Please look at this session handler class

PHP
1

Hello!
Just came across this class that lets you use mysql as php session handler.
Please look at it and maybe you can answer my question:

Why does it have extra methods for obtaining some type of lock on a session?
Since it uses MySQL, I am pretty sure MySQL would already handle table locking when it needs to write (update) a session. So if MySQL by default locks table when it updates data, that should take care of all the locking, then why does this class even bothers with having its own locking method?

http://race.phux.net/code/session_mysqlpervar.phps

2

OK, I think I got it, it’s basically the same idea as using synchronized() in Java, so that you read and write session in one atomic operation and not just locking table during the write, otherwise it is possible, in theory for one process to modify the session data while another process already opened the same session for read.