Package org.apache.nifi.util

Class ComponentIdGenerator

java.lang.Object

org.apache.nifi.util.ComponentIdGenerator

public class ComponentIdGenerator
extends Object

IMPORTANT: This component is not part of public API! ====================================================

This component generates type-one UUID. It is used for generating ID of all NiFi components. Giving the 128-bit UUID structure which consists of Least Significant Bits (LSB) and Most Significant Bits (MSB) this component provides support for generating and maintaining INCEPTION ID of the component (MSB) as well as its INSTANCE ID (LSB).

It is also important to understand that while this component does seed itself from current time which could be extracted from the resulting UUID via call to UUID.timestamp() operation, one should not be relying on such time as the exact time when such ID was generated since in the event the same time is passed to one of the generateId() operation it will be incremented by 1 since the goal of this component to only ensure uniqueness and type-one semantics where each UUID generated by this component is comparable and each subsequent ID is > then previous ID.

For more details on how it is interacted with please see org.apache.nifi.web.util.SnippetUtils as well as org.apache.nifi.web.util.SnippetUtilsTest which contain additional documentation on its usage as well as ID generation contracts defined in NiFi.

Field Summary

Fields

Modifier and Type	Field	Description
private static long	clockSequence
private static long	lastTime
static final Object	lock
private static final org.slf4j.Logger	logger
private static final SecureRandom	randomGenerator

Constructor Summary

Constructors

Constructor	Description
ComponentIdGenerator()

Method Summary

Modifier and Type	Method	Description
static final UUID	generateId()	Will generate unique time based UUID where the next UUID is always greater then the previous.
static final UUID	generateId(long currentTime)
static final UUID	generateId(long msb, long lsb, boolean ensureUnique)

Methods inherited from class java.lang.Object

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

Field Details

logger

private static final org.slf4j.Logger logger

lock

public static final Object lock

lastTime

private static long lastTime

clockSequence

private static long clockSequence

randomGenerator

private static final SecureRandom randomGenerator

Constructor Details

ComponentIdGenerator

public ComponentIdGenerator()

Method Details

generateId

public static final UUID generateId()

Will generate unique time based UUID where the next UUID is always greater then the previous.

generateId

public static final UUID generateId(long currentTime)

generateId

public static final UUID generateId(long msb,
 long lsb,
 boolean ensureUnique)