...PHP Doctrine Cache library is a popular cache implementation that supports many different drivers such as redis, memcache, apc, mongodb and others. Doctrine ships with several common drivers that you can easily use. The ApcCache driver uses the apc_fetch, apc_exists, etc. functions that come with PHP so no additional setup is required in order to use it. The ApcuCache driver uses the apcu_fetch, apcu_exists, etc. functions that come with PHP so no additional setup is required in order to use it. The ArrayCache driver stores the cache data in PHPs memory and is not persisted anywhere.