summaryrefslogtreecommitdiff
path: root/includes/QueryPage.php
blob: 69912cbfa2e3815e01f087ac72bf276a7a5bc23c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
<?php
/**
 * Contain a class for special pages
 * @file
 * @ingroup SpecialPages
 */

/**
 * List of query page classes and their associated special pages,
 * for periodic updates.
 *
 * DO NOT CHANGE THIS LIST without testing that
 * maintenance/updateSpecialPages.php still works.
 */
global $wgQueryPages; // not redundant
$wgQueryPages = array(
//         QueryPage subclass           Special page name         Limit (false for none, none for the default)
// ----------------------------------------------------------------------------
	array( 'AncientPagesPage',              'Ancientpages'                  ),
	array( 'BrokenRedirectsPage',           'BrokenRedirects'               ),
	array( 'DeadendPagesPage',              'Deadendpages'                  ),
	array( 'DisambiguationsPage',           'Disambiguations'               ),
	array( 'DoubleRedirectsPage',           'DoubleRedirects'               ),
	array( 'FileDuplicateSearchPage',       'FileDuplicateSearch'           ),
	array( 'LinkSearchPage',                'LinkSearch'                    ),
	array( 'ListredirectsPage',             'Listredirects'                 ),
	array( 'LonelyPagesPage',               'Lonelypages'                   ),
	array( 'LongPagesPage',                 'Longpages'                     ),
	array( 'MIMEsearchPage',                'MIMEsearch'                    ),
	array( 'MostcategoriesPage',            'Mostcategories'                ),
	array( 'MostimagesPage',                'Mostimages'                    ),
	array( 'MostlinkedCategoriesPage',      'Mostlinkedcategories'          ),
	array( 'MostlinkedtemplatesPage',       'Mostlinkedtemplates'           ),
	array( 'MostlinkedPage',                'Mostlinked'                    ),
	array( 'MostrevisionsPage',             'Mostrevisions'                 ),
	array( 'FewestrevisionsPage',           'Fewestrevisions'               ),
	array( 'ShortPagesPage',                'Shortpages'                    ),
	array( 'UncategorizedCategoriesPage',   'Uncategorizedcategories'       ),
	array( 'UncategorizedPagesPage',        'Uncategorizedpages'            ),
	array( 'UncategorizedImagesPage',       'Uncategorizedimages'           ),
	array( 'UncategorizedTemplatesPage',    'Uncategorizedtemplates'        ),
	array( 'UnusedCategoriesPage',          'Unusedcategories'              ),
	array( 'UnusedimagesPage',              'Unusedimages'                  ),
	array( 'WantedCategoriesPage',          'Wantedcategories'              ),
	array( 'WantedFilesPage',               'Wantedfiles'                   ),
	array( 'WantedPagesPage',               'Wantedpages'                   ),
	array( 'WantedTemplatesPage',           'Wantedtemplates'               ),
	array( 'UnwatchedPagesPage',            'Unwatchedpages'                ),
	array( 'UnusedtemplatesPage',           'Unusedtemplates'               ),
	array( 'WithoutInterwikiPage',          'Withoutinterwiki'              ),
);
wfRunHooks( 'wgQueryPages', array( &$wgQueryPages ) );

global $wgDisableCounters;
if ( !$wgDisableCounters )
	$wgQueryPages[] = array( 'PopularPagesPage', 'Popularpages' );


/**
 * This is a class for doing query pages; since they're almost all the same,
 * we factor out some of the functionality into a superclass, and let
 * subclasses derive from it.
 * @ingroup SpecialPage
 */
abstract class QueryPage extends SpecialPage {
	/**
	 * Whether or not we want plain listoutput rather than an ordered list
	 *
	 * @var bool
	 */
	var $listoutput = false;

	/**
	 * The offset and limit in use, as passed to the query() function
	 *
	 * @var integer
	 */
	var $offset = 0;
	var $limit = 0;

	/**
	 * The number of rows returned by the query. Reading this variable
	 * only makes sense in functions that are run after the query has been
	 * done, such as preprocessResults() and formatRow().
	 */
	protected $numRows;

	protected $cachedTimestamp = null;

	/**
	 * Wheter to show prev/next links
	 */
	protected $shownavigation = true;

	/**
	 * A mutator for $this->listoutput;
	 *
	 * @param $bool Boolean
	 */
	function setListoutput( $bool ) {
		$this->listoutput = $bool;
	}

	/**
	 * Subclasses return an SQL query here, formatted as an array with the
	 * following keys:
	 *    tables => Table(s) for passing to Database::select()
	 *    fields => Field(s) for passing to Database::select(), may be *
	 *    conds => WHERE conditions
	 *    options => options
	 *    join_conds => JOIN conditions
	 *
	 * Note that the query itself should return the following three columns:
	 * 'namespace', 'title', and 'value'. 'value' is used for sorting.
	 *
	 * These may be stored in the querycache table for expensive queries,
	 * and that cached data will be returned sometimes, so the presence of
	 * extra fields can't be relied upon. The cached 'value' column will be
	 * an integer; non-numeric values are useful only for sorting the
	 * initial query (except if they're timestamps, see usesTimestamps()).
	 *
	 * Don't include an ORDER or LIMIT clause, they will be added.
	 *
	 * If this function is not overridden or returns something other than
	 * an array, getSQL() will be used instead. This is for backwards
	 * compatibility only and is strongly deprecated.
	 * @return array
	 * @since 1.18
	 */
	function getQueryInfo() {
		return null;
	}

	/**
	 * For back-compat, subclasses may return a raw SQL query here, as a string.
	 * This is stronly deprecated; getQueryInfo() should be overridden instead.
	 * @return string
	 */
	function getSQL() {
		/* Implement getQueryInfo() instead */
		throw new MWException( "Bug in a QueryPage: doesn't implement getQueryInfo() nor getQuery() properly" );
	}

	/**
	 * Subclasses return an array of fields to order by here. Don't append
	 * DESC to the field names, that'll be done automatically if
	 * sortDescending() returns true.
	 * @return array
	 * @since 1.18
	 */
	function getOrderFields() {
		return array( 'value' );
	}

	/**
	 * Does this query return timestamps rather than integers in its
	 * 'value' field? If true, this class will convert 'value' to a
	 * UNIX timestamp for caching.
	 * NOTE: formatRow() may get timestamps in TS_MW (mysql), TS_DB (pgsql)
	 *       or TS_UNIX (querycache) format, so be sure to always run them
	 *       through wfTimestamp()
	 * @return bool
	 * @since 1.18
	 */
	function usesTimestamps() {
		return false;
	}

	/**
	 * Override to sort by increasing values
	 *
	 * @return Boolean
	 */
	function sortDescending() {
		return true;
	}

	/**
	 * Is this query expensive (for some definition of expensive)? Then we
	 * don't let it run in miser mode. $wgDisableQueryPages causes all query
	 * pages to be declared expensive. Some query pages are always expensive.
	 *
	 * @return Boolean
	 */
	function isExpensive() {
		global $wgDisableQueryPages;
		return $wgDisableQueryPages;
	}

	/**
	 * Is the output of this query cacheable? Non-cacheable expensive pages
	 * will be disabled in miser mode and will not have their results written
	 * to the querycache table.
	 * @return Boolean
	 * @since 1.18
	 */
	public function isCacheable() {
		return true;
	}

	/**
	 * Whether or not the output of the page in question is retrieved from
	 * the database cache.
	 *
	 * @return Boolean
	 */
	function isCached() {
		global $wgMiserMode;

		return $this->isExpensive() && $wgMiserMode;
	}

	/**
	 * Sometime we dont want to build rss / atom feeds.
	 *
	 * @return Boolean
	 */
	function isSyndicated() {
		return true;
	}

	/**
	 * Formats the results of the query for display. The skin is the current
	 * skin; you can use it for making links. The result is a single row of
	 * result data. You should be able to grab SQL results off of it.
	 * If the function returns false, the line output will be skipped.
	 * @param $skin Skin
	 * @param $result object Result row
	 * @return mixed String or false to skip
	 *
	 * @param $skin Skin object
	 * @param $result Object: database row
	 */
	abstract function formatResult( $skin, $result );

	/**
	 * The content returned by this function will be output before any result
	 *
	 * @return String
	 */
	function getPageHeader() {
		return '';
	}

	/**
	 * If using extra form wheely-dealies, return a set of parameters here
	 * as an associative array. They will be encoded and added to the paging
	 * links (prev/next/lengths).
	 *
	 * @return Array
	 */
	function linkParameters() {
		return array();
	}

	/**
	 * Some special pages (for example SpecialListusers) might not return the
	 * current object formatted, but return the previous one instead.
	 * Setting this to return true will ensure formatResult() is called
	 * one more time to make sure that the very last result is formatted
	 * as well.
	 */
	function tryLastResult() {
		return false;
	}

	/**
	 * Clear the cache and save new results
	 *
	 * @param $limit Integer: limit for SQL statement
	 * @param $ignoreErrors Boolean: whether to ignore database errors
	 */
	function recache( $limit, $ignoreErrors = true ) {
		if ( !$this->isCacheable() ) {
			return 0;
		}

		$fname = get_class( $this ) . '::recache';
		$dbw = wfGetDB( DB_MASTER );
		$dbr = wfGetDB( DB_SLAVE, array( $this->getName(), __METHOD__, 'vslow' ) );
		if ( !$dbw || !$dbr ) {
			return false;
		}

		if ( $ignoreErrors ) {
			$ignoreW = $dbw->ignoreErrors( true );
			$ignoreR = $dbr->ignoreErrors( true );
		}

		# Clear out any old cached data
		$dbw->delete( 'querycache', array( 'qc_type' => $this->getName() ), $fname );
		# Do query
		$res = $this->reallyDoQuery( $limit, false );
		$num = false;
		if ( $res ) {
			$num = $dbr->numRows( $res );
			# Fetch results
			$vals = array();
			while ( $res && $row = $dbr->fetchObject( $res ) ) {
				if ( isset( $row->value ) ) {
					if ( $this->usesTimestamps() ) {
						$value = wfTimestamp( TS_UNIX,
							$row->value );
					} else {
						$value = intval( $row->value ); // @bug 14414
					}
				} else {
					$value = 0;
				}

				$vals[] = array( 'qc_type' => $this->getName(),
						'qc_namespace' => $row->namespace,
						'qc_title' => $row->title,
						'qc_value' => $value );
			}

			# Save results into the querycache table on the master
			if ( count( $vals ) ) {
				if ( !$dbw->insert( 'querycache', $vals, __METHOD__ ) ) {
					// Set result to false to indicate error
					$num = false;
				}
			}
			if ( $ignoreErrors ) {
				$dbw->ignoreErrors( $ignoreW );
				$dbr->ignoreErrors( $ignoreR );
			}

			# Update the querycache_info record for the page
			$dbw->delete( 'querycache_info', array( 'qci_type' => $this->getName() ), $fname );
			$dbw->insert( 'querycache_info', array( 'qci_type' => $this->getName(), 'qci_timestamp' => $dbw->timestamp() ), $fname );

		}
		return $num;
	}

	/**
	 * Run the query and return the result
	 * @param $limit mixed Numerical limit or false for no limit
	 * @param $offset mixed Numerical offset or false for no offset
	 * @return ResultWrapper
	 * @since 1.18
	 */
	function reallyDoQuery( $limit, $offset = false ) {
		$fname = get_class( $this ) . "::reallyDoQuery";
		$dbr = wfGetDB( DB_SLAVE );
		$query = $this->getQueryInfo();
		$order = $this->getOrderFields();
		if ( $this->sortDescending() ) {
			foreach ( $order as &$field ) {
				$field .= ' DESC';
			}
		}
		if ( is_array( $query ) ) {
			$tables = isset( $query['tables'] ) ? (array)$query['tables'] : array();
			$fields = isset( $query['fields'] ) ? (array)$query['fields'] : array();
			$conds = isset( $query['conds'] ) ? (array)$query['conds'] : array();
			$options = isset( $query['options'] ) ? (array)$query['options'] : array();
			$join_conds = isset( $query['join_conds'] ) ? (array)$query['join_conds'] : array();
			if ( count( $order ) ) {
				$options['ORDER BY'] = implode( ', ', $order );
			}
			if ( $limit !== false ) {
				$options['LIMIT'] = intval( $limit );
			}
			if ( $offset !== false ) {
				$options['OFFSET'] = intval( $offset );
			}

			$res = $dbr->select( $tables, $fields, $conds, $fname,
					$options, $join_conds
			);
		} else {
			// Old-fashioned raw SQL style, deprecated
			$sql = $this->getSQL();
			$sql .= ' ORDER BY ' . implode( ', ', $order );
			$sql = $dbr->limitResult( $sql, $limit, $offset );
			$res = $dbr->query( $sql, $fname );
		}
		return $dbr->resultObject( $res );
	}

	/**
	 * Somewhat deprecated, you probably want to be using execute()
	 */
	function doQuery( $offset = false, $limit = false ) {
		if ( $this->isCached() && $this->isCacheable() ) {
			return $this->fetchFromCache( $limit, $offset );
		} else {
			return $this->reallyDoQuery( $limit, $offset );
		}
	}

	/**
	 * Fetch the query results from the query cache
	 * @param $limit mixed Numerical limit or false for no limit
	 * @param $offset mixed Numerical offset or false for no offset
	 * @return ResultWrapper
	 * @since 1.18
	 */
	function fetchFromCache( $limit, $offset = false ) {
		$dbr = wfGetDB( DB_SLAVE );
		$options = array ();
		if ( $limit !== false ) {
			$options['LIMIT'] = intval( $limit );
		}
		if ( $offset !== false ) {
			$options['OFFSET'] = intval( $offset );
		}
		if ( $this->sortDescending() ) {
			$options['ORDER BY'] = 'qc_value DESC';
		} else {
			$options['ORDER BY'] = 'qc_value ASC';
		}
		$res = $dbr->select( 'querycache', array( 'qc_type',
				'qc_namespace AS namespace',
				'qc_title AS title',
				'qc_value AS value' ),
				array( 'qc_type' => $this->getName() ),
				__METHOD__, $options
		);
		return $dbr->resultObject( $res );
	}

	public function getCachedTimestamp() {
		if ( is_null( $this->cachedTimestamp ) ) {
			$dbr = wfGetDB( DB_SLAVE );
			$fname = get_class( $this ) . '::getCachedTimestamp';
			$this->cachedTimestamp = $dbr->selectField( 'querycache_info', 'qci_timestamp',
				array( 'qci_type' => $this->getName() ), $fname );
		}
		return $this->cachedTimestamp;
	}

	/**
	 * This is the actual workhorse. It does everything needed to make a
	 * real, honest-to-gosh query page.
	 */
	function execute( $par ) {
		global $wgQueryCacheLimit, $wgDisableQueryPageUpdate;

		$user = $this->getUser();
		if ( !$this->userCanExecute( $user ) ) {
			$this->displayRestrictionError();
			return;
		}

		$this->setHeaders();
		$this->outputHeader();

		$out = $this->getOutput();

		if ( $this->isCached() && !$this->isCacheable() ) {
			$out->addWikiMsg( 'querypage-disabled' );
			return 0;
		}

		$out->setSyndicated( $this->isSyndicated() );

		if ( $this->limit == 0 && $this->offset == 0 ) {
			list( $this->limit, $this->offset ) = $this->getRequest()->getLimitOffset();
		}

		// TODO: Use doQuery()
		if ( !$this->isCached() ) {
			$res = $this->reallyDoQuery( $this->limit, $this->offset );
		} else {
			# Get the cached result
			$res = $this->fetchFromCache( $this->limit, $this->offset );
			if ( !$this->listoutput ) {

				# Fetch the timestamp of this update
				$ts = $this->getCachedTimestamp();
				$lang = $this->getLanguage();
				$maxResults = $lang->formatNum( $wgQueryCacheLimit );

				if ( $ts ) {
					$updated = $lang->userTimeAndDate( $ts, $user );
					$updateddate = $lang->userDate( $ts, $user );
					$updatedtime = $lang->userTime( $ts, $user );
					$out->addMeta( 'Data-Cache-Time', $ts );
					$out->addInlineScript( "var dataCacheTime = '$ts';" );
					$out->addWikiMsg( 'perfcachedts', $updated, $updateddate, $updatedtime, $maxResults );
				} else {
					$out->addWikiMsg( 'perfcached', $maxResults );
				}

				# If updates on this page have been disabled, let the user know
				# that the data set won't be refreshed for now
				if ( is_array( $wgDisableQueryPageUpdate ) && in_array( $this->getName(), $wgDisableQueryPageUpdate ) ) {
					$out->addWikiMsg( 'querypage-no-updates' );
				}
			}
		}

		$this->numRows = $res->numRows();

		$dbr = wfGetDB( DB_SLAVE );
		$this->preprocessResults( $dbr, $res );

		$out->addHTML( Xml::openElement( 'div', array( 'class' => 'mw-spcontent' ) ) );

		# Top header and navigation
		if ( $this->shownavigation ) {
			$out->addHTML( $this->getPageHeader() );
			if ( $this->numRows > 0 ) {
				$out->addHTML( $this->msg( 'showingresults' )->numParams(
					$this->numRows, $this->offset + 1 )->parseAsBlock() );
				# Disable the "next" link when we reach the end
				$paging = $this->getLanguage()->viewPrevNext( $this->getTitle( $par ), $this->offset,
					$this->limit, $this->linkParameters(), ( $this->numRows < $this->limit ) );
				$out->addHTML( '<p>' . $paging . '</p>' );
			} else {
				# No results to show, so don't bother with "showing X of Y" etc.
				# -- just let the user know and give up now
				$out->addWikiMsg( 'specialpage-empty' );
				$out->addHTML( Xml::closeElement( 'div' ) );
				return;
			}
		}

		# The actual results; specialist subclasses will want to handle this
		# with more than a straight list, so we hand them the info, plus
		# an OutputPage, and let them get on with it
		$this->outputResults( $out,
			$this->getSkin(),
			$dbr, # Should use a ResultWrapper for this
			$res,
			$this->numRows,
			$this->offset );

		# Repeat the paging links at the bottom
		if ( $this->shownavigation ) {
			$out->addHTML( '<p>' . $paging . '</p>' );
		}

		$out->addHTML( Xml::closeElement( 'div' ) );

		return $this->numRows;
	}

	/**
	 * Format and output report results using the given information plus
	 * OutputPage
	 *
	 * @param $out OutputPage to print to
	 * @param $skin Skin: user skin to use
	 * @param $dbr Database (read) connection to use
	 * @param $res Integer: result pointer
	 * @param $num Integer: number of available result rows
	 * @param $offset Integer: paging offset
	 */
	protected function outputResults( $out, $skin, $dbr, $res, $num, $offset ) {
		global $wgContLang;

		if ( $num > 0 ) {
			$html = array();
			if ( !$this->listoutput ) {
				$html[] = $this->openList( $offset );
			}

			# $res might contain the whole 1,000 rows, so we read up to
			# $num [should update this to use a Pager]
			for ( $i = 0; $i < $num && $row = $dbr->fetchObject( $res ); $i++ ) {
				$line = $this->formatResult( $skin, $row );
				if ( $line ) {
					$attr = ( isset( $row->usepatrol ) && $row->usepatrol && $row->patrolled == 0 )
						? ' class="not-patrolled"'
						: '';
					$html[] = $this->listoutput
						? $line
						: "<li{$attr}>{$line}</li>\n";
				}
			}

			# Flush the final result
			if ( $this->tryLastResult() ) {
				$row = null;
				$line = $this->formatResult( $skin, $row );
				if ( $line ) {
					$attr = ( isset( $row->usepatrol ) && $row->usepatrol && $row->patrolled == 0 )
						? ' class="not-patrolled"'
						: '';
					$html[] = $this->listoutput
						? $line
						: "<li{$attr}>{$line}</li>\n";
				}
			}

			if ( !$this->listoutput ) {
				$html[] = $this->closeList();
			}

			$html = $this->listoutput
				? $wgContLang->listToText( $html )
				: implode( '', $html );

			$out->addHTML( $html );
		}
	}

	/**
	 * @param $offset
	 * @return string
	 */
	function openList( $offset ) {
		return "\n<ol start='" . ( $offset + 1 ) . "' class='special'>\n";
	}

	/**
	 * @return string
	 */
	function closeList() {
		return "</ol>\n";
	}

	/**
	 * Do any necessary preprocessing of the result object.
	 */
	function preprocessResults( $db, $res ) {}

	/**
	 * Similar to above, but packaging in a syndicated feed instead of a web page
	 */
	function doFeed( $class = '', $limit = 50 ) {
		global $wgFeed, $wgFeedClasses;

		if ( !$wgFeed ) {
			$this->getOutput()->addWikiMsg( 'feed-unavailable' );
			return;
		}

		global $wgFeedLimit;
		if ( $limit > $wgFeedLimit ) {
			$limit = $wgFeedLimit;
		}

		if ( isset( $wgFeedClasses[$class] ) ) {
			$feed = new $wgFeedClasses[$class](
				$this->feedTitle(),
				$this->feedDesc(),
				$this->feedUrl() );
			$feed->outHeader();

			$res = $this->reallyDoQuery( $limit, 0 );
			foreach ( $res as $obj ) {
				$item = $this->feedResult( $obj );
				if ( $item ) {
					$feed->outItem( $item );
				}
			}

			$feed->outFooter();
			return true;
		} else {
			return false;
		}
	}

	/**
	 * Override for custom handling. If the titles/links are ok, just do
	 * feedItemDesc()
	 */
	function feedResult( $row ) {
		if ( !isset( $row->title ) ) {
			return null;
		}
		$title = Title::MakeTitle( intval( $row->namespace ), $row->title );
		if ( $title ) {
			$date = isset( $row->timestamp ) ? $row->timestamp : '';
			$comments = '';
			if ( $title ) {
				$talkpage = $title->getTalkPage();
				$comments = $talkpage->getFullURL();
			}

			return new FeedItem(
				$title->getPrefixedText(),
				$this->feedItemDesc( $row ),
				$title->getFullURL(),
				$date,
				$this->feedItemAuthor( $row ),
				$comments );
		} else {
			return null;
		}
	}

	function feedItemDesc( $row ) {
		return isset( $row->comment ) ? htmlspecialchars( $row->comment ) : '';
	}

	function feedItemAuthor( $row ) {
		return isset( $row->user_text ) ? $row->user_text : '';
	}

	function feedTitle() {
		global $wgLanguageCode, $wgSitename;
		$desc = $this->getDescription();
		return "$wgSitename - $desc [$wgLanguageCode]";
	}

	function feedDesc() {
		return $this->msg( 'tagline' )->text();
	}

	function feedUrl() {
		return $this->getTitle()->getFullURL();
	}
}

/**
 * Class definition for a wanted query page like
 * WantedPages, WantedTemplates, etc
 */
abstract class WantedQueryPage extends QueryPage {

	function isExpensive() {
		return true;
	}

	function isSyndicated() {
		return false;
	}

	/**
	 * Cache page existence for performance
	 */
	function preprocessResults( $db, $res ) {
		$batch = new LinkBatch;
		foreach ( $res as $row ) {
			$batch->add( $row->namespace, $row->title );
		}
		$batch->execute();

		// Back to start for display
		if ( $db->numRows( $res ) > 0 )
			// If there are no rows we get an error seeking.
			$db->dataSeek( $res, 0 );
	}

	/**
	 * Should formatResult() always check page existence, even if
	 * the results are fresh?  This is a (hopefully temporary)
	 * kluge for Special:WantedFiles, which may contain false
	 * positives for files that exist e.g. in a shared repo (bug
	 * 6220).
	 */
	function forceExistenceCheck() {
		return false;
	}

	/**
	 * Format an individual result
	 *
	 * @param $skin Skin to use for UI elements
	 * @param $result Result row
	 * @return string
	 */
	public function formatResult( $skin, $result ) {
		$title = Title::makeTitleSafe( $result->namespace, $result->title );
		if ( $title instanceof Title ) {
			if ( $this->isCached() || $this->forceExistenceCheck() ) {
				$pageLink = $title->isKnown()
					? '<del>' . Linker::link( $title ) . '</del>'
					: Linker::link(
						$title,
						null,
						array(),
						array(),
						array( 'broken' )
					);
			} else {
				$pageLink = Linker::link(
					$title,
					null,
					array(),
					array(),
					array( 'broken' )
				);
			}
			return $this->getLanguage()->specialList( $pageLink, $this->makeWlhLink( $title, $result ) );
		} else {
			return $this->msg( 'wantedpages-badtitle', $result->title )->escaped();
		}
	}

	/**
	 * Make a "what links here" link for a given title
	 *
	 * @param $title Title to make the link for
	 * @param $result Object: result row
	 * @return string
	 */
	private function makeWlhLink( $title, $result ) {
		$wlh = SpecialPage::getTitleFor( 'Whatlinkshere', $title->getPrefixedText() );
		$label = $this->msg( 'nlinks' )->numParams( $result->value )->escaped();
		return Linker::link( $wlh, $label );
	}
}