lib/WebPAC/Input.pm

package WebPAC::Input;

use warnings;
use strict;

use blib;

use WebPAC::Common;
use base qw/WebPAC::Common/;
use Text::Iconv;

=head1 NAME

WebPAC::Input - read different file formats into WebPAC

=head1 VERSION

Version 0.03

=cut

our $VERSION = '0.03';

=head1 SYNOPSIS

This module implements input as database which have fixed and known
I<size> while indexing and single unique numeric identifier for database
position ranging from 1 to I<size>.

Simply, something that is indexed by unmber from 1 .. I<size>.

Examples of such databases are CDS/ISIS files, MARC files, lines in
text file, and so on.

Specific file formats are implemented using low-level interface modules,
located in C<WebPAC::Input::*> namespace which export C<open_db>,
C<fetch_rec> and optional C<init> functions.

Perhaps a little code snippet.

    use WebPAC::Input;

    my $db = WebPAC::Input->new(
        module => 'WebPAC::Input::ISIS',
                config => $config,
                lookup => $lookup_obj,
                low_mem => 1,
    );

    $db->open('/path/to/database');
    print "database size: ",$db->size,"\n";
    while (my $rec = $db->fetch) {
    }


=head1 FUNCTIONS

=head2 new

Create new input database object.

  my $db = new WebPAC::Input(
        module => 'WebPAC::Input::MARC',
        code_page => 'ISO-8859-2',
        low_mem => 1,
  );

C<module> is low-level file format module. See L<WebPAC::Input::Isis> and
L<WebPAC::Input::MARC>.

Optional parametar C<code_page> specify application code page (which will be
used internally). This should probably be your terminal encoding, and by
default, it C<ISO-8859-2>.

Default is not to use C<low_mem> options (see L<MEMORY USAGE> below).

This function will also call low-level C<init> if it exists with same
parametars.

=cut

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

        my $log = $self->_get_logger;

        $log->logconfess("specify low-level file format module") unless ($self->{module});
        my $module = $self->{module};
        $module =~ s#::#/#g;
        $module .= '.pm';
        $log->debug("require low-level module $self->{module} from $module");

        require $module;
        #eval $self->{module} .'->import';

        # check if required subclasses are implemented
        foreach my $subclass (qw/open_db fetch_rec init/) {
                my $n = $self->{module} . '::' . $subclass;
                if (! defined &{ $n }) {
                        $log->logwarn("missing implementation of $subclass");
                } else {
                        $self->{$subclass} = \&{ $n };
                }
        }

        if ($self->{init}) {
                $log->debug("calling init");
                $self->{init}->($self, @_);
        }

        $self->{'code_page'} ||= 'ISO-8859-2';

        # running with low_mem flag? well, use DBM::Deep then.
        if ($self->{'low_mem'}) {
                $log->info("running with low_mem which impacts performance (<32 Mb memory usage)");

                my $db_file = "data.db";

                if (-e $db_file) {
                        unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
                        $log->debug("removed '$db_file' from last run");
                }

                require DBM::Deep;

                my $db = new DBM::Deep $db_file;

                $log->logdie("DBM::Deep error: $!") unless ($db);

                if ($db->error()) {
                        $log->logdie("can't open '$db_file' under low_mem: ",$db->error());
                } else {
                        $log->debug("using file '$db_file' for DBM::Deep");
                }

                $self->{'db'} = $db;
        }

        $self ? return $self : return undef;
}

=head2 open

This function will read whole database in memory and produce lookups.

 $input->open(
        path => '/path/to/database/file',
        code_page => '852',
        limit => 500,
        offset => 6000,
        lookup => $lookup_obj,
 );

By default, C<code_page> is assumed to be C<852>.

C<offset> is optional parametar to position at some offset before reading from database.

C<limit> is optional parametar to read just C<limit> records from database

Returns size of database, regardless of C<offset> and C<limit>
parametars, see also C<size>.

=cut

sub open {
        my $self = shift;
        my $arg = {@_};

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

        $log->logcroak("need path") if (! $arg->{'path'});
        my $code_page = $arg->{'code_page'} || '852';

        # store data in object
        $self->{'code_page'} = $code_page;
        foreach my $v (qw/path offset limit/) {
                $self->{$v} = $arg->{$v} if ($arg->{$v});
        }

        # create Text::Iconv object
        $self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});

        my ($db, $size) = $self->{open_db}->( $self, 
                path => $arg->{path},
        );

        unless ($db) {
                $log->logwarn("can't open database $arg->{path}, skipping...");
                return;
        }

        unless ($size) {
                $log->logwarn("no records in database $arg->{path}, skipping...");
                return;
        }

        my $offset = 1;
        my $limit = $size;

        if (my $s = $self->{offset}) {
                $log->info("skipping to MFN $s");
                $offset = $s;
        } else {
                $self->{offset} = $offset;
        }

        if ($self->{limit}) {
                $log->info("limiting to ",$self->{limit}," records");
                $limit = $offset + $self->{limit} - 1;
                $limit = $size if ($limit > $size);
        }

        # store size for later
        $self->{size} = ($limit - $offset) ? ($limit - $offset + 1) : 0;

        $log->info("processing $self->{size} records in $code_page, convert to $self->{code_page}");

        # read database
        for (my $pos = $offset; $pos <= $limit; $pos++) {

                $log->debug("position: $pos\n");

                my $rec = $self->{fetch_rec}->($self, $db, $pos );

                if (! $rec) {
                        $log->warn("record $pos empty? skipping...");
                        next;
                }

                # store
                if ($self->{low_mem}) {
                        $self->{db}->put($pos, $rec);
                } else {
                        $self->{data}->{$pos} = $rec;
                }

                # create lookup
                $self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});

                $self->progress_bar($pos,$limit);

        }

        $self->{pos} = -1;
        $self->{last_pcnt} = 0;

        # store max mfn and return it.
        $self->{max_pos} = $limit;
        $log->debug("max_pos: $limit");

        return $size;
}

=head2 fetch

Fetch next record from database. It will also displays progress bar.

 my $rec = $isis->fetch;

Record from this function should probably go to C<data_structure> for
normalisation.

=cut

sub fetch {
        my $self = shift;

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

        $log->logconfess("it seems that you didn't load database!") unless ($self->{pos});

        if ($self->{pos} == -1) {
                $self->{pos} = $self->{offset};
        } else {
                $self->{pos}++;
        }

        my $mfn = $self->{pos};

        if ($mfn > $self->{max_pos}) {
                $self->{pos} = $self->{max_pos};
                $log->debug("at EOF");
                return;
        }

        $self->progress_bar($mfn,$self->{max_pos});

        my $rec;

        if ($self->{low_mem}) {
                $rec = $self->{db}->get($mfn);
        } else {
                $rec = $self->{data}->{$mfn};
        }

        $rec ||= 0E0;
}

=head2 pos

Returns current record number (MFN).

 print $isis->pos;

First record in database has position 1.

=cut

sub pos {
        my $self = shift;
        return $self->{pos};
}


=head2 size

Returns number of records in database

 print $isis->size;

Result from this function can be used to loop through all records

 foreach my $mfn ( 1 ... $isis->size ) { ... }

because it takes into account C<offset> and C<limit>.

=cut

sub size {
        my $self = shift;
        return $self->{size};
}

=head2 seek

Seek to specified MFN in file.

 $isis->seek(42);

First record in database has position 1.

=cut

sub seek {
        my $self = shift;
        my $pos = shift || return;

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

        if ($pos < 1) {
                $log->warn("seek before first record");
                $pos = 1;
        } elsif ($pos > $self->{max_pos}) {
                $log->warn("seek beyond last record");
                $pos = $self->{max_pos};
        }

        return $self->{pos} = (($pos - 1) || -1);
}


=head1 MEMORY USAGE

C<low_mem> options is double-edged sword. If enabled, WebPAC
will run on memory constraint machines (which doesn't have enough
physical RAM to create memory structure for whole source database).

If your machine has 512Mb or more of RAM and database is around 10000 records,
memory shouldn't be an issue. If you don't have enough physical RAM, you
might consider using virtual memory (if your operating system is handling it
well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle
parsed structure of ISIS database (this is what C<low_mem> option does).

Hitting swap at end of reading source database is probably o.k. However,
hitting swap before 90% will dramatically decrease performance and you will
be better off with C<low_mem> and using rest of availble memory for
operating system disk cache (Linux is particuallary good about this).
However, every access to database record will require disk access, so
generation phase will be slower 10-100 times.

Parsed structures are essential - you just have option to trade RAM memory
(which is fast) for disk space (which is slow). Be sure to have planty of
disk space if you are using C<low_mem> and thus L<DBM::Deep>.

However, when WebPAC is running on desktop machines (or laptops :-), it's
highly undesireable for system to start swapping. Using C<low_mem> option can
reduce WecPAC memory usage to around 64Mb for same database with lookup
fields and sorted indexes which stay in RAM. Performance will suffer, but
memory usage will really be minimal. It might be also more confortable to
run WebPAC reniced on those machines.


=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::Input
1	dpavlin	1	package WebPAC::Input;
2
3			use warnings;
4			use strict;
5
6	dpavlin	285	use blib;
7
8			use WebPAC::Common;
9			use base qw/WebPAC::Common/;
10			use Text::Iconv;
11
12	dpavlin	1	=head1 NAME
13
14	dpavlin	286	WebPAC::Input - read different file formats into WebPAC
15	dpavlin	1
16			=head1 VERSION
17
18	dpavlin	286	Version 0.03
19	dpavlin	1
20			=cut
21
22	dpavlin	286	our $VERSION = '0.03';
23	dpavlin	1
24			=head1 SYNOPSIS
25
26	dpavlin	286	This module implements input as database which have fixed and known
27			I<size> while indexing and single unique numeric identifier for database
28			position ranging from 1 to I<size>.
29	dpavlin	1
30	dpavlin	286	Simply, something that is indexed by unmber from 1 .. I<size>.
31
32			Examples of such databases are CDS/ISIS files, MARC files, lines in
33			text file, and so on.
34
35			Specific file formats are implemented using low-level interface modules,
36			located in C<WebPAC::Input::*> namespace which export C<open_db>,
37			C<fetch_rec> and optional C<init> functions.
38
39	dpavlin	1	Perhaps a little code snippet.
40
41			use WebPAC::Input;
42
43	dpavlin	3	my $db = WebPAC::Input->new(
44	dpavlin	286	module => 'WebPAC::Input::ISIS',
45			config => $config,
46			lookup => $lookup_obj,
47			low_mem => 1,
48	dpavlin	3	);
49	dpavlin	1
50	dpavlin	3	$db->open('/path/to/database');
51			print "database size: ",$db->size,"\n";
52	dpavlin	286	while (my $rec = $db->fetch) {
53	dpavlin	3	}
54	dpavlin	1
55	dpavlin	286
56
57	dpavlin	1	=head1 FUNCTIONS
58
59	dpavlin	3	=head2 new
60	dpavlin	1
61	dpavlin	3	Create new input database object.
62
63	dpavlin	9	my $db = new WebPAC::Input(
64	dpavlin	286	module => 'WebPAC::Input::MARC',
65	dpavlin	9	code_page => 'ISO-8859-2',
66	dpavlin	10	low_mem => 1,
67	dpavlin	9	);
68	dpavlin	3
69	dpavlin	286	C<module> is low-level file format module. See L<WebPAC::Input::Isis> and
70			L<WebPAC::Input::MARC>.
71
72	dpavlin	9	Optional parametar C<code_page> specify application code page (which will be
73			used internally). This should probably be your terminal encoding, and by
74			default, it C<ISO-8859-2>.
75
76	dpavlin	10	Default is not to use C<low_mem> options (see L<MEMORY USAGE> below).
77
78	dpavlin	285	This function will also call low-level C<init> if it exists with same
79			parametars.
80
81	dpavlin	1	=cut
82
83	dpavlin	3	sub new {
84	dpavlin	285	my $class = shift;
85			my $self = {@_};
86	dpavlin	3	bless($self, $class);
87
88	dpavlin	285	my $log = $self->_get_logger;
89
90	dpavlin	286	$log->logconfess("specify low-level file format module") unless ($self->{module});
91			my $module = $self->{module};
92			$module =~ s#::#/#g;
93			$module .= '.pm';
94			$log->debug("require low-level module $self->{module} from $module");
95	dpavlin	289
96	dpavlin	286	require $module;
97	dpavlin	289	#eval $self->{module} .'->import';
98	dpavlin	286
99	dpavlin	285	# check if required subclasses are implemented
100	dpavlin	289	foreach my $subclass (qw/open_db fetch_rec init/) {
101			my $n = $self->{module} . '::' . $subclass;
102			if (! defined &{ $n }) {
103			$log->logwarn("missing implementation of $subclass");
104	dpavlin	286	} else {
105	dpavlin	289	$self->{$subclass} = \&{ $n };
106	dpavlin	286	}
107	dpavlin	285	}
108
109	dpavlin	289	if ($self->{init}) {
110	dpavlin	285	$log->debug("calling init");
111	dpavlin	289	$self->{init}->($self, @_);
112	dpavlin	285	}
113
114	dpavlin	9	$self->{'code_page'} \|\|= 'ISO-8859-2';
115
116	dpavlin	10	# running with low_mem flag? well, use DBM::Deep then.
117			if ($self->{'low_mem'}) {
118			$log->info("running with low_mem which impacts performance (<32 Mb memory usage)");
119
120			my $db_file = "data.db";
121
122			if (-e $db_file) {
123			unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
124			$log->debug("removed '$db_file' from last run");
125			}
126
127			require DBM::Deep;
128
129			my $db = new DBM::Deep $db_file;
130
131			$log->logdie("DBM::Deep error: $!") unless ($db);
132
133			if ($db->error()) {
134			$log->logdie("can't open '$db_file' under low_mem: ",$db->error());
135			} else {
136			$log->debug("using file '$db_file' for DBM::Deep");
137			}
138
139			$self->{'db'} = $db;
140			}
141
142	dpavlin	3	$self ? return $self : return undef;
143	dpavlin	1	}
144
145	dpavlin	285	=head2 open
146
147			This function will read whole database in memory and produce lookups.
148
149	dpavlin	286	$input->open(
150	dpavlin	285	path => '/path/to/database/file',
151			code_page => '852',
152	dpavlin	286	limit => 500,
153			offset => 6000,
154	dpavlin	285	lookup => $lookup_obj,
155			);
156
157			By default, C<code_page> is assumed to be C<852>.
158
159	dpavlin	286	C<offset> is optional parametar to position at some offset before reading from database.
160	dpavlin	285
161	dpavlin	286	C<limit> is optional parametar to read just C<limit> records from database
162	dpavlin	285
163	dpavlin	286	Returns size of database, regardless of C<offset> and C<limit>
164			parametars, see also C<size>.
165	dpavlin	285
166			=cut
167
168			sub open {
169			my $self = shift;
170			my $arg = {@_};
171
172			my $log = $self->_get_logger();
173
174			$log->logcroak("need path") if (! $arg->{'path'});
175			my $code_page = $arg->{'code_page'} \|\| '852';
176
177			# store data in object
178			$self->{'code_page'} = $code_page;
179	dpavlin	286	foreach my $v (qw/path offset limit/) {
180	dpavlin	285	$self->{$v} = $arg->{$v} if ($arg->{$v});
181			}
182
183			# create Text::Iconv object
184			$self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});
185
186	dpavlin	289	my ($db, $size) = $self->{open_db}->( $self,
187	dpavlin	285	path => $arg->{path},
188			);
189
190			unless ($db) {
191			$log->logwarn("can't open database $arg->{path}, skipping...");
192			return;
193			}
194
195			unless ($size) {
196			$log->logwarn("no records in database $arg->{path}, skipping...");
197			return;
198			}
199
200	dpavlin	286	my $offset = 1;
201			my $limit = $size;
202	dpavlin	285
203	dpavlin	286	if (my $s = $self->{offset}) {
204	dpavlin	285	$log->info("skipping to MFN $s");
205	dpavlin	286	$offset = $s;
206	dpavlin	285	} else {
207	dpavlin	286	$self->{offset} = $offset;
208	dpavlin	285	}
209
210	dpavlin	286	if ($self->{limit}) {
211			$log->info("limiting to ",$self->{limit}," records");
212			$limit = $offset + $self->{limit} - 1;
213			$limit = $size if ($limit > $size);
214	dpavlin	285	}
215
216			# store size for later
217	dpavlin	286	$self->{size} = ($limit - $offset) ? ($limit - $offset + 1) : 0;
218	dpavlin	285
219			$log->info("processing $self->{size} records in $code_page, convert to $self->{code_page}");
220
221			# read database
222	dpavlin	287	for (my $pos = $offset; $pos <= $limit; $pos++) {
223	dpavlin	285
224	dpavlin	286	$log->debug("position: $pos\n");
225	dpavlin	285
226	dpavlin	289	my $rec = $self->{fetch_rec}->($self, $db, $pos );
227	dpavlin	285
228			if (! $rec) {
229	dpavlin	286	$log->warn("record $pos empty? skipping...");
230	dpavlin	285	next;
231			}
232
233			# store
234	dpavlin	286	if ($self->{low_mem}) {
235			$self->{db}->put($pos, $rec);
236	dpavlin	285	} else {
237	dpavlin	286	$self->{data}->{$pos} = $rec;
238	dpavlin	285	}
239
240			# create lookup
241			$self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});
242
243	dpavlin	286	$self->progress_bar($pos,$limit);
244	dpavlin	285
245			}
246
247	dpavlin	286	$self->{pos} = -1;
248			$self->{last_pcnt} = 0;
249	dpavlin	285
250			# store max mfn and return it.
251	dpavlin	286	$self->{max_pos} = $limit;
252			$log->debug("max_pos: $limit");
253	dpavlin	285
254			return $size;
255			}
256
257			=head2 fetch
258
259			Fetch next record from database. It will also displays progress bar.
260
261			my $rec = $isis->fetch;
262
263			Record from this function should probably go to C<data_structure> for
264			normalisation.
265
266			=cut
267
268			sub fetch {
269			my $self = shift;
270
271			my $log = $self->_get_logger();
272
273	dpavlin	286	$log->logconfess("it seems that you didn't load database!") unless ($self->{pos});
274	dpavlin	285
275	dpavlin	286	if ($self->{pos} == -1) {
276			$self->{pos} = $self->{offset};
277	dpavlin	285	} else {
278	dpavlin	286	$self->{pos}++;
279	dpavlin	285	}
280
281	dpavlin	286	my $mfn = $self->{pos};
282	dpavlin	285
283	dpavlin	286	if ($mfn > $self->{max_pos}) {
284			$self->{pos} = $self->{max_pos};
285	dpavlin	285	$log->debug("at EOF");
286			return;
287			}
288
289	dpavlin	286	$self->progress_bar($mfn,$self->{max_pos});
290	dpavlin	285
291			my $rec;
292
293	dpavlin	286	if ($self->{low_mem}) {
294			$rec = $self->{db}->get($mfn);
295	dpavlin	285	} else {
296	dpavlin	286	$rec = $self->{data}->{$mfn};
297	dpavlin	285	}
298
299			$rec \|\|= 0E0;
300			}
301
302			=head2 pos
303
304			Returns current record number (MFN).
305
306			print $isis->pos;
307
308			First record in database has position 1.
309
310			=cut
311
312			sub pos {
313			my $self = shift;
314	dpavlin	286	return $self->{pos};
315	dpavlin	285	}
316
317
318			=head2 size
319
320			Returns number of records in database
321
322			print $isis->size;
323
324			Result from this function can be used to loop through all records
325
326			foreach my $mfn ( 1 ... $isis->size ) { ... }
327
328	dpavlin	286	because it takes into account C<offset> and C<limit>.
329	dpavlin	285
330			=cut
331
332			sub size {
333			my $self = shift;
334	dpavlin	286	return $self->{size};
335	dpavlin	285	}
336
337			=head2 seek
338
339			Seek to specified MFN in file.
340
341			$isis->seek(42);
342
343			First record in database has position 1.
344
345			=cut
346
347			sub seek {
348			my $self = shift;
349			my $pos = shift \|\| return;
350
351			my $log = $self->_get_logger();
352
353			if ($pos < 1) {
354			$log->warn("seek before first record");
355			$pos = 1;
356	dpavlin	286	} elsif ($pos > $self->{max_pos}) {
357	dpavlin	285	$log->warn("seek beyond last record");
358	dpavlin	286	$pos = $self->{max_pos};
359	dpavlin	285	}
360
361	dpavlin	286	return $self->{pos} = (($pos - 1) \|\| -1);
362	dpavlin	285	}
363
364
365	dpavlin	3	=head1 MEMORY USAGE
366	dpavlin	1
367	dpavlin	3	C<low_mem> options is double-edged sword. If enabled, WebPAC
368			will run on memory constraint machines (which doesn't have enough
369			physical RAM to create memory structure for whole source database).
370	dpavlin	1
371	dpavlin	3	If your machine has 512Mb or more of RAM and database is around 10000 records,
372			memory shouldn't be an issue. If you don't have enough physical RAM, you
373			might consider using virtual memory (if your operating system is handling it
374			well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle
375			parsed structure of ISIS database (this is what C<low_mem> option does).
376	dpavlin	1
377	dpavlin	3	Hitting swap at end of reading source database is probably o.k. However,
378			hitting swap before 90% will dramatically decrease performance and you will
379			be better off with C<low_mem> and using rest of availble memory for
380			operating system disk cache (Linux is particuallary good about this).
381			However, every access to database record will require disk access, so
382			generation phase will be slower 10-100 times.
383
384			Parsed structures are essential - you just have option to trade RAM memory
385			(which is fast) for disk space (which is slow). Be sure to have planty of
386			disk space if you are using C<low_mem> and thus L<DBM::Deep>.
387
388			However, when WebPAC is running on desktop machines (or laptops :-), it's
389			highly undesireable for system to start swapping. Using C<low_mem> option can
390			reduce WecPAC memory usage to around 64Mb for same database with lookup
391			fields and sorted indexes which stay in RAM. Performance will suffer, but
392			memory usage will really be minimal. It might be also more confortable to
393			run WebPAC reniced on those machines.
394
395
396			=head1 AUTHOR
397
398			Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>
399
400	dpavlin	1	=head1 COPYRIGHT & LICENSE
401
402			Copyright 2005 Dobrica Pavlinusic, All Rights Reserved.
403
404			This program is free software; you can redistribute it and/or modify it
405			under the same terms as Perl itself.
406
407			=cut
408
409			1; # End of WebPAC::Input