io.neba.core.util

Class ConcurrentDistinctMultiValueMap<K,V>

java.lang.Object

io.neba.core.util.ConcurrentDistinctMultiValueMap<K,V>

Type Parameters:

K - The key's type.

V - The value's type.

public class ConcurrentDistinctMultiValueMap<K,V>
extends Object

A thread-safe storage for key -> value associations. Unlike ConcurrentHashMap, this map synchronizes writes since the multi-value associations require two independent read/writes to the map state; one to retrieve an existing collection, a second one to add another value to it.
Note that it is not save to modify the contents of the collection returned by this map since it is still based on the contents of this map and not a shallow copy for performance considerations.
In addition, the values stored in this map are distinct, i.e. if a value already exists in the values collection it is removed prior to the insertion of the new element.

Author:

Olaf Otto

Constructor Summary

Constructors

Constructor and Description
ConcurrentDistinctMultiValueMap()

Method Summary

Methods

Modifier and Type	Method and Description
void	clear()
Set<Map.Entry<K,Collection<V>>>	entrySet()
Collection<V>	get(K key)
Map<K,Collection<V>>	getContents()
boolean	isEmpty()
void	put(K key, Collection<V> values)
void	put(K key, V value)
Collection<V>	remove(K key)
int	size()
Collection<Collection<V>>	values()

Methods inherited from class java.lang.Object

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

Constructor Detail

ConcurrentDistinctMultiValueMap

public ConcurrentDistinctMultiValueMap()

Method Detail

get

public Collection<V> get(K key)

put

public void put(K key,
       V value)

clear

public void clear()

remove

public Collection<V> remove(K key)

entrySet

public Set<Map.Entry<K,Collection<V>>> entrySet()

values

public Collection<Collection<V>> values()

put

public void put(K key,
       Collection<V> values)

getContents

public Map<K,Collection<V>> getContents()

Returns:

a shallow copy of the current state of this map. Note that the map values (the collection) are also copied; it is thus save to modify the state of the returned map and the state of the collections returned as the map values. Never returns null.

size

public int size()

isEmpty

public boolean isEmpty()