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                         return;
 203                 }
 204                 $jobs = array();
 205                 foreach ( $batches as $batch ) {
 206                         list( $start, $end ) = $batch;
 207                         $params = array(
 208                                 'start' => $start,
 209                                 'end' => $end,
 210                         );
 211                         $jobs[] = new RefreshLinksJob2( $this->mTitle, $params );
 212                 }
 213                 Job::batchInsert( $jobs );
 214
 215                 wfProfileOut( __METHOD__ );
 216         }
 217
 218         /**
 219          * Invalidate the cache of a list of pages from a single namespace
 220          *
 221          * @param integer $namespace
 222          * @param array $dbkeys
 223          */
 224         function invalidatePages( $namespace, $dbkeys ) {
 225                 if ( !count( $dbkeys ) ) {
 226                         return;
 227                 }
 228
 229                 /**
 230                  * Determine which pages need to be updated
 231                  * This is necessary to prevent the job queue from smashing the DB with
 232                  * large numbers of concurrent invalidations of the same page
 233                  */
 234                 $now = $this->mDb->timestamp();
 235                 $ids = array();
 236                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 237                         array(
 238                                 'page_namespace' => $namespace,
 239                                 'page_title IN (' . $this->mDb->makeList( $dbkeys ) . ')',
 240                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 241                         ), __METHOD__
 242                 );
 243                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 244                         $ids[] = $row->page_id;
 245                 }
 246                 if ( !count( $ids ) ) {
 247                         return;
 248                 }
 249
 250                 /**
 251                  * Do the update
 252                  * We still need the page_touched condition, in case the row has changed since
 253                  * the non-locking select above.
 254                  */
 255                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 256                         array(
 257                                 'page_id IN (' . $this->mDb->makeList( $ids ) . ')',
 258                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 259                         ), __METHOD__
 260                 );
 261         }
 262
 263         function invalidateCategories( $cats ) {
 264                 $this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
 265         }
 266
 267         /**
 268          * Update all the appropriate counts in the category table.
 269          * @param $added associative array of category name => sort key
 270          * @param $deleted associative array of category name => sort key
 271          */
 272         function updateCategoryCounts( $added, $deleted ) {
 273                 $a = new Article($this->mTitle);
 274                 $a->updateCategoryCounts(
 275                         array_keys( $added ), array_keys( $deleted )
 276                 );
 277         }
 278
 279         function invalidateImageDescriptions( $images ) {
 280                 $this->invalidatePages( NS_FILE, array_keys( $images ) );
 281         }
 282
 283         function dumbTableUpdate( $table, $insertions, $fromField ) {
 284                 $this->mDb->delete( $table, array( $fromField => $this->mId ), __METHOD__ );
 285                 if ( count( $insertions ) ) {
 286                         # The link array was constructed without FOR UPDATE, so there may
 287                         # be collisions.  This may cause minor link table inconsistencies,
 288                         # which is better than crippling the site with lock contention.
 289                         $this->mDb->insert( $table, $insertions, __METHOD__, array( 'IGNORE' ) );
 290                 }
 291         }
 292
 293         /**
 294          * Make a WHERE clause from a 2-d NS/dbkey array
 295          *
 296          * @param array $arr 2-d array indexed by namespace and DB key
 297          * @param string $prefix Field name prefix, without the underscore
 298          */
 299         function makeWhereFrom2d( &$arr, $prefix ) {
 300                 $lb = new LinkBatch;
 301                 $lb->setArray( $arr );
 302                 return $lb->constructSet( $prefix, $this->mDb );
 303         }
 304
 305         /**
 306          * Update a table by doing a delete query then an insert query
 307          * @private
 308          */
 309         function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
 310                 if ( $table == 'page_props' ) {
 311                         $fromField = 'pp_page';
 312                 } else {
 313                         $fromField = "{$prefix}_from";
 314                 }
 315                 $where = array( $fromField => $this->mId );
 316                 if ( $table == 'pagelinks' || $table == 'templatelinks' ) {
 317                         $clause = $this->makeWhereFrom2d( $deletions, $prefix );
 318                         if ( $clause ) {
 319                                 $where[] = $clause;
 320                         } else {
 321                                 $where = false;
 322                         }
 323                 } else {
 324                         if ( $table == 'langlinks' ) {
 325                                 $toField = 'll_lang';
 326                         } elseif ( $table == 'page_props' ) {
 327                                 $toField = 'pp_propname';
 328                         } else {
 329                                 $toField = $prefix . '_to';
 330                         }
 331                         if ( count( $deletions ) ) {
 332                                 $where[] = "$toField IN (" . $this->mDb->makeList( array_keys( $deletions ) ) . ')';
 333                         } else {
 334                                 $where = false;
 335                         }
 336                 }
 337                 if ( $where ) {
 338                         $this->mDb->delete( $table, $where, __METHOD__ );
 339                 }
 340                 if ( count( $insertions ) ) {
 341                         $this->mDb->insert( $table, $insertions, __METHOD__, 'IGNORE' );
 342                 }
 343         }
 344
 345
 346         /**
 347          * Get an array of pagelinks insertions for passing to the DB
 348          * Skips the titles specified by the 2-D array $existing
 349          * @private
 350          */
 351         function getLinkInsertions( $existing = array() ) {
 352                 $arr = array();
 353                 foreach( $this->mLinks as $ns => $dbkeys ) {
 354                         # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
 355                         # in GlobalFunctions.php
 356                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 357                         foreach ( $diffs as $dbk => $id ) {
 358                                 $arr[] = array(
 359                                         'pl_from'      => $this->mId,
 360                                         'pl_namespace' => $ns,
 361                                         'pl_title'     => $dbk
 362                                 );
 363                         }
 364                 }
 365                 return $arr;
 366         }
 367
 368         /**
 369          * Get an array of template insertions. Like getLinkInsertions()
 370          * @private
 371          */
 372         function getTemplateInsertions( $existing = array() ) {
 373                 $arr = array();
 374                 foreach( $this->mTemplates as $ns => $dbkeys ) {
 375                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 376                         foreach ( $diffs as $dbk => $id ) {
 377                                 $arr[] = array(
 378                                         'tl_from'      => $this->mId,
 379                                         'tl_namespace' => $ns,
 380                                         'tl_title'     => $dbk
 381                                 );
 382                         }
 383                 }
 384                 return $arr;
 385         }
 386
 387         /**
 388          * Get an array of image insertions
 389          * Skips the names specified in $existing
 390          * @private
 391          */
 392         function getImageInsertions( $existing = array() ) {
 393                 $arr = array();
 394                 $diffs = array_diff_key( $this->mImages, $existing );
 395                 foreach( $diffs as $iname => $dummy ) {
 396                         $arr[] = array(
 397                                 'il_from' => $this->mId,
 398                                 'il_to'   => $iname
 399                         );
 400                 }
 401                 return $arr;
 402         }
 403
 404         /**
 405          * Get an array of externallinks insertions. Skips the names specified in $existing
 406          * @private
 407          */
 408         function getExternalInsertions( $existing = array() ) {
 409                 $arr = array();
 410                 $diffs = array_diff_key( $this->mExternals, $existing );
 411                 foreach( $diffs as $url => $dummy ) {
 412                         $arr[] = array(
 413                                 'el_from'   => $this->mId,
 414                                 'el_to'     => $url,
 415                                 'el_index'  => wfMakeUrlIndex( $url ),
 416                         );
 417                 }
 418                 return $arr;
 419         }
 420
 421         /**
 422          * Get an array of category insertions
 423          * @param array $existing Array mapping existing category names to sort keys. If both
 424          * match a link in $this, the link will be omitted from the output
 425          * @private
 426          */
 427         function getCategoryInsertions( $existing = array() ) {
 428                 global $wgContLang;
 429                 $diffs = array_diff_assoc( $this->mCategories, $existing );
 430                 foreach ( $this->mCategories as $name => $sortkey ) {
 431                         $newname = $name;
 432                         $nt = Title::makeTitleSafe( NS_CATEGORY, $newname );
 433                         $wgContLang->findVariantLink( $newname, $nt, true );
 434                         // for category redirection
 435                         if ( $nt->isRedirect() ) {
 436                                 $at = new Article( $nt );
 437                                 $nt = $at->getRedirectTarget();
 438                                 $newname = $nt->getText();
 439                                 // we only redirect a category to another category
 440                                 if ( ! array_key_exists( $newname, $existing )
 441                                          and $nt->getNamespace() == NS_CATEGORY )
 442                                         $diffs[$newname] = $sortkey;
 443                         }
 444                 }
 445                 $arr = array();
 446                 foreach ( $diffs as $name => $sortkey ) {
 447                         $nt = Title::makeTitleSafe( NS_CATEGORY, $name );
 448                         $wgContLang->findVariantLink( $name, $nt, true );
 449                         $arr[] = array(
 450                                 'cl_from'    => $this->mId,
 451                                 'cl_to'      => $name,
 452                                 'cl_sortkey' => $sortkey,
 453                                 'cl_timestamp' => $this->mDb->timestamp()
 454                         );
 455                 }
 456                 return $arr;
 457         }
 458
 459         /**
 460          * Get an array of interlanguage link insertions
 461          * @param array $existing Array mapping existing language codes to titles
 462          * @private
 463          */
 464         function getInterlangInsertions( $existing = array() ) {
 465             $diffs = array_diff_assoc( $this->mInterlangs, $existing );
 466             $arr = array();
 467             foreach( $diffs as $lang => $title ) {
 468                 $arr[] = array(
 469                     'll_from'  => $this->mId,
 470                     'll_lang'  => $lang,
 471                     'll_title' => $title
 472                 );
 473             }
 474             return $arr;
 475         }
 476
 477         /**
 478          * Get an array of page property insertions
 479          */
 480         function getPropertyInsertions( $existing = array() ) {
 481                 $diffs = array_diff_assoc( $this->mProperties, $existing );
 482                 $arr = array();
 483                 foreach ( $diffs as $name => $value ) {
 484                         $arr[] = array(
 485                                 'pp_page'      => $this->mId,
 486                                 'pp_propname'  => $name,
 487                                 'pp_value'     => $value,
 488                         );
 489                 }
 490                 return $arr;
 491         }
 492
 493
 494         /**
 495          * Given an array of existing links, returns those links which are not in $this
 496          * and thus should be deleted.
 497          * @private
 498          */
 499         function getLinkDeletions( $existing ) {
 500                 $del = array();
 501                 foreach ( $existing as $ns => $dbkeys ) {
 502                         if ( isset( $this->mLinks[$ns] ) ) {
 503                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
 504                         } else {
 505                                 $del[$ns] = $existing[$ns];
 506                         }
 507                 }
 508                 return $del;
 509         }
 510
 511         /**
 512          * Given an array of existing templates, returns those templates which are not in $this
 513          * and thus should be deleted.
 514          * @private
 515          */
 516         function getTemplateDeletions( $existing ) {
 517                 $del = array();
 518                 foreach ( $existing as $ns => $dbkeys ) {
 519                         if ( isset( $this->mTemplates[$ns] ) ) {
 520                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
 521                         } else {
 522                                 $del[$ns] = $existing[$ns];
 523                         }
 524                 }
 525                 return $del;
 526         }
 527
 528         /**
 529          * Given an array of existing images, returns those images which are not in $this
 530          * and thus should be deleted.
 531          * @private
 532          */
 533         function getImageDeletions( $existing ) {
 534                 return array_diff_key( $existing, $this->mImages );
 535         }
 536
 537         /**
 538          * Given an array of existing external links, returns those links which are not
 539          * in $this and thus should be deleted.
 540          * @private
 541          */
 542         function getExternalDeletions( $existing ) {
 543                 return array_diff_key( $existing, $this->mExternals );
 544         }
 545
 546         /**
 547          * Given an array of existing categories, returns those categories which are not in $this
 548          * and thus should be deleted.
 549          * @private
 550          */
 551         function getCategoryDeletions( $existing ) {
 552                 return array_diff_assoc( $existing, $this->mCategories );
 553         }
 554
 555         /**
 556          * Given an array of existing interlanguage links, returns those links which are not
 557          * in $this and thus should be deleted.
 558          * @private
 559          */
 560         function getInterlangDeletions( $existing ) {
 561             return array_diff_assoc( $existing, $this->mInterlangs );
 562         }
 563
 564         /**
 565          * Get array of properties which should be deleted.
 566          * @private
 567          */
 568         function getPropertyDeletions( $existing ) {
 569                 return array_diff_assoc( $existing, $this->mProperties );
 570         }
 571
 572         /**
 573          * Get an array of existing links, as a 2-D array
 574          * @private
 575          */
 576         function getExistingLinks() {
 577                 $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
 578                         array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
 579                 $arr = array();
 580                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 581                         if ( !isset( $arr[$row->pl_namespace] ) ) {
 582                                 $arr[$row->pl_namespace] = array();
 583                         }
 584                         $arr[$row->pl_namespace][$row->pl_title] = 1;
 585                 }
 586                 $this->mDb->freeResult( $res );
 587                 return $arr;
 588         }
 589
 590         /**
 591          * Get an array of existing templates, as a 2-D array
 592          * @private
 593          */
 594         function getExistingTemplates() {
 595                 $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
 596                         array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
 597                 $arr = array();
 598                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 599                         if ( !isset( $arr[$row->tl_namespace] ) ) {
 600                                 $arr[$row->tl_namespace] = array();
 601                         }
 602                         $arr[$row->tl_namespace][$row->tl_title] = 1;
 603                 }
 604                 $this->mDb->freeResult( $res );
 605                 return $arr;
 606         }
 607
 608         /**
 609          * Get an array of existing images, image names in the keys
 610          * @private
 611          */
 612         function getExistingImages() {
 613                 $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
 614                         array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
 615                 $arr = array();
 616                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 617                         $arr[$row->il_to] = 1;
 618                 }
 619                 $this->mDb->freeResult( $res );
 620                 return $arr;
 621         }
 622
 623         /**
 624          * Get an array of existing external links, URLs in the keys
 625          * @private
 626          */
 627         function getExistingExternals() {
 628                 $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
 629                         array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
 630                 $arr = array();
 631                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 632                         $arr[$row->el_to] = 1;
 633                 }
 634                 $this->mDb->freeResult( $res );
 635                 return $arr;
 636         }
 637
 638         /**
 639          * Get an array of existing categories, with the name in the key and sort key in the value.
 640          * @private
 641          */
 642         function getExistingCategories() {
 643                 $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
 644                         array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
 645                 $arr = array();
 646                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 647                         $arr[$row->cl_to] = $row->cl_sortkey;
 648                 }
 649                 $this->mDb->freeResult( $res );
 650                 return $arr;
 651         }
 652
 653         /**
 654          * Get an array of existing interlanguage links, with the language code in the key and the
 655          * title in the value.
 656          * @private
 657          */
 658         function getExistingInterlangs() {
 659                 $res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
 660                         array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
 661                 $arr = array();
 662                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 663                         $arr[$row->ll_lang] = $row->ll_title;
 664                 }
 665                 return $arr;
 666         }
 667
 668         /**
 669          * Get an array of existing categories, with the name in the key and sort key in the value.
 670          * @private
 671          */
 672         function getExistingProperties() {
 673                 $res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
 674                         array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
 675                 $arr = array();
 676                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 677                         $arr[$row->pp_propname] = $row->pp_value;
 678                 }
 679                 $this->mDb->freeResult( $res );
 680                 return $arr;
 681         }
 682
 683
 684         /**
 685          * Return the title object of the page being updated
 686          */
 687         function getTitle() {
 688                 return $this->mTitle;
 689         }
 690
 691         /**
 692          * Invalidate any necessary link lists related to page property changes
 693          */
 694         function invalidateProperties( $changed ) {
 695                 global $wgPagePropLinkInvalidations;
 696
 697                 foreach ( $changed as $name => $value ) {
 698                         if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
 699                                 $inv = $wgPagePropLinkInvalidations[$name];
 700                                 if ( !is_array( $inv ) ) {
 701                                         $inv = array( $inv );
 702                                 }
 703                                 foreach ( $inv as $table ) {
 704                                         $update = new HTMLCacheUpdate( $this->mTitle, $table );
 705                                         $update->doUpdate();
 706                                 }
 707                         }
 708                 }
 709         }
 710 }