org.sandev.basics.util
Class SingletonIDCache

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

All Implemented Interfaces:

IDCache

public class SingletonIDCache
extends IDCacheBase
implements IDCache

A singleton IDCache for shared object caching. One cache is instantiated per virtual machine. This is optimal for minimizing the overall memory footprint of the application, and for maximizing the chance that a retrieved object will be found in the cache, but is NOT recommended for multiapp or multiserver development:

• In multiapp development (multiple instances of the same application running in a shared memory space), the separate instances will end up sharing the same IDCache, leading to data crosstalk. The recommended approach in this case is to use a NamedSingletonIDCache initialized with the deployment prefix.
• In multiserver development (separate parts of one application running on different servers), you will want to run all servers collapsed onto a single box for development and testing. This won't be accurate unless you ensure that the caches stay separate when the application is collapsed. The recommended approach in this case is to use a NamedSingletonIDCache initialized with the name of the server.

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 SingletonIDCache

cache Our singleton reference

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

callback, map, revisionCheck, timeToLiveMillis

Constructor Summary

protected

SingletonIDCache() no access, default ctor.

Method Summary

static SingletonIDCache	getSingletonIDCache() return the singleton reference
protected static void	instantiateCache() Instantiate the cache.

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

checkRevisionNumber, cleanup, clear, find, getCallback, getInstance, getMap, getSortedItems, getStats, getTimeToLiveMillis, idToKey, init, putInstance, removeInstance, setCallback, setRevisionCheck, setTimeToLiveMillis

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

cleanup, clear, find, getCallback, getInstance, getMap, getStats, getTimeToLiveMillis, putInstance, removeInstance, setCallback, setTimeToLiveMillis

Field Detail

cache

protected static SingletonIDCache cache

Our singleton reference

Constructor Detail

SingletonIDCache

protected SingletonIDCache()

no access, default ctor. Does nothing.

Method Detail

getSingletonIDCache

public static SingletonIDCache getSingletonIDCache()

return the singleton reference

instantiateCache

protected static void instantiateCache()

Instantiate the 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.