/[webpac2]/trunk/lib/WebPAC/Input.pm
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revision 6 by dpavlin, Sat Jul 16 14:44:38 2005 UTC revision 286 by dpavlin, Sun Dec 18 21:06:46 2005 UTC
# Line 3  package WebPAC::Input; Line 3  package WebPAC::Input;
3  use warnings;  use warnings;
4  use strict;  use strict;
5    
6    use blib;
7    
8    use WebPAC::Common;
9    use base qw/WebPAC::Common/;
10    use Text::Iconv;
11    
12  =head1 NAME  =head1 NAME
13    
14  WebPAC::Input - core module for input file format  WebPAC::Input - read different file formats into WebPAC
15    
16  =head1 VERSION  =head1 VERSION
17    
18  Version 0.01  Version 0.03
19    
20  =cut  =cut
21    
22  our $VERSION = '0.01';  our $VERSION = '0.03';
23    
24  =head1 SYNOPSIS  =head1 SYNOPSIS
25    
26  This module will load particular loader module and execute it's functions.  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    
30    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  Perhaps a little code snippet.  Perhaps a little code snippet.
40    
41      use WebPAC::Input;      use WebPAC::Input;
42    
43      my $db = WebPAC::Input->new(      my $db = WebPAC::Input->new(
44          format => 'NULL',          module => 'WebPAC::Input::ISIS',
45          config => $config,                  config => $config,
46          lookup => $lookup_obj,                  lookup => $lookup_obj,
47                    low_mem => 1,
48      );      );
49    
50      $db->open('/path/to/database');      $db->open('/path/to/database');
51      print "database size: ",$db->size,"\n";      print "database size: ",$db->size,"\n";
52      while (my $row = $db->fetch) {      while (my $rec = $db->fetch) {
         ...  
53      }      }
54      $db->close;  
55    
56    
57  =head1 FUNCTIONS  =head1 FUNCTIONS
58    
# Line 42  Perhaps a little code snippet. Line 60  Perhaps a little code snippet.
60    
61  Create new input database object.  Create new input database object.
62    
63    my $db = new WebPAC::Input( format => 'NULL' );    my $db = new WebPAC::Input(
64            module => 'WebPAC::Input::MARC',
65            code_page => 'ISO-8859-2',
66            low_mem => 1,
67      );
68    
69    C<module> is low-level file format module. See L<WebPAC::Input::Isis> and
70    L<WebPAC::Input::MARC>.
71    
72    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    Default is not to use C<low_mem> options (see L<MEMORY USAGE> below).
77    
78    This function will also call low-level C<init> if it exists with same
79    parametars.
80    
81  =cut  =cut
82    
83  sub new {  sub new {
84          my $class = shift;          my $class = shift;
85          my $self = {@_};          my $self = {@_};
86          bless($self, $class);          bless($self, $class);
87    
88            my $log = $self->_get_logger;
89    
90            $log->logconfess("specify low-level file format module") unless ($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            require $module;
96            eval $self->{module} .'->import';
97    
98            # check if required subclasses are implemented
99            foreach my $subclass (qw/open_db fetch_rec/) {
100                    if ( $self->can($subclass) ) {
101                            $log->debug("imported $subclass");
102                    } else {
103                            $log->warn("missing $subclass in $self->{module}");
104                    }
105            }
106    
107            if ($self->can('init')) {
108                    $log->debug("calling init");
109                    $self->init(@_);
110            }
111    
112            $self->{'code_page'} ||= 'ISO-8859-2';
113    
114            # running with low_mem flag? well, use DBM::Deep then.
115            if ($self->{'low_mem'}) {
116                    $log->info("running with low_mem which impacts performance (<32 Mb memory usage)");
117    
118                    my $db_file = "data.db";
119    
120                    if (-e $db_file) {
121                            unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
122                            $log->debug("removed '$db_file' from last run");
123                    }
124    
125                    require DBM::Deep;
126    
127                    my $db = new DBM::Deep $db_file;
128    
129                    $log->logdie("DBM::Deep error: $!") unless ($db);
130    
131                    if ($db->error()) {
132                            $log->logdie("can't open '$db_file' under low_mem: ",$db->error());
133                    } else {
134                            $log->debug("using file '$db_file' for DBM::Deep");
135                    }
136    
137                    $self->{'db'} = $db;
138            }
139    
140          $self ? return $self : return undef;          $self ? return $self : return undef;
141  }  }
142    
143    =head2 open
144    
145    This function will read whole database in memory and produce lookups.
146    
147     $input->open(
148            path => '/path/to/database/file',
149            code_page => '852',
150            limit => 500,
151            offset => 6000,
152            lookup => $lookup_obj,
153     );
154    
155    By default, C<code_page> is assumed to be C<852>.
156    
157    C<offset> is optional parametar to position at some offset before reading from database.
158    
159    C<limit> is optional parametar to read just C<limit> records from database
160    
161    Returns size of database, regardless of C<offset> and C<limit>
162    parametars, see also C<size>.
163    
164    =cut
165    
166    sub open {
167            my $self = shift;
168            my $arg = {@_};
169    
170            my $log = $self->_get_logger();
171    
172            $log->logcroak("need path") if (! $arg->{'path'});
173            my $code_page = $arg->{'code_page'} || '852';
174    
175            # store data in object
176            $self->{'code_page'} = $code_page;
177            foreach my $v (qw/path offset limit/) {
178                    $self->{$v} = $arg->{$v} if ($arg->{$v});
179            }
180    
181            # create Text::Iconv object
182            $self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});
183    
184            my ($db, $size) = $self->open_db(
185                    path => $arg->{path},
186            );
187    
188            unless ($db) {
189                    $log->logwarn("can't open database $arg->{path}, skipping...");
190                    return;
191            }
192    
193            unless ($size) {
194                    $log->logwarn("no records in database $arg->{path}, skipping...");
195                    return;
196            }
197    
198            my $offset = 1;
199            my $limit = $size;
200    
201            if (my $s = $self->{offset}) {
202                    $log->info("skipping to MFN $s");
203                    $offset = $s;
204            } else {
205                    $self->{offset} = $offset;
206            }
207    
208            if ($self->{limit}) {
209                    $log->info("limiting to ",$self->{limit}," records");
210                    $limit = $offset + $self->{limit} - 1;
211                    $limit = $size if ($limit > $size);
212            }
213    
214            # store size for later
215            $self->{size} = ($limit - $offset) ? ($limit - $offset + 1) : 0;
216    
217            $log->info("processing $self->{size} records in $code_page, convert to $self->{code_page}");
218    
219            # read database
220            for (my $pos = $offset; $pos <= $limit; $mfn++) {
221    
222                    $log->debug("position: $pos\n");
223    
224                    my $rec = $self->fetch_rec( $db, $pos );
225    
226                    if (! $rec) {
227                            $log->warn("record $pos empty? skipping...");
228                            next;
229                    }
230    
231                    # store
232                    if ($self->{low_mem}) {
233                            $self->{db}->put($pos, $rec);
234                    } else {
235                            $self->{data}->{$pos} = $rec;
236                    }
237    
238                    # create lookup
239                    $self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});
240    
241                    $self->progress_bar($pos,$limit);
242    
243            }
244    
245            $self->{pos} = -1;
246            $self->{last_pcnt} = 0;
247    
248            # store max mfn and return it.
249            $self->{max_pos} = $limit;
250            $log->debug("max_pos: $limit");
251    
252            return $size;
253    }
254    
255    =head2 fetch
256    
257    Fetch next record from database. It will also displays progress bar.
258    
259     my $rec = $isis->fetch;
260    
261    Record from this function should probably go to C<data_structure> for
262    normalisation.
263    
264    =cut
265    
266    sub fetch {
267            my $self = shift;
268    
269            my $log = $self->_get_logger();
270    
271            $log->logconfess("it seems that you didn't load database!") unless ($self->{pos});
272    
273            if ($self->{pos} == -1) {
274                    $self->{pos} = $self->{offset};
275            } else {
276                    $self->{pos}++;
277            }
278    
279            my $mfn = $self->{pos};
280    
281            if ($mfn > $self->{max_pos}) {
282                    $self->{pos} = $self->{max_pos};
283                    $log->debug("at EOF");
284                    return;
285            }
286    
287            $self->progress_bar($mfn,$self->{max_pos});
288    
289            my $rec;
290    
291            if ($self->{low_mem}) {
292                    $rec = $self->{db}->get($mfn);
293            } else {
294                    $rec = $self->{data}->{$mfn};
295            }
296    
297            $rec ||= 0E0;
298    }
299    
300    =head2 pos
301    
302    Returns current record number (MFN).
303    
304     print $isis->pos;
305    
306    First record in database has position 1.
307    
308    =cut
309    
310    sub pos {
311            my $self = shift;
312            return $self->{pos};
313    }
314    
315    
316    =head2 size
317    
318    Returns number of records in database
319    
320     print $isis->size;
321    
322    Result from this function can be used to loop through all records
323    
324     foreach my $mfn ( 1 ... $isis->size ) { ... }
325    
326    because it takes into account C<offset> and C<limit>.
327    
328    =cut
329    
330    sub size {
331            my $self = shift;
332            return $self->{size};
333    }
334    
335    =head2 seek
336    
337    Seek to specified MFN in file.
338    
339     $isis->seek(42);
340    
341    First record in database has position 1.
342    
343    =cut
344    
345    sub seek {
346            my $self = shift;
347            my $pos = shift || return;
348    
349            my $log = $self->_get_logger();
350    
351            if ($pos < 1) {
352                    $log->warn("seek before first record");
353                    $pos = 1;
354            } elsif ($pos > $self->{max_pos}) {
355                    $log->warn("seek beyond last record");
356                    $pos = $self->{max_pos};
357            }
358    
359            return $self->{pos} = (($pos - 1) || -1);
360    }
361    
362    
363  =head1 MEMORY USAGE  =head1 MEMORY USAGE
364    
365  C<low_mem> options is double-edged sword. If enabled, WebPAC  C<low_mem> options is double-edged sword. If enabled, WebPAC
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