NAME¶
Paranoid::Lockfile - Paranoid Lockfile support
VERSION¶
$Id: Lockfile.pm,v 0.65 2011/12/08 07:53:07 acorliss Exp $
SYNOPSIS¶
use Paranoid::Lockfile;
$rv = plock($lockfile);
$rv = punlock($lockfile);
$rv = pcloseLockfile($lockfile);
DESCRIPTION¶
This modules provides a relatively safe locking mechanism across multiple
processes. This does not work over NFS or across remote systems, this is only
intended for use on a single system at a time, and only on those that support
flock.
sysopen is used to avoid race conditions with multiple process attempting
to create the same file simultaneously.
SUBROUTINES/METHODS¶
plock¶
$rv = plock($filename);
This function attempts to safely create or open the lockfile. It uses
sysopen with
O_CREAT | O_EXCL to avoid race conditions with
other processes. Returns a true if successful.
Your can pass an optional second argument which would be a string of either
'write' or 'shared'. The default is 'write', which locks the file in exclusive
write mode.
You can pass an optional third argument which would be the lockfile filesystem
permissions if the file is created. The default is 0600.
NOTE: This function will block until the advisory lock is granted.
punlock¶
$rv = punlock($filename);
This function removes any existing locks on the specified filename using
flock. If no previous lock existed or it was successful it returns
true. This does not, however, close the open filehandle to the lockfile.
pcloseLockfile¶
$rv = pcloseLockfile($filename);
This function releases any existing locks and closes the open filehandle to the
lockfile. Returns true if the file isn't currently open or the operation
succeeds.
DEPENDENCIES¶
- o
- Fcntl
- o
- Paranoid
- o
- Paranoid::Debug
BUGS AND LIMITATIONS¶
AUTHOR¶
Arthur Corliss (corliss@digitalmages.com)
LICENSE AND COPYRIGHT¶
This software is licensed under the same terms as Perl, itself. Please see
http://dev.perl.org/licenses/ for more information.
(c) 2005, Arthur Corliss (corliss@digitalmages.com)