# Apache::Session::Lock::File - phpMan

## NAME
    [Apache::Session::Lock::File] - Provides mutual exclusion using flock

## 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@acm.org>>.

## SEE ALSO
    [Apache::Session]