NAME

PerlIO::flock - Easy flock() interface

SYNOPSIS

        open my $in,  '< :flock', $file; # shared lock
        open my $out, '+<:flock', $file; # exclusive lock

        binmode($fh, ':flock(blocking)');
        binmode($fh, ':flock(non-blocking)');

DESCRIPTION

PerlIO::flock provides an interface to flock().

It tries to lock the filehandle with flock() according to the open mode. That is, if a file is opened for writing, :flock attempts exclusive lock (using LOCK_EX). Otherwise, it attempts shared lock (using LOCK_SH).

It waits until the lock is granted. If an argument non-blocking (or LOCK_NB) is supplied, the call of open() (or binmode()) fails when the lock cannot be granted.

This is a pseudo layer that doesn't be pushed on the layer stack.

EXAMPLE

        # tries shared lock, or waits until the lock is granted
        open my $in, "<:flock", $file;
        open my $in, "<:flock(blocking)", $file;     # ditto.

        # tries shared lock, or returns undef
        open my $in, "<:flock(non-blocking)", $file; 
        open my $in, "<:flock(LOCK_NB)", $file;      # ditto.

SEE ALSO

PerlIO::Util.

"flock" in perlfunc.

AUTHOR

Goro Fuji (藤 吾郎) <gfuji (at) cpan.org>

LICENSE AND COPYRIGHT

Copyright (c) 2008, Goro Fuji <gfuji (at) cpan.org>. Some rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.