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