 4) + "-" +
digits(mostSigBits, 4) + "-" +
digits(leastSigBits >> 48, 4) + "-" +
digits(leastSigBits, 12));
}
/**
* Returns val represented by the specified number of hex digits.
*/
private static String digits(long val, int digits) {
long hi = 1L << (digits * 4);
return Long.toHexString(hi | (val & (hi - 1))).substring(1);
}
/**
* Returns a hash code for this UUID.
*
* @return a hash code value for this UUID.
*/
public int hashCode() {
return (int) ((mostSigBits >> 32) ^
mostSigBits ^
(leastSigBits >> 32) ^
leastSigBits);
}
/**
* Compares this object to the specified object. The result is
* true if and only if the argument is not
* null, is a UUID object, has the same variant,
* and contains the same value, bit for bit, as this UUID.
*
* @param obj the object to compare with.
* @return true if the objects are the same;
* false otherwise.
*/
public boolean equals(Object obj) {
if (!(obj instanceof UUID))
return false;
UUID id = (UUID) obj;
return (mostSigBits == id.mostSigBits &&
leastSigBits == id.leastSigBits);
}
// Comparison Operations
/**
* Compares this UUID with the specified UUID.
*
* The first of two UUIDs follows the second if the most significant
* field in which the UUIDs differ is greater for the first UUID.
*
* @param val UUID to which this UUID is to be compared.
* @return -1, 0 or 1 as this UUID is less than, equal
* to, or greater than val.
*/
public int compareTo(UUID val) {
// The ordering is intentionally set up so that the UUIDs
// can simply be numerically compared as two numbers
return (this.mostSigBits < val.mostSigBits ? -1 :
(this.mostSigBits > val.mostSigBits ? 1 :
(this.leastSigBits < val.leastSigBits ? -1 :
(this.leastSigBits > val.leastSigBits ? 1 :
0))));
}
}