Class ReadThroughAtlassianCache<K,​V>

    • Constructor Detail

      • ReadThroughAtlassianCache

        public ReadThroughAtlassianCache​(com.atlassian.cache.Cache<K,​V> delegate)
    • Method Detail

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