org.apache.jcs.auxiliary.disk.indexed
Class IndexedDiskCache

java.lang.Object
  org.apache.jcs.auxiliary.disk.AbstractDiskCache
      org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCache

All Implemented Interfaces:

AuxiliaryCache, ICache, ICacheType, java.io.Serializable

public class IndexedDiskCache

extends AbstractDiskCache

Disk cache that uses a RandomAccessFile with keys stored in memory

Version:

$Id: IndexedDiskCache.java,v 1.7 2003/08/22 11:57:17 mpoeschl Exp $

Author:

Aaron Smuts, James Taylor

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class org.apache.jcs.auxiliary.disk.AbstractDiskCache

Field Summary

(package private) IndexedDiskCacheAttributes	cattr
private IndexedDisk	dataFile
private java.lang.String	fileName
private IndexedDisk	keyFile
private java.util.HashMap	keyHash
private static org.apache.commons.logging.Log	log
private java.io.File	rafDir
protected ReadWriteLock	storageLock Each instance of a Disk cache should use this lock to synchronize reads and writes to the underlying storage mechansism.

Fields inherited from class org.apache.jcs.auxiliary.disk.AbstractDiskCache

alive, cacheEventQueue, cacheName, lock, locker, purgatory, purgHits

Fields inherited from interface org.apache.jcs.engine.behavior.ICacheType

CACHE_HUB, DISK_CACHE, LATERAL_CACHE, REMOTE_CACHE

Constructor Summary

IndexedDiskCache(IndexedDiskCacheAttributes cattr)
Constructor for the DiskCache object

Method Summary

void	doDispose() Description of the Method
protected ICacheElement	doGet(java.io.Serializable key) Get a value from the persistent store.
boolean	doRemove(java.io.Serializable key) Returns true if the removal was succesful; or false if there is nothing to remove.
void	doRemoveAll() Description of the Method
void	doUpdate(ICacheElement ce) Update the disk cache.
void	dump() For debugging.
java.util.Set	getGroupKeys(java.lang.String groupName) Gets the set of keys of objects currently in the group
int	getSize() Returns the current cache size.
private void	loadKeys() Description of the Method
private void	optimizeFile() Note: synchronization currently managed by the only caller method - dispose.
private CacheElement	readElement(java.io.Serializable key)
private void	reset() handle error by last resort, force content update, or removeall
private void	saveKeys() Saves key file to disk

Methods inherited from class org.apache.jcs.auxiliary.disk.AbstractDiskCache

dispose, get, getCacheName, getCacheType, getStatus, remove, removeAll, update

Methods inherited from class java.lang.Object

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

Field Detail

log

private static final org.apache.commons.logging.Log log

fileName

private java.lang.String fileName

dataFile

private IndexedDisk dataFile

keyFile

private IndexedDisk keyFile

keyHash

private java.util.HashMap keyHash

rafDir

private java.io.File rafDir

cattr

IndexedDiskCacheAttributes cattr

storageLock

protected ReadWriteLock storageLock

Each instance of a Disk cache should use this lock to synchronize reads and writes to the underlying storage mechansism.

Constructor Detail

IndexedDiskCache

public IndexedDiskCache(IndexedDiskCacheAttributes cattr)

Constructor for the DiskCache object

Parameters:

cattr -

Method Detail

loadKeys

private void loadKeys()
               throws java.lang.InterruptedException

Description of the Method

Throws:

java.lang.InterruptedException

saveKeys

private void saveKeys()

Saves key file to disk

doUpdate

public void doUpdate(ICacheElement ce)

Update the disk cache. Called from the Queue. Makes sure the Item has not been retireved from purgatory while in queue for disk. Remove items from purgatory when they go to disk.

Specified by:

doUpdate in class AbstractDiskCache

doGet

protected ICacheElement doGet(java.io.Serializable key)

Description copied from class: AbstractDiskCache

Get a value from the persistent store.

Specified by:

doGet in class AbstractDiskCache

Parameters:

key - Key to locate value for.

Returns:

An object matching key, or null.

See Also:

AbstractDiskCache.doGet(java.io.Serializable)

readElement

private CacheElement readElement(java.io.Serializable key)
                          throws java.lang.Exception

Throws:

java.lang.Exception

getGroupKeys

public java.util.Set getGroupKeys(java.lang.String groupName)

Description copied from interface: AuxiliaryCache

Gets the set of keys of objects currently in the group

Specified by:

getGroupKeys in interface AuxiliaryCache

Specified by:

getGroupKeys in class AbstractDiskCache

doRemove

public boolean doRemove(java.io.Serializable key)

Returns true if the removal was succesful; or false if there is nothing to remove. Current implementation always result in a disk orphan.

Specified by:

doRemove in class AbstractDiskCache

Parameters:

key -

Returns:

doRemoveAll

public void doRemoveAll()

Description of the Method

Specified by:

doRemoveAll in class AbstractDiskCache

reset

private void reset()

handle error by last resort, force content update, or removeall

doDispose

public void doDispose()

Description of the Method

Specified by:

doDispose in class AbstractDiskCache

optimizeFile

private void optimizeFile()

Note: synchronization currently managed by the only caller method - dispose.

getSize

public int getSize()

Returns the current cache size.

Specified by:

getSize in interface AuxiliaryCache

Specified by:

getSize in class AbstractDiskCache

Returns:

The size value

See Also:

ICache#getSize

dump

public void dump()

For debugging.