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->mParserOutput = $parserOutput;
  51                 $this->mLinks = $parserOutput->getLinks();
  52                 $this->mImages = $parserOutput->getImages();
  53                 $this->mTemplates = $parserOutput->getTemplates();
  54                 $this->mExternals = $parserOutput->getExternalLinks();
  55                 $this->mCategories = $parserOutput->getCategories();
  56                 $this->mProperties = $parserOutput->getProperties();
  57
  58                 # Convert the format of the interlanguage links
  59                 # I didn't want to change it in the ParserOutput, because that array is passed all
  60                 # the way back to the skin, so either a skin API break would be required, or an
  61                 # inefficient back-conversion.
  62                 $ill = $parserOutput->getLanguageLinks();
  63                 $this->mInterlangs = array();
  64                 foreach ( $ill as $link ) {
  65                         list( $key, $title ) = explode( ':', $link, 2 );
  66                         $this->mInterlangs[$key] = $title;
  67                 }
  68
  69                 $this->mRecursive = $recursive;
  70                 $this->mTouchTmplLinks = false;
  71
  72                 wfRunHooks( 'LinksUpdateConstructed', array( &$this ) );
  73         }
  74
  75         /**
  76          * Update link tables with outgoing links from an updated article
  77          */
  78         public function doUpdate() {
  79                 global $wgUseDumbLinkUpdate;
  80
  81                 wfRunHooks( 'LinksUpdate', array( &$this ) );
  82                 if ( $wgUseDumbLinkUpdate ) {
  83                         $this->doDumbUpdate();
  84                 } else {
  85                         $this->doIncrementalUpdate();
  86                 }
  87                 wfRunHooks( 'LinksUpdateComplete', array( &$this ) );
  88         }
  89
  90         protected function doIncrementalUpdate() {
  91                 wfProfileIn( __METHOD__ );
  92
  93                 # Page links
  94                 $existing = $this->getExistingLinks();
  95                 $this->incrTableUpdate( 'pagelinks', 'pl', $this->getLinkDeletions( $existing ),
  96                         $this->getLinkInsertions( $existing ) );
  97
  98                 # Image links
  99                 $existing = $this->getExistingImages();
 100
 101                 $imageDeletes = $this->getImageDeletions( $existing );
 102                 $this->incrTableUpdate( 'imagelinks', 'il', $imageDeletes, $this->getImageInsertions( $existing ) );
 103
 104                 # Invalidate all image description pages which had links added or removed
 105                 $imageUpdates = $imageDeletes + array_diff_key( $this->mImages, $existing );
 106                 $this->invalidateImageDescriptions( $imageUpdates );
 107
 108                 # External links
 109                 $existing = $this->getExistingExternals();
 110                 $this->incrTableUpdate( 'externallinks', 'el', $this->getExternalDeletions( $existing ),
 111                 $this->getExternalInsertions( $existing ) );
 112
 113                 # Language links
 114                 $existing = $this->getExistingInterlangs();
 115                 $this->incrTableUpdate( 'langlinks', 'll', $this->getInterlangDeletions( $existing ),
 116                         $this->getInterlangInsertions( $existing ) );
 117
 118                 # Template links
 119                 $existing = $this->getExistingTemplates();
 120                 $this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
 121                         $this->getTemplateInsertions( $existing ) );
 122
 123                 # Category links
 124                 $existing = $this->getExistingCategories();
 125
 126                 $categoryDeletes = $this->getCategoryDeletions( $existing );
 127
 128                 $this->incrTableUpdate( 'categorylinks', 'cl', $categoryDeletes, $this->getCategoryInsertions( $existing ) );
 129
 130                 # Invalidate all categories which were added, deleted or changed (set symmetric difference)
 131                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 132                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 133                 $this->invalidateCategories( $categoryUpdates );
 134                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 135
 136                 # Page properties
 137                 $existing = $this->getExistingProperties();
 138
 139                 $propertiesDeletes = $this->getPropertyDeletions( $existing );
 140
 141                 $this->incrTableUpdate( 'page_props', 'pp', $propertiesDeletes, $this->getPropertyInsertions( $existing ) );
 142
 143                 # Invalidate the necessary pages
 144                 $changed = $propertiesDeletes + array_diff_assoc( $this->mProperties, $existing );
 145                 $this->invalidateProperties( $changed );
 146
 147                 # Refresh links of all pages including this page
 148                 # This will be in a separate transaction
 149                 if ( $this->mRecursive ) {
 150                         $this->queueRecursiveJobs();
 151                 }
 152
 153                 wfProfileOut( __METHOD__ );
 154         }
 155
 156         /**
 157          * Link update which clears the previous entries and inserts new ones
 158          * May be slower or faster depending on level of lock contention and write speed of DB
 159          * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
 160          */
 161         protected function doDumbUpdate() {
 162                 wfProfileIn( __METHOD__ );
 163
 164                 # Refresh category pages and image description pages
 165                 $existing = $this->getExistingCategories();
 166                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 167                 $categoryDeletes = array_diff_assoc( $existing, $this->mCategories );
 168                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 169                 $existing = $this->getExistingImages();
 170                 $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
 171
 172                 $this->dumbTableUpdate( 'pagelinks',     $this->getLinkInsertions(),     'pl_from' );
 173                 $this->dumbTableUpdate( 'imagelinks',    $this->getImageInsertions(),    'il_from' );
 174                 $this->dumbTableUpdate( 'categorylinks', $this->getCategoryInsertions(), 'cl_from' );
 175                 $this->dumbTableUpdate( 'templatelinks', $this->getTemplateInsertions(), 'tl_from' );
 176                 $this->dumbTableUpdate( 'externallinks', $this->getExternalInsertions(), 'el_from' );
 177                 $this->dumbTableUpdate( 'langlinks',     $this->getInterlangInsertions(),'ll_from' );
 178                 $this->dumbTableUpdate( 'page_props',    $this->getPropertyInsertions(), 'pp_page' );
 179
 180                 # Update the cache of all the category pages and image description
 181                 # pages which were changed, and fix the category table count
 182                 $this->invalidateCategories( $categoryUpdates );
 183                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 184                 $this->invalidateImageDescriptions( $imageUpdates );
 185
 186                 # Refresh links of all pages including this page
 187                 # This will be in a separate transaction
 188                 if ( $this->mRecursive ) {
 189                         $this->queueRecursiveJobs();
 190                 }
 191
 192                 wfProfileOut( __METHOD__ );
 193         }
 194
 195         function queueRecursiveJobs() {
 196                 global $wgUpdateRowsPerJob;
 197                 wfProfileIn( __METHOD__ );
 198
 199                 $cache = $this->mTitle->getBacklinkCache();
 200                 $batches = $cache->partition( 'templatelinks', $wgUpdateRowsPerJob );
 201                 if ( !$batches ) {
 202                         wfProfileOut( __METHOD__ );
 203                         return;
 204                 }
 205                 $jobs = array();
 206                 foreach ( $batches as $batch ) {
 207                         list( $start, $end ) = $batch;
 208                         $params = array(
 209                                 'start' => $start,
 210                                 'end' => $end,
 211                         );
 212                         $jobs[] = new RefreshLinksJob2( $this->mTitle, $params );
 213                 }
 214                 Job::batchInsert( $jobs );
 215
 216                 wfProfileOut( __METHOD__ );
 217         }
 218
 219         /**
 220          * Invalidate the cache of a list of pages from a single namespace
 221          *
 222          * @param integer $namespace
 223          * @param array $dbkeys
 224          */
 225         function invalidatePages( $namespace, $dbkeys ) {
 226                 if ( !count( $dbkeys ) ) {
 227                         return;
 228                 }
 229
 230                 /**
 231                  * Determine which pages need to be updated
 232                  * This is necessary to prevent the job queue from smashing the DB with
 233                  * large numbers of concurrent invalidations of the same page
 234                  */
 235                 $now = $this->mDb->timestamp();
 236                 $ids = array();
 237                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 238                         array(
 239                                 'page_namespace' => $namespace,
 240                                 'page_title IN (' . $this->mDb->makeList( $dbkeys ) . ')',
 241                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 242                         ), __METHOD__
 243                 );
 244                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 245                         $ids[] = $row->page_id;
 246                 }
 247                 if ( !count( $ids ) ) {
 248                         return;
 249                 }
 250
 251                 /**
 252                  * Do the update
 253                  * We still need the page_touched condition, in case the row has changed since
 254                  * the non-locking select above.
 255                  */
 256                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 257                         array(
 258                                 'page_id IN (' . $this->mDb->makeList( $ids ) . ')',
 259                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 260                         ), __METHOD__
 261                 );
 262         }
 263
 264         function invalidateCategories( $cats ) {
 265                 $this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
 266         }
 267
 268         /**
 269          * Update all the appropriate counts in the category table.
 270          * @param $added associative array of category name => sort key
 271          * @param $deleted associative array of category name => sort key
 272          */
 273         function updateCategoryCounts( $added, $deleted ) {
 274                 $a = new Article($this->mTitle);
 275                 $a->updateCategoryCounts(
 276                         array_keys( $added ), array_keys( $deleted )
 277                 );
 278         }
 279
 280         function invalidateImageDescriptions( $images ) {
 281                 $this->invalidatePages( NS_FILE, array_keys( $images ) );
 282         }
 283
 284         function dumbTableUpdate( $table, $insertions, $fromField ) {
 285                 $this->mDb->delete( $table, array( $fromField => $this->mId ), __METHOD__ );
 286                 if ( count( $insertions ) ) {
 287                         # The link array was constructed without FOR UPDATE, so there may
 288                         # be collisions.  This may cause minor link table inconsistencies,
 289                         # which is better than crippling the site with lock contention.
 290                         $this->mDb->insert( $table, $insertions, __METHOD__, array( 'IGNORE' ) );
 291                 }
 292         }
 293
 294         /**
 295          * Make a WHERE clause from a 2-d NS/dbkey array
 296          *
 297          * @param array $arr 2-d array indexed by namespace and DB key
 298          * @param string $prefix Field name prefix, without the underscore
 299          */
 300         function makeWhereFrom2d( &$arr, $prefix ) {
 301                 $lb = new LinkBatch;
 302                 $lb->setArray( $arr );
 303                 return $lb->constructSet( $prefix, $this->mDb );
 304         }
 305
 306         /**
 307          * Update a table by doing a delete query then an insert query
 308          * @private
 309          */
 310         function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
 311                 if ( $table == 'page_props' ) {
 312                         $fromField = 'pp_page';
 313                 } else {
 314                         $fromField = "{$prefix}_from";
 315                 }
 316                 $where = array( $fromField => $this->mId );
 317                 if ( $table == 'pagelinks' || $table == 'templatelinks' ) {
 318                         $clause = $this->makeWhereFrom2d( $deletions, $prefix );
 319                         if ( $clause ) {
 320                                 $where[] = $clause;
 321                         } else {
 322                                 $where = false;
 323                         }
 324                 } else {
 325                         if ( $table == 'langlinks' ) {
 326                                 $toField = 'll_lang';
 327                         } elseif ( $table == 'page_props' ) {
 328                                 $toField = 'pp_propname';
 329                         } else {
 330                                 $toField = $prefix . '_to';
 331                         }
 332                         if ( count( $deletions ) ) {
 333                                 $where[] = "$toField IN (" . $this->mDb->makeList( array_keys( $deletions ) ) . ')';
 334                         } else {
 335                                 $where = false;
 336                         }
 337                 }
 338                 if ( $where ) {
 339                         $this->mDb->delete( $table, $where, __METHOD__ );
 340                 }
 341                 if ( count( $insertions ) ) {
 342                         $this->mDb->insert( $table, $insertions, __METHOD__, 'IGNORE' );
 343                 }
 344         }
 345
 346
 347         /**
 348          * Get an array of pagelinks insertions for passing to the DB
 349          * Skips the titles specified by the 2-D array $existing
 350          * @private
 351          */
 352         function getLinkInsertions( $existing = array() ) {
 353                 $arr = array();
 354                 foreach( $this->mLinks as $ns => $dbkeys ) {
 355                         # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
 356                         # in GlobalFunctions.php
 357                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 358                         foreach ( $diffs as $dbk => $id ) {
 359                                 $arr[] = array(
 360                                         'pl_from'      => $this->mId,
 361                                         'pl_namespace' => $ns,
 362                                         'pl_title'     => $dbk
 363                                 );
 364                         }
 365                 }
 366                 return $arr;
 367         }
 368
 369         /**
 370          * Get an array of template insertions. Like getLinkInsertions()
 371          * @private
 372          */
 373         function getTemplateInsertions( $existing = array() ) {
 374                 $arr = array();
 375                 foreach( $this->mTemplates as $ns => $dbkeys ) {
 376                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 377                         foreach ( $diffs as $dbk => $id ) {
 378                                 $arr[] = array(
 379                                         'tl_from'      => $this->mId,
 380                                         'tl_namespace' => $ns,
 381                                         'tl_title'     => $dbk
 382                                 );
 383                         }
 384                 }
 385                 return $arr;
 386         }
 387
 388         /**
 389          * Get an array of image insertions
 390          * Skips the names specified in $existing
 391          * @private
 392          */
 393         function getImageInsertions( $existing = array() ) {
 394                 $arr = array();
 395                 $diffs = array_diff_key( $this->mImages, $existing );
 396                 foreach( $diffs as $iname => $dummy ) {
 397                         $arr[] = array(
 398                                 'il_from' => $this->mId,
 399                                 'il_to'   => $iname
 400                         );
 401                 }
 402                 return $arr;
 403         }
 404
 405         /**
 406          * Get an array of externallinks insertions. Skips the names specified in $existing
 407          * @private
 408          */
 409         function getExternalInsertions( $existing = array() ) {
 410                 $arr = array();
 411                 $diffs = array_diff_key( $this->mExternals, $existing );
 412                 foreach( $diffs as $url => $dummy ) {
 413                         $arr[] = array(
 414                                 'el_from'   => $this->mId,
 415                                 'el_to'     => $url,
 416                                 'el_index'  => wfMakeUrlIndex( $url ),
 417                         );
 418                 }
 419                 return $arr;
 420         }
 421
 422         /**
 423          * Get an array of category insertions
 424          * @param array $existing Array mapping existing category names to sort keys. If both
 425          * match a link in $this, the link will be omitted from the output
 426          * @private
 427          */
 428         function getCategoryInsertions( $existing = array() ) {
 429                 global $wgContLang;
 430                 $diffs = array_diff_assoc( $this->mCategories, $existing );
 431                 foreach ( $this->mCategories as $name => $sortkey ) {
 432                         $newname = $name;
 433                         $nt = Title::makeTitleSafe( NS_CATEGORY, $newname );
 434                         $wgContLang->findVariantLink( $newname, $nt, true );
 435                         // for category redirection
 436                         if ( $nt->isRedirect() ) {
 437                                 $at = new Article( $nt );
 438                                 $nt = $at->getRedirectTarget();
 439                                 $newname = $nt->getText();
 440                                 // we only redirect a category to another category
 441                                 if ( ! array_key_exists( $newname, $existing )
 442                                          and $nt->getNamespace() == NS_CATEGORY )
 443                                         $diffs[$newname] = $sortkey;
 444                         }
 445                 }
 446                 $arr = array();
 447                 foreach ( $diffs as $name => $sortkey ) {
 448                         $nt = Title::makeTitleSafe( NS_CATEGORY, $name );
 449                         $wgContLang->findVariantLink( $name, $nt, true );
 450                         $arr[] = array(
 451                                 'cl_from'    => $this->mId,
 452                                 'cl_to'      => $name,
 453                                 'cl_sortkey' => $sortkey,
 454                                 'cl_timestamp' => $this->mDb->timestamp()
 455                         );
 456                 }
 457                 return $arr;
 458         }
 459
 460         /**
 461          * Get an array of interlanguage link insertions
 462          * @param array $existing Array mapping existing language codes to titles
 463          * @private
 464          */
 465         function getInterlangInsertions( $existing = array() ) {
 466             $diffs = array_diff_assoc( $this->mInterlangs, $existing );
 467             $arr = array();
 468             foreach( $diffs as $lang => $title ) {
 469                 $arr[] = array(
 470                     'll_from'  => $this->mId,
 471                     'll_lang'  => $lang,
 472                     'll_title' => $title
 473                 );
 474             }
 475             return $arr;
 476         }
 477
 478         /**
 479          * Get an array of page property insertions
 480          */
 481         function getPropertyInsertions( $existing = array() ) {
 482                 $diffs = array_diff_assoc( $this->mProperties, $existing );
 483                 $arr = array();
 484                 foreach ( $diffs as $name => $value ) {
 485                         $arr[] = array(
 486                                 'pp_page'      => $this->mId,
 487                                 'pp_propname'  => $name,
 488                                 'pp_value'     => $value,
 489                         );
 490                 }
 491                 return $arr;
 492         }
 493
 494
 495         /**
 496          * Given an array of existing links, returns those links which are not in $this
 497          * and thus should be deleted.
 498          * @private
 499          */
 500         function getLinkDeletions( $existing ) {
 501                 $del = array();
 502                 foreach ( $existing as $ns => $dbkeys ) {
 503                         if ( isset( $this->mLinks[$ns] ) ) {
 504                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
 505                         } else {
 506                                 $del[$ns] = $existing[$ns];
 507                         }
 508                 }
 509                 return $del;
 510         }
 511
 512         /**
 513          * Given an array of existing templates, returns those templates which are not in $this
 514          * and thus should be deleted.
 515          * @private
 516          */
 517         function getTemplateDeletions( $existing ) {
 518                 $del = array();
 519                 foreach ( $existing as $ns => $dbkeys ) {
 520                         if ( isset( $this->mTemplates[$ns] ) ) {
 521                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
 522                         } else {
 523                                 $del[$ns] = $existing[$ns];
 524                         }
 525                 }
 526                 return $del;
 527         }
 528
 529         /**
 530          * Given an array of existing images, returns those images which are not in $this
 531          * and thus should be deleted.
 532          * @private
 533          */
 534         function getImageDeletions( $existing ) {
 535                 return array_diff_key( $existing, $this->mImages );
 536         }
 537
 538         /**
 539          * Given an array of existing external links, returns those links which are not
 540          * in $this and thus should be deleted.
 541          * @private
 542          */
 543         function getExternalDeletions( $existing ) {
 544                 return array_diff_key( $existing, $this->mExternals );
 545         }
 546
 547         /**
 548          * Given an array of existing categories, returns those categories which are not in $this
 549          * and thus should be deleted.
 550          * @private
 551          */
 552         function getCategoryDeletions( $existing ) {
 553                 return array_diff_assoc( $existing, $this->mCategories );
 554         }
 555
 556         /**
 557          * Given an array of existing interlanguage links, returns those links which are not
 558          * in $this and thus should be deleted.
 559          * @private
 560          */
 561         function getInterlangDeletions( $existing ) {
 562             return array_diff_assoc( $existing, $this->mInterlangs );
 563         }
 564
 565         /**
 566          * Get array of properties which should be deleted.
 567          * @private
 568          */
 569         function getPropertyDeletions( $existing ) {
 570                 return array_diff_assoc( $existing, $this->mProperties );
 571         }
 572
 573         /**
 574          * Get an array of existing links, as a 2-D array
 575          * @private
 576          */
 577         function getExistingLinks() {
 578                 $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
 579                         array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
 580                 $arr = array();
 581                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 582                         if ( !isset( $arr[$row->pl_namespace] ) ) {
 583                                 $arr[$row->pl_namespace] = array();
 584                         }
 585                         $arr[$row->pl_namespace][$row->pl_title] = 1;
 586                 }
 587                 $this->mDb->freeResult( $res );
 588                 return $arr;
 589         }
 590
 591         /**
 592          * Get an array of existing templates, as a 2-D array
 593          * @private
 594          */
 595         function getExistingTemplates() {
 596                 $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
 597                         array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
 598                 $arr = array();
 599                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 600                         if ( !isset( $arr[$row->tl_namespace] ) ) {
 601                                 $arr[$row->tl_namespace] = array();
 602                         }
 603                         $arr[$row->tl_namespace][$row->tl_title] = 1;
 604                 }
 605                 $this->mDb->freeResult( $res );
 606                 return $arr;
 607         }
 608
 609         /**
 610          * Get an array of existing images, image names in the keys
 611          * @private
 612          */
 613         function getExistingImages() {
 614                 $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
 615                         array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
 616                 $arr = array();
 617                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 618                         $arr[$row->il_to] = 1;
 619                 }
 620                 $this->mDb->freeResult( $res );
 621                 return $arr;
 622         }
 623
 624         /**
 625          * Get an array of existing external links, URLs in the keys
 626          * @private
 627          */
 628         function getExistingExternals() {
 629                 $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
 630                         array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
 631                 $arr = array();
 632                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 633                         $arr[$row->el_to] = 1;
 634                 }
 635                 $this->mDb->freeResult( $res );
 636                 return $arr;
 637         }
 638
 639         /**
 640          * Get an array of existing categories, with the name in the key and sort key in the value.
 641          * @private
 642          */
 643         function getExistingCategories() {
 644                 $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
 645                         array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
 646                 $arr = array();
 647                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 648                         $arr[$row->cl_to] = $row->cl_sortkey;
 649                 }
 650                 $this->mDb->freeResult( $res );
 651                 return $arr;
 652         }
 653
 654         /**
 655          * Get an array of existing interlanguage links, with the language code in the key and the
 656          * title in the value.
 657          * @private
 658          */
 659         function getExistingInterlangs() {
 660                 $res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
 661                         array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
 662                 $arr = array();
 663                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 664                         $arr[$row->ll_lang] = $row->ll_title;
 665                 }
 666                 return $arr;
 667         }
 668
 669         /**
 670          * Get an array of existing categories, with the name in the key and sort key in the value.
 671          * @private
 672          */
 673         function getExistingProperties() {
 674                 $res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
 675                         array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
 676                 $arr = array();
 677                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 678                         $arr[$row->pp_propname] = $row->pp_value;
 679                 }
 680                 $this->mDb->freeResult( $res );
 681                 return $arr;
 682         }
 683
 684
 685         /**
 686          * Return the title object of the page being updated
 687          */
 688         function getTitle() {
 689                 return $this->mTitle;
 690         }
 691
 692         /**
 693          * Invalidate any necessary link lists related to page property changes
 694          */
 695         function invalidateProperties( $changed ) {
 696                 global $wgPagePropLinkInvalidations;
 697
 698                 foreach ( $changed as $name => $value ) {
 699                         if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
 700                                 $inv = $wgPagePropLinkInvalidations[$name];
 701                                 if ( !is_array( $inv ) ) {
 702                                         $inv = array( $inv );
 703                                 }
 704                                 foreach ( $inv as $table ) {
 705                                         $update = new HTMLCacheUpdate( $this->mTitle, $table );
 706                                         $update->doUpdate();
 707                                 }
 708                         }
 709                 }
 710         }
 711 }