LruKCache (egothor2 4.0.5-SNAPSHOT API)

java.lang.Object
- org.egothor.cache.AbstractCache<K,V>
- - org.egothor.cache.lruk.LruKCache<K,V>

Type Parameters:

K - type of the key

V - type of the value

All Implemented Interfaces:

Cache<K,V>
```
public class LruKCache<K,V>
extends AbstractCache<K,V>
```
Implementation of Cache that uses the LRU-K algorithm as an eviction policy.

Field Summary
- Fields inherited from class org.egothor.cache.AbstractCache
  DEFAULT_CAPACITY

Constructor Summary

Constructors
Constructor and Description
`LruKCache()` Constructor for the LruKCache object.
`LruKCache(int capacity, int historyCapacity, int numberOfIds)` Constructor for the LruKCache object.
`LruKCache(Resolver<K,V> resolver)` Constructor for the LruKCache object.
`LruKCache(Resolver<K,V> resolver, int capacity)` Constructor for the LruKCache object.
`LruKCache(Resolver<K,V> resolver, int capacity, int historyCapacity, int numberOfIds)` Constructor for the LruKCache object.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Removes all key-value mappings from the cache and cleans the history queue.
`boolean`	`containsKey(K key)` Checks whether the specified key is cached.
`void`	`evict()` Removes the key with the highest backward-K-distance.
`V`	`get(K key)` Gets the value associated with the specified key from the cache if a mapping exists, or the value returned by the resolver.
`int`	`historyCapacity()` Returns the maximum capacity of the history queue.
`Set<K>`	`keySet()` Gets all keys contained in the cache.
`K`	`nextEvicted()` Gets the key with the highest backward-K-distance.
`int`	`numberOfIds()` Returns the number of id's the LRU-K algorithm uses.
`V`	`put(K key, V value)` Adds a new key-value mapping to the cache.
`V`	`remove(K key)` Removes the specified key and its value from the cache.
`int`	`size()` Returns the number of key-value mappings in the cache.
`String`	`toString()` Returns a text representation of the cache.
`V`	`update(K key, V value)` Updates the value associated with the specified key in the cache if a mapping exists for the key.

Methods inherited from class org.egothor.cache.AbstractCache
capacity, getResolver, hitRatio, hits, misses, requests, resetCounters, setResolver

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - LruKCache
```
public LruKCache()
```
    Constructor for the LruKCache object. Uses default capacity, history capacity, number of id's and the resolver always returns null.
  - LruKCache
```
public LruKCache(Resolver<K,V> resolver)
```
    Constructor for the LruKCache object. Uses default capacity, history capacity and number of id's.
    
    Parameters:
    
    resolver - resolver to associate with the cache
  - LruKCache
```
public LruKCache(int capacity,
                 int historyCapacity,
                 int numberOfIds)
```
    Constructor for the LruKCache object. Resolver always returns null.
    
    Parameters:
    
    capacity - capacity of the cache
    
    historyCapacity - capacity of the history queue
    
    numberOfIds - number of id's the LRU-K algorithm should use
  - LruKCache
```
public LruKCache(Resolver<K,V> resolver,
                 int capacity)
```
    Constructor for the LruKCache object. Uses default history capacity and number of id's.
    
    Parameters:
    
    resolver - resolver to associate with the cache
    
    capacity - capacity of the cache
  - LruKCache
```
public LruKCache(Resolver<K,V> resolver,
                 int capacity,
                 int historyCapacity,
                 int numberOfIds)
          throws IllegalArgumentException
```
    Constructor for the LruKCache object.
    
    Parameters:
    
    resolver - resolver to associate with the cache
    
    capacity - capacity of the cache
    
    historyCapacity - capacity of the history queue
    
    numberOfIds - number of id's the LRU-K algorithm should use
    
    Throws:
    
    IllegalArgumentException - when history capacity is smaller or equal to zero
- Method Detail
  - put
```
public V put(K key,
             V value)
```
    Adds a new key-value mapping to the cache. If a mapping previously existed for the specified key, it is removed at first. If the cache is full, the key with the highest backward-K-distance is removed.
    
    Specified by:
    
    put in interface Cache<K,V>
    
    Overrides:
    
    put in class AbstractCache<K,V>
    
    Parameters:
    
    key - key to add to the cache
    
    value - value to map the key on
    
    Returns:
    
    previous value associated with the key or null if a previous mapping did not exists in the cache for the specified key
  - get
```
public V get(K key)
```
    Gets the value associated with the specified key from the cache if a mapping exists, or the value returned by the resolver.
    
    Specified by:
    
    get in interface Cache<K,V>
    
    Overrides:
    
    get in class AbstractCache<K,V>
    
    Parameters:
    
    key - key to get the value for
    
    Returns:
    
    value associated with the key from the cache, or from the resolver if a mapping does not exits in the cache
  - remove
```
public V remove(K key)
```
    Removes the specified key and its value from the cache.
    
    Specified by:
    
    remove in interface Cache<K,V>
    
    Overrides:
    
    remove in class AbstractCache<K,V>
    
    Parameters:
    
    key - key to remove from the cache.
    
    Returns:
    
    value associated with the key, or null if a mapping did not exist
  - update
```
public V update(K key,
                V value)
```
    Updates the value associated with the specified key in the cache if a mapping exists for the key.
    
    Specified by:
    
    update in interface Cache<K,V>
    
    Overrides:
    
    update in class AbstractCache<K,V>
    
    Parameters:
    
    key - key to change the value for
    
    value - new value associated with the key
    
    Returns:
    
    previous associated value or null if the key is not cached
  - containsKey
```
public boolean containsKey(K key)
```
    Checks whether the specified key is cached.
    
    Specified by:
    
    containsKey in interface Cache<K,V>
    
    Specified by:
    
    containsKey in class AbstractCache<K,V>
    
    Parameters:
    
    key - key to check
    
    Returns:
    
    true, if the key is currently cached, false otherwise
  - clear
```
public void clear()
```
    Removes all key-value mappings from the cache and cleans the history queue.
  - keySet
```
public Set<K> keySet()
```
    Gets all keys contained in the cache.
    
    Returns:
    
    Set of keys contained in the cache.
  - size
```
public int size()
```
    Returns the number of key-value mappings in the cache.
    
    Specified by:
    
    size in interface Cache<K,V>
    
    Specified by:
    
    size in class AbstractCache<K,V>
    
    Returns:
    
    number of key-value mappings in the cache
  - nextEvicted
```
public K nextEvicted()
```
    Gets the key with the highest backward-K-distance.
    
    Specified by:
    
    nextEvicted in interface Cache<K,V>
    
    Specified by:
    
    nextEvicted in class AbstractCache<K,V>
    
    Returns:
    
    key, that has the highest backward-K-distance
  - evict
```
public void evict()
```
    Removes the key with the highest backward-K-distance.
    
    Specified by:
    
    evict in interface Cache<K,V>
    
    Specified by:
    
    evict in class AbstractCache<K,V>
  - numberOfIds
```
public int numberOfIds()
```
    Returns the number of id's the LRU-K algorithm uses.
    
    Returns:
    
    number of id's LRU-K uses
  - historyCapacity
```
public int historyCapacity()
```
    Returns the maximum capacity of the history queue.
    
    Returns:
    
    capacity of the history queue
  - toString
```
public String toString()
```
    Returns a text representation of the cache.
    
    Specified by:
    
    toString in class AbstractCache<K,V>
    
    Returns:
    
    text representation of the cache

Class LruKCache<K,V>

Field Summary

Fields inherited from class org.egothor.cache.AbstractCache

Constructor Summary

Method Summary

Methods inherited from class org.egothor.cache.AbstractCache

Methods inherited from class java.lang.Object

Constructor Detail

LruKCache

LruKCache

LruKCache

LruKCache

LruKCache

Method Detail

put

get

remove

update

containsKey

clear

keySet

size

nextEvicted

evict

numberOfIds

historyCapacity

toString