lib/WebPAC/Store.pm

package WebPAC::Store;

use warnings;
use strict;

use base 'WebPAC::Common';
use Storable;
use File::Path;
use Data::Dumper;

=head1 NAME

WebPAC::Store - Store normalized data on disk

=head1 VERSION

Version 0.05

=cut

our $VERSION = '0.05';

=head1 SYNOPSIS

This module provides disk storage for normalised data.

It is newest component of WebPAC, so it will change quite often or be in
flux. However, I will try to keep backward compatiblity by providing
multiple back-ends.

This has additional advantage. I can create single place to plugin other
file formats which provide better performance for particular type of data.

For now, this is a prototype version.

    use WebPAC::Store;

    my $foo = WebPAC::Store->new();
    ...

=head1 FUNCTIONS

=head2 new

Create new normalised database object

  my $db = new WebPAC::Store(
        path => '/path/to/cache/ds/',
        database => 'name',
        read_only => 1,
  );

Optional parameter C<path> defines path to directory
in which cache file for C<data_structure> call will be created.

If called with C<read_only> it will not disable caching if
called without write permission (but will die on C<save_ds>).

=cut

sub new {
        my $class = shift;
        my $self = {@_};
        bless($self, $class);

        $self->path( $self->{'path'} );

        $self ? return $self : return undef;
}

=head2 path

Check if specified cache directory exist, and if not, disable caching.

 $db->path('./cache/ds/');

If you pass false or zero value to this function, it will disable
cacheing.

You can also example C<< $db->{path} >> to get current cache path.

=cut

sub path {
        my $self = shift;

        my $dir = shift;

        my $log = $self->_get_logger();

        if ($dir) {
                my $msg;
                if (! -e $dir) {
                        if ($self->{'read_only'}) {
                                $msg = "doesn't exist";
                        } else {
                                $log->info("creating $dir");
                                mkpath $dir;
                        }
                } elsif (! -d $dir) {
                        $msg = "is not directory";
                } elsif (! -w $dir) {
                        $msg = "not writable" unless ($self->{'read_only'});
                }

                if ($msg) {
                        $log->warn("cache path $dir $msg, disabling...");
                        undef $self->{'path'};
                } else {
                        $log->debug("using cache dir $dir");
                        $self->{'path'} = $dir;
                }
        } else {
                $log->debug("disabling cache");
                undef $self->{'path'};
        }
}

=head2 load_ds

Retrive from disk one data_structure records usually using field 000 as key

  my $ds = $db->load_ds( id => 42, database => 'name' );

This function will also perform basic sanity checking on returned
data and disable caching if data is corrupted (or changed since last
update).

Returns hash or undef if cacheing is disabled or unavailable.

=cut

sub load_ds {
        my $self = shift;

        my $log = $self->_get_logger;

        my $cache_path = $self->{'path'};

        if (! $cache_path) {
                $log->warn("path not set, ignoring load_ds");
                return;
        }

        $log->logconfess("arguments for load_ds must be HASH") unless (ref(\@_) eq 'ARRAY' && ($#_ % 2 == 1));

        my $args = {@_};
        my $id = $args->{id};

        $log->logconfess("got hash, but without id") unless (defined($id));
        $log->logconfess("got hash, but id isn't number") unless ($id =~ /^\d+$/);

        my $database = $args->{database} || $self->{database};

        $log->logconfess("can't find database name") unless ($database);

        my $cache_file = "$cache_path/$database#$id";
        $cache_file =~ s#//#/#g;

        $log->debug("using cache_file $cache_file");

        if (-r $cache_file) {
                my $ds_ref = retrieve($cache_file);
                if ($ds_ref) {
                        $log->debug("cache hit: $cache_file");
                        if ($ds_ref->{'ds'}) {
                                return $ds_ref->{'ds'};
                        } else {
                                $log->warn("cache entry $cache_file corrupt. Use rm $cache_path/* to re-create it on next run!");
                                undef $self->{'path'};
                        }
                }
        } else {
                #$log->warn("cache entry $cache_file doesn't exist");
                return undef;
        }

        return undef;
}

=head2 save_ds

Store data_structure on disk.

  $db->save_ds(
        id => $ds->{000}->[0],
        database => 'name',
        ds => $ds,
  );

B<Totally broken, but fast.>

Depends on filename generated by C<load_ds>.

=cut

sub save_ds {
        my $self = shift;

        die "can't write to database in read_only mode!" if ($self->{'read_only'});

        return unless($self->{'path'});

        my $arg = {@_};

        my $log = $self->_get_logger;

        foreach my $f (qw/id ds/) {
                $log->logconfess("need $f") unless ($arg->{$f});
        }

        my $database = $arg->{database} ||  $self->{database};
        $log->logconfess("can't find database name") unless ($database);

        my $cache_file = $self->{path} . '/' . $database . '#' . $arg->{id};

        $log->debug("creating storable cache file $cache_file");

        return store {
                ds => $arg->{ds},
                id => $arg->{id},
        }, $cache_file;

}

=head1 AUTHOR

Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>

=head1 COPYRIGHT & LICENSE

Copyright 2005 Dobrica Pavlinusic, All Rights Reserved.

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

=cut

1; # End of WebPAC::Store
1	package WebPAC::Store;
2
3	use warnings;
4	use strict;
5
6	use base 'WebPAC::Common';
7	use Storable;
8	use File::Path;
9	use Data::Dumper;
10
11	=head1 NAME
12
13	WebPAC::Store - Store normalized data on disk
14
15	=head1 VERSION
16
17	Version 0.05
18
19	=cut
20
21	our $VERSION = '0.05';
22
23	=head1 SYNOPSIS
24
25	This module provides disk storage for normalised data.
26
27	It is newest component of WebPAC, so it will change quite often or be in
28	flux. However, I will try to keep backward compatiblity by providing
29	multiple back-ends.
30
31	This has additional advantage. I can create single place to plugin other
32	file formats which provide better performance for particular type of data.
33
34	For now, this is a prototype version.
35
36	use WebPAC::Store;
37
38	my $foo = WebPAC::Store->new();
39	...
40
41	=head1 FUNCTIONS
42
43	=head2 new
44
45	Create new normalised database object
46
47	my $db = new WebPAC::Store(
48	path => '/path/to/cache/ds/',
49	database => 'name',
50	read_only => 1,
51	);
52
53	Optional parameter C<path> defines path to directory
54	in which cache file for C<data_structure> call will be created.
55
56	If called with C<read_only> it will not disable caching if
57	called without write permission (but will die on C<save_ds>).
58
59	=cut
60
61	sub new {
62	my $class = shift;
63	my $self = {@_};
64	bless($self, $class);
65
66	$self->path( $self->{'path'} );
67
68	$self ? return $self : return undef;
69	}
70
71	=head2 path
72
73	Check if specified cache directory exist, and if not, disable caching.
74
75	$db->path('./cache/ds/');
76
77	If you pass false or zero value to this function, it will disable
78	cacheing.
79
80	You can also example C<< $db->{path} >> to get current cache path.
81
82	=cut
83
84	sub path {
85	my $self = shift;
86
87	my $dir = shift;
88
89	my $log = $self->_get_logger();
90
91	if ($dir) {
92	my $msg;
93	if (! -e $dir) {
94	if ($self->{'read_only'}) {
95	$msg = "doesn't exist";
96	} else {
97	$log->info("creating $dir");
98	mkpath $dir;
99	}
100	} elsif (! -d $dir) {
101	$msg = "is not directory";
102	} elsif (! -w $dir) {
103	$msg = "not writable" unless ($self->{'read_only'});
104	}
105
106	if ($msg) {
107	$log->warn("cache path $dir $msg, disabling...");
108	undef $self->{'path'};
109	} else {
110	$log->debug("using cache dir $dir");
111	$self->{'path'} = $dir;
112	}
113	} else {
114	$log->debug("disabling cache");
115	undef $self->{'path'};
116	}
117	}
118
119	=head2 load_ds
120
121	Retrive from disk one data_structure records usually using field 000 as key
122
123	my $ds = $db->load_ds( id => 42, database => 'name' );
124
125	This function will also perform basic sanity checking on returned
126	data and disable caching if data is corrupted (or changed since last
127	update).
128
129	Returns hash or undef if cacheing is disabled or unavailable.
130
131	=cut
132
133	sub load_ds {
134	my $self = shift;
135
136	my $log = $self->_get_logger;
137
138	my $cache_path = $self->{'path'};
139
140	if (! $cache_path) {
141	$log->warn("path not set, ignoring load_ds");
142	return;
143	}
144
145	$log->logconfess("arguments for load_ds must be HASH") unless (ref(\@_) eq 'ARRAY' && ($#_ % 2 == 1));
146
147	my $args = {@_};
148	my $id = $args->{id};
149
150	$log->logconfess("got hash, but without id") unless (defined($id));
151	$log->logconfess("got hash, but id isn't number") unless ($id =~ /^\d+$/);
152
153	my $database = $args->{database} \|\| $self->{database};
154
155	$log->logconfess("can't find database name") unless ($database);
156
157	my $cache_file = "$cache_path/$database#$id";
158	$cache_file =~ s#//#/#g;
159
160	$log->debug("using cache_file $cache_file");
161
162	if (-r $cache_file) {
163	my $ds_ref = retrieve($cache_file);
164	if ($ds_ref) {
165	$log->debug("cache hit: $cache_file");
166	if ($ds_ref->{'ds'}) {
167	return $ds_ref->{'ds'};
168	} else {
169	$log->warn("cache entry $cache_file corrupt. Use rm $cache_path/* to re-create it on next run!");
170	undef $self->{'path'};
171	}
172	}
173	} else {
174	#$log->warn("cache entry $cache_file doesn't exist");
175	return undef;
176	}
177
178	return undef;
179	}
180
181	=head2 save_ds
182
183	Store data_structure on disk.
184
185	$db->save_ds(
186	id => $ds->{000}->[0],
187	database => 'name',
188	ds => $ds,
189	);
190
191	B<Totally broken, but fast.>
192
193	Depends on filename generated by C<load_ds>.
194
195	=cut
196
197	sub save_ds {
198	my $self = shift;
199
200	die "can't write to database in read_only mode!" if ($self->{'read_only'});
201
202	return unless($self->{'path'});
203
204	my $arg = {@_};
205
206	my $log = $self->_get_logger;
207
208	foreach my $f (qw/id ds/) {
209	$log->logconfess("need $f") unless ($arg->{$f});
210	}
211
212	my $database = $arg->{database} \|\| $self->{database};
213	$log->logconfess("can't find database name") unless ($database);
214
215	my $cache_file = $self->{path} . '/' . $database . '#' . $arg->{id};
216
217	$log->debug("creating storable cache file $cache_file");
218
219	return store {
220	ds => $arg->{ds},
221	id => $arg->{id},
222	}, $cache_file;
223
224	}
225
226	=head1 AUTHOR
227
228	Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>
229
230	=head1 COPYRIGHT & LICENSE
231
232	Copyright 2005 Dobrica Pavlinusic, All Rights Reserved.
233
234	This program is free software; you can redistribute it and/or modify it
235	under the same terms as Perl itself.
236
237	=cut
238
239	1; # End of WebPAC::Store