jodd.cache

Class AbstractCacheMap<K,V>

java.lang.Object

jodd.cache.AbstractCacheMap<K,V>

All Implemented Interfaces:

Cache<K,V>

Direct Known Subclasses:

FIFOCache, LFUCache, LRUCache, TimedCache

public abstract class AbstractCacheMap<K,V>
extends java.lang.Object
implements Cache<K,V>

Default implementation of timed and size cache map. Implementations should:

• create a new cache map
• implements own prune strategy

Uses ReentrantReadWriteLock to synchronize access. Since upgrading from a read lock to the write lock is not possible, be careful withing get(Object) method.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Map<K,jodd.cache.AbstractCacheMap.CacheObject<K,V>>	cacheMap
protected int	cacheSize
protected boolean	existCustomTimeout Identifies if objects has custom timeouts.
protected int	hitCount
protected int	missCount
protected long	timeout

Constructor Summary

Constructors

Constructor and Description
AbstractCacheMap()

Method Summary

Modifier and Type	Method and Description
void	clear() Clears current cache.
protected jodd.cache.AbstractCacheMap.CacheObject<K,V>	createCacheObject(K key, V object, long timeout)
V	get(K key) Retrieves an object from the cache.
int	getHitCount() Returns hit count.
int	getMissCount() Returns miss count.
boolean	isEmpty() Returns true if cache is empty.
boolean	isFull() Returns true if max cache capacity has been reached only if cache is size limited.
protected boolean	isPruneExpiredActive() Returns true if prune of expired objects should be invoked.
protected boolean	isReallyFull(K key)
int	limit() Returns cache size or 0 if there is no size limit.
protected void	onRemove(K key, V cachedObject) Callback called on item removal.
int	prune() Prunes objects from cache and returns the number of removed objects.
protected abstract int	pruneCache() Prune implementation.
void	put(K key, V object) Adds an object to the cache with default timeout.
void	put(K key, V object, long timeout) Adds an object to the cache with specified timeout after which it becomes expired.
V	remove(K key) Removes an object from the cache and returns removed value of null if object was not in the cache or was expired.
int	size() Returns current cache size.
java.util.Map<K,V>	snapshot(boolean peek) Creates a snapshot from current cache values.
long	timeout() Returns default cache timeout or 0 if it is not set.

Methods inherited from class java.lang.Object

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

Methods inherited from interface jodd.cache.Cache

snapshot

Field Detail

cacheMap

protected java.util.Map<K,jodd.cache.AbstractCacheMap.CacheObject<K,V>> cacheMap

cacheSize

protected int cacheSize

timeout

protected long timeout

existCustomTimeout

protected boolean existCustomTimeout

Identifies if objects has custom timeouts. Should be used to determine if prune for existing objects is needed.

hitCount

protected int hitCount

missCount

protected int missCount

Constructor Detail

AbstractCacheMap

public AbstractCacheMap()

Method Detail

limit

public int limit()

Returns cache size or 0 if there is no size limit.

Specified by:

limit in interface Cache<K,V>

timeout

public long timeout()

Returns default cache timeout or 0 if it is not set. Timeout can be set individually for each object.

Specified by:

timeout in interface Cache<K,V>

isPruneExpiredActive

protected boolean isPruneExpiredActive()

Returns true if prune of expired objects should be invoked. For internal use.

put

public void put(K key,
                V object)

Adds an object to the cache with default timeout.

Specified by:

put in interface Cache<K,V>

See Also:

Cache.put(Object, Object, long)

put

public void put(K key,
                V object,
                long timeout)

Adds an object to the cache with specified timeout after which it becomes expired. If cache is full, Cache.prune() is invoked to make room for new object. Cached value must be non-null.

Specified by:

put in interface Cache<K,V>

createCacheObject

protected jodd.cache.AbstractCacheMap.CacheObject<K,V> createCacheObject(K key,
                                                                         V object,
                                                                         long timeout)

getHitCount

public int getHitCount()

Returns hit count.

getMissCount

public int getMissCount()

Returns miss count.

get

public V get(K key)

Retrieves an object from the cache. Returns null if object is not longer in cache or if it is expired.

Specified by:

get in interface Cache<K,V>

pruneCache

protected abstract int pruneCache()

Prune implementation.

prune

public final int prune()

Prunes objects from cache and returns the number of removed objects. Used strategy depends on cache implementation.

Specified by:

prune in interface Cache<K,V>

isFull

public boolean isFull()

Returns true if max cache capacity has been reached only if cache is size limited.

Specified by:

isFull in interface Cache<K,V>

isReallyFull

protected boolean isReallyFull(K key)

remove

public V remove(K key)

Removes an object from the cache and returns removed value of null if object was not in the cache or was expired.

Specified by:

remove in interface Cache<K,V>

clear

public void clear()

Clears current cache.

Specified by:

clear in interface Cache<K,V>

size

public int size()

Returns current cache size.

Specified by:

size in interface Cache<K,V>

isEmpty

public boolean isEmpty()

Returns true if cache is empty.

Specified by:

isEmpty in interface Cache<K,V>

snapshot

public java.util.Map<K,V> snapshot(boolean peek)

Creates a snapshot from current cache values. Returned values may not longer be valid or they might be already expired! Cache is locked during the snapshot creation.

Specified by:

snapshot in interface Cache<K,V>

Parameters:

peek - if set, snapshot will just peek the object and not get them (and modify last access)

onRemove

protected void onRemove(K key,
                        V cachedObject)

Callback called on item removal. The cache is still locked.