org.sandev.basics.util
Class IDCacheBase

java.lang.Object
  org.sandev.basics.util.IDCacheBase

All Implemented Interfaces:

IDCache

Direct Known Subclasses:

NamedSingletonIDCache, NodeLocalIDCache, SingletonIDCache

public class IDCacheBase

extends java.lang.Object

implements IDCache

Provides common methods for all IDCache implementations. This class provides utilities and a framework for cache implementation using a Map, override the init method to change what kind of map is used.

Field Summary

protected java.util.Map	map The caching data structure.
protected boolean	revisionCheck If true, then only newer revisions of a message will be accepted by put.

Constructor Summary

IDCacheBase()
Default ctor calls init

Method Summary

boolean	checkRevisionNumber() accessor for revisionCheck
void	clear() Remove all entries from this cache.
SandPersistMessage	getInstance(long id) Given a persistent ID, return the associated message instance.
java.util.Map	getMap() Return the underlying map used by the cache.
static java.lang.Object	idToKey(long id) We need an object to use as a key.
void	init() Initialize the Map to a synchronized HashMap.
boolean	putInstance(SandPersistMessage msg) Given a persistent messsage, store it in the cache.
SandPersistMessage	removeInstance(long id) Given a persistent ID, remove it from the cache.
void	setRevisionCheck(boolean val) mutator for revisionCheck

Methods inherited from class java.lang.Object

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

Field Detail

map

protected java.util.Map map

The caching data structure. See the init method.

revisionCheck

protected boolean revisionCheck

If true, then only newer revisions of a message will be accepted by put. Older or equivalent revisions will be ignored and put will return false. By default revisionCheck is true.

Constructor Detail

IDCacheBase

public IDCacheBase()

Default ctor calls init

Method Detail

checkRevisionNumber

public boolean checkRevisionNumber()

accessor for revisionCheck

setRevisionCheck

public void setRevisionCheck(boolean val)

mutator for revisionCheck

putInstance

public boolean putInstance(SandPersistMessage msg)

Description copied from interface: IDCache

Given a persistent messsage, store it in the cache. Returns true if the cached instance was replaced or added. Returns false if the instance already exists but was not replaced.

Specified by:

putInstance in interface IDCache

getInstance

public SandPersistMessage getInstance(long id)

Description copied from interface: IDCache

Given a persistent ID, return the associated message instance. Return null if the instance cannot be retrieved.

Specified by:

getInstance in interface IDCache

removeInstance

public SandPersistMessage removeInstance(long id)

Description copied from interface: IDCache

Given a persistent ID, remove it from the cache. Return null if the instance cannot be retrieved.

Specified by:

removeInstance in interface IDCache

clear

public void clear()

Description copied from interface: IDCache

Remove all entries from this cache.

Specified by:

clear in interface IDCache

getMap

public java.util.Map getMap()

Description copied from interface: IDCache

Return the underlying map used by the cache. Since this returns a live reference to the map, manipulating the map directly can invalidate or corrupt the contents of the cache. Generally the IDCache.putInstance(org.sandev.basics.structs.SandPersistMessage) and IDCache.removeInstance(long) methods should be used for cache manipulation, and this method should only be used for read-only access like iteration over the map's contents.

If the IDCache is not backed by a map, returns null.

Specified by:

getMap in interface IDCache

idToKey

public static java.lang.Object idToKey(long id)

We need an object to use as a key. From what I can tell, two separate Long objects with the same value aren't necessarily the same hash, so they don't refer to the same key. I know this works if you intern the String value, so that's what we do.

init

public void init()

Initialize the Map to a synchronized HashMap. Override to use something else.