org.jgroups.util.UUID Maven / Gradle / Ivy
package org.jgroups.util;
import org.jgroups.Address;
import org.jgroups.Constructable;
import org.jgroups.Global;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Supplier;
/**
* Logical address which is unique over space and time.
* Copied from java.util.UUID, but unneeded fields from the latter have been removed. UUIDs needs to
* have a small memory footprint.
*
* @author Bela Ban
*/
public class UUID implements Address, Constructable {
protected long mostSigBits;
protected long leastSigBits;
protected static final int SIZE=Global.LONG_SIZE * 2;
public UUID() {
}
public UUID(long mostSigBits, long leastSigBits) {
this.mostSigBits = mostSigBits;
this.leastSigBits = leastSigBits;
}
public UUID(java.util.UUID uuid) {
this.mostSigBits = uuid.getMostSignificantBits();
this.leastSigBits = uuid.getLeastSignificantBits();
}
/** Private constructor which uses a byte array to construct the new UUID */
protected UUID(byte[] data) {
long msb = 0;
long lsb = 0;
if(data.length != 16)
throw new RuntimeException("UUID needs a 16-byte array");
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;
}
public Supplier create() {
return UUID::new;
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
* The {@code UUID} is generated using a {@link ThreadLocalRandom}.
* @return A randomly generated {@code UUID}
*/
public static UUID randomUUID() {
return new UUID(generateRandomBytes());
}
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;
}
public String toString() {
String val=NameCache.get(this);
return val != null? val : toStringLong();
}
/**
* Returns a {@code String} object representing this {@code 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 {@code UUID}
*/
public String toStringLong() {
return (digits(mostSigBits >> 32, 8) + "-" +
digits(mostSigBits >> 16, 4) + "-" +
digits(mostSigBits, 4) + "-" +
digits(leastSigBits >> 48, 4) + "-" +
digits(leastSigBits, 12));
}
/**
* Creates a {@code UUID} from the string standard representation as
* described in the {@link #toString} method.
*
* @param name
* A string that specifies a {@code UUID}
*
* @return A {@code 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]);
mostSigBits <<= 16;
mostSigBits |=Long.decode(components[1]);
mostSigBits <<= 16;
mostSigBits |=Long.decode(components[2]);
long leastSigBits =Long.decode(components[3]);
leastSigBits <<= 48;
leastSigBits |=Long.decode(components[4]);
return new UUID(mostSigBits, leastSigBits);
}
/** Returns val represented by the specified number of hex digits. */
protected 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 {@code UUID}.
* @return A hash code value for this {@code UUID}
*/
public int hashCode() {
return (int)((mostSigBits >> 32) ^
mostSigBits ^
(leastSigBits >> 32) ^
leastSigBits);
}
/**
* Compares this object to the specified object. The result is {@code
* true} if and only if the argument is not {@code null}, is a {@code UUID}
* object, has the same variant, and contains the same value, bit for bit,
* as this {@code UUID}.
* @param obj The object to be compared
* @return {@code true} if the objects are the same; {@code false} otherwise
*/
public boolean equals(Object obj) {
if (!(obj instanceof UUID))
return false;
return compareTo((UUID)obj) == 0;
}
/**
* Compares this UUID with the specified UUID.
* The first of two UUIDs is greater than the second if the most
* significant field in which the UUIDs differ is greater for the first UUID.
* @param other {@code UUID} to which this {@code UUID} is to be compared
* @return -1, 0 or 1 as this {@code UUID} is less than, equal to, or greater than {@code val}
*/
public int compareTo(Address other) {
UUID val=(UUID)other;
if(this == val)
return 0;
int most=Long.compare(this.mostSigBits, val.mostSigBits);
return most != 0? most : Long.compare(this.leastSigBits, val.leastSigBits);
}
@Override
public void writeTo(DataOutput out) throws IOException {
out.writeLong(leastSigBits);
out.writeLong(mostSigBits);
}
@Override
public void readFrom(DataInput in) throws IOException {
leastSigBits=in.readLong();
mostSigBits=in.readLong();
}
@Override
public int serializedSize() {
return SIZE;
}
public UUID copy() {
return new UUID(mostSigBits, leastSigBits);
}
/**
* Generate random bytes and adjusts them for a type-4 UUID
*/
public static byte[] generateRandomBytes() {
byte[] data = new byte[16];
ThreadLocalRandom.current().nextBytes(data);
data[6] &= 0x0f; /* clear version */
data[6] |= 0x40; /* set to version 4 */
data[8] &= 0x3f; /* clear variant */
data[8] |= 0x80; /* set to IETF variant */
return data;
}
}