com.fasterxml.uuid.impl

Class TimeBasedReorderedGenerator

java.lang.Object

com.fasterxml.uuid.UUIDGenerator

com.fasterxml.uuid.NoArgGenerator

com.fasterxml.uuid.impl.TimeBasedReorderedGenerator

public class TimeBasedReorderedGenerator
extends NoArgGenerator

Implementation of UUID generator that uses time/location based generation method field compatible with UUIDv1, reorderd for improved DB locality. This is usually referred to as "Version 6".

As all JUG provided implementations, this generator is fully thread-safe. Additionally it can also be made externally synchronized with other instances (even ones running on other JVMs); to do this, use FileBasedTimestampSynchronizer (or equivalent).

Since:

4.1

Field Summary

Fields

Modifier and Type	Field and Description
protected EthernetAddress	_ethernetAddress
protected UUIDTimer	_timer Object used for synchronizing access to timestamps, to guarantee that timestamps produced by this generator are unique and monotonically increasings.
protected long	_uuidL2 Base values for the second long (last 8 bytes) of UUID to construct
static int	BYTE_OFFSET_TIME_HIGH
static int	BYTE_OFFSET_TIME_LOW
static int	BYTE_OFFSET_TIME_MID

Constructor Summary

Constructors

Constructor and Description
TimeBasedReorderedGenerator(EthernetAddress ethAddr, UUIDTimer timer)

Method Summary

Modifier and Type	Method and Description
UUID	construct(long rawTimestamp) Method that will construct actual UUID instance for given timestamp: called by generate() but may alternatively be called directly to construct an instance with known timestamp.
UUID	generate() Method for generating a UUID.
EthernetAddress	getEthernetAddress()
UUIDType	getType() Accessor for determining type of UUIDs (version) that this generator instance will produce.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTE_OFFSET_TIME_HIGH

public static int BYTE_OFFSET_TIME_HIGH

BYTE_OFFSET_TIME_MID

public static int BYTE_OFFSET_TIME_MID

BYTE_OFFSET_TIME_LOW

public static int BYTE_OFFSET_TIME_LOW

_ethernetAddress

protected final EthernetAddress _ethernetAddress

_timer

protected final UUIDTimer _timer

Object used for synchronizing access to timestamps, to guarantee that timestamps produced by this generator are unique and monotonically increasings. Some implementations offer even stronger guarantees, for example that same guarantee holds between instances running on different JVMs (or with native code).

_uuidL2

protected final long _uuidL2

Base values for the second long (last 8 bytes) of UUID to construct

Constructor Detail

TimeBasedReorderedGenerator

public TimeBasedReorderedGenerator(EthernetAddress ethAddr,
                                   UUIDTimer timer)

Parameters:

ethAddr - Hardware address (802.1) to use for generating spatially unique part of UUID. If system has more than one NIC,

Method Detail

getType

public UUIDType getType()

Description copied from class: UUIDGenerator

Accessor for determining type of UUIDs (version) that this generator instance will produce.

Specified by:

getType in class UUIDGenerator

getEthernetAddress

public EthernetAddress getEthernetAddress()

generate

public UUID generate()

Description copied from class: NoArgGenerator

Method for generating a UUID.

Specified by:

generate in class NoArgGenerator

Returns:

Newly generated UUID

construct

public UUID construct(long rawTimestamp)

Method that will construct actual UUID instance for given timestamp: called by generate() but may alternatively be called directly to construct an instance with known timestamp. NOTE: calling this method directly does NOT guarantee uniqueness of resulting UUID (caller has to guarantee uniqueness)

Parameters:

rawTimestamp - Timestamp usually obtained from UUIDTimer.getTimestamp(), used for constructing UUID instance

Returns:

unix Time-based, Reordered UUID constructed for given timestamp

Since:

4.3