2 layer caching.

thing.php

    protected function _get_contact_info($contact_id) {
        //check local process cache first
        if (!isset($this->_contact_info_cache[$contact_id])) {
            $memcache_key = "contact_info_cache_" . $contact_id;
            $memcache_res = $this->cache->get($memcache_key);
            //then check memcache
            if ($memcache_res) {
                $this->_contact_info_cache[$contact_id] = json_decode($memcache_res, true);
            } else {
                //fall back to DB retrieval and store in both memcache and local process cache.
                $contact_info = $this->contacts->get_contact_info($contact_id);
                $this->_contact_info_cache[$contact_id] = $contact_info;
                $this->cache->set($memcache_key, json_encode($contact_info), 3600 * 12);
            }
        }
        return $this->_contact_info_cache[$contact_id];
    }