be.bagofwords.cache.fastutil

Class Long2LongOpenHashMap

java.lang.Object

be.bagofwords.cache.fastutil.AbstractLong2LongMap

be.bagofwords.cache.fastutil.Long2LongOpenHashMap

All Implemented Interfaces:

Long2LongMap, LongMap<Long>, it.unimi.dsi.fastutil.Hash, Serializable, Cloneable

public class Long2LongOpenHashMap
extends AbstractLong2LongMap
implements Serializable, Cloneable, it.unimi.dsi.fastutil.Hash

A type-specific hash map with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a map. The table is enlarged as needed by doubling its size when new entries are created, but it is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

Warning: The implementation of this class has significantly changed in fastutil 6.1.0. Please read the comments about this issue in the section “Faster Hash Tables” of the overview.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class be.bagofwords.cache.fastutil.AbstractLong2LongMap

AbstractLong2LongMap.BasicEntry

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash

it.unimi.dsi.fastutil.Hash.Strategy<K>

Nested classes/interfaces inherited from interface be.bagofwords.cache.fastutil.Long2LongMap

Long2LongMap.FastEntrySet

Nested classes/interfaces inherited from interface be.bagofwords.cache.fastutil.LongMap

LongMap.Entry<V>

Field Summary

Fields

Modifier and Type	Field and Description
protected Long2LongMap.FastEntrySet	entries Cached set of entries.
protected float	f The acceptable load factor.
protected long[]	key The array of keys.
protected it.unimi.dsi.fastutil.longs.LongSet	keys Cached set of keys.
protected int	mask The mask for wrapping a position counter.
protected int	maxFill Threshold after which we rehash.
protected int	n The current table size.
protected int	size Number of entries in the set.
protected boolean[]	used The array telling whether a position is used.
protected long[]	value The array of values.
protected it.unimi.dsi.fastutil.longs.LongCollection	values Cached collection of values.

Fields inherited from interface it.unimi.dsi.fastutil.Hash

DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR

Constructor Summary

Constructors

Constructor and Description
Long2LongOpenHashMap() Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Long2LongOpenHashMap(int expected) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Long2LongOpenHashMap(int expected, float f) Creates a new hash map.
Long2LongOpenHashMap(long[] k, long[] v) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.
Long2LongOpenHashMap(long[] k, long[] v, float f) Creates a new hash map using the elements of two parallel arrays.

Method Summary

Modifier and Type	Method and Description
void	clear()
Long2LongOpenHashMap	clone() Returns a deep copy of this map.
boolean	containsKey(long k)
boolean	containsValue(Long obj)
Long	get(long k)
int	growthFactor() Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
void	growthFactor(int growthFactor) Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
int	hashCode() Returns a hash code for this map.
boolean	isEmpty()
it.unimi.dsi.fastutil.longs.LongSet	keySet() Returns a type-specific-set view of the keys of this map.
Long2LongMap.FastEntrySet	long2LongEntrySet() Returns a type-specific set view of the mappings contained in this map.
Long	put(long k, Long ov)
boolean	rehash() Deprecated. A no-op.
protected void	rehash(int newN) Rehashes the map.
Long	remove(long k)
protected int	shiftKeys(int pos) Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
int	size()
boolean	trim() Rehashes the map, making the table as small as possible.
boolean	trim(int n) Rehashes this map if the table is too large.
it.unimi.dsi.fastutil.longs.LongCollection	values() Returns a type-specific-set view of the values of this map.

Methods inherited from class be.bagofwords.cache.fastutil.AbstractLong2LongMap

entrySet, equals, toString

Methods inherited from class java.lang.Object

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

Field Detail

key

protected transient long[] key

The array of keys.

value

protected transient long[] value

The array of values.

used

protected transient boolean[] used

The array telling whether a position is used.

f

protected final float f

The acceptable load factor.

n

protected transient int n

The current table size.

maxFill

protected transient int maxFill

Threshold after which we rehash. It must be the table size times f.

mask

protected transient int mask

The mask for wrapping a position counter.

size

protected int size

Number of entries in the set.

entries

protected transient volatile Long2LongMap.FastEntrySet entries

Cached set of entries.

keys

protected transient volatile it.unimi.dsi.fastutil.longs.LongSet keys

Cached set of keys.

values

protected transient volatile it.unimi.dsi.fastutil.longs.LongCollection values

Cached collection of values.

Constructor Detail

Long2LongOpenHashMap

public Long2LongOpenHashMap(int expected,
                            float f)

Creates a new hash map.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash set.

f - the load factor.

Long2LongOpenHashMap

public Long2LongOpenHashMap(int expected)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

expected - the expected number of elements in the hash map.

Long2LongOpenHashMap

public Long2LongOpenHashMap()

Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Long2LongOpenHashMap

public Long2LongOpenHashMap(long[] k,
                            long[] v,
                            float f)

Creates a new hash map using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

f - the load factor.

Throws:

IllegalArgumentException - if k and v have different lengths.

Long2LongOpenHashMap

public Long2LongOpenHashMap(long[] k,
                            long[] v)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

Throws:

IllegalArgumentException - if k and v have different lengths.

Method Detail

put

public Long put(long k,
                Long ov)

Specified by:

put in interface LongMap<Long>

shiftKeys

protected final int shiftKeys(int pos)

Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.

Parameters:

pos - a starting position.

Returns:

the position cleared by the shifting process.

remove

public Long remove(long k)

Specified by:

remove in interface LongMap<Long>

get

public Long get(long k)

Specified by:

get in interface LongMap<Long>

containsKey

public boolean containsKey(long k)

Specified by:

containsKey in interface LongMap<Long>

containsValue

public boolean containsValue(Long obj)

Specified by:

containsValue in interface LongMap<Long>

clear

public void clear()

Specified by:

clear in interface LongMap<Long>

size

public int size()

Specified by:

size in interface LongMap<Long>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface LongMap<Long>

Overrides:

isEmpty in class AbstractLong2LongMap

growthFactor

@Deprecated
public void growthFactor(int growthFactor)

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

A no-op for backward compatibility.

Parameters:

growthFactor - unused.

growthFactor

@Deprecated
public int growthFactor()

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

Gets the growth factor (2).

Returns:

the growth factor of this set, which is fixed (2).

See Also:

growthFactor(int)

long2LongEntrySet

public Long2LongMap.FastEntrySet long2LongEntrySet()

Description copied from interface: Long2LongMap

Returns a type-specific set view of the mappings contained in this map.

This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen Long2LongMap.entrySet() so that it returns an ObjectSet of objects of type Map.Entry (the latter makes it possible to access keys and values with type-specific methods).

Specified by:

long2LongEntrySet in interface Long2LongMap

Returns:

a type-specific set view of the mappings contained in this map.

See Also:

Long2LongMap.entrySet()

keySet

public it.unimi.dsi.fastutil.longs.LongSet keySet()

Description copied from class: AbstractLong2LongMap

Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by AbstractLong2LongMap.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

keySet in interface Long2LongMap

Specified by:

keySet in interface LongMap<Long>

Overrides:

keySet in class AbstractLong2LongMap

Returns:

a set view of the keys of this map; it may be safely cast to a type-specific interface.

See Also:

Map.keySet()

values

public it.unimi.dsi.fastutil.longs.LongCollection values()

Description copied from class: AbstractLong2LongMap

Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by AbstractLong2LongMap.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

values in interface Long2LongMap

Specified by:

values in interface LongMap<Long>

Overrides:

values in class AbstractLong2LongMap

Returns:

a set view of the values of this map; it may be safely cast to a type-specific interface.

See Also:

Map.values()

rehash

@Deprecated
public boolean rehash()

Deprecated. A no-op.

A no-op for backward compatibility. The kind of tables implemented by this class never need rehashing.

If you need to reduce the table size to fit exactly this set, use trim().

Returns:

true.

See Also:

trim()

trim

public boolean trim()

Rehashes the map, making the table as small as possible.

This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.

Returns:

true if there was enough memory to trim the map.

See Also:

trim(int)

trim

public boolean trim(int n)

Rehashes this map if the table is too large.

Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.

This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the map.

See Also:

trim()

rehash

protected void rehash(int newN)

Rehashes the map.

This method implements the basic rehashing strategy, and may be overriden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.

Parameters:

newN - the new size

clone

public Long2LongOpenHashMap clone()

Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

Overrides:

clone in class Object

Returns:

a deep copy of this map.

hashCode

public int hashCode()

Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:

hashCode in interface LongMap<Long>

Overrides:

hashCode in class AbstractLong2LongMap

Returns:

a hash code for this map.