* If $paths is given, then only the cache for those files will be cleared.
*
* @param $paths Array Storage paths
+ * @return void
*/
abstract public function clearCache( array $paths = null );
/**
* Prune the cache if it is too big to add an item
+ *
+ * @return void
*/
protected function trimCache() {
if ( count( $this->cache ) >= $this->maxCacheSize ) {