/[webpac2]/trunk/lib/WebPAC/Input.pm
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revision 6 by dpavlin, Sat Jul 16 14:44:38 2005 UTC revision 289 by dpavlin, Sun Dec 18 22:16:44 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    
96            require $module;
97            #eval $self->{module} .'->import';
98    
99            # check if required subclasses are implemented
100            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                    } else {
105                            $self->{$subclass} = \&{ $n };
106                    }
107            }
108    
109            if ($self->{init}) {
110                    $log->debug("calling init");
111                    $self->{init}->($self, @_);
112            }
113    
114            $self->{'code_page'} ||= 'ISO-8859-2';
115    
116            # running with low_mem flag? well, use DBM::Deep then.
117            if ($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          $self ? return $self : return undef;          $self ? return $self : return undef;
143  }  }
144    
145    =head2 open
146    
147    This function will read whole database in memory and produce lookups.
148    
149     $input->open(
150            path => '/path/to/database/file',
151            code_page => '852',
152            limit => 500,
153            offset => 6000,
154            lookup => $lookup_obj,
155     );
156    
157    By default, C<code_page> is assumed to be C<852>.
158    
159    C<offset> is optional parametar to position at some offset before reading from database.
160    
161    C<limit> is optional parametar to read just C<limit> records from database
162    
163    Returns size of database, regardless of C<offset> and C<limit>
164    parametars, see also C<size>.
165    
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            foreach my $v (qw/path offset limit/) {
180                    $self->{$v} = $arg->{$v} if ($arg->{$v});
181            }
182    
183            # create Text::Iconv object
184            $self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});
185    
186            my ($db, $size) = $self->{open_db}->( $self,
187                    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            my $offset = 1;
201            my $limit = $size;
202    
203            if (my $s = $self->{offset}) {
204                    $log->info("skipping to MFN $s");
205                    $offset = $s;
206            } else {
207                    $self->{offset} = $offset;
208            }
209    
210            if ($self->{limit}) {
211                    $log->info("limiting to ",$self->{limit}," records");
212                    $limit = $offset + $self->{limit} - 1;
213                    $limit = $size if ($limit > $size);
214            }
215    
216            # store size for later
217            $self->{size} = ($limit - $offset) ? ($limit - $offset + 1) : 0;
218    
219            $log->info("processing $self->{size} records in $code_page, convert to $self->{code_page}");
220    
221            # read database
222            for (my $pos = $offset; $pos <= $limit; $pos++) {
223    
224                    $log->debug("position: $pos\n");
225    
226                    my $rec = $self->{fetch_rec}->($self, $db, $pos );
227    
228                    if (! $rec) {
229                            $log->warn("record $pos empty? skipping...");
230                            next;
231                    }
232    
233                    # store
234                    if ($self->{low_mem}) {
235                            $self->{db}->put($pos, $rec);
236                    } else {
237                            $self->{data}->{$pos} = $rec;
238                    }
239    
240                    # create lookup
241                    $self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});
242    
243                    $self->progress_bar($pos,$limit);
244    
245            }
246    
247            $self->{pos} = -1;
248            $self->{last_pcnt} = 0;
249    
250            # store max mfn and return it.
251            $self->{max_pos} = $limit;
252            $log->debug("max_pos: $limit");
253    
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            $log->logconfess("it seems that you didn't load database!") unless ($self->{pos});
274    
275            if ($self->{pos} == -1) {
276                    $self->{pos} = $self->{offset};
277            } else {
278                    $self->{pos}++;
279            }
280    
281            my $mfn = $self->{pos};
282    
283            if ($mfn > $self->{max_pos}) {
284                    $self->{pos} = $self->{max_pos};
285                    $log->debug("at EOF");
286                    return;
287            }
288    
289            $self->progress_bar($mfn,$self->{max_pos});
290    
291            my $rec;
292    
293            if ($self->{low_mem}) {
294                    $rec = $self->{db}->get($mfn);
295            } else {
296                    $rec = $self->{data}->{$mfn};
297            }
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            return $self->{pos};
315    }
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    because it takes into account C<offset> and C<limit>.
329    
330    =cut
331    
332    sub size {
333            my $self = shift;
334            return $self->{size};
335    }
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                    $pos = 1;
356            } elsif ($pos > $self->{max_pos}) {
357                    $log->warn("seek beyond last record");
358                    $pos = $self->{max_pos};
359            }
360    
361            return $self->{pos} = (($pos - 1) || -1);
362    }
363    
364    
365  =head1 MEMORY USAGE  =head1 MEMORY USAGE
366    
367  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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