planetj.dataengine.cache
Class CacheManager

java.lang.Object
  |
  +--planetj.dataengine.cache.CacheManager

public class CacheManager

extends Object

Manages all of the DataEngine's caches.

Field Summary

static int	CACHING_OFF Completely disables caching.
static short	CLEAR_ON_UPDATES An update, delete, or insert will remove all RowCollections retrieved from the affected table from the cache.
static boolean	cTrackCache Flag to indicate if cache tracking should be done.
static boolean	cWriteCacheToFile Flag to indicate if cache tracking should be written to a file.
static short	IGNORE_UPDATES Updates, inserts, and deletes do not affect the cache
static byte	SMART_CACHING_COMPLETE Enable smart caching across all aliases
static byte	SMART_CACHING_OFF Don't use smart caching
static byte	SMART_CACHING_PER_ALIAS Enable smart caching only within the same alias
static int	SYSTEM_LEVEL_CACHE Uses a single cache for each system

Method Summary

void	clearAll() Removes all entries from all caches.
RowCollection	get(SQLContext key) Gets a RowCollection out of the cache, based on the SQLContext.
Map	getAllCaches() Returns a Map containing all the caches being managed.
DataEngineCache	getCache(SQLContext context) Gets the appropriate cache for the SQLContext.
int	getCachingLevel() Gets the caching level.
long	getEstimatedSize() Gets the estimated number of bytes of all field values take up in every RowCollection in cache.
int	getGlobalTimeout() Gets the timeout value (in seconds) for all caches.
static CacheManager	getInstance() Gets the CacheManager instance.
byte	getSmartCachingLevel() Gets the smart caching level
short	getUpdatePolicy() Gets the update policy.
static boolean	isCacheTrackingOn() Check to see if caching should be tracked.
static boolean	isCacheTrackingWrittenToFile() Check to see if cache tracking should be written to a file.
void	put(SQLContext key, RowCollection results) Puts a RowCollection in the cache, keyed by the SQLContext.
RowCollection	remove(SQLContext key) Removes a RowCollection from the cache, based on the SQLContext.
void	rowAltered(SQLContext context, ExecutingContext ec, long timestamp) This method is invoked when a single row is deleted, inserted, or updated.
static void	setCacheTrackingOff() Turn cache tracking off.
static void	setCacheTrackingOn() Turn cache tracking on.
static void	setCacheTrackingTime(long period) Set the time period to which cache tracking is to be run
static void	setCacheTrackingWrittenToFileOff() Turn cache tracking written to file off.
static void	setCacheTrackingWrittenToFileOn() Turn cache tracking written to file on.
void	setCachingLevel(int cacheLevel) Sets the caching level.
void	setGlobalTimeout(int seconds) Sets the timeout value (in seconds) for all caches.
static void	setInstance(CacheManager instance) Sets the CacheManager instance.
void	setSmartCachingLevel(byte smartCaching) Sets the smart caching level
void	setUpdatePolicy(short pUpdatePolicy) Sets the update policy.
static CacheManager	singleton() Gets the CacheManager instance.

Methods inherited from class java.lang.Object

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

Field Detail

CACHING_OFF

public static final int CACHING_OFF

Completely disables caching.

See Also:

Constant Field Values

cTrackCache

public static boolean cTrackCache

Flag to indicate if cache tracking should be done. By default, nothing is tracked.

cWriteCacheToFile

public static boolean cWriteCacheToFile

Flag to indicate if cache tracking should be written to a file. By default, nothing is written to a file.

SYSTEM_LEVEL_CACHE

public static final int SYSTEM_LEVEL_CACHE

Uses a single cache for each system

See Also:

Constant Field Values

IGNORE_UPDATES

public static final short IGNORE_UPDATES

Updates, inserts, and deletes do not affect the cache

See Also:

Constant Field Values

CLEAR_ON_UPDATES

public static final short CLEAR_ON_UPDATES

An update, delete, or insert will remove all RowCollections retrieved from the affected table from the cache.

See Also:

Constant Field Values

SMART_CACHING_OFF

public static final byte SMART_CACHING_OFF

Don't use smart caching

See Also:

Constant Field Values

SMART_CACHING_PER_ALIAS

public static final byte SMART_CACHING_PER_ALIAS

Enable smart caching only within the same alias

See Also:

Constant Field Values

SMART_CACHING_COMPLETE

public static final byte SMART_CACHING_COMPLETE

Enable smart caching across all aliases

See Also:

Constant Field Values

Method Detail

clearAll

public void clearAll()

Removes all entries from all caches. Use caution when invoking this method.

get

public RowCollection get(SQLContext key)
                  throws DataEngineException

Gets a RowCollection out of the cache, based on the SQLContext.

Parameters:

key - The SQLContext, which is the RowCollection's key

Returns:

The RowCollection in the cache which corresponds to the SQLContext, or null if no such RowCollection exists.

DataEngineException

getAllCaches

public Map getAllCaches()

Returns a Map containing all the caches being managed. The Map is for reading purposes only, and cannot be altered. In the Map, DataEngineCache objects are keyed by their system aliases

getCache

public DataEngineCache getCache(SQLContext context)
                         throws DataEngineException

Gets the appropriate cache for the SQLContext. Right now, only a single cache per system is supported, but that may change in the future.

DataEngineException

getCachingLevel

public final int getCachingLevel()

Gets the caching level.

Returns:

One of the constants such as CACHING_OFF or SINGLE_CACHE describing what level of caching will be used.

getEstimatedSize

public long getEstimatedSize()

Gets the estimated number of bytes of all field values take up in every RowCollection in cache.

getGlobalTimeout

public int getGlobalTimeout()

Gets the timeout value (in seconds) for all caches. After they are created, caches will start out with this timeout value

getInstance

public static final CacheManager getInstance()

Gets the CacheManager instance.

getSmartCachingLevel

public byte getSmartCachingLevel()

Gets the smart caching level

getUpdatePolicy

public final short getUpdatePolicy()

Gets the update policy.

Returns:

One of the constants such as IGNORE_UPDATESor CLEAR_ON_UPDATES (the default) describing what the update policy will be

isCacheTrackingOn

public static boolean isCacheTrackingOn()

Check to see if caching should be tracked.

isCacheTrackingWrittenToFile

public static boolean isCacheTrackingWrittenToFile()

Check to see if cache tracking should be written to a file.

put

public void put(SQLContext key,
                RowCollection results)
         throws DataEngineException

Puts a RowCollection in the cache, keyed by the SQLContext.

Parameters:

key - The SQLContext, which is the RowCollection's key

DataEngineException

remove

public RowCollection remove(SQLContext key)
                     throws DataEngineException

Removes a RowCollection from the cache, based on the SQLContext.

Parameters:

key - The SQLContext, which is the RowCollection's key

Returns:

The RowCollection in the cache which corresponds to the SQLContext, or null if no such RowCollection exists.

DataEngineException

rowAltered

public void rowAltered(SQLContext context,
                       ExecutingContext ec,
                       long timestamp)
                throws CMException

This method is invoked when a single row is deleted, inserted, or updated. RowCollections are then notified so they can take appropriate action

Parameters:

context - The SQLContext containing the alteration information

ec - The current executing context

timestamp - The time associated with the alteration

CMException

setCachingLevel

public void setCachingLevel(int cacheLevel)

Sets the caching level.

Parameters:

cacheLevel - One of the constants such as CACHING_OFF or SYSTEM_LEVEL_CACHE describing what level of caching will be used.

setCacheTrackingOff

public static void setCacheTrackingOff()

Turn cache tracking off.

setCacheTrackingOn

public static void setCacheTrackingOn()

Turn cache tracking on.

setCacheTrackingTime

public static void setCacheTrackingTime(long period)

Set the time period to which cache tracking is to be run

setCacheTrackingWrittenToFileOn

public static void setCacheTrackingWrittenToFileOn()

Turn cache tracking written to file on.

setCacheTrackingWrittenToFileOff

public static void setCacheTrackingWrittenToFileOff()

Turn cache tracking written to file off.

setGlobalTimeout

public void setGlobalTimeout(int seconds)

Sets the timeout value (in seconds) for all caches. After they are created, caches will start out with this timeout value. A negative value indicates that items should never expire from the cache.

setInstance

public static void setInstance(CacheManager instance)

Sets the CacheManager instance. Invoke this method only if you want to use a subclass of CacheManager instead of the default implementation.

setSmartCachingLevel

public void setSmartCachingLevel(byte smartCaching)

Sets the smart caching level

setUpdatePolicy

public void setUpdatePolicy(short pUpdatePolicy)

Sets the update policy.

Parameters:

pUpdatePolicy - One of the constants such as IGNORE_UPDATES (the default) or CLEAR_ON_UPDATES describing what the update policy will be

singleton

public static final CacheManager singleton()

Gets the CacheManager instance.