org.sandev.basics.util
Class NamedSingletonIDCache

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

All Implemented Interfaces:

IDCache

public class NamedSingletonIDCache

extends IDCacheBase

implements IDCache

Provides singleton instances of one or more IDCaches. Instances are accessed by unique key. Using multiple caches allows multi-server deployments to run in a single VM without compromising the boundaries between server-specific or node-specific caches.

WARNING: Nodes sharing access to the same IDCache must have the same security and authorization to avoid retrieving more or less information than what should be there.

To share the same cache across multiple nodes with different authorization, write a "privileged" node to hold the cache, and then have all the client nodes get their info served from the privileged node via Authorizers.

Field Summary

protected static java.util.Hashtable

caches Map of cache instances

Fields inherited from class org.sandev.basics.util.IDCacheBase

map, revisionCheck

Constructor Summary

protected

NamedSingletonIDCache() no access, default ctor.

Method Summary

static IDCache	getSingletonIDCache(java.lang.String key) return the correct singleton cache
protected static IDCache	instantiateCache(java.lang.String key) Instantiate a cache.

Methods inherited from class org.sandev.basics.util.IDCacheBase

checkRevisionNumber, clear, getInstance, getMap, idToKey, init, putInstance, removeInstance, setRevisionCheck

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.sandev.basics.util.IDCache

clear, getInstance, getMap, putInstance, removeInstance

Field Detail

caches

protected static java.util.Hashtable caches

Map of cache instances

Constructor Detail

NamedSingletonIDCache

protected NamedSingletonIDCache()

no access, default ctor. Does nothing.

Method Detail

getSingletonIDCache

public static IDCache getSingletonIDCache(java.lang.String key)

return the correct singleton cache

instantiateCache

protected static IDCache instantiateCache(java.lang.String key)

Instantiate a cache. Make sure we only do this once. It is possible to have several threads try and instantiate the singleton at once. For a cache, it's important to prevent that from happening so you don't throw away a retrieved instance by accident.

Because of the thread lineup, the initial conditional test is actually necessary.