# Arch Perl library, Copyright (C) 2004 Mikhael Goikhman
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
use 5.005;
use strict;
package Arch::SharedCache;
use base 'Arch::SharedIndex';
use Arch::Util qw(save_file load_file);
sub new ($%) {
my $class = shift;
my %init = @_;
my $dir = $init{dir} or die "No cache directory given\n";
unless (-d $dir) {
mkdir($dir, 0777) or die "Can't create cache directory $dir: $!\n";
}
-d $dir or die "No cache directory ($dir)\n";
my $index_file = $init{index_file} || $init{file} || '.index';
$index_file = "$dir/$index_file" unless $index_file =~ m!^\.?/!;
my $self = $class->SUPER::new(
# default to a more readable serialization output
perl_data_indent => 1,
perl_data_pair => " => ",
%init,
file => $index_file,
);
$self->{dir} = $dir;
$self->{generic_filenames} = $init{generic_filenames} || 0;
return $self;
}
sub generate_unique_token ($) {
my $self = shift;
my $dir = $self->{dir};
my $prefix = time() . "-";
my $token = $prefix . "000000";
return $token unless -e "$dir/$token";
my $tries = 1000000;
do {
$token = $prefix . sprintf("%06d", rand(1000000));
} while -e "$dir/$token" && --$tries;
die "Failed to acquire unused file name $dir/$prefix*\n" unless $tries;
return $token;
}
sub file_name_by_token ($$) {
my $self = shift;
my $token = shift;
$token =~ s!/!%!g;
return "$self->{dir}/$token";
}
sub delete_value ($$$) {
my $self = shift;
my ($key, $token) = @_;
$token = $key if $token eq "";
my $file_name = $self->file_name_by_token($token);
return unless -e $file_name;
unlink($file_name) or warn "Can't unlink $file_name: $!\n";
}
sub fetch_value ($$$) {
my $self = shift;
my ($key, $token) = @_;
$token = $key if $token eq "";
my $file_name = $self->file_name_by_token($token);
my $value = eval { load_file($file_name); };
warn $@ if $@;
$self->decode_value(\$value);
return $value;
}
sub store_value ($$$) {
my $self = shift;
my ($key, $token, $value) = @_;
$token = $key
if defined $token && $token eq "";
$token = $key
if !defined $token && !$self->{generic_filenames};
$token = $self->generate_unique_token
if !defined $token || $token eq "";
my $file_name = $self->file_name_by_token($token);
$self->encode_value(\$value);
eval { save_file($file_name, \$value); };
warn $@ if $@;
$token = "" if $key eq $token;
$token = undef if $@;
return $token;
}
1;
__END__
=head1 NAME
Arch::SharedCache - a synchronized data structure (map) for IPC
=head1 SYNOPSIS
use Arch::SharedCache;
my $cache = Arch::SharedCache->new(
dir => '/tmp/dir-listings',
max_size => 100,
expiration => 600, # 10 minutes
);
sub ls_long { scalar `ls -l $_[0]` }
my $user_dir = '/usr/share';
$cache->store($user_dir => ls_long($user_dir));
$cache->fetch_store(sub { ls_long($_[0]) }, qw(/tmp /bin /usr/share));
printf "Cached listing of $user_dir:\n%s", $cache->fetch($user_dir);
$cache->delete($user_dir);
# examine /tmp/dir-listings/ after running this script
# see also synopsys of Arch::SharedIndex
=head1 DESCRIPTION
Arch::SharedCache provides an Arch::SharedIndex implementation using a
single file per value.
=head1 METHODS
The following methods are available:
B<new>.
Other methods are documented in L<Arch::SharedIndex>.
=over 4
=item B<new> I<options>
Create a new Arch::SharedCache object. I<options> is a hash of options.
=over 4
=item B<dir>
The cache directory used to store data. Will be created if it doesn't exist.
=item B<index_file>
Name of the index file for the cache. Defaults to C<B<dir>/.index>.
=back
=back
=head1 BUGS
Awaiting for your reports.
=head1 AUTHORS
Mikhael Goikhman (migo@homemail.com--Perl-GPL/arch-perl--devel).
Enno Cramer (uebergeek@web.de--2003/arch-perl--devel).
=head1 SEE ALSO
For more information, see L<Arch::SharedIndex>.
=cut