Package org.jboss.jandex

Class StrongInternPool<E>

java.lang.Object

org.jboss.jandex.StrongInternPool<E>

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

Direct Known Subclasses:

StrongInternPool.ByteArrayInternPool, StrongInternPool.FieldInternPool, StrongInternPool.MethodInternPool, StrongInternPool.RecordComponentInternPool, StrongInternPool.StringInternPool, StrongInternPool.TypeArrayInternPool, StrongInternPool.TypeInternPool

abstract class StrongInternPool<E>
extends java.lang.Object
implements java.lang.Cloneable, java.io.Serializable

A strong intern pool. The pool acts as a set where the first stored entry can be retrieved. This can be used to conserve memory by eliminating duplicate objects (those that are equal but have different identity). It however holds strong references to every item in the pool, so it must be cleared to allow for GC.

Note: It is very important to use a smaller load factor than you normally would for HashSet, since the implementation is open-addressed with linear probing. With a 50% load-factor a get is expected to return in only 2 probes. However, a 90% load-factor is expected to return in around 50 probes.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	StrongInternPool.ByteArrayInternPool
private static class	StrongInternPool.FieldInternPool
private class	StrongInternPool.IdentityHashSetIterator
class	StrongInternPool.Index
private static class	StrongInternPool.MethodInternPool
private static class	StrongInternPool.RecordComponentInternPool
private static class	StrongInternPool.StringInternPool
private static class	StrongInternPool.TypeArrayInternPool
private static class	StrongInternPool.TypeInternPool

Field Summary

Fields

Modifier and Type	Field	Description
private static int	DEFAULT_CAPACITY	Same default as HashMap, must be a power of 2
private static float	DEFAULT_LOAD_FACTOR	67%, just like IdentityHashMap
private java.lang.Class<E>	elementType	The class of values that may be present in table.
private StrongInternPool.Index	index	Cache for an index
private float	loadFactor	The user defined load factor which defines when to resize
private static int	MAXIMUM_CAPACITY	MAX_INT - 1
private int	modCount	Counter used to detect changes made outside of an iterator
private static java.lang.Object	NULL	Marks null keys.
private static long	serialVersionUID	Serialization ID
private int	size	The current number of key-value pairs
private java.lang.Object[]	table	The open-addressed table
private int	threshold	The next resize

Constructor Summary

Constructors

Constructor	Description
StrongInternPool(java.lang.Class<E> elementType)
StrongInternPool(java.lang.Class<E> elementType, int initialCapacity)
StrongInternPool(java.lang.Class<E> elementType, int initialCapacity, float loadFactor)

Method Summary

Modifier and Type	Method	Description
void	clear()
StrongInternPool<E>	clone()
boolean	contains(java.lang.Object entry)
(package private) boolean	eq(java.lang.Object o1, java.lang.Object o2)
(package private) abstract boolean	equality(E o1, E o2)
(package private) static StrongInternPool<byte[]>	forByteArrays()
(package private) static StrongInternPool<FieldInternal>	forFields()
(package private) static StrongInternPool<MethodInternal>	forMethods()
(package private) static StrongInternPool<RecordComponentInternal>	forRecordComponents()
(package private) static StrongInternPool<java.lang.String>	forStrings()
(package private) static StrongInternPool<Type[]>	forTypeArrays()
(package private) static StrongInternPool<Type>	forTypes()
(package private) int	hash(java.lang.Object o)
(package private) abstract int	hashCode(E o)
StrongInternPool.Index	index()
private static int	index(int hashCode, int length)
private void	init(int initialCapacity, float loadFactor)
E	intern(E entry)	Internalizes the specified object by always returning the first ever stored.
boolean	isEmpty()
java.util.Iterator<E>	iterator()
private static <K> K	maskNull(K key)
(package private) boolean	mayContain(java.lang.Object o)
private int	nextIndex(int index, int length)
private int	offset(java.lang.Object entry)
void	printDebugStats()
private void	putForCreate(E entry)
private void	readObject(java.io.ObjectInputStream s)
private void	relocate(int start)
boolean	remove(java.lang.Object o)
private void	resize(int from)
int	size()
java.lang.Object[]	toInternalArray()	Advanced method that returns the internal table.
java.lang.String	toString()
private static <K> K	unmaskNull(K key)
private void	writeObject(java.io.ObjectOutputStream s)

Methods inherited from class java.lang.Object

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

Field Detail

NULL

private static final java.lang.Object NULL

Marks null keys.

serialVersionUID

private static final long serialVersionUID

Serialization ID

See Also:

Constant Field Values

DEFAULT_CAPACITY

private static final int DEFAULT_CAPACITY

Same default as HashMap, must be a power of 2

See Also:

Constant Field Values

MAXIMUM_CAPACITY

private static final int MAXIMUM_CAPACITY

MAX_INT - 1

See Also:

Constant Field Values

DEFAULT_LOAD_FACTOR

private static final float DEFAULT_LOAD_FACTOR

67%, just like IdentityHashMap

See Also:

Constant Field Values

elementType

private final java.lang.Class<E> elementType

The class of values that may be present in table.

table

private transient java.lang.Object[] table

The open-addressed table

Must be Object[] instead of E[] to allow storing the NULL marker.

size

private transient int size

The current number of key-value pairs

threshold

private transient int threshold

The next resize

loadFactor

private final float loadFactor

The user defined load factor which defines when to resize

modCount

private transient int modCount

Counter used to detect changes made outside of an iterator

index

private transient StrongInternPool.Index index

Cache for an index

Constructor Detail

StrongInternPool

StrongInternPool(java.lang.Class<E> elementType,
                 int initialCapacity,
                 float loadFactor)

StrongInternPool

StrongInternPool(java.lang.Class<E> elementType,
                 int initialCapacity)

StrongInternPool

StrongInternPool(java.lang.Class<E> elementType)

Method Detail

init

private void init(int initialCapacity,
                  float loadFactor)

mayContain

boolean mayContain(java.lang.Object o)

eq

boolean eq(java.lang.Object o1,
           java.lang.Object o2)

hash

int hash(java.lang.Object o)

equality

abstract boolean equality(E o1,
                          E o2)

hashCode

abstract int hashCode(E o)

maskNull

private static <K> K maskNull(K key)

unmaskNull

private static <K> K unmaskNull(K key)

nextIndex

private int nextIndex(int index,
                      int length)

index

private static int index(int hashCode,
                         int length)

size

public int size()

isEmpty

public boolean isEmpty()

contains

public boolean contains(java.lang.Object entry)

offset

private int offset(java.lang.Object entry)

intern

public E intern(E entry)

Internalizes the specified object by always returning the first ever stored. Equal objects with different identity (aka duplicates) can be eliminated with this method.

Parameters:

entry - the object to internalize

Returns:

the one true unique object (equal to entry)

resize

private void resize(int from)

remove

public boolean remove(java.lang.Object o)

relocate

private void relocate(int start)

clear

public void clear()

clone

public StrongInternPool<E> clone()

Overrides:

clone in class java.lang.Object

toInternalArray

public java.lang.Object[] toInternalArray()

Advanced method that returns the internal table. The resulting array will contain nulls at random places that must be skipped. In addition, it will not operate correctly if a null was inserted into the set. Use at your own risk....

Returns:

an array containing elements in this set along with randomly placed nulls,

printDebugStats

public void printDebugStats()

readObject

private void readObject(java.io.ObjectInputStream s)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException

Throws:

java.io.IOException

java.lang.ClassNotFoundException

putForCreate

private void putForCreate(E entry)

writeObject

private void writeObject(java.io.ObjectOutputStream s)
                  throws java.io.IOException

Throws:

java.io.IOException

iterator

public java.util.Iterator<E> iterator()

index

public StrongInternPool.Index index()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

forByteArrays

static StrongInternPool<byte[]> forByteArrays()

forStrings

static StrongInternPool<java.lang.String> forStrings()

forTypes

static StrongInternPool<Type> forTypes()

forTypeArrays

static StrongInternPool<Type[]> forTypeArrays()

forMethods

static StrongInternPool<MethodInternal> forMethods()

forFields

static StrongInternPool<FieldInternal> forFields()

forRecordComponents

static StrongInternPool<RecordComponentInternal> forRecordComponents()