| 1 |
package WebPAC::Input; |
| 2 |
|
| 3 |
use warnings; |
| 4 |
use strict; |
| 5 |
|
| 6 |
use blib; |
| 7 |
|
| 8 |
use WebPAC::Common; |
| 9 |
use base qw/WebPAC::Common/; |
| 10 |
use Data::Dumper; |
| 11 |
use Encode qw/from_to/; |
| 12 |
|
| 13 |
=head1 NAME |
| 14 |
|
| 15 |
WebPAC::Input - read different file formats into WebPAC |
| 16 |
|
| 17 |
=head1 VERSION |
| 18 |
|
| 19 |
Version 0.11 |
| 20 |
|
| 21 |
=cut |
| 22 |
|
| 23 |
our $VERSION = '0.11'; |
| 24 |
|
| 25 |
=head1 SYNOPSIS |
| 26 |
|
| 27 |
This module implements input as database which have fixed and known |
| 28 |
I<size> while indexing and single unique numeric identifier for database |
| 29 |
position ranging from 1 to I<size>. |
| 30 |
|
| 31 |
Simply, something that is indexed by unmber from 1 .. I<size>. |
| 32 |
|
| 33 |
Examples of such databases are CDS/ISIS files, MARC files, lines in |
| 34 |
text file, and so on. |
| 35 |
|
| 36 |
Specific file formats are implemented using low-level interface modules, |
| 37 |
located in C<WebPAC::Input::*> namespace which export C<open_db>, |
| 38 |
C<fetch_rec> and optional C<init> functions. |
| 39 |
|
| 40 |
Perhaps a little code snippet. |
| 41 |
|
| 42 |
use WebPAC::Input; |
| 43 |
|
| 44 |
my $db = WebPAC::Input->new( |
| 45 |
module => 'WebPAC::Input::ISIS', |
| 46 |
low_mem => 1, |
| 47 |
); |
| 48 |
|
| 49 |
$db->open( path => '/path/to/database' ); |
| 50 |
print "database size: ",$db->size,"\n"; |
| 51 |
while (my $rec = $db->fetch) { |
| 52 |
# do something with $rec |
| 53 |
} |
| 54 |
|
| 55 |
|
| 56 |
|
| 57 |
=head1 FUNCTIONS |
| 58 |
|
| 59 |
=head2 new |
| 60 |
|
| 61 |
Create new input database object. |
| 62 |
|
| 63 |
my $db = new WebPAC::Input( |
| 64 |
module => 'WebPAC::Input::MARC', |
| 65 |
encoding => 'ISO-8859-2', |
| 66 |
low_mem => 1, |
| 67 |
recode => 'char pairs', |
| 68 |
no_progress_bar => 1, |
| 69 |
); |
| 70 |
|
| 71 |
C<module> is low-level file format module. See L<WebPAC::Input::ISIS> and |
| 72 |
L<WebPAC::Input::MARC>. |
| 73 |
|
| 74 |
Optional parametar C<encoding> specify application code page (which will be |
| 75 |
used internally). This should probably be your terminal encoding, and by |
| 76 |
default, it C<ISO-8859-2>. |
| 77 |
|
| 78 |
Default is not to use C<low_mem> options (see L<MEMORY USAGE> below). |
| 79 |
|
| 80 |
C<recode> is optional string constisting of character or words pairs that |
| 81 |
should be replaced in input stream. |
| 82 |
|
| 83 |
C<no_progress_bar> disables progress bar output on C<STDOUT> |
| 84 |
|
| 85 |
This function will also call low-level C<init> if it exists with same |
| 86 |
parametars. |
| 87 |
|
| 88 |
=cut |
| 89 |
|
| 90 |
sub new { |
| 91 |
my $class = shift; |
| 92 |
my $self = {@_}; |
| 93 |
bless($self, $class); |
| 94 |
|
| 95 |
my $log = $self->_get_logger; |
| 96 |
|
| 97 |
$log->logconfess("code_page argument is not suppored any more. change it to encoding") if ($self->{lookup}); |
| 98 |
$log->logconfess("lookup argument is not suppored any more. rewrite call to lookup_ref") if ($self->{lookup}); |
| 99 |
|
| 100 |
$log->logconfess("specify low-level file format module") unless ($self->{module}); |
| 101 |
my $module = $self->{module}; |
| 102 |
$module =~ s#::#/#g; |
| 103 |
$module .= '.pm'; |
| 104 |
$log->debug("require low-level module $self->{module} from $module"); |
| 105 |
|
| 106 |
require $module; |
| 107 |
#eval $self->{module} .'->import'; |
| 108 |
|
| 109 |
# check if required subclasses are implemented |
| 110 |
foreach my $subclass (qw/open_db fetch_rec init/) { |
| 111 |
my $n = $self->{module} . '::' . $subclass; |
| 112 |
if (! defined &{ $n }) { |
| 113 |
my $missing = "missing $subclass in $self->{module}"; |
| 114 |
$self->{$subclass} = sub { $log->logwarn($missing) }; |
| 115 |
} else { |
| 116 |
$self->{$subclass} = \&{ $n }; |
| 117 |
} |
| 118 |
} |
| 119 |
|
| 120 |
if ($self->{init}) { |
| 121 |
$log->debug("calling init"); |
| 122 |
$self->{init}->($self, @_); |
| 123 |
} |
| 124 |
|
| 125 |
$self->{'encoding'} ||= 'ISO-8859-2'; |
| 126 |
|
| 127 |
# running with low_mem flag? well, use DBM::Deep then. |
| 128 |
if ($self->{'low_mem'}) { |
| 129 |
$log->info("running with low_mem which impacts performance (<32 Mb memory usage)"); |
| 130 |
|
| 131 |
my $db_file = "data.db"; |
| 132 |
|
| 133 |
if (-e $db_file) { |
| 134 |
unlink $db_file or $log->logdie("can't remove '$db_file' from last run"); |
| 135 |
$log->debug("removed '$db_file' from last run"); |
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} |
| 137 |
|
| 138 |
require DBM::Deep; |
| 139 |
|
| 140 |
my $db = new DBM::Deep $db_file; |
| 141 |
|
| 142 |
$log->logdie("DBM::Deep error: $!") unless ($db); |
| 143 |
|
| 144 |
if ($db->error()) { |
| 145 |
$log->logdie("can't open '$db_file' under low_mem: ",$db->error()); |
| 146 |
} else { |
| 147 |
$log->debug("using file '$db_file' for DBM::Deep"); |
| 148 |
} |
| 149 |
|
| 150 |
$self->{'db'} = $db; |
| 151 |
} |
| 152 |
|
| 153 |
$self ? return $self : return undef; |
| 154 |
} |
| 155 |
|
| 156 |
=head2 open |
| 157 |
|
| 158 |
This function will read whole database in memory and produce lookups. |
| 159 |
|
| 160 |
$input->open( |
| 161 |
path => '/path/to/database/file', |
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code_page => 'cp852', |
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limit => 500, |
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offset => 6000, |
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lookup => $lookup_obj, |
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stats => 1, |
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lookup_ref => sub { |
| 168 |
my ($k,$v) = @_; |
| 169 |
# store lookup $k => $v |
| 170 |
}, |
| 171 |
modify_records => { |
| 172 |
900 => { '^a' => { ' : ' => '^b' } }, |
| 173 |
901 => { '*' => { '^b' => ' ; ' } }, |
| 174 |
}, |
| 175 |
); |
| 176 |
|
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By default, C<code_page> is assumed to be C<cp852>. |
| 178 |
|
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C<offset> is optional parametar to position at some offset before reading from database. |
| 180 |
|
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C<limit> is optional parametar to read just C<limit> records from database |
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|
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C<stats> create optional report about usage of fields and subfields |
| 184 |
|
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C<lookup_coderef> is closure to call when adding C<< key => 'value' >> combinations to |
| 186 |
lookup. |
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|
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C<modify_records> specify mapping from subfields to delimiters or from |
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delimiters to subfields, as well as oprations on fields (if subfield is |
| 190 |
defined as C<*>. |
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|
| 192 |
Returns size of database, regardless of C<offset> and C<limit> |
| 193 |
parametars, see also C<size>. |
| 194 |
|
| 195 |
=cut |
| 196 |
|
| 197 |
sub open { |
| 198 |
my $self = shift; |
| 199 |
my $arg = {@_}; |
| 200 |
|
| 201 |
my $log = $self->_get_logger(); |
| 202 |
|
| 203 |
$log->logconfess("lookup argument is not suppored any more. rewrite call to lookup_coderef") if ($arg->{lookup}); |
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$log->logconfess("lookup_coderef must be CODE, not ",ref($arg->{lookup_coderef})) |
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if ($arg->{lookup_coderef} && ref($arg->{lookup_coderef}) ne 'CODE'); |
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|
| 207 |
$log->logcroak("need path") if (! $arg->{'path'}); |
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my $code_page = $arg->{'code_page'} || 'cp852'; |
| 209 |
|
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# store data in object |
| 211 |
$self->{'input_code_page'} = $code_page; |
| 212 |
foreach my $v (qw/path offset limit/) { |
| 213 |
$self->{$v} = $arg->{$v} if ($arg->{$v}); |
| 214 |
} |
| 215 |
|
| 216 |
my $filter_ref; |
| 217 |
my $recode_regex; |
| 218 |
my $recode_map; |
| 219 |
|
| 220 |
if ($self->{recode}) { |
| 221 |
my @r = split(/\s/, $self->{recode}); |
| 222 |
if ($#r % 2 != 1) { |
| 223 |
$log->logwarn("recode needs even number of elements (some number of valid pairs)"); |
| 224 |
} else { |
| 225 |
while (@r) { |
| 226 |
my $from = shift @r; |
| 227 |
my $to = shift @r; |
| 228 |
$recode_map->{$from} = $to; |
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} |
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|
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$recode_regex = join '|' => keys %{ $recode_map }; |
| 232 |
|
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$log->debug("using recode regex: $recode_regex"); |
| 234 |
} |
| 235 |
|
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} |
| 237 |
|
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my $rec_regex = $self->modify_record_regexps(%{ $arg->{modify_records} }); |
| 239 |
$log->debug("rec_regex: ", Dumper($rec_regex)); |
| 240 |
|
| 241 |
my ($db, $size) = $self->{open_db}->( $self, |
| 242 |
path => $arg->{path}, |
| 243 |
# filter => sub { |
| 244 |
# my ($l,$f_nr) = @_; |
| 245 |
# return unless defined($l); |
| 246 |
# from_to($l, $code_page, $self->{'encoding'}); |
| 247 |
# $l =~ s/($recode_regex)/$recode_map->{$1}/g if ($recode_regex && $recode_map); |
| 248 |
# return $l; |
| 249 |
# }, |
| 250 |
%{ $arg }, |
| 251 |
); |
| 252 |
|
| 253 |
unless (defined($db)) { |
| 254 |
$log->logwarn("can't open database $arg->{path}, skipping..."); |
| 255 |
return; |
| 256 |
} |
| 257 |
|
| 258 |
unless ($size) { |
| 259 |
$log->logwarn("no records in database $arg->{path}, skipping..."); |
| 260 |
return; |
| 261 |
} |
| 262 |
|
| 263 |
my $from_rec = 1; |
| 264 |
my $to_rec = $size; |
| 265 |
|
| 266 |
if (my $s = $self->{offset}) { |
| 267 |
$log->debug("skipping to MFN $s"); |
| 268 |
$from_rec = $s; |
| 269 |
} else { |
| 270 |
$self->{offset} = $from_rec; |
| 271 |
} |
| 272 |
|
| 273 |
if ($self->{limit}) { |
| 274 |
$log->debug("limiting to ",$self->{limit}," records"); |
| 275 |
$to_rec = $from_rec + $self->{limit} - 1; |
| 276 |
$to_rec = $size if ($to_rec > $size); |
| 277 |
} |
| 278 |
|
| 279 |
# store size for later |
| 280 |
$self->{size} = ($to_rec - $from_rec) ? ($to_rec - $from_rec + 1) : 0; |
| 281 |
|
| 282 |
$log->info("processing $self->{size}/$size records [$from_rec-$to_rec] convert $code_page -> $self->{encoding}", $self->{stats} ? ' [stats]' : ''); |
| 283 |
|
| 284 |
# read database |
| 285 |
for (my $pos = $from_rec; $pos <= $to_rec; $pos++) { |
| 286 |
|
| 287 |
$log->debug("position: $pos\n"); |
| 288 |
|
| 289 |
my $rec = $self->{fetch_rec}->($self, $db, $pos, sub { |
| 290 |
my ($l,$f_nr) = @_; |
| 291 |
# return unless defined($l); |
| 292 |
# return $l unless ($rec_regex && $f_nr); |
| 293 |
|
| 294 |
$log->debug("-=> $f_nr ## $l"); |
| 295 |
|
| 296 |
# codepage conversion and recode_regex |
| 297 |
from_to($l, $code_page, $self->{'encoding'}); |
| 298 |
$l =~ s/($recode_regex)/$recode_map->{$1}/g if ($recode_regex && $recode_map); |
| 299 |
|
| 300 |
# apply regexps |
| 301 |
if ($rec_regex && defined($rec_regex->{$f_nr})) { |
| 302 |
$log->logconfess("regexps->{$f_nr} must be ARRAY") if (ref($rec_regex->{$f_nr}) ne 'ARRAY'); |
| 303 |
my $c = 0; |
| 304 |
foreach my $r (@{ $rec_regex->{$f_nr} }) { |
| 305 |
my $old_l = $l; |
| 306 |
eval '$l =~ ' . $r; |
| 307 |
if ($old_l ne $l) { |
| 308 |
$log->debug("REGEX on $f_nr eval \$l =~ $r\n## old l: [$old_l]\n## new l: [$l]"); |
| 309 |
} |
| 310 |
$log->error("error applying regex: $r") if ($@); |
| 311 |
} |
| 312 |
} |
| 313 |
|
| 314 |
$log->debug("<=- $f_nr ## $l"); |
| 315 |
return $l; |
| 316 |
}); |
| 317 |
|
| 318 |
$log->debug(sub { Dumper($rec) }); |
| 319 |
|
| 320 |
if (! $rec) { |
| 321 |
$log->warn("record $pos empty? skipping..."); |
| 322 |
next; |
| 323 |
} |
| 324 |
|
| 325 |
# store |
| 326 |
if ($self->{low_mem}) { |
| 327 |
$self->{db}->put($pos, $rec); |
| 328 |
} else { |
| 329 |
$self->{data}->{$pos} = $rec; |
| 330 |
} |
| 331 |
|
| 332 |
# create lookup |
| 333 |
$arg->{'lookup_coderef'}->( $rec ) if ($rec && $arg->{'lookup_coderef'}); |
| 334 |
|
| 335 |
# update counters for statistics |
| 336 |
if ($self->{stats}) { |
| 337 |
|
| 338 |
# fetch clean record with regexpes applied for statistics |
| 339 |
my $rec = $self->{fetch_rec}->($self, $db, $pos); |
| 340 |
|
| 341 |
foreach my $fld (keys %{ $rec }) { |
| 342 |
$self->{_stats}->{fld}->{ $fld }++; |
| 343 |
|
| 344 |
$log->logdie("invalid record fild $fld, not ARRAY") |
| 345 |
unless (ref($rec->{ $fld }) eq 'ARRAY'); |
| 346 |
|
| 347 |
foreach my $row (@{ $rec->{$fld} }) { |
| 348 |
|
| 349 |
if (ref($row) eq 'HASH') { |
| 350 |
|
| 351 |
foreach my $sf (keys %{ $row }) { |
| 352 |
next if ($sf eq 'subfields'); |
| 353 |
$self->{_stats}->{sf}->{ $fld }->{ $sf }->{count}++; |
| 354 |
$self->{_stats}->{sf}->{ $fld }->{ $sf }->{repeatable}++ |
| 355 |
if (ref($row->{$sf}) eq 'ARRAY'); |
| 356 |
} |
| 357 |
|
| 358 |
} else { |
| 359 |
$self->{_stats}->{repeatable}->{ $fld }++; |
| 360 |
} |
| 361 |
} |
| 362 |
} |
| 363 |
} |
| 364 |
|
| 365 |
$self->progress_bar($pos,$to_rec) unless ($self->{no_progress_bar}); |
| 366 |
|
| 367 |
} |
| 368 |
|
| 369 |
$self->{pos} = -1; |
| 370 |
$self->{last_pcnt} = 0; |
| 371 |
|
| 372 |
# store max mfn and return it. |
| 373 |
$self->{max_pos} = $to_rec; |
| 374 |
$log->debug("max_pos: $to_rec"); |
| 375 |
|
| 376 |
return $size; |
| 377 |
} |
| 378 |
|
| 379 |
=head2 fetch |
| 380 |
|
| 381 |
Fetch next record from database. It will also displays progress bar. |
| 382 |
|
| 383 |
my $rec = $isis->fetch; |
| 384 |
|
| 385 |
Record from this function should probably go to C<data_structure> for |
| 386 |
normalisation. |
| 387 |
|
| 388 |
=cut |
| 389 |
|
| 390 |
sub fetch { |
| 391 |
my $self = shift; |
| 392 |
|
| 393 |
my $log = $self->_get_logger(); |
| 394 |
|
| 395 |
$log->logconfess("it seems that you didn't load database!") unless ($self->{pos}); |
| 396 |
|
| 397 |
if ($self->{pos} == -1) { |
| 398 |
$self->{pos} = $self->{offset}; |
| 399 |
} else { |
| 400 |
$self->{pos}++; |
| 401 |
} |
| 402 |
|
| 403 |
my $mfn = $self->{pos}; |
| 404 |
|
| 405 |
if ($mfn > $self->{max_pos}) { |
| 406 |
$self->{pos} = $self->{max_pos}; |
| 407 |
$log->debug("at EOF"); |
| 408 |
return; |
| 409 |
} |
| 410 |
|
| 411 |
$self->progress_bar($mfn,$self->{max_pos}) unless ($self->{no_progress_bar}); |
| 412 |
|
| 413 |
my $rec; |
| 414 |
|
| 415 |
if ($self->{low_mem}) { |
| 416 |
$rec = $self->{db}->get($mfn); |
| 417 |
} else { |
| 418 |
$rec = $self->{data}->{$mfn}; |
| 419 |
} |
| 420 |
|
| 421 |
$rec ||= 0E0; |
| 422 |
} |
| 423 |
|
| 424 |
=head2 pos |
| 425 |
|
| 426 |
Returns current record number (MFN). |
| 427 |
|
| 428 |
print $isis->pos; |
| 429 |
|
| 430 |
First record in database has position 1. |
| 431 |
|
| 432 |
=cut |
| 433 |
|
| 434 |
sub pos { |
| 435 |
my $self = shift; |
| 436 |
return $self->{pos}; |
| 437 |
} |
| 438 |
|
| 439 |
|
| 440 |
=head2 size |
| 441 |
|
| 442 |
Returns number of records in database |
| 443 |
|
| 444 |
print $isis->size; |
| 445 |
|
| 446 |
Result from this function can be used to loop through all records |
| 447 |
|
| 448 |
foreach my $mfn ( 1 ... $isis->size ) { ... } |
| 449 |
|
| 450 |
because it takes into account C<offset> and C<limit>. |
| 451 |
|
| 452 |
=cut |
| 453 |
|
| 454 |
sub size { |
| 455 |
my $self = shift; |
| 456 |
return $self->{size}; |
| 457 |
} |
| 458 |
|
| 459 |
=head2 seek |
| 460 |
|
| 461 |
Seek to specified MFN in file. |
| 462 |
|
| 463 |
$isis->seek(42); |
| 464 |
|
| 465 |
First record in database has position 1. |
| 466 |
|
| 467 |
=cut |
| 468 |
|
| 469 |
sub seek { |
| 470 |
my $self = shift; |
| 471 |
my $pos = shift || return; |
| 472 |
|
| 473 |
my $log = $self->_get_logger(); |
| 474 |
|
| 475 |
if ($pos < 1) { |
| 476 |
$log->warn("seek before first record"); |
| 477 |
$pos = 1; |
| 478 |
} elsif ($pos > $self->{max_pos}) { |
| 479 |
$log->warn("seek beyond last record"); |
| 480 |
$pos = $self->{max_pos}; |
| 481 |
} |
| 482 |
|
| 483 |
return $self->{pos} = (($pos - 1) || -1); |
| 484 |
} |
| 485 |
|
| 486 |
=head2 stats |
| 487 |
|
| 488 |
Dump statistics about field and subfield usage |
| 489 |
|
| 490 |
print $input->stats; |
| 491 |
|
| 492 |
=cut |
| 493 |
|
| 494 |
sub stats { |
| 495 |
my $self = shift; |
| 496 |
|
| 497 |
my $log = $self->_get_logger(); |
| 498 |
|
| 499 |
my $s = $self->{_stats}; |
| 500 |
if (! $s) { |
| 501 |
$log->warn("called stats, but there is no statistics collected"); |
| 502 |
return; |
| 503 |
} |
| 504 |
|
| 505 |
my $max_fld = 0; |
| 506 |
|
| 507 |
my $out = join("\n", |
| 508 |
map { |
| 509 |
my $f = $_ || die "no field"; |
| 510 |
my $v = $s->{fld}->{$f} || die "no s->{fld}->{$f}"; |
| 511 |
$max_fld = $v if ($v > $max_fld); |
| 512 |
|
| 513 |
my $o = sprintf("%4s %d ~", $f, $v); |
| 514 |
|
| 515 |
if (defined($s->{sf}->{$f})) { |
| 516 |
map { |
| 517 |
$o .= sprintf(" %s:%d%s", $_, |
| 518 |
$s->{sf}->{$f}->{$_}->{count}, |
| 519 |
$s->{sf}->{$f}->{$_}->{repeatable} ? '*' : '', |
| 520 |
); |
| 521 |
} sort keys %{ $s->{sf}->{$f} }; |
| 522 |
} |
| 523 |
|
| 524 |
if (my $v_r = $s->{repeatable}->{$f}) { |
| 525 |
$o .= " ($v_r)" if ($v_r != $v); |
| 526 |
} |
| 527 |
|
| 528 |
$o; |
| 529 |
} sort { $a cmp $b } keys %{ $s->{fld} } |
| 530 |
); |
| 531 |
|
| 532 |
$log->debug( sub { Dumper($s) } ); |
| 533 |
|
| 534 |
return $out; |
| 535 |
} |
| 536 |
|
| 537 |
=head2 modify_record_regexps |
| 538 |
|
| 539 |
Generate hash with regexpes to be applied using L<filter>. |
| 540 |
|
| 541 |
my $regexpes = $input->modify_record_regexps( |
| 542 |
900 => { '^a' => { ' : ' => '^b' } }, |
| 543 |
901 => { '*' => { '^b' => ' ; ' } }, |
| 544 |
); |
| 545 |
|
| 546 |
=cut |
| 547 |
|
| 548 |
sub modify_record_regexps { |
| 549 |
my $self = shift; |
| 550 |
my $modify_record = {@_}; |
| 551 |
|
| 552 |
my $regexpes; |
| 553 |
|
| 554 |
foreach my $f (keys %$modify_record) { |
| 555 |
warn "--- f: $f\n"; |
| 556 |
foreach my $sf (keys %{ $modify_record->{$f} }) { |
| 557 |
warn "---- sf: $sf\n"; |
| 558 |
foreach my $from (keys %{ $modify_record->{$f}->{$sf} }) { |
| 559 |
my $to = $modify_record->{$f}->{$sf}->{$from}; |
| 560 |
#die "no field?" unless defined($to); |
| 561 |
warn "----- transform: |$from| -> |$to|\n"; |
| 562 |
|
| 563 |
if ($sf =~ /^\^/) { |
| 564 |
my $regex = |
| 565 |
's/\Q'. $sf .'\E([^\^]+)\Q'. $from .'\E([^\^]+)/'. $sf .'$1'. $to .'$2/g'; |
| 566 |
push @{ $regexpes->{$f} }, $regex; |
| 567 |
warn ">>>>> $regex [sf]\n"; |
| 568 |
} else { |
| 569 |
my $regex = |
| 570 |
's/\Q'. $from .'\E/'. $to .'/g'; |
| 571 |
push @{ $regexpes->{$f} }, $regex; |
| 572 |
warn ">>>>> $regex [global]\n"; |
| 573 |
} |
| 574 |
|
| 575 |
} |
| 576 |
} |
| 577 |
} |
| 578 |
|
| 579 |
return $regexpes; |
| 580 |
} |
| 581 |
|
| 582 |
=head1 MEMORY USAGE |
| 583 |
|
| 584 |
C<low_mem> options is double-edged sword. If enabled, WebPAC |
| 585 |
will run on memory constraint machines (which doesn't have enough |
| 586 |
physical RAM to create memory structure for whole source database). |
| 587 |
|
| 588 |
If your machine has 512Mb or more of RAM and database is around 10000 records, |
| 589 |
memory shouldn't be an issue. If you don't have enough physical RAM, you |
| 590 |
might consider using virtual memory (if your operating system is handling it |
| 591 |
well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle |
| 592 |
parsed structure of ISIS database (this is what C<low_mem> option does). |
| 593 |
|
| 594 |
Hitting swap at end of reading source database is probably o.k. However, |
| 595 |
hitting swap before 90% will dramatically decrease performance and you will |
| 596 |
be better off with C<low_mem> and using rest of availble memory for |
| 597 |
operating system disk cache (Linux is particuallary good about this). |
| 598 |
However, every access to database record will require disk access, so |
| 599 |
generation phase will be slower 10-100 times. |
| 600 |
|
| 601 |
Parsed structures are essential - you just have option to trade RAM memory |
| 602 |
(which is fast) for disk space (which is slow). Be sure to have planty of |
| 603 |
disk space if you are using C<low_mem> and thus L<DBM::Deep>. |
| 604 |
|
| 605 |
However, when WebPAC is running on desktop machines (or laptops :-), it's |
| 606 |
highly undesireable for system to start swapping. Using C<low_mem> option can |
| 607 |
reduce WecPAC memory usage to around 64Mb for same database with lookup |
| 608 |
fields and sorted indexes which stay in RAM. Performance will suffer, but |
| 609 |
memory usage will really be minimal. It might be also more confortable to |
| 610 |
run WebPAC reniced on those machines. |
| 611 |
|
| 612 |
|
| 613 |
=head1 AUTHOR |
| 614 |
|
| 615 |
Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >> |
| 616 |
|
| 617 |
=head1 COPYRIGHT & LICENSE |
| 618 |
|
| 619 |
Copyright 2005-2006 Dobrica Pavlinusic, All Rights Reserved. |
| 620 |
|
| 621 |
This program is free software; you can redistribute it and/or modify it |
| 622 |
under the same terms as Perl itself. |
| 623 |
|
| 624 |
=cut |
| 625 |
|
| 626 |
1; # End of WebPAC::Input |
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