Package org.deltava.util.cache

Class ExpiringCache<T extends Cacheable>

java.lang.Object

org.deltava.util.cache.Cache<T>

org.deltava.util.cache.ExpiringCache<T>

Type Parameters:

T - the Cacheable object type

Direct Known Subclasses:

ExpiringGeoCache

public class ExpiringCache<T extends Cacheable>
extends Cache<T>

An object cache that supports expiration dates.

Since:

1.0

Version:

11.0

Author:

Luke

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	ExpiringCache.ExpiringLocalCacheEntry<U extends T>
protected class	ExpiringCache.ExpiringNullCacheEntry<U extends T>	A null cache entry for expiring caches.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	_expiry
protected long	_lastCreationTime

Fields inherited from class org.deltava.util.cache.Cache

_cache

Constructor Summary

Constructors

Constructor	Description
ExpiringCache(int maxSize, int expiryTime)	Creates a new Cache.

Method Summary

Modifier and Type	Method	Description
protected void	addEntry(T obj)	Adds an entry to the cache.
protected void	addNullEntry(Object key)	Adds a null entry to the cache.
protected void	checkOverflow()	Purges expired entries from the cache.
boolean	contains(Object key)	Returns if the cache contains a particular cache key and the key has not expired.
T	get(Object key)	Returns an unexpired entry from the cache.
T	get(Object key, boolean ifExpired)	Returns an entry from the cache.
boolean	isExpired(Object key)	Queries the cache to determine if an object has expired
void	setExpiration(int expiry)	Sets the cache's expiration interval.

Methods inherited from class org.deltava.util.cache.Cache

add, addAll, addNull, clear, getErrors, getHits, getMaxSize, getRequests, hit, isRemote, remove, request, setMaxSize, size

Methods inherited from class java.lang.Object

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

Field Details

_lastCreationTime

protected long _lastCreationTime

_expiry

protected int _expiry

Constructor Details

ExpiringCache

public ExpiringCache(int maxSize,
 int expiryTime)

Creates a new Cache.

Parameters:

maxSize - the maximum number of entries

expiryTime - the expiration time in seconds

Throws:

IllegalArgumentException - if maxSize or expiryTime are zero or negative

See Also:

• Cache.setMaxSize(int)
• setExpiration(int)

Method Details

setExpiration

public void setExpiration(int expiry)

Sets the cache's expiration interval.

Parameters:

expiry - the expiration interval in seconds

get

public T get(Object key)

Returns an unexpired entry from the cache.

Specified by:

get in class Cache<T extends Cacheable>

Parameters:

key - the cache key

Returns:

the cache entry, or null if not present or expired

See Also:

• get(Object, boolean)

contains

public boolean contains(Object key)

Returns if the cache contains a particular cache key and the key has not expired.

Overrides:

contains in class Cache<T extends Cacheable>

Parameters:

key - the cache key

Returns:

TRUE if the cache contains the key, otherwise FALSE

get

public T get(Object key,
 boolean ifExpired)

Returns an entry from the cache.

Parameters:

key - the cache key

ifExpired - TRUE if expired entries can be returned, otherwise FALSE

Returns:

the cache entry, or null if not present

See Also:

• get(Object)
• isExpired(Object)

isExpired

public boolean isExpired(Object key)

Queries the cache to determine if an object has expired

Parameters:

key - the cache key

Returns:

TRUE if the object is present and expired, otherwise FALSE

addEntry

protected void addEntry(T obj)

Adds an entry to the cache. If this operation would cause the cache to exceed its maximum size, then the entry with the earliest expiration date will be removed.

Specified by:

addEntry in class Cache<T extends Cacheable>

Parameters:

obj - the entry to add to the cache

addNullEntry

protected void addNullEntry(Object key)

Adds a null entry to the cache.

Specified by:

addNullEntry in class Cache<T extends Cacheable>

Parameters:

key - the entry key

checkOverflow

protected void checkOverflow()

Purges expired entries from the cache.

Overrides:

checkOverflow in class Cache<T extends Cacheable>