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.\" ========================================================================
.\"
.IX Title "Paranoid::IO::Lockfile 3pm"
.TH Paranoid::IO::Lockfile 3pm "2018-11-09" "perl v5.28.0" "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"
Paranoid::IO::Lockfile \- Paranoid Lockfile support
.SH "VERSION"
.IX Header "VERSION"
\&\f(CW$Id:\fR lib/Paranoid/IO/Lockfile.pm, 2.06 2018/08/05 01:21:48 acorliss Exp $
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&  use Paranoid::IO::Lockfile;
\&  use Fcntl qw(:flock);  # only needed if you use plock in lieu 
\&                         # of the other functions
\&
\&  $rv = plock($lockfile);
\&  $rv = plock($lockfile, LOCK_SH | LOCK_NB);
\&  $rv = plock($lockfile, LOCK_SH | LOCK_NB, $mode);
\&
\&  $rv = pexclock($lockfile);
\&  $rv = pshlock($lockfile);
\&  $rv = punlock($lockfile);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module provides convenience functions for using a lockfile to coordinate
multi-process activities.  While basically just a thin wrapper for
Paranoid::IO functions it removes the small tedium of having to perform
the multiple opens required to ensure all processes are working off the same
files while avoiding race conditions.
.SH "SUBROUTINES/METHODS"
.IX Header "SUBROUTINES/METHODS"
.SS "plock"
.IX Subsection "plock"
.Vb 3
\&  $rv = plock($filename);
\&  $rv = plock($filename, LOCK_EX);
\&  $rv = plock($filename, LOCK_EX, 0666);
.Ve
.PP
Creates or opens the requested file while applying the lock condition.  The
lock type defaults to \fB\s-1LOCK_EX\s0\fR if omitted, while the file permissions
default to \fB0660\fR.  As always, umask applies.
.PP
There is one scenario in which one would want to use \fIplock\fR in lieu of
\&\fIpexclock\fR, etc:  if you wish to perform non-blocking lock attempts.  All
convenience functions are blocking.
.SS "pexclock"
.IX Subsection "pexclock"
.Vb 2
\&  $rv = pexclock($filename);
\&  $rv = pexclock($filename, $mode);
.Ve
.PP
A wrapper for \fBplock($filename, \s-1LOCK_EX\s0)\fR.
.SS "pshlock"
.IX Subsection "pshlock"
.Vb 2
\&  $rv = pshlock($filename);
\&  $rv = pshlock($filename, $mode);
.Ve
.PP
A wrapper for \fBplock($filename, \s-1LOCK_SH\s0)\fR.
.SS "punlock"
.IX Subsection "punlock"
.Vb 2
\&  $rv = punlock($filename);
\&  $rv = punlock($filename, $mode);
.Ve
.PP
A wrapper for \fBplock($filename, \s-1LOCK_UN\s0)\fR.  This does not close the open 
file handle to the lock file.  For that you need to call Paranoid::IO's
\&\fIpclose\fR function.
.SH "DEPENDENCIES"
.IX Header "DEPENDENCIES"
.IP "o" 4
.IX Item "o"
Fcntl
.IP "o" 4
.IX Item "o"
Paranoid
.IP "o" 4
.IX Item "o"
Paranoid::Debug
.IP "o" 4
.IX Item "o"
Paranoid::IO
.SH "BUGS AND LIMITATIONS"
.IX Header "BUGS AND LIMITATIONS"
.SH "AUTHOR"
.IX Header "AUTHOR"
Arthur Corliss (corliss@digitalmages.com)
.SH "LICENSE AND COPYRIGHT"
.IX Header "LICENSE AND COPYRIGHT"
This software is licensed under the same terms as Perl, itself. 
Please see http://dev.perl.org/licenses/ for more information.
.PP
(c) 2005 \- 2017, Arthur Corliss (corliss@digitalmages.com)