dk.heick.caching.persistences.file

Class AbstractFileValueManager<K,V>

java.lang.Object

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

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

Type Parameters:

K - the key type.

V - the value type.

All Implemented Interfaces:

ValueManager<K,V>

Direct Known Subclasses:

AbstractFilenameFileValueManager, AbstractIndexedFileValueManager, AbstractKeyedFileValueManager, DefaultFilenameFileReferenceValueManager

public abstract class AbstractFileValueManager<K,V>
extends AbstractPersistenceValueManager<K,V>

ValueWrapper to stored values in a file.
This class will handle load,save and delete of the value which will be stored in a file.
This will cache file in a directory.
On restore:

• PersistencesRestoreMethod.NONE: No restore is performed. Files is left in the caching directory.
• PersistencesRestoreMethod.DELETE_ALL: Deleting all the files in the caching directory and sub directories if stated.
• PersistencesRestoreMethod.LOAD_ALL: Load all files from the caching directory and sub directories. The next cleanup handles the cache.
• PersistencesRestoreMethod.LOAD_WITHIN_EXPIRETIME: Load all files from the caching directory and sub directories where "File.lastModified" is below "new Date().getTime() + expireTime".

Author:

Frederik Heick

See Also:

File.lastModified(), LRUCachingMapConfiguration.getExpireTime(), CachingDirectory.isRecursive()

Constructor Summary

Constructors

Constructor and Description
AbstractFileValueManager(CachingDirectory cachingDirectory, PersistencesRestoreMethod persistencesRestoreMethod) Constructor - see class description.

Method Summary

Modifier and Type	Method and Description
DefaultFileValueWrapper<K,V>	cast(AbstractValueWrapper<K,V> valueWrapper) A convience method that cast the "AbstractValueWrapper" to a "DefaultFileValueWrapper"
abstract File	constructFile(K key, V value) Constructs a file using the Key and Value.
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"
CachingDirectory	getCachingDirectory() The directory to store the Value as a file.
File	getFile(AbstractValueWrapper<K,V> valueWrapper) Gets the file where the value is stored.
abstract K	reconstructKey(File file) When restoring a persisted LRUCachingMap, we need the ability to reconstruct the Key.
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.
void	updateExpireTime(AbstractValueWrapper<K,V> valueWrapper, Date expireDateTime) Update the expiration date time for a value.

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

Methods inherited from interface dk.heick.caching.ValueManager

flush, retrieveValue, storeValue

Constructor Detail

AbstractFileValueManager

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

Constructor - see class description.

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.

See Also:

CachingDirectory.validate()

Method Detail

getCachingDirectory

public final CachingDirectory getCachingDirectory()

The directory to store the Value as a file.

Returns:

the cache directory.

restore

public final void restore(LRUCachingMap<K,V> map)

Description copied from interface: ValueManager

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, ValueManager.flush()

constructWrapper

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

Description copied from interface: ValueManager

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:

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

removeValue

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

Description copied from interface: ValueManager

Removes the value

Throws:

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

removeAll

public int removeAll()

Description copied from interface: ValueManager

Remove all persisted values from the value "storage".

Returns:

the number of values is removed.

updateExpireTime

public final void updateExpireTime(AbstractValueWrapper<K,V> valueWrapper,
                                   Date expireDateTime)

Description copied from interface: ValueManager

Update the expiration date time for a value.

Parameters:

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

expireDateTime - the new expireDateTime

cast

public final DefaultFileValueWrapper<K,V> cast(AbstractValueWrapper<K,V> valueWrapper)

A convience method that cast the "AbstractValueWrapper" to a "DefaultFileValueWrapper"

Parameters:

valueWrapper - AbstractValueWrapper

Returns:

a casted version of "AbstractValueWrapper" to "DefaultFileValueWrapper".

getFile

public final File getFile(AbstractValueWrapper<K,V> valueWrapper)

Gets the file where the value is stored.

Parameters:

valueWrapper - the which is a (DefaultFileValueWrapper)

Returns:

the file in the DefaultFileValueWrapper.

reconstructKey

public abstract K reconstructKey(File file)

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:

Parameters:

file - the file.

Returns:

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

constructFile

public abstract File constructFile(K key,
                                   V value)

Constructs a file using the Key and Value.

Parameters:

key - the key

value - the value

Returns:

a file