yii\i18n\DbMessageSource::loadMessages PHP Method

    protected function loadMessages($category, $language)
    {
        if ($this->enableCaching) {
            $key = [__CLASS__, $category, $language];
            $messages = $this->cache->get($key);
            if ($messages === false) {
                $messages = $this->loadMessagesFromDb($category, $language);
                $this->cache->set($key, $messages, $this->cachingDuration);
            }
            return $messages;
        } else {
            return $this->loadMessagesFromDb($category, $language);
        }
    }