Apache...k::File(3pm)

💖 Apache::Session::Lock::File(3pm) 💖

okay bestie, so this is a page from the User Contributed Perl Documentation, and it's all about Apache::Session::Lock::File — the module that does the mutual exclusion thing so two processes don't fight over the same session file like it's the last iced coffee at the café. 🫶

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✨ NAME ✨

Apache::Session::Lock::File — bestie, it provides mutual exclusion using flock. that's the whole vibe. 🔒

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🌸 SYNOPSIS 🌸

like, here's how you actually use it:

use Apache::Session::Lock::File;

my $locker = Apache::Session::Lock::File->new;

$locker->acquire_read_lock($ref);
$locker->acquire_write_lock($ref);
$locker->release_read_lock($ref);
$locker->release_write_lock($ref);
$locker->release_all_locks($ref);

$locker->clean($dir, $age);

so you make a $locker, you grab locks, you release locks, and sometimes you clean up. iconic honestly. 💅

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🦋 DESCRIPTION 🦋

Apache::Session::Lock::File fulfills the locking interface of Apache::Session. no cap, that's its whole job. Mutual exclusion is achieved through the use of temporary files and the flock function — so it's temp files plus flock, doing their little dance together so everyone plays nice. ✨

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🎀 CONFIGURATION 🎀

okay so the module must know where to create its temporary files. you must pass an argument in the usual Apache::Session style, no skipping this step bestie.

The name of the argument is LockDirectory and its value is the path where you want the lockfiles created. Example:

tie %s, 'Apache::Session::Blah', $id, {LockDirectory => '/var/lock/sessions'}

and if you do not supply this argument, temporary files will be created in /tmp. lowkey a fallback, but there it is. 🙈

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👑 NOTES 👑

🧚 clean

This module does not unlink temporary files, because it interferes with proper locking. periodt — that's the reason, don't come for it.

This can cause problems on certain systems (Linux) whose file systems (ext2) do not perform well with lots of files in one directory. 😭 so yeah, directory clutter is real.

To prevent this you should use a script to clean out old files from your lock directory. The meaning of old is left as a policy decision for the implementor, but a method is provided for implementing that policy. you get to decide what "old" means, bestie, that's your main character moment. 💖

You can use the clean method of this module to remove files unmodified in the last $age seconds. Example:

my $l = Apache::Session::Lock::File->new;
$l->clean('/var/lock/sessions', 3600) #remove files older than 1 hour

🔥 acquire_read_lock

Will do nothing if write lock is in effect, only set readlock flag to true. that's it, that's the whole function. 💀

🌈 release_read_lock

Will do nothing if write lock is in effect, only set readlock flag to false. matching energy, honestly. ⭐

💀 Win32 and Cygwin

Windows cannot escalate lock, so all locks will be exclusive. just so you know.

release_read_lock not supported — it is not used by Apache::Session. so like, don't stress about it.

When deleting files, they are not locked (Win32 only). ⚠️ noted, bestie.

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💜 AUTHOR 💜

This module was written by Jeffrey William Baker <jwbaker@acm.org>. shoutout to the author, we love a legend. 👑

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🌟 SEE ALSO 🌟

• Apache::Session — go read that one too, iykyk.

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and that's the whole page, bestie!! 🎀 this was Apache::Session::Lock::File(3pm) from the User Contributed Perl Documentation, and the footer was serving perl v5.36.0 with a date of 2022-11-19 — so yeah, go forth and flock responsibly. mwah. 💖✨🦋