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.\" ========================================================================
.\"
.IX Title "Apache::Session::Lock::File 3pm"
.TH Apache::Session::Lock::File 3pm "2022-11-19" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
Apache::Session::Lock::File \- Provides mutual exclusion using flock
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& 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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Apache::Session::Lock::File fulfills the locking interface of 
Apache::Session.  Mutual exclusion is achieved through the use of temporary
files and the \f(CW\*(C`flock\*(C'\fR function.
.SH "CONFIGURATION"
.IX Header "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:
.PP
.Vb 1
\& tie %s, \*(AqApache::Session::Blah\*(Aq, $id, {LockDirectory => \*(Aq/var/lock/sessions\*(Aq}
.Ve
.PP
If you do not supply this argument, temporary files will be created in /tmp.
.SH "NOTES"
.IX Header "NOTES"
.SS "clean"
.IX Subsection "clean"
This module does not unlink temporary files, because it interferes with proper
locking.  This can cause problems on certain systems (Linux) whose file systems
(ext2) do not perform well with lots of files in one directory.  To prevent this
you should use a script to clean out old files from your lock directory.
The meaning of old is left as a policy decision for the implementor, but a
method is provided for implementing that policy.  You can use the \f(CW\*(C`clean\*(C'\fR
method of this module to remove files unmodified in the last \f(CW$age\fR seconds.
Example:
.PP
.Vb 2
\& my $l = Apache::Session::Lock::File\->new;
\& $l\->clean(\*(Aq/var/lock/sessions\*(Aq, 3600) #remove files older than 1 hour
.Ve
.SS "acquire_read_lock"
.IX Subsection "acquire_read_lock"
Will do nothing if write lock is in effect, only set readlock flag to true.
.SS "release_read_lock"
.IX Subsection "release_read_lock"
Will do nothing if write lock is in effect, only set readlock flag to false.
.SS "Win32 and Cygwin"
.IX Subsection "Win32 and Cygwin"
Windows cannot escalate lock, so all locks will be exclusive.
.PP
release_read_lock not supported \- it is not used by Apache::Session.
.PP
When deleting files, they are not locked (Win32 only).
.SH "AUTHOR"
.IX Header "AUTHOR"
This module was written by Jeffrey William Baker <jwbaker@acm.org>.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Apache::Session