org.apache.jcs.auxiliary.disk.jdbc

Class JDBCDiskCache

java.lang.Object

org.apache.jcs.auxiliary.AbstractAuxiliaryCache

org.apache.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging

org.apache.jcs.auxiliary.disk.AbstractDiskCache

org.apache.jcs.auxiliary.disk.jdbc.JDBCDiskCache

All Implemented Interfaces:

java.io.Serializable, AuxiliaryCache, ICache, ICacheType

Direct Known Subclasses:

MySQLDiskCache

public class JDBCDiskCache
extends AbstractDiskCache

This is the jdbc disk cache plugin.

It expects a table created by the following script. The table name is configurable.

                       drop TABLE JCS_STORE;
                       CREATE TABLE JCS_STORE
                       (
                       CACHE_KEY                  VARCHAR(250)          NOT NULL,
                       REGION                     VARCHAR(250)          NOT NULL,
                       ELEMENT                    BLOB,
                       CREATE_TIME                DATE,
                       CREATE_TIME_SECONDS        BIGINT,
                       MAX_LIFE_SECONDS           BIGINT,
                       SYSTEM_EXPIRE_TIME_SECONDS BIGINT,
                       IS_ETERNAL                 CHAR(1),
                       PRIMARY KEY (CACHE_KEY, REGION)
                       );
 

The cleanup thread will delete non eternal items where (now - create time) > max life seconds * 1000

To speed up the deletion the SYSTEM_EXPIRE_TIME_SECONDS is used instead. It is recommended that an index be created on this column is you will have over a million records.

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, keyMatcher

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

CACHE_HUB, DISK_CACHE, LATERAL_CACHE, REMOTE_CACHE

Constructor Summary

Constructors

Constructor and Description
JDBCDiskCache(JDBCDiskCacheAttributes cattr, TableState tableState, ICompositeCacheManager compositeCacheManager) Constructs a JDBC Disk Cache for the provided cache attributes.

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	constructLikeParameterFromPattern(java.lang.String pattern)
protected int	deleteExpired() Removed the expired.
protected boolean	doesElementExist(ICacheElement ce) Does an element exist for this key?
AuxiliaryCacheAttributes	getAuxiliaryCacheAttributes() This returns the generic attributes for an auxiliary cache.
protected java.lang.String	getDiskLocation() This is used by the event logging.
IElementSerializer	getElementSerializer() Allows it to be injected.
java.util.Set	getGroupKeys(java.lang.String groupName) The keys in a group.
protected JDBCDiskCacheAttributes	getJdbcDiskCacheAttributes()
JDBCDiskCachePoolAccess	getPoolAccess() Public so managers can access it.
int	getSize() Returns the current cache size.
IStats	getStatistics() Extends the parent stats.
protected java.lang.String	getTableName() Returns the name of the table.
TableState	getTableState()
protected JDBCDiskCachePoolAccess	initializePoolAccess(JDBCDiskCacheAttributes cattr, ICompositeCacheManager compositeCacheManager) Registers the driver and creates a poolAccess class.
void	processDispose() Shuts down the pool
protected ICacheElement	processGet(java.io.Serializable key) Queries the database for the value.
protected java.util.Map	processGetMatching(java.lang.String pattern) This will run a like query.
protected boolean	processRemove(java.io.Serializable key) Returns true if the removal was successful; or false if there is nothing to remove.
protected void	processRemoveAll() This should remove all elements.
protected void	processUpdate(ICacheElement ce) Inserts or updates.
void	reset() Typically this is used to handle errors by last resort, force content update, or removeall
protected byte[]	serialize(java.io.Serializable obj) Returns the serialized form of the given object in a byte array.
void	setElementSerializer(IElementSerializer elementSerializer) Allows you to inject a custom serializer.
protected void	setJdbcDiskCacheAttributes(JDBCDiskCacheAttributes jdbcDiskCacheAttributes)
protected void	setPoolAccess(JDBCDiskCachePoolAccess poolAccess)
void	setTableState(TableState tableState)
java.lang.String	toString() For debugging.

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

dispose, doDispose, doGet, doGetMatching, doRemove, doRemoveAll, doUpdate, get, getCacheName, getCacheType, getEventLoggingExtraInfo, getMatching, getStats, 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, getKeyMatcher, logApplicationEvent, logError, logICacheEvent, setCacheEventLogger, setKeyMatcher

Methods inherited from class java.lang.Object

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

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

setCacheEventLogger

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

getMultiple, setKeyMatcher

Constructor Detail

JDBCDiskCache

public JDBCDiskCache(JDBCDiskCacheAttributes cattr,
             TableState tableState,
             ICompositeCacheManager compositeCacheManager)

Constructs a JDBC Disk Cache for the provided cache attributes. The table state object is used to mark deletions.

Parameters:

cattr -

tableState -

compositeCacheManager -

Method Detail

initializePoolAccess

protected JDBCDiskCachePoolAccess initializePoolAccess(JDBCDiskCacheAttributes cattr,
                                           ICompositeCacheManager compositeCacheManager)

Registers the driver and creates a poolAccess class.

Parameters:

cattr -

compositeCacheManager -

Returns:

JDBCDiskCachePoolAccess for testing

processUpdate

protected void processUpdate(ICacheElement ce)

Inserts or updates. By default it will try to insert. If the item exists we will get an error. It will then update. This behavior is configurable. The cache can be configured to check before inserting.

Specified by:

processUpdate in class AbstractAuxiliaryCacheEventLogging

Parameters:

ce -

doesElementExist

protected boolean doesElementExist(ICacheElement ce)

Does an element exist for this key?

Parameters:

ce -

Returns:

boolean

processGet

protected ICacheElement processGet(java.io.Serializable key)

Queries the database for the value. If it gets a result, the value is deserialized.

Specified by:

processGet in class AbstractAuxiliaryCacheEventLogging

Parameters:

key -

Returns:

ICacheElement

See Also:

AbstractDiskCache.doGet(java.io.Serializable)

processGetMatching

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

This will run a like query. It will try to construct a usable query but different implementations will be needed to adjust the syntax.

Specified by:

processGetMatching in class AbstractAuxiliaryCacheEventLogging

Parameters:

pattern -

Returns:

key,value map

constructLikeParameterFromPattern

public java.lang.String constructLikeParameterFromPattern(java.lang.String pattern)

Parameters:

pattern -

Returns:

String to use in the like query.

processRemove

protected boolean processRemove(java.io.Serializable key)

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

Specified by:

processRemove in class AbstractAuxiliaryCacheEventLogging

Parameters:

key -

Returns:

boolean

processRemoveAll

protected void processRemoveAll()

This should remove all elements. The auxiliary can be configured to forbid this behavior. If remove all is not allowed, the method balks.

Specified by:

processRemoveAll in class AbstractAuxiliaryCacheEventLogging

deleteExpired

protected int deleteExpired()

Removed the expired. (now - create time) > max life seconds * 1000

Returns:

the number deleted

reset

public void reset()

Typically this is used to handle errors by last resort, force content update, or removeall

processDispose

public void processDispose()

Shuts down the pool

Specified by:

processDispose in class AbstractAuxiliaryCacheEventLogging

getSize

public int getSize()

Returns the current cache size. Just does a count(*) for the region.

Specified by:

getSize in interface ICache

Specified by:

getSize in class AbstractDiskCache

Returns:

The size value

See Also:

ICache.getSize()

serialize

protected byte[] serialize(java.io.Serializable obj)
                    throws java.io.IOException

Returns the serialized form of the given object in a byte array.

Parameters:

obj -

Returns:

byte[]

Throws:

java.io.IOException

getGroupKeys

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

Description copied from class: AbstractDiskCache

The keys in a group.

(non-Javadoc)

Specified by:

getGroupKeys in interface AuxiliaryCache

Specified by:

getGroupKeys in class AbstractDiskCache

Parameters:

groupName -

Returns:

Set

See Also:

AuxiliaryCache.getGroupKeys(java.lang.String)

setElementSerializer

public void setElementSerializer(IElementSerializer elementSerializer)

Description copied from class: AbstractAuxiliaryCache

Allows you to inject a custom serializer. A good example would be a compressing standard serializer.

Does not allow you to set it to null.

Specified by:

setElementSerializer in interface AuxiliaryCache

Overrides:

setElementSerializer in class AbstractAuxiliaryCache

Parameters:

elementSerializer - The elementSerializer to set.

getElementSerializer

public IElementSerializer getElementSerializer()

Description copied from class: AbstractAuxiliaryCache

Allows it to be injected.

Overrides:

getElementSerializer in class AbstractAuxiliaryCache

Returns:

Returns the elementSerializer.

setJdbcDiskCacheAttributes

protected void setJdbcDiskCacheAttributes(JDBCDiskCacheAttributes jdbcDiskCacheAttributes)

Parameters:

jdbcDiskCacheAttributes - The jdbcDiskCacheAttributes to set.

getJdbcDiskCacheAttributes

protected JDBCDiskCacheAttributes getJdbcDiskCacheAttributes()

Returns:

Returns the jdbcDiskCacheAttributes.

getAuxiliaryCacheAttributes

public AuxiliaryCacheAttributes getAuxiliaryCacheAttributes()

Description copied from interface: AuxiliaryCache

This returns the generic attributes for an auxiliary cache. Most implementations will cast this to a more specific type.

Returns:

Returns the AuxiliaryCacheAttributes.

getStatistics

public IStats getStatistics()

Extends the parent stats.

Specified by:

getStatistics in interface AuxiliaryCache

Overrides:

getStatistics in class AbstractDiskCache

Returns:

IStats

See Also:

AuxiliaryCache.getStatistics()

getTableName

protected java.lang.String getTableName()

Returns the name of the table.

Returns:

the table name or UNDEFINED

setTableState

public void setTableState(TableState tableState)

Parameters:

tableState - The tableState to set.

getTableState

public TableState getTableState()

Returns:

Returns the tableState.

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.

setPoolAccess

protected void setPoolAccess(JDBCDiskCachePoolAccess poolAccess)

Parameters:

poolAccess - the poolAccess to set

getPoolAccess

public JDBCDiskCachePoolAccess getPoolAccess()

Public so managers can access it.

Returns:

the poolAccess

toString

public java.lang.String toString()

For debugging.

Overrides:

toString in class java.lang.Object

Returns:

this.getStats();