org.apache.jcs.auxiliary.disk.block
Class BlockDiskCache

java.lang.Object
  org.apache.jcs.auxiliary.AbstractAuxiliaryCache
      org.apache.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging
          org.apache.jcs.auxiliary.disk.AbstractDiskCache
              org.apache.jcs.auxiliary.disk.block.BlockDiskCache

All Implemented Interfaces:

java.io.Serializable, AuxiliaryCache, ICache, ICacheType

public class BlockDiskCache
extends AbstractDiskCache

There is one BlockDiskCache per region. It manages the key and data store.

Author:

Aaron Smuts

See Also:

Serialized Form

Field Summary

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

alive, cacheEventQueue, cacheName, purgatory, purgHits

Fields inherited from class org.apache.jcs.auxiliary.AbstractAuxiliaryCache

cacheEventLogger, elementSerializer, keyMatcher

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

CACHE_HUB, DISK_CACHE, LATERAL_CACHE, REMOTE_CACHE

Constructor Summary

BlockDiskCache(BlockDiskCacheAttributes cacheAttributes)
Constructs the BlockDisk after setting up the root directory.

Method Summary

protected void	freeBlocks(int[] blocksToFree) Add these blocks to the emptyBlock list.
AuxiliaryCacheAttributes	getAuxiliaryCacheAttributes() Returns the attributes.
protected java.lang.String	getDiskLocation() This is used by the event logging.
java.util.Set	getGroupKeys(java.lang.String groupName) This requires a full iteration through the keys.
int	getSize() Returns the number of keys.
IStats	getStatistics() Returns info about the disk cache.
java.lang.String	getStats() Gets basic stats for the disk cache.
void	processDispose() Dispose of the disk cache in a background thread.
protected ICacheElement	processGet(java.io.Serializable key) Gets the ICacheElement for the key if it is in the cache.
java.util.Map	processGetMatching(java.lang.String pattern) Gets matching items from the cache.
protected boolean	processRemove(java.io.Serializable key) Returns true if the removal was succesful; or false if there is nothing to remove.
protected void	processRemoveAll() Resets the keyfile, the disk file, and the memory key map.
protected void	processUpdate(ICacheElement element) Writes an element to disk.
protected boolean	verifyDisk() We need to verify that the file on disk uses the same block size and that the file is the proper size.

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

dispose, doDispose, doGet, doGetMatching, doRemove, doRemoveAll, doUpdate, get, getCacheName, getCacheType, getEventLoggingExtraInfo, getMatching, getStatus, processGetMultiple, remove, removeAll, update

Methods inherited from class org.apache.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging

disposeWithEventLogging, getMatchingWithEventLogging, getMultiple, getMultipleWithEventLogging, getWithEventLogging, removeAllWithEventLogging, removeWithEventLogging, updateWithEventLogging

Methods inherited from class org.apache.jcs.auxiliary.AbstractAuxiliaryCache

createICacheEvent, createICacheEvent, getCacheEventLogger, getElementSerializer, getKeyMatcher, logApplicationEvent, logError, logICacheEvent, setCacheEventLogger, setElementSerializer, setKeyMatcher

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jcs.auxiliary.AuxiliaryCache

setCacheEventLogger, setElementSerializer

Methods inherited from interface org.apache.jcs.engine.behavior.ICache

getMultiple, setKeyMatcher

Constructor Detail

BlockDiskCache

public BlockDiskCache(BlockDiskCacheAttributes cacheAttributes)

Constructs the BlockDisk after setting up the root directory.

Parameters:

cacheAttributes -

Method Detail

verifyDisk

protected boolean verifyDisk()

We need to verify that the file on disk uses the same block size and that the file is the proper size.

Returns:

true if it looks ok

getGroupKeys

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

This requires a full iteration through the keys.

(non-Javadoc)

Specified by:

getGroupKeys in interface AuxiliaryCache

Specified by:

getGroupKeys in class AbstractDiskCache

Returns:

a set of group keys

See Also:

AbstractDiskCache.getGroupKeys(java.lang.String)

processGetMatching

public java.util.Map processGetMatching(java.lang.String pattern)

Gets matching items from the cache.

Specified by:

processGetMatching in class AbstractAuxiliaryCacheEventLogging

Parameters:

pattern -

Returns:

a map of Serializable key to ICacheElement element, or an empty map if there is no data in cache matching keys

getSize

public int getSize()

Returns the number of keys.

(non-Javadoc)

Specified by:

getSize in interface ICache

Specified by:

getSize in class AbstractDiskCache

Returns:

the number of items.

See Also:

AbstractDiskCache.getSize()

processGet

protected ICacheElement processGet(java.io.Serializable key)

Gets the ICacheElement for the key if it is in the cache. The program flow is as follows:

1. Make sure the disk cache is alive.
2. Get a read lock.
3. See if the key is in the key store.
4. If we found a key, ask the BlockDisk for the object at the blocks..
5. Release the lock.

(non-Javadoc)

Specified by:

processGet in class AbstractAuxiliaryCacheEventLogging

Parameters:

key -

Returns:

ICacheElement

See Also:

AbstractDiskCache.doGet(java.io.Serializable)

processUpdate

protected void processUpdate(ICacheElement element)

Writes an element to disk. The program flow is as follows:

1. Aquire write lock.
2. See id an item exists for this key.
3. If an itme already exists, add its blocks to the remove list.
4. Have the Block disk write the item.
5. Create a descriptor and add it to the key map.
6. Release the write lock.

(non-Javadoc)

Specified by:

processUpdate in class AbstractAuxiliaryCacheEventLogging

Parameters:

element -

See Also:

AbstractDiskCache.doUpdate(org.apache.jcs.engine.behavior.ICacheElement)

processRemove

protected boolean processRemove(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.

(non-Javadoc)

Specified by:

processRemove in class AbstractAuxiliaryCacheEventLogging

Parameters:

key -

Returns:

true if removed anything

See Also:

AbstractDiskCache.doRemove(java.io.Serializable)

processRemoveAll

protected void processRemoveAll()

Resets the keyfile, the disk file, and the memory key map.

(non-Javadoc)

Specified by:

processRemoveAll in class AbstractAuxiliaryCacheEventLogging

See Also:

AbstractDiskCache.doRemoveAll()

processDispose

public void processDispose()

Dispose of the disk cache in a background thread. Joins against this thread to put a cap on the disposal time.

TODO make dispose window configurable.

Specified by:

processDispose in class AbstractAuxiliaryCacheEventLogging

getAuxiliaryCacheAttributes

public AuxiliaryCacheAttributes getAuxiliaryCacheAttributes()

Returns the attributes.

(non-Javadoc)

Returns:

the attributes for the auxiliary cache

See Also:

AuxiliaryCache.getAuxiliaryCacheAttributes()

freeBlocks

protected void freeBlocks(int[] blocksToFree)

Add these blocks to the emptyBlock list.

Parameters:

blocksToFree -

getStats

public java.lang.String getStats()

Gets basic stats for the disk cache.

Specified by:

getStats in interface ICache

Overrides:

getStats in class AbstractDiskCache

Returns:

String

getStatistics

public IStats getStatistics()

Returns info about the disk cache.

(non-Javadoc)

Specified by:

getStatistics in interface AuxiliaryCache

Overrides:

getStatistics in class AbstractDiskCache

Returns:

the historical and statistical data for a region's auxiliary cache.

See Also:

AuxiliaryCache.getStatistics()

getDiskLocation

protected java.lang.String getDiskLocation()

This is used by the event logging.

Specified by:

getDiskLocation in class AbstractDiskCache

Returns:

the location of the disk, either path or ip.