org.agrona.collections

Class LongHashSet

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<Long>

org.agrona.collections.LongHashSet

All Implemented Interfaces:

Iterable<Long>, Collection<Long>, Set<Long>

public class LongHashSet
extends AbstractSet<Long>

Open-addressing with linear-probing expandable hash set. Allocation free in steady state use when expanded.

By storing elements as long primitives this significantly reduces memory consumption compared with Java's builtin HashSet<Long>. It implements Set<Long> for convenience, but calling functionality via those methods can add boxing overhead to your usage.

This class is not Threadsafe.

This HashSet caches its iterator object by default, so nested iteration is not supported. You can override this behaviour at construction by indicating that the iterator should not be cached.

See Also:

LongHashSet.LongIterator, Set

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	LongHashSet.LongIterator Iterator which supports unboxed access to the values via LongHashSet.LongIterator.nextValue().

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_INITIAL_CAPACITY The initial capacity used when none is specified in the constructor.

Constructor Summary

Constructors

Constructor and Description
LongHashSet() Construct a hash set with DEFAULT_INITIAL_CAPACITY, Hashing.DEFAULT_LOAD_FACTOR, and iterator caching support.
LongHashSet(int proposedCapacity) Construct a hash set with a proposed capacity, Hashing.DEFAULT_LOAD_FACTOR, and iterator caching support.
LongHashSet(int proposedCapacity, float loadFactor) Construct a hash set with a proposed initial capacity, load factor, and iterator caching support.
LongHashSet(int proposedCapacity, float loadFactor, boolean shouldAvoidAllocation) Construct a hash set with a proposed initial capacity, load factor, and indicated iterator caching support.

Method Summary

Modifier and Type	Method and Description
boolean	add(long value) Primitive specialised overload of {this#add(Long)}.
boolean	add(Long value)
boolean	addAll(Collection<? extends Long> coll)
boolean	addAll(LongHashSet coll) Alias for addAll(Collection) for the specialized case when adding another LongHashSet, avoids boxing and allocations.
int	capacity() Get the total capacity for the set to which the load factor with be a fraction of.
void	clear()
void	compact() Compact the backing arrays by rehashing with a capacity just larger than current size and giving consideration to the load factor.
boolean	contains(long value) Contains method that does not box values.
boolean	contains(Object value)
boolean	containsAll(LongHashSet other) LongHashSet specialised variant of {this#containsAll(Collection)}.
void	copy(LongHashSet that) Copye values from another LongHashSet longo this one.
LongHashSet	difference(LongHashSet other) Fast Path set difference for comparison with another LongHashSet.
boolean	equals(Object other)
int	hashCode()
boolean	isEmpty()
LongHashSet.LongIterator	iterator()
float	loadFactor() Get the load factor beyond which the set will increase size.
boolean	remove(long value) Specialised version of {this#remove(Object)} for long.
boolean	remove(Object value)
boolean	removeAll(Collection<?> coll)
boolean	removeAll(LongHashSet coll) Alias for removeAll(Collection) for the specialized case when removing another LongHashSet, avoids boxing and allocations
int	resizeThreshold() Get the actual threshold which when reached the map will resize.
int	size()
Object[]	toArray()
<T> T[]	toArray(T[] a)
String	toString()

Methods inherited from class java.util.AbstractCollection

containsAll, retainAll

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

containsAll, retainAll, spliterator

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

DEFAULT_INITIAL_CAPACITY

public static final int DEFAULT_INITIAL_CAPACITY

The initial capacity used when none is specified in the constructor.

See Also:

Constant Field Values

Constructor Detail

LongHashSet

public LongHashSet()

Construct a hash set with DEFAULT_INITIAL_CAPACITY, Hashing.DEFAULT_LOAD_FACTOR, and iterator caching support.

LongHashSet

public LongHashSet(int proposedCapacity)

Construct a hash set with a proposed capacity, Hashing.DEFAULT_LOAD_FACTOR, and iterator caching support.

Parameters:

proposedCapacity - for the initial capacity of the set.

LongHashSet

public LongHashSet(int proposedCapacity,
                   float loadFactor)

Construct a hash set with a proposed initial capacity, load factor, and iterator caching support.

Parameters:

proposedCapacity - for the initial capacity of the set.

loadFactor - to be used for resizing.

LongHashSet

public LongHashSet(int proposedCapacity,
                   float loadFactor,
                   boolean shouldAvoidAllocation)

Construct a hash set with a proposed initial capacity, load factor, and indicated iterator caching support.

Parameters:

proposedCapacity - for the initial capacity of the set.

loadFactor - to be used for resizing.

shouldAvoidAllocation - should the iterator be cached to avoid further allocation.

Method Detail

loadFactor

public float loadFactor()

Get the load factor beyond which the set will increase size.

Returns:

load factor for when the set should increase size.

capacity

public int capacity()

Get the total capacity for the set to which the load factor with be a fraction of.

Returns:

the total capacity for the set.

resizeThreshold

public int resizeThreshold()

Get the actual threshold which when reached the map will resize. This is a function of the current capacity and load factor.

Returns:

the threshold when the map will resize.

add

public boolean add(Long value)

Specified by:

add in interface Collection<Long>

Specified by:

add in interface Set<Long>

Overrides:

add in class AbstractCollection<Long>

add

public boolean add(long value)

Primitive specialised overload of {this#add(Long)}.

Parameters:

value - the value to add.

Returns:

true if the collection has changed, false otherwise.

Throws:

IllegalArgumentException - if value is missingValue.

remove

public boolean remove(Object value)

Specified by:

remove in interface Collection<Long>

Specified by:

remove in interface Set<Long>

Overrides:

remove in class AbstractCollection<Long>

remove

public boolean remove(long value)

Specialised version of {this#remove(Object)} for long.

Parameters:

value - the value to remove.

Returns:

true if the value was present, false otherwise.

compact

public void compact()

Compact the backing arrays by rehashing with a capacity just larger than current size and giving consideration to the load factor.

contains

public boolean contains(Object value)

Specified by:

contains in interface Collection<Long>

Specified by:

contains in interface Set<Long>

Overrides:

contains in class AbstractCollection<Long>

contains

public boolean contains(long value)

Contains method that does not box values.

Parameters:

value - to be checked for if the set contains it.

Returns:

true if the value is contained in the set otherwise false.

See Also:

Collection.contains(Object)

size

public int size()

Specified by:

size in interface Collection<Long>

Specified by:

size in interface Set<Long>

Specified by:

size in class AbstractCollection<Long>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<Long>

Specified by:

isEmpty in interface Set<Long>

Overrides:

isEmpty in class AbstractCollection<Long>

clear

public void clear()

Specified by:

clear in interface Collection<Long>

Specified by:

clear in interface Set<Long>

Overrides:

clear in class AbstractCollection<Long>

addAll

public boolean addAll(Collection<? extends Long> coll)

Specified by:

addAll in interface Collection<Long>

Specified by:

addAll in interface Set<Long>

Overrides:

addAll in class AbstractCollection<Long>

addAll

public boolean addAll(LongHashSet coll)

Alias for addAll(Collection) for the specialized case when adding another LongHashSet, avoids boxing and allocations.

Parameters:

coll - containing the values to be added.

Returns:

true if this set changed as a result of the call.

containsAll

public boolean containsAll(LongHashSet other)

LongHashSet specialised variant of {this#containsAll(Collection)}.

Parameters:

other - long hash set to compare against.

Returns:

true if every element in other is in this.

difference

public LongHashSet difference(LongHashSet other)

Fast Path set difference for comparison with another LongHashSet.

Note: garbage free in the identical case, allocates otherwise.

Parameters:

other - the other set to subtract.

Returns:

null if identical, otherwise the set of differences.

removeAll

public boolean removeAll(Collection<?> coll)

Specified by:

removeAll in interface Collection<Long>

Specified by:

removeAll in interface Set<Long>

Overrides:

removeAll in class AbstractSet<Long>

removeAll

public boolean removeAll(LongHashSet coll)

Alias for removeAll(Collection) for the specialized case when removing another LongHashSet, avoids boxing and allocations

Parameters:

coll - containing the values to be removed.

Returns:

true if this set changed as a result of the call.

iterator

public LongHashSet.LongIterator iterator()

Specified by:

iterator in interface Iterable<Long>

Specified by:

iterator in interface Collection<Long>

Specified by:

iterator in interface Set<Long>

Specified by:

iterator in class AbstractCollection<Long>

copy

public void copy(LongHashSet that)

Copye values from another LongHashSet longo this one.

Parameters:

that - set to copy values from.

toString

public String toString()

Overrides:

toString in class AbstractCollection<Long>

toArray

public <T> T[] toArray(T[] a)

Specified by:

toArray in interface Collection<Long>

Specified by:

toArray in interface Set<Long>

Overrides:

toArray in class AbstractCollection<Long>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<Long>

Specified by:

toArray in interface Set<Long>

Overrides:

toArray in class AbstractCollection<Long>

equals

public boolean equals(Object other)

Specified by:

equals in interface Collection<Long>

Specified by:

equals in interface Set<Long>

Overrides:

equals in class AbstractSet<Long>

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<Long>

Specified by:

hashCode in interface Set<Long>

Overrides:

hashCode in class AbstractSet<Long>