Package org.messaginghub.pooled.jms.util

Class LRUCache<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,V>

java.util.LinkedHashMap<K,V>

org.messaginghub.pooled.jms.util.LRUCache<K,V>

Type Parameters:

K - The type of the map key.

V - The type of the map value.

All Implemented Interfaces:

Serializable, Cloneable, Map<K,V>

public class LRUCache<K,V>
extends LinkedHashMap<K,V>

A Simple LRU Cache based on a LinkedHashMap. Not thread-safe.

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K extends Object,V extends Object>, AbstractMap.SimpleImmutableEntry<K extends Object,V extends Object>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Field Summary

Fields

Modifier and Type	Field	Description
protected int	maxCacheSize

Constructor Summary

Constructors

Constructor	Description
LRUCache()	Default constructor for an LRU Cache The default capacity is 10000
LRUCache(int maximumCacheSize)	Constructs a LRUCache with a maximum capacity
LRUCache(int initialCapacity, int maximumCacheSize, float loadFactor, boolean accessOrder)	Constructs an empty LRUCache instance with the specified initial capacity, maximumCacheSize,load factor and ordering mode.

Method Summary

Modifier and Type	Method	Description
int	getMaxCacheSize()
protected void	onCacheEviction(Map.Entry<K,V> eldest)	Event point used by subclasses to perform some cleanup action when an element is evicted from the cache.
protected boolean	removeEldestEntry(Map.Entry<K,V> eldest)
void	setMaxCacheSize(int maxCacheSize)

Methods inherited from class java.util.LinkedHashMap

clear, containsValue, entrySet, forEach, get, getOrDefault, keySet, replaceAll, values

Methods inherited from class java.util.HashMap

clone, compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, equals, hashCode, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Field Details

maxCacheSize

protected int maxCacheSize

Constructor Details

LRUCache

public LRUCache()

Default constructor for an LRU Cache The default capacity is 10000

LRUCache

public LRUCache(int maximumCacheSize)

Constructs a LRUCache with a maximum capacity

Parameters:

maximumCacheSize - The maximum number of elements to keep in the Cache before eviction starts.

LRUCache

public LRUCache(int initialCapacity,
 int maximumCacheSize,
 float loadFactor,
 boolean accessOrder)

Constructs an empty LRUCache instance with the specified initial capacity, maximumCacheSize,load factor and ordering mode.

Parameters:

initialCapacity - The initial capacity.

maximumCacheSize - The maximum number of elements to keep in the Cache before eviction starts.

loadFactor - The load factor to configure on the underlying map.

accessOrder - the ordering mode true for access-order, false for insertion-order.

Throws:

IllegalArgumentException - if the initial capacity is negative or the load factor is non-positive.

Method Details

getMaxCacheSize

public int getMaxCacheSize()

Returns:

Returns the maxCacheSize.

setMaxCacheSize

public void setMaxCacheSize(int maxCacheSize)

Parameters:

maxCacheSize - The maxCacheSize to set.

removeEldestEntry

protected boolean removeEldestEntry(Map.Entry<K,V> eldest)

Overrides:

removeEldestEntry in class LinkedHashMap<K,V>

onCacheEviction

protected void onCacheEviction(Map.Entry<K,V> eldest)

Event point used by subclasses to perform some cleanup action when an element is evicted from the cache.

Parameters:

eldest - the item being evicted from the LRUCache.