dk.heick.caching.persistences.file

Class AbstractFilenameFileValueManager<V>

java.lang.Object

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

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

dk.heick.caching.persistences.file.AbstractFilenameFileValueManager<V>

Type Parameters:

V - the value type

All Implemented Interfaces:

ValueManager<String,V>

Direct Known Subclasses:

DefaultFilenameSerializableFileValueManager, DefaultFilenameXmlFileValueManager

public abstract class AbstractFilenameFileValueManager<V>
extends AbstractFileValueManager<String,V>

A subclass AbstractFileValueManager, where we determines that the Key is a String and its file.getName().
NOTE:
This is IMPORTANT the file name of the file is also the KEY,
hence the Key is type String, this gives the ability to restore the cache, but it also means that ANY file in the CachingDirectory and/or subdirectories the name of the file MUST be unqiue.

The value is still undetermined as a type V the their must be further implementations to save and load the value.

Since:

1.0

Author:

Frederik Heick

Constructor Summary

Constructors

Constructor and Description
AbstractFilenameFileValueManager(CachingDirectory cachingDirectory, PersistencesRestoreMethod persistencesRestoreMethod) Constructor

Method Summary

Modifier and Type	Method and Description
File	constructFile(String 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.
String	reconstructKey(File file) Reconstructs the key which is the filename.
abstract V	retrieveFileValue(DefaultFileValueWrapper<String,V> valueWrapper) Loads the value from the file in valueWrapper.
V	retrieveValue(AbstractValueWrapper<String,V> valueWrapper) Retrives value via the data contained in the ValueWrapper
abstract void	storeFileValue(DefaultFileValueWrapper<String,V> valueWrapper, String key, V value) This method shall the take the Value and stored it in a file given by the valueWrapper.
void	storeValue(AbstractValueWrapper<String,V> valueWrapper, String 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

AbstractFilenameFileValueManager

public AbstractFilenameFileValueManager(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 cacheDirectory isnt a valid directory.

NullPointerException - if persistencesRestoreMethod or cachingDirectory is null.

Method Detail

reconstructKey

public final String reconstructKey(File file)

Reconstructs the key which is the filename. 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<String,V>

Parameters:

file - the file.

Returns:

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

See Also:

File.getName()

constructFile

public final File constructFile(String key,
                                V value)

Description copied from class: AbstractFileValueManager

Constructs a file using the Key and Value.

Specified by:

constructFile in class AbstractFileValueManager<String,V>

Parameters:

key - the key

value - the value

Returns:

a file

storeValue

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

Stores the value and giving the ValueWrapper enough information to retrieve/remove it again. This methods call "storeFileValue" and "updateExpireTime".

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.

See Also:

storeFileValue(DefaultFileValueWrapper, String, Object), AbstractFileValueManager.updateExpireTime(AbstractValueWrapper, Date)

retrieveValue

public final V retrieveValue(AbstractValueWrapper<String,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.

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<String,V> valueWrapper,
                                    String 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<String,V> valueWrapper)

Loads the value from the file in valueWrapper.

Parameters:

valueWrapper - the value wrapper

Returns:

the value V.