man > Apache::Session::Lock::File

man perldoc info pydoc3 ri search

📛 NAME

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

🚀 Quick Reference

Use Case	Command	Description
Create a lock manager	my $locker = Apache::Session::Lock::File->new;	Instantiate a new lock object
Acquire exclusive write lock	$locker->acquire_write_lock($ref);	Obtain an exclusive lock for writing
Acquire shared read lock	$locker->acquire_read_lock($ref);	Obtain a shared lock for reading
Release write lock	$locker->release_write_lock($ref);	Release the exclusive write lock
Release read lock	$locker->release_read_lock($ref);	Release the shared read lock
Release all locks	$locker->release_all_locks($ref);	Release all locks held by this session
Clean old lock files	$locker->clean($dir, $age);	Remove lock files older than specified age
Configure lock directory	tie %s, 'Apache::Session::Blah', $id, {LockDirectory => '/var/lock/sessions'}	Set custom directory for lock files (default /tmp)

📋 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

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