org.jgroups.util

Class UUID

java.lang.Object

org.jgroups.util.UUID

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, java.lang.Comparable<Address>, Address, Streamable

Direct Known Subclasses:

ExtendedUUID

public class UUID
extends java.lang.Object
implements Address

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

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static LazyRemovalCache<Address,java.lang.String>	cache Keeps track of associations between logical addresses (UUIDs) and logical names
protected long	leastSigBits
protected long	mostSigBits
protected static java.security.SecureRandom	numberGenerator The random number generator used by this class to create random based UUIDs
protected static LazyRemovalCache.Printable<Address,LazyRemovalCache.Entry<java.lang.String>>	print_function
protected static boolean	print_uuids
protected static int	SIZE

Fields inherited from interface org.jgroups.Address

IP_ADDR, NULL, SITE_MASTER, SITE_UUID, UUID_ADDR

Constructor Summary

Constructors

Modifier	Constructor and Description
	UUID()
protected	UUID(byte[] data) Private constructor which uses a byte array to construct the new UUID
	UUID(long mostSigBits, long leastSigBits)

Method Summary

Modifier and Type	Method and Description
static void	add(Address uuid, java.lang.String logical_name)
static void	add(java.util.Map<Address,java.lang.String> map)
int	compareTo(Address other) Compares this UUID with the specified UUID.
UUID	copy()
protected static java.lang.String	digits(long val, int digits) Returns val represented by the specified number of hex digits.
boolean	equals(java.lang.Object obj) Compares this object to the specified object.
static UUID	fromString(java.lang.String name) Creates a UUID from the string standard representation as described in the toString() method.
protected static byte[]	generateRandomBytes()
static java.lang.String	get(Address logical_addr)
static Address	getByName(java.lang.String logical_name)
static java.util.Map<Address,java.lang.String>	getContents() Returns a copy of the cache's contents
long	getLeastSignificantBits()
long	getMostSignificantBits() Returns the most significant 64 bits of this UUID's 128 bit value.
int	hashCode() Returns a hash code for this UUID.
static java.lang.String	printCache()
static UUID	randomUUID() Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
void	readExternal(java.io.ObjectInput in)
void	readFrom(java.io.DataInput in) Read the state of the current object (including superclasses) from instream Note that the input stream must not be closed
static void	remove(Address addr)
static void	removeAll(java.util.Collection<Address> mbrs)
static void	retainAll(java.util.Collection<Address> logical_addrs)
int	size() Returns serialized size of this address
java.lang.String	toString()
java.lang.String	toStringLong() Returns a String object representing this UUID.
void	writeExternal(java.io.ObjectOutput out)
void	writeTo(java.io.DataOutput out) Write the entire state of the current object (including superclasses) to outstream.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

mostSigBits

protected long mostSigBits

leastSigBits

protected long leastSigBits

numberGenerator

protected static volatile java.security.SecureRandom numberGenerator

The random number generator used by this class to create random based UUIDs

cache

protected static final LazyRemovalCache<Address,java.lang.String> cache

Keeps track of associations between logical addresses (UUIDs) and logical names

print_uuids

protected static boolean print_uuids

SIZE

protected static final int SIZE

See Also:

Constant Field Values

print_function

protected static final LazyRemovalCache.Printable<Address,LazyRemovalCache.Entry<java.lang.String>> print_function

Constructor Detail

UUID

public UUID()

UUID

public UUID(long mostSigBits,
            long leastSigBits)

UUID

protected UUID(byte[] data)

Private constructor which uses a byte array to construct the new UUID

Method Detail

add

public static void add(Address uuid,
                       java.lang.String logical_name)

add

public static void add(java.util.Map<Address,java.lang.String> map)

get

public static java.lang.String get(Address logical_addr)

getByName

public static Address getByName(java.lang.String logical_name)

getContents

public static java.util.Map<Address,java.lang.String> getContents()

Returns a copy of the cache's contents

remove

public static void remove(Address addr)

removeAll

public static void removeAll(java.util.Collection<Address> mbrs)

retainAll

public static void retainAll(java.util.Collection<Address> logical_addrs)

printCache

public static java.lang.String printCache()

randomUUID

public static UUID randomUUID()

Static factory to retrieve a type 4 (pseudo randomly generated) UUID. The UUID is generated using a cryptographically strong pseudo random number generator.

Returns:

A randomly generated UUID

getLeastSignificantBits

public long getLeastSignificantBits()

getMostSignificantBits

public long getMostSignificantBits()

Returns the most significant 64 bits of this UUID's 128 bit value.

Returns:

The most significant 64 bits of this UUID's 128 bit value

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toStringLong

public java.lang.String toStringLong()

Returns a String object representing this UUID.

The UUID string representation is as described by this BNF:

 
 UUID                   = <time_low> "-" <time_mid> "-"
                          <time_high_and_version> "-"
                          <variant_and_sequence> "-"
                          <node>
 time_low               = 4*<hexOctet>
 time_mid               = 2*<hexOctet>
 time_high_and_version  = 2*<hexOctet>
 variant_and_sequence   = 2*<hexOctet>
 node                   = 6*<hexOctet>
 hexOctet               = <hexDigit><hexDigit>
 hexDigit               =
       "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
       | "a" | "b" | "c" | "d" | "e" | "f"
       | "A" | "B" | "C" | "D" | "E" | "F"
 

Returns:

A string representation of this UUID

fromString

public static UUID fromString(java.lang.String name)

Creates a UUID from the string standard representation as described in the toString() method.

Parameters:

name - A string that specifies a UUID

Returns:

A UUID with the specified value

Throws:

java.lang.IllegalArgumentException - If name does not conform to the string representation as described in toString()

digits

protected static java.lang.String digits(long val,
                                         int digits)

Returns val represented by the specified number of hex digits.

hashCode

public int hashCode()

Returns a hash code for this UUID.

Overrides:

hashCode in class java.lang.Object

Returns:

A hash code value for this UUID

equals

public boolean equals(java.lang.Object obj)

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.

Overrides:

equals in class java.lang.Object

Parameters:

obj - The object to be compared

Returns:

true if the objects are the same; false otherwise

compareTo

public int compareTo(Address other)

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.

Specified by:

compareTo in interface java.lang.Comparable<Address>

Parameters:

other - UUID to which this UUID is to be compared

Returns:

-1, 0 or 1 as this UUID is less than, equal to, or greater than val

writeTo

public void writeTo(java.io.DataOutput out)
             throws java.lang.Exception

Description copied from interface: Streamable

Write the entire state of the current object (including superclasses) to outstream. Note that the output stream must not be closed

Specified by:

writeTo in interface Streamable

Throws:

java.lang.Exception

readFrom

public void readFrom(java.io.DataInput in)
              throws java.lang.Exception

Description copied from interface: Streamable

Read the state of the current object (including superclasses) from instream Note that the input stream must not be closed

Specified by:

readFrom in interface Streamable

Throws:

java.lang.Exception

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException

size

public int size()

Description copied from interface: Address

Returns serialized size of this address

Specified by:

size in interface Address

copy

public UUID copy()

generateRandomBytes

protected static byte[] generateRandomBytes()