Package com.atlassian.confluence.impl.cache

Class ReadThroughAtlassianCache<K,V>

java.lang.Object

com.atlassian.confluence.impl.cache.ReadThroughAtlassianCache<K,V>

All Implemented Interfaces:

ReadThroughCache<K,V>

public final class ReadThroughAtlassianCache<K,V>
extends Object
implements ReadThroughCache<K,V>

An implementation of ReadThroughCache backed by an atlassian-cache Cache.

Since:

7.5

Constructor Summary

Constructors

Constructor	Description
ReadThroughAtlassianCache(com.atlassian.cache.Cache<K,V> delegate)

Method Summary

Modifier and Type	Method	Description
static <K,V> ReadThroughAtlassianCache<K,V>	create(com.atlassian.cache.CacheFactory atlassianCacheFactory, CoreCache cacheName)
V	get(K key, Supplier<V> valueSupplier, Predicate<V> valueTester)	This is essentially an extension method for Cache.
Map<K,V>	getBulk(Set<K> keys, Function<Set<K>,Map<K,V>> valuesLoader)	Retrieves multiple values for the given keys.
void	remove(K key)	Removs the cache entry for the given key.
void	removeAll()	Removes all cache entries.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.atlassian.confluence.impl.cache.ReadThroughCache

get

Constructor Detail

ReadThroughAtlassianCache

public ReadThroughAtlassianCache(com.atlassian.cache.Cache<K,V> delegate)

Method Detail

create

public static <K,V> ReadThroughAtlassianCache<K,V> create(com.atlassian.cache.CacheFactory atlassianCacheFactory,
                                                                      CoreCache cacheName)

getBulk

public Map<K,V> getBulk(Set<K> keys,
                              Function<Set<K>,Map<K,V>> valuesLoader)

Description copied from interface: ReadThroughCache

Retrieves multiple values for the given keys. Any entries not already present in the cache will be supplied via the delegate loader.

Specified by:

getBulk in interface ReadThroughCache<K,V>

removeAll

public void removeAll()

Description copied from interface: ReadThroughCache

Removes all cache entries.

Specified by:

removeAll in interface ReadThroughCache<K,V>

remove

public void remove(K key)

Description copied from interface: ReadThroughCache

Removs the cache entry for the given key.

Specified by:

remove in interface ReadThroughCache<K,V>

get

public V get(K key,
             Supplier<V> valueSupplier,
             Predicate<V> valueTester)

This is essentially an extension method for Cache.

It provides an overloaded varant of Cache.get(Object, com.atlassian.cache.Supplier) which also takes a predicate which will be used to filter values both (a) after they're loaded from the valueSupplier, and (b) after they're retrieved from the cache.

This gives us the concept of the "uncacheable value" as well as the "stale value". These are both caching anti-patterns, but the older code in Confluence is really quite attached to these ideas and doesn't want to give them up, doesn't want to let them down, doesn't want to turn around and forget them.

Note also that the atlassian-cache API has no such concepts, i.e. the value supplier cannot return null, and whatever the supplier returns will always be added to the cache. In order to work around this, we use exceptions to escape from the stack (I know, I know, don't @ me), which are then caught and decoded. It's butt ugly, but it's contained within this doozy of a method and won't leak out.

Specified by:

get in interface ReadThroughCache<K,V>

Parameters:

key - the key to resolve in the cache

valueSupplier - A Supplier which will be called if there is no value in the cache (may return null).

valueTester - A Predicate that will be used to test the validity of any value in the cache or loaded from the supplier

Returns:

the cached value, or the value which was loaded from the supplier (may be null)