sillypog

/**
 * Speed up retrieval of rankable objects with a cache.
 *
 * We have a primary data store which implements the DataSource interface.
 * Any class implementing this interface is likely to be slow as it has to
 * fetch the data from disk or across the network. Therefore, it will be
 * useful to temporarily store some of that data in a faster, in memory
 * cache. This cache is not big enough to store all of the data from the
 * primary store though.
 *