org.apache.commons.jcs.auxiliary.disk.jdbc

Class JDBCDiskCache<K,V>

java.lang.Object

org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCache<K,V>

org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging<K,V>

org.apache.commons.jcs.auxiliary.disk.AbstractDiskCache<K,V>

org.apache.commons.jcs.auxiliary.disk.jdbc.JDBCDiskCache<K,V>

All Implemented Interfaces:

AuxiliaryCache<K,V>, ICache<K,V>, ICacheType

Direct Known Subclasses:

MySQLDiskCache

public class JDBCDiskCache<K,V>
extends AbstractDiskCache<K,V>

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                TIMESTAMP,
                       UPDATE_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

Nested Class Summary

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

AbstractDiskCache.MyCacheListener

Nested classes/interfaces inherited from interface org.apache.commons.jcs.engine.behavior.ICacheType

ICacheType.CacheType

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
String	constructLikeParameterFromPattern(String pattern)
protected int	deleteExpired() Removed the expired.
protected boolean	doesElementExist(ICacheElement<K,V> ce, Connection con) Does an element exist for this key?
AuxiliaryCacheAttributes	getAuxiliaryCacheAttributes() This returns the generic attributes for an auxiliary cache.
DataSource	getDataSource() Public so managers can access it.
protected String	getDiskLocation() This is used by the event logging.
IElementSerializer	getElementSerializer() Allows it to be injected.
protected JDBCDiskCacheAttributes	getJdbcDiskCacheAttributes()
Set<K>	getKeySet() Return the keys in this cache.
int	getSize() Returns the current cache size.
IStats	getStatistics() Extends the parent stats.
protected String	getTableName() Returns the name of the table.
TableState	getTableState()
void	processDispose() Shuts down the pool
protected ICacheElement<K,V>	processGet(K key) Queries the database for the value.
protected Map<K,ICacheElement<K,V>>	processGetMatching(String pattern) This will run a like query.
protected boolean	processRemove(K 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<K,V> ce) Inserts or updates.
void	reset() Typically this is used to handle errors by last resort, force content update, or removeall
void	setElementSerializer(IElementSerializer elementSerializer) Allows you to inject a custom serializer.
protected void	setJdbcDiskCacheAttributes(JDBCDiskCacheAttributes jdbcDiskCacheAttributes)
void	setTableState(TableState tableState)
String	toString() For debugging.

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

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

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

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

Methods inherited from class org.apache.commons.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

Constructor Detail

JDBCDiskCache

public JDBCDiskCache(JDBCDiskCacheAttributes cattr,
                     DataSourceFactory dsFactory,
                     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 - the configuration object for this cache

dsFactory - the DataSourceFactory for this cache

tableState - an object to track table operations

compositeCacheManager - the global cache manager

Method Detail

processUpdate

protected void processUpdate(ICacheElement<K,V> 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<K,V>

Parameters:

ce -

doesElementExist

protected boolean doesElementExist(ICacheElement<K,V> ce,
                                   Connection con)

Does an element exist for this key?

Parameters:

ce - the cache element

con - a database connection

Returns:

boolean

processGet

protected ICacheElement<K,V> processGet(K key)

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

Specified by:

processGet in class AbstractAuxiliaryCacheEventLogging<K,V>

Parameters:

key -

Returns:

ICacheElement

See Also:

AbstractDiskCache.get(Object)

processGetMatching

protected Map<K,ICacheElement<K,V>> processGetMatching(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<K,V>

Parameters:

pattern -

Returns:

key,value map

constructLikeParameterFromPattern

public String constructLikeParameterFromPattern(String pattern)

Parameters:

pattern -

Returns:

String to use in the like query.

processRemove

protected boolean processRemove(K 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<K,V>

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<K,V>

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<K,V>

getSize

public int getSize()

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

Specified by:

getSize in interface ICache<K,V>

Specified by:

getSize in class AbstractDiskCache<K,V>

Returns:

The size value

See Also:

ICache.getSize()

getKeySet

public Set<K> getKeySet()
                 throws IOException

Return the keys in this cache.

Specified by:

getKeySet in interface AuxiliaryCache<K,V>

Specified by:

getKeySet in class AbstractDiskCache<K,V>

Returns:

a set of the key type TODO This should probably be done in chunks with a range passed in. This will be a problem if someone puts a 1,000,000 or so items in a region.

Throws:

IOException - if access to the auxiliary cache fails

See Also:

AbstractDiskCache.getKeySet()

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<K,V>

Overrides:

setElementSerializer in class AbstractAuxiliaryCache<K,V>

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<K,V>

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<K,V>

Overrides:

getStatistics in class AbstractDiskCache<K,V>

Returns:

IStats

See Also:

AuxiliaryCache.getStatistics()

getTableName

protected 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 String getDiskLocation()

This is used by the event logging.

Specified by:

getDiskLocation in class AbstractDiskCache<K,V>

Returns:

the location of the disk, either path or ip.

getDataSource

public DataSource getDataSource()
                         throws SQLException

Public so managers can access it.

Returns:

the dsFactory

Throws:

SQLException - if getting a data source fails

toString

public String toString()

For debugging.

Overrides:

toString in class Object

Returns:

this.getStats();