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Apache::Session::Lock::File(3pm)

🏷️ NAME

Apache::Session::Lock::File - Provides mutual exclusion using flock

🚀 Quick Reference

Use Case	Command	Description
🔒 Acquire read lock	$locker->acquire_read_lock($ref)	Acquire a shared read lock (does nothing if write lock held)
🔑 Acquire write lock	$locker->acquire_write_lock($ref)	Acquire exclusive write lock using flock
🔓 Release read lock	$locker->release_read_lock($ref)	Release shared read lock (no effect if write lock held)
🔓 Release write lock	$locker->release_write_lock($ref)	Release exclusive write lock
🗑️ Release all locks	$locker->release_all_locks($ref)	Release all held locks
🧹 Clean old lock files	$locker->clean($dir, $age)	Remove lock files not modified in last $age seconds

📋 SYNOPSIS

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);

📖 DESCRIPTION

Apache::Session::Lock::File fulfills the locking interface of Apache::Session. Mutual exclusion is achieved through the use of temporary files and the flock function.

⚙️ CONFIGURATION

The module must know where to create its temporary files. You must pass an argument in the usual Apache::Session style. 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'}

If you do not supply this argument, temporary files will be created in /tmp.

📝 NOTES

🧹 clean

This module does not unlink temporary files, because it interferes with proper locking. This can cause problems on certain systems (Linux) whose file systems (ext2) do not perform well with lots of files in one directory. 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 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.

🔓 release_read_lock

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

🪟 Win32 and Cygwin

• Windows cannot escalate lock, so all locks will be exclusive.
• release_read_lock not supported - it is not used by Apache::Session.
• When deleting files, they are not locked (Win32 only).

👤 AUTHOR

This module was written by Jeffrey William Baker <jwbaker AT acm.org>.

🔗 SEE ALSO

Apache::Session

perl v5.30.3 2020-09-20 Apache::Session::Lock::File(3pm)

🏷️ NAME 🚀 Quick Reference 📋 SYNOPSIS 📖 DESCRIPTION ⚙️ CONFIGURATION 📝 NOTES 👤 AUTHOR 🔗 SEE ALSO