Package org.apache.commons.jcs3.engine.memory

Class AbstractMemoryCache<K,V>

java.lang.Object

org.apache.commons.jcs3.engine.memory.AbstractMemoryCache<K,V>

All Implemented Interfaces:

IMemoryCache<K,V>

Direct Known Subclasses:

AbstractDoubleLinkedListMemoryCache, LHMLRUMemoryCache, SoftReferenceMemoryCache

public abstract class AbstractMemoryCache<K,V>
extends Object
implements IMemoryCache<K,V>

This base includes some common code for memory caches.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	chunkSize	How many to spool at a time.
protected AtomicLong	hitCnt	number of hits
protected final Lock	lock
protected Map<K,MemoryElementDescriptor<K,V>>	map	Map where items are stored by key.
protected AtomicLong	missCnt	number of misses
protected AtomicLong	putCnt	number of puts

Constructor Summary

Constructors

Constructor	Description
AbstractMemoryCache()

Method Summary

Modifier and Type	Method	Description
abstract Map<K,MemoryElementDescriptor<K,V>>	createMap()	Children must implement this method.
void	dispose()	Prepares for shutdown.
void	dumpMap()	Dump the cache map for debugging.
ICacheElement<K,V>	get(K key)	Get an item from the cache.
ICompositeCacheAttributes	getCacheAttributes()	Returns the CacheAttributes.
String	getCacheName()	Returns the cache (aka "region") name.
CompositeCache<K,V>	getCompositeCache()	Gets the cache hub / region that the MemoryCache is used by
Set<K>	getKeySet()	Get an Array of the keys for all elements in the memory cache
Map<K,ICacheElement<K,V>>	getMultiple(Set<K> keys)	Gets multiple items from the cache based on the given set of keys.
ICacheElement<K,V>	getQuiet(K key)	Get an item from the cache without affecting its last access time or position.
int	getSize()	Returns the current cache size.
IStats	getStatistics()	Returns the historical and statistical data for a region's memory cache.
void	initialize(CompositeCache<K,V> hub)	For post reflection creation initialization
protected abstract void	lockedGetElement(MemoryElementDescriptor<K,V> me)	Update control structures after get (guarded by the lock)
protected abstract void	lockedRemoveAll()	Removes all cached items from the cache control structures.
protected abstract void	lockedRemoveElement(MemoryElementDescriptor<K,V> me)	Remove element from control structure (guarded by the lock)
boolean	remove(K key)	Removes an item from the cache.
void	removeAll()	Removes all cached items from the cache.
protected boolean	removeByGroup(K key)	Remove all keys of the same group hierarchy.
protected boolean	removeByHierarchy(K key)	Remove all keys of the same name hierarchy.
void	setCacheAttributes(ICompositeCacheAttributes cattr)	Sets the CacheAttributes.
abstract void	update(ICacheElement<K,V> ce)	Puts an item to the cache.
void	waterfal(ICacheElement<K,V> ce)	Puts an item to the cache.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.jcs3.engine.memory.behavior.IMemoryCache

freeElements

Field Details

chunkSize

protected int chunkSize

How many to spool at a time.

lock

protected final Lock lock

map

protected Map<K,MemoryElementDescriptor<K,V>> map

Map where items are stored by key. This is created by the concrete child class.

hitCnt

protected AtomicLong hitCnt

number of hits

missCnt

protected AtomicLong missCnt

number of misses

putCnt

protected AtomicLong putCnt

number of puts

Constructor Details

AbstractMemoryCache

public AbstractMemoryCache()

Method Details

initialize

public void initialize(CompositeCache<K,V> hub)

For post reflection creation initialization

Specified by:

initialize in interface IMemoryCache<K,V>

Parameters:

hub -

createMap

public abstract Map<K,MemoryElementDescriptor<K,V>> createMap()

Children must implement this method. A FIFO implementation may use a tree map. An LRU might use a hashtable. The map returned should be threadsafe.

Returns:

a threadsafe Map

getMultiple

public Map<K,ICacheElement<K,V>> getMultiple(Set<K> keys)
                                      throws IOException

Gets multiple items from the cache based on the given set of keys.

Specified by:

getMultiple in interface IMemoryCache<K,V>

Parameters:

keys -

Returns:

a map of K key to ICacheElement<K, V> element, or an empty map if there is no data in cache for any of these keys

Throws:

IOException

getQuiet

public ICacheElement<K,V> getQuiet(K key)
                            throws IOException

Get an item from the cache without affecting its last access time or position. Not all memory cache implementations can get quietly.

Specified by:

getQuiet in interface IMemoryCache<K,V>

Parameters:

key - Identifies item to find

Returns:

Element matching key if found, or null

Throws:

IOException

update

public abstract void update(ICacheElement<K,V> ce)
                     throws IOException

Puts an item to the cache.

Specified by:

update in interface IMemoryCache<K,V>

Parameters:

ce - Description of the Parameter

Throws:

IOException - Description of the Exception

removeAll

public void removeAll()
               throws IOException

Removes all cached items from the cache.

Specified by:

removeAll in interface IMemoryCache<K,V>

Throws:

IOException

lockedRemoveAll

protected abstract void lockedRemoveAll()

Removes all cached items from the cache control structures. (guarded by the lock)

dispose

public void dispose()
             throws IOException

Prepares for shutdown. Reset statistics

Specified by:

dispose in interface IMemoryCache<K,V>

Throws:

IOException

getStatistics

public IStats getStatistics()

Description copied from interface: IMemoryCache

Returns the historical and statistical data for a region's memory cache.

Specified by:

getStatistics in interface IMemoryCache<K,V>

Returns:

statistics about the cache

getSize

public int getSize()

Returns the current cache size.

Specified by:

getSize in interface IMemoryCache<K,V>

Returns:

The size value

getCacheName

public String getCacheName()

Returns the cache (aka "region") name.

Returns:

The cacheName value

waterfal

public void waterfal(ICacheElement<K,V> ce)

Puts an item to the cache.

Specified by:

waterfal in interface IMemoryCache<K,V>

Parameters:

ce - the item

dumpMap

public void dumpMap()

Dump the cache map for debugging.

getCacheAttributes

public ICompositeCacheAttributes getCacheAttributes()

Returns the CacheAttributes.

Specified by:

getCacheAttributes in interface IMemoryCache<K,V>

Returns:

The CacheAttributes value

setCacheAttributes

public void setCacheAttributes(ICompositeCacheAttributes cattr)

Sets the CacheAttributes.

Specified by:

setCacheAttributes in interface IMemoryCache<K,V>

Parameters:

cattr - The new CacheAttributes value

getCompositeCache

public CompositeCache<K,V> getCompositeCache()

Gets the cache hub / region that the MemoryCache is used by

Specified by:

getCompositeCache in interface IMemoryCache<K,V>

Returns:

The cache value

removeByGroup

protected boolean removeByGroup(K key)

Remove all keys of the same group hierarchy.

Parameters:

key - the key

Returns:

true if something has been removed

removeByHierarchy

protected boolean removeByHierarchy(K key)

Remove all keys of the same name hierarchy.

Parameters:

key - the key

Returns:

true if something has been removed

lockedRemoveElement

protected abstract void lockedRemoveElement(MemoryElementDescriptor<K,V> me)

Remove element from control structure (guarded by the lock)

Parameters:

me - the memory element descriptor

remove

public boolean remove(K key)
               throws IOException

Removes an item from the cache. This method handles hierarchical removal. If the key is a String and ends with the CacheConstants.NAME_COMPONENT_DELIMITER, then all items with keys starting with the argument String will be removed.

Specified by:

remove in interface IMemoryCache<K,V>

Parameters:

key -

Returns:

true if the removal was successful

Throws:

IOException

getKeySet

public Set<K> getKeySet()

Get an Array of the keys for all elements in the memory cache

Specified by:

getKeySet in interface IMemoryCache<K,V>

Returns:

An Object[]

get

public ICacheElement<K,V> get(K key)
                       throws IOException

Get an item from the cache.

Specified by:

get in interface IMemoryCache<K,V>

Parameters:

key - Identifies item to find

Returns:

ICacheElement<K, V> if found, else null

Throws:

IOException

lockedGetElement

protected abstract void lockedGetElement(MemoryElementDescriptor<K,V> me)

Update control structures after get (guarded by the lock)

Parameters:

me - the memory element descriptor