lib/WebPAC/Store.pm

package WebPAC::Store;

use warnings;
use strict;

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

=head1 NAME

WebPAC::Store - Store normalized data on disk

=head1 VERSION

Version 0.04

=cut

our $VERSION = '0.04';

=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/',
        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 using field 000 as key

  my $ds = $db->load_ds( 42 );

There is also a more verbose form, similar to C<save_ds>

  my $ds = $db->load_ds( id => 42 );

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;

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

        my $log = $self->_get_logger;

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

        my $id = shift;
        if (lc($id) eq 'id') {
                $id = shift;
                $log->logconfess("got hash, but without key id") unless (defined($id));
                $log->logconfess("got hash, but id isn't number") unless ($id =~ /^\d+$/);
        }

        if (! defined($id)) {
                $log->warn("called without id");
                return undef;
        } else {
                my $cache_file = "$cache_path/$id";
                if (-r $cache_file) {
                        my $ds_ref = retrieve($cache_file);
                        if ($ds_ref) {
                                $log->debug("cache hit: $cache_file");
                                my $ok = 1;
#                               foreach my $f (qw(current_filename headline)) {
#                                       if ($ds_ref->{$f}) {
#                                               $self->{$f} = $ds_ref->{$f};
#                                       } else {
#                                               $ok = 0;
#                                       }
#                               };
                                if ($ok && $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],
        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 $cache_file = $self->{path} . '/' . $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
10	=head1 NAME
11
12	WebPAC::Store - Store normalized data on disk
13
14	=head1 VERSION
15
16	Version 0.04
17
18	=cut
19
20	our $VERSION = '0.04';
21
22	=head1 SYNOPSIS
23
24	This module provides disk storage for normalised data.
25
26	It is newest component of WebPAC, so it will change quite often or be in
27	flux. However, I will try to keep backward compatiblity by providing
28	multiple back-ends.
29
30	This has additional advantage. I can create single place to plugin other
31	file formats which provide better performance for particular type of data.
32
33	For now, this is a prototype version.
34
35	use WebPAC::Store;
36
37	my $foo = WebPAC::Store->new();
38	...
39
40	=head1 FUNCTIONS
41
42	=head2 new
43
44	Create new normalised database object
45
46	my $db = new WebPAC::Store(
47	path => '/path/to/cache/ds/',
48	read_only => 1,
49	);
50
51	Optional parameter C<path> defines path to directory
52	in which cache file for C<data_structure> call will be created.
53
54	If called with C<read_only> it will not disable caching if
55	called without write permission (but will die on C<save_ds>).
56
57	=cut
58
59	sub new {
60	my $class = shift;
61	my $self = {@_};
62	bless($self, $class);
63
64	$self->path( $self->{'path'} );
65
66	$self ? return $self : return undef;
67	}
68
69	=head2 path
70
71	Check if specified cache directory exist, and if not, disable caching.
72
73	$db->path('./cache/ds/');
74
75	If you pass false or zero value to this function, it will disable
76	cacheing.
77
78	You can also example C<< $db->{path} >> to get current cache path.
79
80	=cut
81
82	sub path {
83	my $self = shift;
84
85	my $dir = shift;
86
87	my $log = $self->_get_logger();
88
89	if ($dir) {
90	my $msg;
91	if (! -e $dir) {
92	if ($self->{'read_only'}) {
93	$msg = "doesn't exist";
94	} else {
95	$log->info("creating $dir");
96	mkpath $dir;
97	}
98	} elsif (! -d $dir) {
99	$msg = "is not directory";
100	} elsif (! -w $dir) {
101	$msg = "not writable" unless ($self->{'read_only'});
102	}
103
104	if ($msg) {
105	$log->warn("cache path $dir $msg, disabling...");
106	undef $self->{'path'};
107	} else {
108	$log->debug("using cache dir $dir");
109	$self->{'path'} = $dir;
110	}
111	} else {
112	$log->debug("disabling cache");
113	undef $self->{'path'};
114	}
115	}
116
117	=head2 load_ds
118
119	Retrive from disk one data_structure records using field 000 as key
120
121	my $ds = $db->load_ds( 42 );
122
123	There is also a more verbose form, similar to C<save_ds>
124
125	my $ds = $db->load_ds( id => 42 );
126
127	This function will also perform basic sanity checking on returned
128	data and disable caching if data is corrupted (or changed since last
129	update).
130
131	Returns hash or undef if cacheing is disabled or unavailable.
132
133	=cut
134
135	sub load_ds {
136	my $self = shift;
137
138	return unless $self->{'path'};
139
140	my $log = $self->_get_logger;
141
142	my $cache_path = $self->{'path'};
143
144	my $id = shift;
145	if (lc($id) eq 'id') {
146	$id = shift;
147	$log->logconfess("got hash, but without key id") unless (defined($id));
148	$log->logconfess("got hash, but id isn't number") unless ($id =~ /^\d+$/);
149	}
150
151	if (! defined($id)) {
152	$log->warn("called without id");
153	return undef;
154	} else {
155	my $cache_file = "$cache_path/$id";
156	if (-r $cache_file) {
157	my $ds_ref = retrieve($cache_file);
158	if ($ds_ref) {
159	$log->debug("cache hit: $cache_file");
160	my $ok = 1;
161	# foreach my $f (qw(current_filename headline)) {
162	# if ($ds_ref->{$f}) {
163	# $self->{$f} = $ds_ref->{$f};
164	# } else {
165	# $ok = 0;
166	# }
167	# };
168	if ($ok && $ds_ref->{'ds'}) {
169	return $ds_ref->{'ds'};
170	} else {
171	$log->warn("cache entry $cache_file corrupt. Use rm $cache_path/* to re-create it on next run!");
172	undef $self->{'path'};
173	}
174	}
175	} else {
176	#$log->warn("cache entry $cache_file doesn't exist");
177	return undef;
178	}
179	}
180
181	return undef;
182	}
183
184	=head2 save_ds
185
186	Store data_structure on disk.
187
188	$db->save_ds(
189	id => $ds->{000}->[0],
190	ds => $ds,
191	);
192
193	B<Totally broken, but fast.>
194
195	Depends on filename generated by C<load_ds>.
196
197	=cut
198
199	sub save_ds {
200	my $self = shift;
201
202	die "can't write to database in read_only mode!" if ($self->{'read_only'});
203
204	return unless($self->{'path'});
205
206	my $arg = {@_};
207
208	my $log = $self->_get_logger;
209
210	foreach my $f (qw/id ds/) {
211	$log->logconfess("need $f") unless ($arg->{$f});
212	}
213
214	my $cache_file = $self->{path} . '/' . $arg->{id};
215
216	$log->debug("creating storable cache file $cache_file");
217
218	return store {
219	ds => $arg->{ds},
220	id => $arg->{id},
221	}, $cache_file;
222
223	}
224
225	=head1 AUTHOR
226
227	Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>
228
229	=head1 COPYRIGHT & LICENSE
230
231	Copyright 2005 Dobrica Pavlinusic, All Rights Reserved.
232
233	This program is free software; you can redistribute it and/or modify it
234	under the same terms as Perl itself.
235
236	=cut
237
238	1; # End of WebPAC::Store