com.bea.p13n.cache
Interface Cache

All Superinterfaces

CacheDefaults, CacheStats, ReloadableCache

public interface Cache
extends CacheDefaults, CacheStats, ReloadableCache

The main interface for the cache. Provides methods to add, access, and remove entries from a cache.

Cache instances are obtained from the CacheFactory.

Keys may be any object, although it is suggested that Strings or lightweight Serializable objects be used. In order to receive notifications to invalidate a particular key in the cache (from other nodes of a cluster or from Admin server), the key must be Serializable (so it can be transmitted between servers). Such keys must also have properly implemented equals() and hashcode() methods.

CAUTION: The cache data structure does not itself provide immutability of its values. In other words, it returns references to its actual objects. It is recommended that those values protect themselves from change unless that change is actually desired - remember these objects will eventually expire from the Cache.

Field Summary

Fields inherited from interface com.bea.p13n.cache.CacheDefaults

DEFAULT_ENABLED, DEFAULT_MAX_ENTRIES, DEFAULT_TTL, MAX_ENTRIES_MAX, TTL_NEVER_EXPIRE

Method Summary

void	clear() Remove all elements from the cache.
boolean	containsKey(Object key) Determines if an entry exists in the cache.
Set	entrySet() Access the values of the key/value pair of the Cache.
Object	get(Object key) Retrieve an entry in the Cache.
int	getMaxEntries() Get the max number of entries the cache can have.
String	getName() Get cache name.
long	getTtl() Get the time-to-live, in milliseconds, of entries for the cache.
boolean	isEnabled() Is the cache enabled?
Set	keySet() Access the keys of the key/value pair of the Cache.
Object	put(Object key, Object value) Put a value into the cache.
Object	put(Object key, Object value, long ttl) Put a value into the cache, with a specific time-to-live.
Object	remove(Object key) Removes a single entry from the Cache if it exists.
void	setEnabled(boolean newEnabled) Set enabled mode of cache.
void	setMaxEntries(int maxEntries) Set the max number of items the cache can have.
void	setTtl(long timeToLive) Set the default time-to-live for all elements in cache.
int	size() Size of the cache.
String	toString() Describes the attributes of the cache.

Methods inherited from interface com.bea.p13n.cache.CacheStats

getHitCount, getHitRate, getMissCount, resetStats

Methods inherited from interface com.bea.p13n.cache.ReloadableCache

getReloader, put, put, reload, setReloader, unsetReloader

Method Detail

put

Object put(Object key,
           Object value)

Put a value into the cache.

Neither the key nor the value can be null

Parameters

key - the key of the entry to create

value - the value to associate with the key

Returns

Object the previous value for the key

put

Object put(Object key,
           Object value,
           long ttl)

Put a value into the cache, with a specific time-to-live.

Neither the key nor the value can be null

Parameters

key - the key of the entry to create

value - the value to associate with the key

ttl - time-to-live, in milliseconds, of the object. This ttl overrides the default ttl for the cache, and applies only to this object.

Returns

Object the previous value for the key

get

Object get(Object key)

Retrieve an entry in the Cache. Returns null if the entry does not exist or has expired or if the cache is not enabled. Otherwise, it returns the Value associated with the key and moves the entry to the top of the LRU list (making it the most recently used object.

Parameters

key - The key of a key/value pair to retrieve from the cache.

Returns

Object the value of the key/value pair asslciated with the key, or null if the entry does not exist or has expired.

clear

void clear()

Remove all elements from the cache. For a cluster-aware flush or clear of a cache, see CacheFactory.flush(String).

remove

Object remove(Object key)

Removes a single entry from the Cache if it exists. For a cluster-aware flush or removal of cached items, see CacheFactory.flush(String, java.io.Serializable).

Parameters

key - The key of a key/value pair to remove from the cache.

Returns

The object that was removed, or null if object did not exist.

size

int size()

Size of the cache. This returns the size of the internal map. This may or may not match the size of the collection returned from the values method. The values method will strip out all expired values.

Returns

int The number of entries in the cache.

keySet

Set keySet()

Access the keys of the key/value pair of the Cache. Values that have expired are not included in this set.

Returns

Set The set of keys in the key/value entries of the cacbe.

entrySet

Set entrySet()

Access the values of the key/value pair of the Cache. Values that have expired are not included in this set.

Returns

Set The set of values of the key/value pair of the Cache.

isEnabled

boolean isEnabled()

Is the cache enabled?

Returns

boolean, true if it is enabled, flase otherwise.

setEnabled

void setEnabled(boolean newEnabled)

Set enabled mode of cache. Disabling the cache will flush the cache and cause fetch, add, and remove to do nothing.

Parameters

newEnabled - true to enable the cache, false to disable the cache.

containsKey

boolean containsKey(Object key)

Determines if an entry exists in the cache.

Parameters

key - The key of a key/value pair to check for existence in the cache.

Returns

boolean true if the object associated with that key exists in the cache, false otherwise.

getTtl

long getTtl()

Get the time-to-live, in milliseconds, of entries for the cache. Unless specified for each entry individually, the time-to-live is set upon creation of the cache and applies to all entries in the cache.

Returns

the cache's time-to-live value in milliseconds

setTtl

void setTtl(long timeToLive)

Set the default time-to-live for all elements in cache. Note that using a value of TTL_NEVER_EXPIRE, means elements will never expire.

Parameters

timeToLive - the default time to live for items in this cache , in milliseconds

getMaxEntries

int getMaxEntries()

Get the max number of entries the cache can have. The cache uses a LRU strategy, so that it will never contain more than maxEntries entries.

Returns

the maximum number of entries of the cache

setMaxEntries

void setMaxEntries(int maxEntries)

Set the max number of items the cache can have. Because the cache implements a LRU (least-recently-used) strategy, the maximum allowed value for this is defined in CacheDefaults.MAX_ENTRIES_MAX.

Parameters

maxEntries - the maximum size of the cache

getName

String getName()

Get cache name. Each cache has a unique name, and is referenced by that name. The CacheFactory maintains a collection of cache objects, and the cache name represents the key in the key/value pair in the collection.

Returns

The cache name

toString

String toString()

Describes the attributes of the cache.

Overrides:

toString in class Object

Returns

the attributes of the cache.