Store sessions in database #3165
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Sessions are currently saved to memcached. The drawback of this setup is that sessions disappear on reboot or restart of memcached daemon, which makes server updates not very seamless. Besides, this setup prevents us from invalidating existing sessions, such as after a password update or user ban. So we need to store sessions to databse instead. Enters ComboSession, copied from CakePHP docs [1]. It both reads sessions from memcached and database, which allows seamless transition from memcached to database (strictly speaking, from memcached to memcached-assisted database). Not sure why, but I had to remove PHP-FPM ini session config in order to have session_set_save_handler() work and get this whole thing to work. The sessions table schema comes from CakePHP [2]. [1] https://book.cakephp.org/3/en/development/sessions.html#creating-a-custom-session-handler [2] https://github.com/cakephp/app/blob/d2d6a243a4a975bb89355d083ee2e9fd8315f308/config/schema/sessions.sql
This will allow invalidating sessions for a given user.
Since Cache::gc() returns void, parent::gc() was never called and garbage collection was never executed.
Sessions are going to pile up in the database, so we need to clean them up regularly. PHP has a built-in probability-based garbage collector triggered randomly, the probability equals to session.gc_probability / session.gc_divisor. The downside of that approach is that some unlucky request will have to do all the cleanup work for everybody every now and then. By the way, Debian purposely sets the probability to zero and provides its own garbage collection script (in /usr/lib/php/sessionclean), but that script is for the built-in file-based session handler that uses /var/lib/php/sessions by default. Since we use a custom session handler, here is a custom cleanup script, which should work for any CakePHP app in theory.
localhost resolves to both ::1 and 127.0.0.1, but our memcached is configured to only listen on IPv4. As a result, when using localhost as value for host, CakePHP tries connecting to ::1 first, which fails, and then tries connecting to 127.0.0.1. This commits avoids the unnecessary connection to ::1.
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Solves #3160.