dk.heick.caching.persistences.file

Class AbstractKeyedFileValueManager<K,V extends Keyed<K>>

java.lang.Object

dk.heick.caching.persistences.AbstractPersistenceValueManager<K,V>

dk.heick.caching.persistences.file.AbstractFileValueManager<K,V>

dk.heick.caching.persistences.file.AbstractKeyedFileValueManager<K,V>

Type Parameters:

K - the key type.

V - the value type.

All Implemented Interfaces:

ValueManager<K,V>

Direct Known Subclasses:

DefaultKeyedSerializableFileValueManager, DefaultKeyedXmlFileValueManager

public abstract class AbstractKeyedFileValueManager<K,V extends Keyed<K>>
extends AbstractFileValueManager<K,V>

A persisted file valuemanager which holds the Key to Filein the value it self.
This ValueManager works that all keys is stored in the file and the filename gets a random UUID.
This makes it easy just to persist a Object type, because the object it selfs contains the Key, but reload/restore is expensive.

Author:

Frederik Heick

Constructor Summary

Constructors

Constructor and Description
AbstractKeyedFileValueManager(CachingDirectory cachingDirectory, PersistencesRestoreMethod persistencesRestoreMethod) Constructor.

Method Summary

Modifier and Type	Method and Description
File	constructFile(K key, V value) Constructs a file using the Key and Value.
void	flush() This is ensures that any memory data that needs to be persisted is flushed.
K	reconstructKey(File file) When restoring a persisted LRUCachingMap, we need the ability to reconstruct the Key.
abstract V	retrieveFileValue(DefaultFileValueWrapper<K,V> valueWrapper) Loads the value from the file in valueWrapper.
V	retrieveValue(AbstractValueWrapper<K,V> valueWrapper) Retrives value via the data contained in the ValueWrapper
abstract void	storeFileValue(DefaultFileValueWrapper<K,V> valueWrapper, K key, V value) This method shall the take the Value and stored it in a file given by 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.

Methods inherited from class dk.heick.caching.persistences.file.AbstractFileValueManager

cast, constructWrapper, getCachingDirectory, getFile, removeAll, removeValue, restore, updateExpireTime

Methods inherited from class dk.heick.caching.persistences.AbstractPersistenceValueManager

getLogger, getPersistencesRestoreMethod, isPersisted

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractKeyedFileValueManager

public AbstractKeyedFileValueManager(CachingDirectory cachingDirectory,
                                     PersistencesRestoreMethod persistencesRestoreMethod)
                              throws IllegalArgumentException,
                                     NullPointerException

Constructor.

Parameters:

cachingDirectory - the directory where to store the cached values.

persistencesRestoreMethod - the restore method, when reconstructing the LRUCachingMap.

Throws:

IllegalArgumentException - if cachingDirectory isnt a valid directory.

NullPointerException - if persistencesRestoreMethod or cachingDirectory is null.

Method Detail

storeValue

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

Description copied from interface: ValueManager

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.

retrieveValue

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

Description copied from interface: ValueManager

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.

reconstructKey

public K reconstructKey(File file)

Description copied from class: AbstractFileValueManager

When restoring a persisted LRUCachingMap, we need the ability to reconstruct the Key.
Typical the filename is the key, otherwise it might be something in the value.
Must take the CachingDirectory into account and only use the path from the base caching directory and below:

Specified by:

reconstructKey in class AbstractFileValueManager<K,V extends Keyed<K>>

Parameters:

file - the file.

Returns:

the key based on the file, if not able to reconstruct the key, the file is deleted.

constructFile

public File constructFile(K key,
                          V value)

Description copied from class: AbstractFileValueManager

Constructs a file using the Key and Value.

Specified by:

constructFile in class AbstractFileValueManager<K,V extends Keyed<K>>

Parameters:

key - the key

value - the value

Returns:

a file

flush

public 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". Does nothing.

See Also:

LRUCachingMap.cleanup(), ValueManager.restore(LRUCachingMap)

storeFileValue

public abstract void storeFileValue(DefaultFileValueWrapper<K,V> valueWrapper,
                                    K key,
                                    V value)
                             throws RuntimeException

This method shall the take the Value and stored it in a file given by the valueWrapper.

Parameters:

valueWrapper - the value wrapper which holds the file.

key - the key.

value - the value.

Throws:

RuntimeException - if the value can not be stored in the file.

retrieveFileValue

public abstract V retrieveFileValue(DefaultFileValueWrapper<K,V> valueWrapper)

Loads the value from the file in valueWrapper.

Parameters:

valueWrapper - the value wrapper

Returns:

the value V.