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#-*- perl -*-
#
# Copyright (C) 2000 Ken'ichi Fukamachi
#
# $Id$
# $FML$
#
package File::SimpleLock;
use vars qw(%LockedFileHandle %FileIsLocked @ISA $Error);
use strict;
use Carp;
use ErrorMessages::Status qw(error_set error error_clear);
=head1 NAME
File::SimpleLock - simple lock by flock(2)
=head1 SYNOPSIS
use File::SimpleLock;
my $lockobj = new File::SimpleLock;
$lockobj->lock( { file => $lock_file } ) || croak "fail to lock";
... do someting under locking ...
$lockobj->unlock( { file => $lock_file } ) || croak "fail to unlock";
=head1 DESCRIPTION
File::SimpleLock module provides simple lock using flock(2).
=head1 METHODS
=head2 C<lock($args)>
flock(2) for $args->{ file };
=head2 C<unlock($args)>
unlock flock(2) for $args->{ file };
=cut
# constants
use POSIX qw(EAGAIN ENOENT EEXIST O_EXCL O_CREAT O_RDONLY O_WRONLY);
sub LOCK_SH {1;}
sub LOCK_EX {2;}
sub LOCK_NB {4;}
sub LOCK_UN {8;}
sub new
{
my ($self) = @_;
my ($type) = ref($self) || $self;
my $me = {};
return bless $me, $type;
}
sub lock
{
my ($self, $args) = @_;
my $file = $args->{ file };
$self->_simple_flock($file);
}
sub unlock
{
my ($self, $args) = @_;
my $file = $args->{ file };
$self->_simple_funlock($file);
}
sub _simple_flock
{
my ($self, $file) = @_;
use FileHandle;
my $fh = new FileHandle $file;
if (defined $fh) {
$LockedFileHandle{ $file } = $fh;
my $r = 0; # return value
eval q{
$r = flock($fh, &LOCK_EX);
};
$self->error_set($@) if $@;
if ($r) {
$FileIsLocked{ $file } = 1;
return 1;
}
}
else {
$self->error_set("cannot open $file");
}
return 0;
}
sub _simple_funlock
{
my ($self, $file) = @_;
return 0 unless $FileIsLocked{ $file };
return 0 unless $LockedFileHandle{ $file };
my $fh = $LockedFileHandle{ $file };
my $r = 0; # return value
eval q{
$r = flock($fh, &LOCK_UN);
};
$self->error_set($@) if $@;
if ($r) {
delete $FileIsLocked{ $file };
delete $LockedFileHandle{ $file };
return 1;
}
return 0;
}
=head1 SEE ALSO
L<FileHandle>,
L<ErrorMessages::Status>,
=head1 AUTHOR
Ken'ichi Fukamachi <F<fukachan@fml.org>>
=head1 COPYRIGHT
Copyright (C) 2000,2001 Ken'ichi Fukamachi
All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
=head1 HISTORY
File::SimpleLock appeared in fml5 mailing list driver package.
See C<http://www.fml.org/> for more details.
=cut
1;
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