Module org.apache.jena.arq

Package org.apache.jena.riot.lang

Class BlankNodeAllocatorHash

java.lang.Object

org.apache.jena.riot.lang.BlankNodeAllocatorHash

All Implemented Interfaces:

BlankNodeAllocator

Direct Known Subclasses:

BlankNodeAllocatorFixedSeedHash

public class BlankNodeAllocatorHash
extends Object
implements BlankNodeAllocator

Allocate bnode labels using a per-run seed and the label presented.

This is the most scalable, always legal allocator.

New allocators must be created per parser run, or .reset() called. These are fed to a digest to give a bit string, (currently MD5, to get a 128bit bit string) that is used to form a bNode AnonId of hex digits.

In addition, there is a cache of label->node allocations, using the natural tendency to locality in a database dump. (subject bNodes, bNodes in lists and other data values structures like unit values).

Not thread safe.

Constructor Summary

Constructors

Constructor	Description
BlankNodeAllocatorHash()

Method Summary

Modifier and Type	Method	Description
org.apache.jena.graph.Node	alloc(String label)	Allocate based on a non-null label.
org.apache.jena.graph.Node	create()	Create a fresh blank node, different from anything generated so far.
void	reset()	Reset allocation state - calls to BlankNodeAllocator.alloc(java.lang.String) will return a different blank node for a label than the one returned before the reset.

Methods inherited from class java.lang.Object

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

Constructor Details

BlankNodeAllocatorHash

public BlankNodeAllocatorHash()

Method Details

reset

public void reset()

Description copied from interface: BlankNodeAllocator

Reset allocation state - calls to BlankNodeAllocator.alloc(java.lang.String) will return a different blank node for a label than the one returned before the reset.

Specified by:

reset in interface BlankNodeAllocator

alloc

public org.apache.jena.graph.Node alloc(String label)

Description copied from interface: BlankNodeAllocator

Allocate based on a non-null label. Calling this twice, with the same label will generate equivalent nodes but they may not be identical (i.e they are .equals but may not be ==)

Specified by:

alloc in interface BlankNodeAllocator

create

public org.apache.jena.graph.Node create()

Description copied from interface: BlankNodeAllocator

Create a fresh blank node, different from anything generated so far. Will not clash with a node allocated by BlankNodeAllocator.alloc(java.lang.String)

Specified by:

create in interface BlankNodeAllocator