https://rifco.ru/blog/2015/01/31/persistent-key-value-%d0%b1%d0%b0%d0%b7%d0%b0-%d1%81-memcached-%d0%b8%d0%bd%d1%82%d0%b5%d1%80%d1%84%d0%b5%d0%b9%d1%81%d0%be%d0%bc/