r62757 MediaWiki - Code Review archive

Why would you use require_once() instead of require()? require() is faster, which is why my LocalSettings.php doesn't contain any instances of require_once().

Because I've had cases (not with MediaWiki, as it happens) where a careless error meant that a file was being included multiple times in a small percentage of cases, which caused a fatal error when I added a function definition to the file. How significant is the performance difference in practice, with the number of inclusions we do? If we should really recommend require() instead of require_once(), then we should do it consistently – pretty much all extension documentation I've seen currently recommends require_once().

The difference is that with APC enabled and the file cached, require_once() opens the file and require() does not. So the amount of time difference depends on how fast your filesystem is. It's very noticeable if you're running over NFS.

When Rasmus was challenged about the problem, in typical fashion, he declared that apps should just know whether they have included their files or not, and that require() should be good enough for any well-designed app. At the time, we were migrating from explicit require_once() calls to the new AutoLoader, which implicitly knows when a file has been included due to class existence, thus we were able to remove almost all require_once() calls from MediaWiki, and speed it up for NFS installations substantially.

Eventually APC acquired the configuration hack "apc.include_once_override", but there are reports that it is buggy.

Yes, I would be happy if the documentation consistently recommended require() over require_once().

Reverted that part in r62881. There's a lot more to do, though:

0 12:12:22 /var/www/git-trunk$ git grep 'require_once(' | wc -l
1576
0 12:12:30 /var/www/git-trunk$ git grep 'require(' | wc -l
163

Of course, a wholesale change to require() would probably be a bad idea, since it would introduce bugs.

Well, bring it on. If they are there, getting to know them and fixing them quickly is one way to get rid of them...