includes/LinksUpdate.php

   1 <?php
   2 /**
   3  * See docs/deferred.txt
   4  *
   5  * @todo document (e.g. one-sentence top-level class description).
   6  */
   7 class LinksUpdate {
   8
   9         /**@{{
  10          * @private
  11          */
  12         var $mId,            //!< Page ID of the article linked from
  13                 $mTitle,         //!< Title object of the article linked from
  14                 $mLinks,         //!< Map of title strings to IDs for the links in the document
  15                 $mImages,        //!< DB keys of the images used, in the array key only
  16                 $mTemplates,     //!< Map of title strings to IDs for the template references, including broken ones
  17                 $mExternals,     //!< URLs of external links, array key only
  18                 $mCategories,    //!< Map of category names to sort keys
  19                 $mInterlangs,    //!< Map of language codes to titles
  20                 $mProperties,    //!< Map of arbitrary name to value
  21                 $mDb,            //!< Database connection reference
  22                 $mOptions,       //!< SELECT options to be used (array)
  23                 $mRecursive;     //!< Whether to queue jobs for recursive updates
  24         /**@}}*/
  25
  26         /**
  27          * Constructor
  28          *
  29          * @param Title $title Title of the page we're updating
  30          * @param ParserOutput $parserOutput Output from a full parse of this page
  31          * @param bool $recursive Queue jobs for recursive updates?
  32          */
  33         function LinksUpdate( $title, $parserOutput, $recursive = true ) {
  34                 global $wgAntiLockFlags;
  35
  36                 if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
  37                         $this->mOptions = array();
  38                 } else {
  39                         $this->mOptions = array( 'FOR UPDATE' );
  40                 }
  41                 $this->mDb = wfGetDB( DB_MASTER );
  42
  43                 if ( !is_object( $title ) ) {
  44                         throw new MWException( "The calling convention to LinksUpdate::LinksUpdate() has changed. " .
  45                                 "Please see Article::editUpdates() for an invocation example.\n" );
  46                 }
  47                 $this->mTitle = $title;
  48                 $this->mId = $title->getArticleID();
  49
  50                 $this->mLinks = $parserOutput->getLinks();
  51                 $this->mImages = $parserOutput->getImages();
  52                 $this->mTemplates = $parserOutput->getTemplates();
  53                 $this->mExternals = $parserOutput->getExternalLinks();
  54                 $this->mCategories = $parserOutput->getCategories();
  55                 $this->mProperties = $parserOutput->getProperties();
  56
  57                 # Convert the format of the interlanguage links
  58                 # I didn't want to change it in the ParserOutput, because that array is passed all
  59                 # the way back to the skin, so either a skin API break would be required, or an
  60                 # inefficient back-conversion.
  61                 $ill = $parserOutput->getLanguageLinks();
  62                 $this->mInterlangs = array();
  63                 foreach ( $ill as $link ) {
  64                         list( $key, $title ) = explode( ':', $link, 2 );
  65                         $this->mInterlangs[$key] = $title;
  66                 }
  67
  68                 $this->mRecursive = $recursive;
  69
  70                 wfRunHooks( 'LinksUpdateConstructed', array( &$this ) );
  71         }
  72
  73         /**
  74          * Update link tables with outgoing links from an updated article
  75          */
  76         function doUpdate() {
  77                 global $wgUseDumbLinkUpdate;
  78
  79                 wfRunHooks( 'LinksUpdate', array( &$this ) );
  80                 if ( $wgUseDumbLinkUpdate ) {
  81                         $this->doDumbUpdate();
  82                 } else {
  83                         $this->doIncrementalUpdate();
  84                 }
  85                 wfRunHooks( 'LinksUpdateComplete', array( &$this ) );
  86
  87         }
  88
  89         function doIncrementalUpdate() {
  90                 wfProfileIn( __METHOD__ );
  91
  92                 # Page links
  93                 $existing = $this->getExistingLinks();
  94                 $this->incrTableUpdate( 'pagelinks', 'pl', $this->getLinkDeletions( $existing ),
  95                         $this->getLinkInsertions( $existing ) );
  96
  97                 # Image links
  98                 $existing = $this->getExistingImages();
  99                 $this->incrTableUpdate( 'imagelinks', 'il', $this->getImageDeletions( $existing ),
 100                         $this->getImageInsertions( $existing ) );
 101
 102                 # Invalidate all image description pages which had links added or removed
 103                 $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
 104                 $this->invalidateImageDescriptions( $imageUpdates );
 105
 106                 # External links
 107                 $existing = $this->getExistingExternals();
 108                 $this->incrTableUpdate( 'externallinks', 'el', $this->getExternalDeletions( $existing ),
 109                 $this->getExternalInsertions( $existing ) );
 110
 111                 # Language links
 112                 $existing = $this->getExistingInterlangs();
 113                 $this->incrTableUpdate( 'langlinks', 'll', $this->getInterlangDeletions( $existing ),
 114                         $this->getInterlangInsertions( $existing ) );
 115
 116                 # Template links
 117                 $existing = $this->getExistingTemplates();
 118                 $this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
 119                         $this->getTemplateInsertions( $existing ) );
 120
 121                 # Category links
 122                 $existing = $this->getExistingCategories();
 123                 $this->incrTableUpdate( 'categorylinks', 'cl', $this->getCategoryDeletions( $existing ),
 124                         $this->getCategoryInsertions( $existing ) );
 125
 126                 # Invalidate all categories which were added, deleted or changed (set symmetric difference)
 127                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 128                 $categoryDeletes = array_diff_assoc( $existing, $this->mCategories );
 129                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 130                 $this->invalidateCategories( $categoryUpdates );
 131                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 132
 133                 # Page properties
 134                 $existing = $this->getExistingProperties();
 135                 $this->incrTableUpdate( 'page_props', 'pp', $this->getPropertyDeletions( $existing ),
 136                         $this->getPropertyInsertions( $existing ) );
 137
 138                 # Invalidate the necessary pages
 139                 $changed = array_diff_assoc( $existing, $this->mProperties ) + array_diff_assoc( $this->mProperties, $existing );
 140                 $this->invalidateProperties( $changed );
 141
 142                 # Refresh links of all pages including this page
 143                 # This will be in a separate transaction
 144                 if ( $this->mRecursive ) {
 145                         $this->queueRecursiveJobs();
 146                 }
 147
 148                 wfProfileOut( __METHOD__ );
 149         }
 150
 151         /**
 152          * Link update which clears the previous entries and inserts new ones
 153          * May be slower or faster depending on level of lock contention and write speed of DB
 154          * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
 155          */
 156         function doDumbUpdate() {
 157                 wfProfileIn( __METHOD__ );
 158
 159                 # Refresh category pages and image description pages
 160                 $existing = $this->getExistingCategories();
 161                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 162                 $categoryDeletes = array_diff_assoc( $existing, $this->mCategoties );
 163                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 164                 $existing = $this->getExistingImages();
 165                 $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
 166
 167                 $this->dumbTableUpdate( 'pagelinks',     $this->getLinkInsertions(),     'pl_from' );
 168                 $this->dumbTableUpdate( 'imagelinks',    $this->getImageInsertions(),    'il_from' );
 169                 $this->dumbTableUpdate( 'categorylinks', $this->getCategoryInsertions(), 'cl_from' );
 170                 $this->dumbTableUpdate( 'templatelinks', $this->getTemplateInsertions(), 'tl_from' );
 171                 $this->dumbTableUpdate( 'externallinks', $this->getExternalInsertions(), 'el_from' );
 172                 $this->dumbTableUpdate( 'langlinks',     $this->getInterlangInsertions(),'ll_from' );
 173                 $this->dumbTableUpdate( 'page_props',    $this->getPropertyInsertions(), 'pp_page' );
 174
 175                 # Update the cache of all the category pages and image description
 176                 # pages which were changed, and fix the category table count
 177                 $this->invalidateCategories( $categoryUpdates );
 178                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 179                 $this->invalidateImageDescriptions( $imageUpdates );
 180
 181                 # Refresh links of all pages including this page
 182                 # This will be in a separate transaction
 183                 if ( $this->mRecursive ) {
 184                         $this->queueRecursiveJobs();
 185                 }
 186
 187                 wfProfileOut( __METHOD__ );
 188         }
 189
 190         function queueRecursiveJobs() {
 191                 wfProfileIn( __METHOD__ );
 192
 193                 $batchSize = 100;
 194                 $dbr = wfGetDB( DB_SLAVE );
 195                 $res = $dbr->select( array( 'templatelinks', 'page' ),
 196                         array( 'page_namespace', 'page_title' ),
 197                         array(
 198                                 'page_id=tl_from',
 199                                 'tl_namespace' => $this->mTitle->getNamespace(),
 200                                 'tl_title' => $this->mTitle->getDBkey()
 201                         ), __METHOD__
 202                 );
 203
 204                 $done = false;
 205                 while ( !$done ) {
 206                         $jobs = array();
 207                         for ( $i = 0; $i < $batchSize; $i++ ) {
 208                                 $row = $dbr->fetchObject( $res );
 209                                 if ( !$row ) {
 210                                         $done = true;
 211                                         break;
 212                                 }
 213                                 $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 214                                 $jobs[] = new RefreshLinksJob( $title, '' );
 215                         }
 216                         Job::batchInsert( $jobs );
 217                 }
 218                 $dbr->freeResult( $res );
 219                 wfProfileOut( __METHOD__ );
 220         }
 221
 222         /**
 223          * Invalidate the cache of a list of pages from a single namespace
 224          *
 225          * @param integer $namespace
 226          * @param array $dbkeys
 227          */
 228         function invalidatePages( $namespace, $dbkeys ) {
 229                 if ( !count( $dbkeys ) ) {
 230                         return;
 231                 }
 232
 233                 /**
 234                  * Determine which pages need to be updated
 235                  * This is necessary to prevent the job queue from smashing the DB with
 236                  * large numbers of concurrent invalidations of the same page
 237                  */
 238                 $now = $this->mDb->timestamp();
 239                 $ids = array();
 240                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 241                         array(
 242                                 'page_namespace' => $namespace,
 243                                 'page_title IN (' . $this->mDb->makeList( $dbkeys ) . ')',
 244                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 245                         ), __METHOD__
 246                 );
 247                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 248                         $ids[] = $row->page_id;
 249                 }
 250                 if ( !count( $ids ) ) {
 251                         return;
 252                 }
 253
 254                 /**
 255                  * Do the update
 256                  * We still need the page_touched condition, in case the row has changed since
 257                  * the non-locking select above.
 258                  */
 259                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 260                         array(
 261                                 'page_id IN (' . $this->mDb->makeList( $ids ) . ')',
 262                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 263                         ), __METHOD__
 264                 );
 265         }
 266
 267         function invalidateCategories( $cats ) {
 268                 $this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
 269         }
 270
 271         /**
 272          * Update all the appropriate counts in the category table.
 273          * @param $added associative array of category name => sort key
 274          * @param $deleted associative array of category name => sort key
 275          */
 276         function updateCategoryCounts( $added, $deleted ) {
 277                 $a = new Article($this->mTitle);
 278                 $a->updateCategoryCounts(
 279                         array_keys( $added ), array_keys( $deleted )
 280                 );
 281         }
 282
 283         function invalidateImageDescriptions( $images ) {
 284                 $this->invalidatePages( NS_IMAGE, array_keys( $images ) );
 285         }
 286
 287         function dumbTableUpdate( $table, $insertions, $fromField ) {
 288                 $this->mDb->delete( $table, array( $fromField => $this->mId ), __METHOD__ );
 289                 if ( count( $insertions ) ) {
 290                         # The link array was constructed without FOR UPDATE, so there may
 291                         # be collisions.  This may cause minor link table inconsistencies,
 292                         # which is better than crippling the site with lock contention.
 293                         $this->mDb->insert( $table, $insertions, __METHOD__, array( 'IGNORE' ) );
 294                 }
 295         }
 296
 297         /**
 298          * Make a WHERE clause from a 2-d NS/dbkey array
 299          *
 300          * @param array $arr 2-d array indexed by namespace and DB key
 301          * @param string $prefix Field name prefix, without the underscore
 302          */
 303         function makeWhereFrom2d( &$arr, $prefix ) {
 304                 $lb = new LinkBatch;
 305                 $lb->setArray( $arr );
 306                 return $lb->constructSet( $prefix, $this->mDb );
 307         }
 308
 309         /**
 310          * Update a table by doing a delete query then an insert query
 311          * @private
 312          */
 313         function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
 314                 if ( $table == 'page_props' ) {
 315                         $fromField = 'pp_page';
 316                 } else {
 317                         $fromField = "{$prefix}_from";
 318                 }
 319                 $where = array( $fromField => $this->mId );
 320                 if ( $table == 'pagelinks' || $table == 'templatelinks' ) {
 321                         $clause = $this->makeWhereFrom2d( $deletions, $prefix );
 322                         if ( $clause ) {
 323                                 $where[] = $clause;
 324                         } else {
 325                                 $where = false;
 326                         }
 327                 } else {
 328                         if ( $table == 'langlinks' ) {
 329                                 $toField = 'll_lang';
 330                         } elseif ( $table == 'page_props' ) {
 331                                 $toField = 'pp_propname';
 332                         } else {
 333                                 $toField = $prefix . '_to';
 334                         }
 335                         if ( count( $deletions ) ) {
 336                                 $where[] = "$toField IN (" . $this->mDb->makeList( array_keys( $deletions ) ) . ')';
 337                         } else {
 338                                 $where = false;
 339                         }
 340                 }
 341                 if ( $where ) {
 342                         $this->mDb->delete( $table, $where, __METHOD__ );
 343                 }
 344                 if ( count( $insertions ) ) {
 345                         $this->mDb->insert( $table, $insertions, __METHOD__, 'IGNORE' );
 346                 }
 347         }
 348
 349
 350         /**
 351          * Get an array of pagelinks insertions for passing to the DB
 352          * Skips the titles specified by the 2-D array $existing
 353          * @private
 354          */
 355         function getLinkInsertions( $existing = array() ) {
 356                 $arr = array();
 357                 foreach( $this->mLinks as $ns => $dbkeys ) {
 358                         # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
 359                         # in GlobalFunctions.php
 360                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 361                         foreach ( $diffs as $dbk => $id ) {
 362                                 $arr[] = array(
 363                                         'pl_from'      => $this->mId,
 364                                         'pl_namespace' => $ns,
 365                                         'pl_title'     => $dbk
 366                                 );
 367                         }
 368                 }
 369                 return $arr;
 370         }
 371
 372         /**
 373          * Get an array of template insertions. Like getLinkInsertions()
 374          * @private
 375          */
 376         function getTemplateInsertions( $existing = array() ) {
 377                 $arr = array();
 378                 foreach( $this->mTemplates as $ns => $dbkeys ) {
 379                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 380                         foreach ( $diffs as $dbk => $id ) {
 381                                 $arr[] = array(
 382                                         'tl_from'      => $this->mId,
 383                                         'tl_namespace' => $ns,
 384                                         'tl_title'     => $dbk
 385                                 );
 386                         }
 387                 }
 388                 return $arr;
 389         }
 390
 391         /**
 392          * Get an array of image insertions
 393          * Skips the names specified in $existing
 394          * @private
 395          */
 396         function getImageInsertions( $existing = array() ) {
 397                 $arr = array();
 398                 $diffs = array_diff_key( $this->mImages, $existing );
 399                 foreach( $diffs as $iname => $dummy ) {
 400                         $arr[] = array(
 401                                 'il_from' => $this->mId,
 402                                 'il_to'   => $iname
 403                         );
 404                 }
 405                 return $arr;
 406         }
 407
 408         /**
 409          * Get an array of externallinks insertions. Skips the names specified in $existing
 410          * @private
 411          */
 412         function getExternalInsertions( $existing = array() ) {
 413                 $arr = array();
 414                 $diffs = array_diff_key( $this->mExternals, $existing );
 415                 foreach( $diffs as $url => $dummy ) {
 416                         $arr[] = array(
 417                                 'el_from'   => $this->mId,
 418                                 'el_to'     => $url,
 419                                 'el_index'  => wfMakeUrlIndex( $url ),
 420                         );
 421                 }
 422                 return $arr;
 423         }
 424
 425         /**
 426          * Get an array of category insertions
 427          * @param array $existing Array mapping existing category names to sort keys. If both
 428          * match a link in $this, the link will be omitted from the output
 429          * @private
 430          */
 431         function getCategoryInsertions( $existing = array() ) {
 432                 $diffs = array_diff_assoc( $this->mCategories, $existing );
 433                 $arr = array();
 434                 foreach ( $diffs as $name => $sortkey ) {
 435                         $arr[] = array(
 436                                 'cl_from'    => $this->mId,
 437                                 'cl_to'      => $name,
 438                                 'cl_sortkey' => $sortkey,
 439                                 'cl_timestamp' => $this->mDb->timestamp()
 440                         );
 441                 }
 442                 return $arr;
 443         }
 444
 445         /**
 446          * Get an array of interlanguage link insertions
 447          * @param array $existing Array mapping existing language codes to titles
 448          * @private
 449          */
 450         function getInterlangInsertions( $existing = array() ) {
 451             $diffs = array_diff_assoc( $this->mInterlangs, $existing );
 452             $arr = array();
 453             foreach( $diffs as $lang => $title ) {
 454                 $arr[] = array(
 455                     'll_from'  => $this->mId,
 456                     'll_lang'  => $lang,
 457                     'll_title' => $title
 458                 );
 459             }
 460             return $arr;
 461         }
 462
 463         /**
 464          * Get an array of page property insertions
 465          */
 466         function getPropertyInsertions( $existing = array() ) {
 467                 $diffs = array_diff_assoc( $this->mProperties, $existing );
 468                 $arr = array();
 469                 foreach ( $diffs as $name => $value ) {
 470                         $arr[] = array(
 471                                 'pp_page'      => $this->mId,
 472                                 'pp_propname'  => $name,
 473                                 'pp_value'     => $value,
 474                         );
 475                 }
 476                 return $arr;
 477         }
 478
 479
 480         /**
 481          * Given an array of existing links, returns those links which are not in $this
 482          * and thus should be deleted.
 483          * @private
 484          */
 485         function getLinkDeletions( $existing ) {
 486                 $del = array();
 487                 foreach ( $existing as $ns => $dbkeys ) {
 488                         if ( isset( $this->mLinks[$ns] ) ) {
 489                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
 490                         } else {
 491                                 $del[$ns] = $existing[$ns];
 492                         }
 493                 }
 494                 return $del;
 495         }
 496
 497         /**
 498          * Given an array of existing templates, returns those templates which are not in $this
 499          * and thus should be deleted.
 500          * @private
 501          */
 502         function getTemplateDeletions( $existing ) {
 503                 $del = array();
 504                 foreach ( $existing as $ns => $dbkeys ) {
 505                         if ( isset( $this->mTemplates[$ns] ) ) {
 506                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
 507                         } else {
 508                                 $del[$ns] = $existing[$ns];
 509                         }
 510                 }
 511                 return $del;
 512         }
 513
 514         /**
 515          * Given an array of existing images, returns those images which are not in $this
 516          * and thus should be deleted.
 517          * @private
 518          */
 519         function getImageDeletions( $existing ) {
 520                 return array_diff_key( $existing, $this->mImages );
 521         }
 522
 523         /**
 524          * Given an array of existing external links, returns those links which are not
 525          * in $this and thus should be deleted.
 526          * @private
 527          */
 528         function getExternalDeletions( $existing ) {
 529                 return array_diff_key( $existing, $this->mExternals );
 530         }
 531
 532         /**
 533          * Given an array of existing categories, returns those categories which are not in $this
 534          * and thus should be deleted.
 535          * @private
 536          */
 537         function getCategoryDeletions( $existing ) {
 538                 return array_diff_assoc( $existing, $this->mCategories );
 539         }
 540
 541         /**
 542          * Given an array of existing interlanguage links, returns those links which are not
 543          * in $this and thus should be deleted.
 544          * @private
 545          */
 546         function getInterlangDeletions( $existing ) {
 547             return array_diff_assoc( $existing, $this->mInterlangs );
 548         }
 549
 550         /**
 551          * Get array of properties which should be deleted.
 552          * @private
 553          */
 554         function getPropertyDeletions( $existing ) {
 555                 return array_diff_assoc( $existing, $this->mProperties );
 556         }
 557
 558         /**
 559          * Get an array of existing links, as a 2-D array
 560          * @private
 561          */
 562         function getExistingLinks() {
 563                 $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
 564                         array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
 565                 $arr = array();
 566                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 567                         if ( !isset( $arr[$row->pl_namespace] ) ) {
 568                                 $arr[$row->pl_namespace] = array();
 569                         }
 570                         $arr[$row->pl_namespace][$row->pl_title] = 1;
 571                 }
 572                 $this->mDb->freeResult( $res );
 573                 return $arr;
 574         }
 575
 576         /**
 577          * Get an array of existing templates, as a 2-D array
 578          * @private
 579          */
 580         function getExistingTemplates() {
 581                 $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
 582                         array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
 583                 $arr = array();
 584                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 585                         if ( !isset( $arr[$row->tl_namespace] ) ) {
 586                                 $arr[$row->tl_namespace] = array();
 587                         }
 588                         $arr[$row->tl_namespace][$row->tl_title] = 1;
 589                 }
 590                 $this->mDb->freeResult( $res );
 591                 return $arr;
 592         }
 593
 594         /**
 595          * Get an array of existing images, image names in the keys
 596          * @private
 597          */
 598         function getExistingImages() {
 599                 $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
 600                         array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
 601                 $arr = array();
 602                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 603                         $arr[$row->il_to] = 1;
 604                 }
 605                 $this->mDb->freeResult( $res );
 606                 return $arr;
 607         }
 608
 609         /**
 610          * Get an array of existing external links, URLs in the keys
 611          * @private
 612          */
 613         function getExistingExternals() {
 614                 $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
 615                         array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
 616                 $arr = array();
 617                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 618                         $arr[$row->el_to] = 1;
 619                 }
 620                 $this->mDb->freeResult( $res );
 621                 return $arr;
 622         }
 623
 624         /**
 625          * Get an array of existing categories, with the name in the key and sort key in the value.
 626          * @private
 627          */
 628         function getExistingCategories() {
 629                 $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
 630                         array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
 631                 $arr = array();
 632                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 633                         $arr[$row->cl_to] = $row->cl_sortkey;
 634                 }
 635                 $this->mDb->freeResult( $res );
 636                 return $arr;
 637         }
 638
 639         /**
 640          * Get an array of existing interlanguage links, with the language code in the key and the
 641          * title in the value.
 642          * @private
 643          */
 644         function getExistingInterlangs() {
 645                 $res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
 646                         array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
 647                 $arr = array();
 648                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 649                         $arr[$row->ll_lang] = $row->ll_title;
 650                 }
 651                 return $arr;
 652         }
 653
 654         /**
 655          * Get an array of existing categories, with the name in the key and sort key in the value.
 656          * @private
 657          */
 658         function getExistingProperties() {
 659                 $res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
 660                         array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
 661                 $arr = array();
 662                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 663                         $arr[$row->pp_propname] = $row->pp_value;
 664                 }
 665                 $this->mDb->freeResult( $res );
 666                 return $arr;
 667         }
 668
 669
 670         /**
 671          * Return the title object of the page being updated
 672          */
 673         function getTitle() {
 674                 return $this->mTitle;
 675         }
 676
 677         /**
 678          * Invalidate any necessary link lists related to page property changes
 679          */
 680         function invalidateProperties( $changed ) {
 681                 global $wgPagePropLinkInvalidations;
 682
 683                 foreach ( $changed as $name => $value ) {
 684                         if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
 685                                 $inv = $wgPagePropLinkInvalidations[$name];
 686                                 if ( !is_array( $inv ) ) {
 687                                         $inv = array( $inv );
 688                                 }
 689                                 foreach ( $inv as $table ) {
 690                                         $update = new HTMLCacheUpdate( $this->mTitle, $table );
 691                                         $update->doUpdate();
 692                                 }
 693                         }
 694                 }
 695         }
 696 }
 697