sapphire.util

Class Cache

java.lang.Object

sapphire.util.Cache

public class Cache
extends java.lang.Object

This object allows you to store and later retrieve values from the cache. It also allows you to selectively remove items from the cache. If the system is running in a cluster, this will also remove items from the caches on the other servers. Note that *Adding* items into a cache does not add the items into the cache on other servers. If a cache does not contain a value for the supplied key, the .get() method returns null. To avoid memory leaks, a cache can have a maximum of 1000 entries. If the cache fills up beyond that it gets cleared to be filled up again. A typical usage pattern for the cache will be Cache cache = new Cache( connectionid ); String value = cache.get( "Addresses", "Fred" ) if ( value == null ) { value = .... go fetch Fred's address cache.put( "Addresses", "Fred", value ); // Lazy populate the cache } ... ... ... actionProcessor( "UpdateAddress", 1, {userid=Fred...} ) // Fred's address just changed Cache cache = new Cache( connectionid ); cache.remove( "Addresses", "Fred" ); // This will remove the cached value from all nodes in the cluster. It will be populated again lazily the next time it's needed Warning: Objects put into the cluster should be immutable or should be copied as soon as they are retrieved. This is to ensure that the code that retrieved does not modify (and potentialyl corrupt) the cached value. Any changes to the cached value will NOT be synchronized across the cluster. The cache value should instead be removed from the cache and lazily loaded on other servers as described above.

Constructor Summary

Constructors

Constructor and Description
Cache(java.io.File rakFile, java.lang.String connectionid)
Cache(java.lang.String connectionid) Constructor with a valid connectionid

Method Summary

Modifier and Type	Method and Description
void	clear(java.lang.String cacheName) Removes ALL items from the cache - and does the same across a cluster
java.lang.Object	get(java.lang.String cacheName, java.lang.String cacheKey) Gets an object out of the cluster
int	getCacheSize(java.lang.String cacheName) Returns the number of items in the cache.
java.util.Set<java.lang.String>	keySet(java.lang.String cacheName) Returns a list of all keys in the cache
void	put(java.lang.String cacheName, java.lang.String cacheKey, java.lang.Object cacheItem) Stored a value in a cache with a given key
void	remove(java.lang.String cacheName, java.lang.String cacheKey) Removes a single item from a cache and from the same cache across a cluster

Methods inherited from class java.lang.Object

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

Constructor Detail

Cache

public Cache(java.lang.String connectionid)
      throws SapphireException

Constructor with a valid connectionid

Parameters:

connectionid - A valid connectionid. Note that this cache is not specific to this connectionid. It will be shared by all users of the user's database. However a valid connectionid is required to use the cache.

Throws:

SapphireException

Cache

public Cache(java.io.File rakFile,
             java.lang.String connectionid)
      throws SapphireException

Parameters:

rakFile - Rak file for remote operation

connectionid - A valid connectionid. Note that this cache is not specific to this connectionid. It will be shared by all users of the user's database. However a valid connectionid is required to use the cache.

Throws:

SapphireException

Method Detail

put

public void put(java.lang.String cacheName,
                java.lang.String cacheKey,
                java.lang.Object cacheItem)

Stored a value in a cache with a given key

Parameters:

cacheName - The name of the cache

cacheKey - The key to use to retrieve the value from the cache

cacheItem - The Object to store in the cache

get

public java.lang.Object get(java.lang.String cacheName,
                            java.lang.String cacheKey)

Gets an object out of the cluster

Parameters:

cacheName - The name of the cache

cacheKey - The key to the stored value

Returns:

the stored value Object

keySet

public java.util.Set<java.lang.String> keySet(java.lang.String cacheName)

Returns a list of all keys in the cache

Parameters:

cacheName - The name of the cache

Returns:

all key strings as a Set

clear

public void clear(java.lang.String cacheName)

Removes ALL items from the cache - and does the same across a cluster

Parameters:

cacheName - The name of the cache

remove

public void remove(java.lang.String cacheName,
                   java.lang.String cacheKey)

Removes a single item from a cache and from the same cache across a cluster

Parameters:

cacheName - The name of the cache

cacheKey - The key to the stored value that is to be removed

getCacheSize

public int getCacheSize(java.lang.String cacheName)

Returns the number of items in the cache.

Parameters:

cacheName - The name of the cache

Returns:

the number of cache entries