dk.heick.caching

Interface ValueManager<K,V>

Type Parameters:

K - the key type.

V - the value type.

All Known Implementing Classes:

AbstractFilenameFileValueManager, AbstractFileValueManager, AbstractIndexedFileValueManager, AbstractKeyedFileValueManager, AbstractPersistenceValueManager, DefaultFilenameFileReferenceValueManager, DefaultFilenameSerializableFileValueManager, DefaultFilenameXmlFileValueManager, DefaultGroupJPAEntityValueManager, DefaultIndexedSerializableFileValueManager, DefaultIndexedXmlFileValueManager, DefaultJPAEntityValueManager, DefaultKeyedSerializableFileValueManager, DefaultKeyedXmlFileValueManager, DefaultMemoryValueManager

public interface ValueManager<K,V>

The interface ValueManagers, which handles how a Value (V) is stored.

Author:

Frederik Heick

See Also:

AbstractValueWrapper

Method Summary

Modifier and Type	Method and Description
AbstractValueWrapper<K,V>	constructWrapper(K key, V value) Construct a ValueWrapper for the value, but do not sets the value, this is done either in "restore" or "storeValue"
void	flush() This is ensures that any memory data that needs to be persisted is flushed.
Logger	getLogger() A logger for getting metrics on how the caching is performing.
boolean	isPersisted() Determine if the values is in a persistence storage.
int	removeAll() Remove all persisted values from the value "storage".
void	removeValue(AbstractValueWrapper<K,V> valueWrapper) Removes the value
void	restore(LRUCachingMap<K,V> map) Restores any persisted key/values to the LRUCachingMap when the map is constructed.
V	retrieveValue(AbstractValueWrapper<K,V> valueWrapper) Retrives value via the data contained in the ValueWrapper
void	storeValue(AbstractValueWrapper<K,V> valueWrapper, K key, V value, Date expireDateTime) Stores the value and giving the ValueWrapper enough information to retrieve/remove it again.
void	updateExpireTime(AbstractValueWrapper<K,V> valueWrapper, Date expireDateTime) Update the expiration date time for a value.

Method Detail

restore

void restore(LRUCachingMap<K,V> map)

Restores any persisted key/values to the LRUCachingMap when the map is constructed.
This is used if your values is stored in a persistence storage like a file etc.
This method should find all persistence instances and reinitialize the "map" using the method "restoreCacheElement(K,AbstractValueWrapper<K,V>,Date)".
This method must call the "flush" method when done.

Parameters:

map - the map instance.

See Also:

LRUCachingMap.restoreCacheElement(Object, AbstractValueWrapper, Date), PersistencesRestoreMethod, AbstractPersistenceValueManager, flush()

isPersisted

boolean isPersisted()

Determine if the values is in a persistence storage.

Returns:

true if value is stored in a persistence storage an can be recovered after "reboot", otherwise false.

constructWrapper

AbstractValueWrapper<K,V> constructWrapper(K key,
                                           V value)

Construct a ValueWrapper for the value, but do not sets the value, this is done either in "restore" or "storeValue"

Parameters:

key - the key

value - the value

Returns:

a ValueWrapper instance.

See Also:

restore(LRUCachingMap), storeValue(AbstractValueWrapper, Object, Object, Date)

storeValue

void storeValue(AbstractValueWrapper<K,V> valueWrapper,
                K key,
                V value,
                Date expireDateTime)
         throws RuntimeException

Stores the value and giving the ValueWrapper enough information to retrieve/remove it again.

Parameters:

valueWrapper - the wrapper instance to store the value or information about the value, this can be used to minimize the memory footprint.

key - the key

value - the value

expireDateTime - the expiration datetime for the key, this can be stored on a persisted key/value and used in case of a restore.

Throws:

RuntimeException - if for any reason the value could not be store.

removeValue

void removeValue(AbstractValueWrapper<K,V> valueWrapper)
          throws RuntimeException

Removes the value

Throws:

RuntimeException - if for any reason the value could not be removed.

retrieveValue

V retrieveValue(AbstractValueWrapper<K,V> valueWrapper)
         throws RuntimeException

Retrives value via the data contained in the ValueWrapper

Parameters:

valueWrapper - the

Returns:

the Value

Throws:

RuntimeException - if for any reason the value could not be retrieved.

updateExpireTime

void updateExpireTime(AbstractValueWrapper<K,V> valueWrapper,
                      Date expireDateTime)
               throws RuntimeException

Update the expiration date time for a value.

Parameters:

valueWrapper - the wrapper which holds enough information to get the value.

expireDateTime - the new expireDateTime

Throws:

RuntimeException - if this for any reasons fails.

removeAll

int removeAll()

Remove all persisted values from the value "storage".

Returns:

the number of values is removed.

flush

void flush()

This is ensures that any memory data that needs to be persisted is flushed.
This is the case with Indexed value managers.
This method must be called by the LRUCachingMap implementation after "cleanup" and after "restore".

See Also:

LRUCachingMap.cleanup(), restore(LRUCachingMap)

getLogger

Logger getLogger()

A logger for getting metrics on how the caching is performing.

Returns:

a logger instance.