net.yacy.cora.storage

Interface ARC<K,V>

All Superinterfaces:

java.lang.Iterable<java.util.Map.Entry<K,V>>

All Known Implementing Classes:

ComparableARC, ConcurrentARC, HashARC, SimpleARC

public interface ARC<K,V>
extends java.lang.Iterable<java.util.Map.Entry<K,V>>

This is a simple cache using two generations of hashtables to store the content with a LFU strategy. The Algorithm is described in a slightly more complex version as Adaptive Replacement Cache, "ARC". For details see http://www.almaden.ibm.com/cs/people/dmodha/ARC.pdf or http://en.wikipedia.org/wiki/Adaptive_Replacement_Cache This version omits the ghost entry handling which is described in ARC, and keeps both cache levels at the same size.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() clear the cache
boolean	containsKey(K key) check if the map contains the key
java.util.Set<java.util.Map.Entry<K,V>>	entrySet() Return a Set view of the mappings contained in this map.
V	get(K s) get a value from the cache.
java.util.Collection<K>	getKeys(V value) check if the map contains the value
int	hashCode() a hash code for this ARC
void	insert(K s, V v) put a value to the cache.
void	insertIfAbsent(K s, V v) put a value to the cache if there was not an entry before do not return a previous content value
java.util.Iterator<java.util.Map.Entry<K,V>>	iterator() iterator implements the Iterable interface the method can easily be implemented using the entrySet method
V	put(K s, V v) put a value to the cache.
V	putIfAbsent(K s, V v) put a value to the cache if there was not an entry before return a previous content value
V	remove(K s) remove an entry from the cache
int	size() get the size of the ARC.

Method Detail

size

int size()

get the size of the ARC. this returns the sum of main and ghost cache

Returns:

the complete number of entries in the ARC cache

insert

void insert(K s,
          V v)

put a value to the cache. do not return a previous content value

Parameters:

s -

v -

insertIfAbsent

void insertIfAbsent(K s,
                  V v)

put a value to the cache if there was not an entry before do not return a previous content value

Parameters:

s -

v -

putIfAbsent

V putIfAbsent(K s,
            V v)

put a value to the cache if there was not an entry before return a previous content value

Parameters:

s -

v -

Returns:

the value before inserting the new value

put

V put(K s,
    V v)

put a value to the cache.

Parameters:

s -

v -

get

V get(K s)

get a value from the cache.

Parameters:

s -

Returns:

the value

getKeys

java.util.Collection<K> getKeys(V value)

check if the map contains the value

Parameters:

value -

Returns:

the keys that have the given value

containsKey

boolean containsKey(K key)

check if the map contains the key

Parameters:

key -

Returns:

true if the map contains the key

remove

V remove(K s)

remove an entry from the cache

Parameters:

s -

Returns:

the old value

clear

void clear()

clear the cache

iterator

java.util.Iterator<java.util.Map.Entry<K,V>> iterator()

iterator implements the Iterable interface the method can easily be implemented using the entrySet method

Specified by:

iterator in interface java.lang.Iterable<java.util.Map.Entry<K,V>>

entrySet

java.util.Set<java.util.Map.Entry<K,V>> entrySet()

Return a Set view of the mappings contained in this map. This method is the basis for all methods that are implemented by a AbstractMap implementation

Returns:

a set view of the mappings contained in this map

hashCode

int hashCode()

a hash code for this ARC

Overrides:

hashCode in class java.lang.Object

Returns:

a hash code