/[webpac2]/trunk/lib/WebPAC/Input.pm
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revision 3 by dpavlin, Sat Jul 16 11:07:38 2005 UTC revision 290 by dpavlin, Sun Dec 18 23:10:02 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,
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 41  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 load needed wrapper module and  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                            my $missing = "missing $subclass in $self->{module}";
104                            $log->logwarn($missing);
105                            $self->{$subclass} = sub { warn "$missing\n" };
106                    } else {
107                            $self->{$subclass} = \&{ $n };
108                    }
109            }
110    
111            if ($self->{init}) {
112                    $log->debug("calling init");
113                    $self->{init}->($self, @_);
114            }
115    
116            $self->{'code_page'} ||= 'ISO-8859-2';
117    
118            # running with low_mem flag? well, use DBM::Deep then.
119            if ($self->{'low_mem'}) {
120                    $log->info("running with low_mem which impacts performance (<32 Mb memory usage)");
121    
122                    my $db_file = "data.db";
123    
124                    if (-e $db_file) {
125                            unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
126                            $log->debug("removed '$db_file' from last run");
127                    }
128    
129                    require DBM::Deep;
130    
131                    my $db = new DBM::Deep $db_file;
132    
133                    $log->logdie("DBM::Deep error: $!") unless ($db);
134    
135                    if ($db->error()) {
136                            $log->logdie("can't open '$db_file' under low_mem: ",$db->error());
137                    } else {
138                            $log->debug("using file '$db_file' for DBM::Deep");
139                    }
140    
141                    $self->{'db'} = $db;
142            }
143    
144          $self ? return $self : return undef;          $self ? return $self : return undef;
145  }  }
146    
147  =head2 open  =head2 open
148    
149    This function will read whole database in memory and produce lookups.
150    
151     $input->open(
152            path => '/path/to/database/file',
153            code_page => '852',
154            limit => 500,
155            offset => 6000,
156            lookup => $lookup_obj,
157     );
158    
159    By default, C<code_page> is assumed to be C<852>.
160    
161    C<offset> is optional parametar to position at some offset before reading from database.
162    
163    C<limit> is optional parametar to read just C<limit> records from database
164    
165    Returns size of database, regardless of C<offset> and C<limit>
166    parametars, see also C<size>.
167    
168  =cut  =cut
169    
170  sub open {  sub open {
171            my $self = shift;
172            my $arg = {@_};
173    
174            my $log = $self->_get_logger();
175    
176            $log->logcroak("need path") if (! $arg->{'path'});
177            my $code_page = $arg->{'code_page'} || '852';
178    
179            # store data in object
180            $self->{'code_page'} = $code_page;
181            foreach my $v (qw/path offset limit/) {
182                    $self->{$v} = $arg->{$v} if ($arg->{$v});
183            }
184    
185            # create Text::Iconv object
186            $self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});
187    
188            my ($db, $size) = $self->{open_db}->( $self,
189                    path => $arg->{path},
190            );
191    
192            unless ($db) {
193                    $log->logwarn("can't open database $arg->{path}, skipping...");
194                    return;
195            }
196    
197            unless ($size) {
198                    $log->logwarn("no records in database $arg->{path}, skipping...");
199                    return;
200            }
201    
202            my $offset = 1;
203            my $limit = $size;
204    
205            if (my $s = $self->{offset}) {
206                    $log->info("skipping to MFN $s");
207                    $offset = $s;
208            } else {
209                    $self->{offset} = $offset;
210            }
211    
212            if ($self->{limit}) {
213                    $log->info("limiting to ",$self->{limit}," records");
214                    $limit = $offset + $self->{limit} - 1;
215                    $limit = $size if ($limit > $size);
216            }
217    
218            # store size for later
219            $self->{size} = ($limit - $offset) ? ($limit - $offset + 1) : 0;
220    
221            $log->info("processing $self->{size} records in $code_page, convert to $self->{code_page}");
222    
223            # read database
224            for (my $pos = $offset; $pos <= $limit; $pos++) {
225    
226                    $log->debug("position: $pos\n");
227    
228                    my $rec = $self->{fetch_rec}->($self, $db, $pos );
229    
230                    if (! $rec) {
231                            $log->warn("record $pos empty? skipping...");
232                            next;
233                    }
234    
235                    # store
236                    if ($self->{low_mem}) {
237                            $self->{db}->put($pos, $rec);
238                    } else {
239                            $self->{data}->{$pos} = $rec;
240                    }
241    
242                    # create lookup
243                    $self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});
244    
245                    $self->progress_bar($pos,$limit);
246    
247            }
248    
249            $self->{pos} = -1;
250            $self->{last_pcnt} = 0;
251    
252            # store max mfn and return it.
253            $self->{max_pos} = $limit;
254            $log->debug("max_pos: $limit");
255    
256            return $size;
257    }
258    
259    =head2 fetch
260    
261    Fetch next record from database. It will also displays progress bar.
262    
263     my $rec = $isis->fetch;
264    
265    Record from this function should probably go to C<data_structure> for
266    normalisation.
267    
268    =cut
269    
270    sub fetch {
271            my $self = shift;
272    
273            my $log = $self->_get_logger();
274    
275            $log->logconfess("it seems that you didn't load database!") unless ($self->{pos});
276    
277            if ($self->{pos} == -1) {
278                    $self->{pos} = $self->{offset};
279            } else {
280                    $self->{pos}++;
281            }
282    
283            my $mfn = $self->{pos};
284    
285            if ($mfn > $self->{max_pos}) {
286                    $self->{pos} = $self->{max_pos};
287                    $log->debug("at EOF");
288                    return;
289            }
290    
291            $self->progress_bar($mfn,$self->{max_pos});
292    
293            my $rec;
294    
295            if ($self->{low_mem}) {
296                    $rec = $self->{db}->get($mfn);
297            } else {
298                    $rec = $self->{data}->{$mfn};
299            }
300    
301            $rec ||= 0E0;
302    }
303    
304    =head2 pos
305    
306    Returns current record number (MFN).
307    
308     print $isis->pos;
309    
310    First record in database has position 1.
311    
312    =cut
313    
314    sub pos {
315            my $self = shift;
316            return $self->{pos};
317  }  }
318    
319  =head2 function2  
320    =head2 size
321    
322    Returns number of records in database
323    
324     print $isis->size;
325    
326    Result from this function can be used to loop through all records
327    
328     foreach my $mfn ( 1 ... $isis->size ) { ... }
329    
330    because it takes into account C<offset> and C<limit>.
331    
332  =cut  =cut
333    
334  sub function2 {  sub size {
335            my $self = shift;
336            return $self->{size};
337  }  }
338    
339    =head2 seek
340    
341    Seek to specified MFN in file.
342    
343     $isis->seek(42);
344    
345    First record in database has position 1.
346    
347    =cut
348    
349    sub seek {
350            my $self = shift;
351            my $pos = shift || return;
352    
353            my $log = $self->_get_logger();
354    
355            if ($pos < 1) {
356                    $log->warn("seek before first record");
357                    $pos = 1;
358            } elsif ($pos > $self->{max_pos}) {
359                    $log->warn("seek beyond last record");
360                    $pos = $self->{max_pos};
361            }
362    
363            return $self->{pos} = (($pos - 1) || -1);
364    }
365    
366    
367  =head1 MEMORY USAGE  =head1 MEMORY USAGE
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