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|
#-*- perl -*-
#
# Copyright (C) 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.
#
# $Id$
# $FML$
#
package IO::File::Atomic;
use strict;
use vars qw(@ISA @EXPORT @EXPORT_OK);
use Carp;
require Exporter;
@ISA = qw(IO::File);
sub BEGIN {}
sub new
{
my ($class) = shift;
my $self = $class->SUPER::new();
$self->open(@_) if @_;
$self;
}
sub open
{
my ($self, $file, $mode) = @_;
# get an instance
ref($self) or $self = $self->new;
# default mode is "w"
$mode ||= "w";
# temporary file
my $temp = $file.".new.".$$;
${*$self}{ _orig } = $file;
${*$self}{ _temp } = $temp;
# real open with $mode
$self->autoflush;
$self->SUPER::open($temp, "w") ? $self : undef;
}
sub rw_open
{
my ($self, $file, $mode) = @_;
use FileHandle;
my $rh = new FileHandle $file;
my $wh = $self->open($file, $mode);
return ($rh, $wh);
}
sub close
{
my ($self) = @_;
my $fh = $self;
my $orig = ${ *$fh }{ _orig };
my $temp = ${ *$fh }{ _temp };
if (rename($temp, $orig)) {
${ *$fh }{ _error } = "fail to rename($temp, $orig)";
}
else {
undef;
}
}
sub error
{
my ($self) = @_;
my $fh = $self;
${ *$fh }{ _error };
}
sub rollback
{
my ($self) = @_;
my $fh = $self;
my $temp = ${ *$fh }{ _temp };
if (-f $temp) { unlink $temp;}
}
sub DESTROY
{
my ($self) = @_;
$self->rollback;
}
=head1 NAME
IO::Atomic.pm - atomic operation
=head1 SYNOPSIS
use IO::Atomic;
my $wh = new IO::Atomic->open($file);
print $wh "new/updated things ...";
$wh->close;
So, in usual cases, you use in this way.
use FileHandle;
use IO::Atomic;
# get read handle for $file
my $rh = new FileHandle $file;
# get handle to update $file
my $wh = new IO::Atomic->open($file);
while (<$rh>) {
print $wh "new/updated things ...";
}
$wh->close;
$rh->close;
You can use this method to open $file for both read and write.
use IO::Atomic;
my ($rh, $wh) = IO::Atomic->rw_open($file);
while (<$rh>) {
print $wh "new/updated things ...";
}
$wh->close;
$rh->close;
=head1 DESCRIPTION
=head2 new
=item Function()
=head1 AUTHOR
=head1 COPYRIGHT
Copyright (C) 2001 __YOUR_NAME__
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
IO::__MODULE_NAME__.pm appeared in fml5.
=cut
1;
|
