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                 $mExistingLinks,
  16                 $mImages,        //!< DB keys of the images used, in the array key only
  17                 $mExistingImages,
  18                 $mTemplates,     //!< Map of title strings to IDs for the template references, including broken ones
  19                 $mExistingTemplates,
  20                 $mExternals,     //!< URLs of external links, array key only
  21                 $mExistingExternals,
  22                 $mCategories,    //!< Map of category names to sort keys
  23                 $mExistingCategories,
  24                 $mInterlangs,    //!< Map of language codes to titles
  25                 $mExistingInterlangs,
  26                 $mProperties,    //!< Map of arbitrary name to value
  27                 $mExistingProperties,
  28                 $mDb,            //!< Database connection reference
  29                 $mOptions,       //!< SELECT options to be used (array)
  30                 $mRecursive;     //!< Whether to queue jobs for recursive updates
  31         /**@}}*/
  32
  33         /**
  34          * Constructor
  35          *
  36          * @param Title $title Title of the page we're updating
  37          * @param ParserOutput $parserOutput Output from a full parse of this page
  38          * @param bool $recursive Queue jobs for recursive updates?
  39          */
  40         function LinksUpdate( $title, $parserOutput, $recursive = true ) {
  41                 global $wgAntiLockFlags;
  42
  43                 if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
  44                         $this->mOptions = array();
  45                 } else {
  46                         $this->mOptions = array( 'FOR UPDATE' );
  47                 }
  48                 $this->mDb = wfGetDB( DB_MASTER );
  49
  50                 if ( !is_object( $title ) ) {
  51                         throw new MWException( "The calling convention to LinksUpdate::LinksUpdate() has changed. " .
  52                                 "Please see Article::editUpdates() for an invocation example.\n" );
  53                 }
  54                 $this->mTitle = $title;
  55                 $this->mId = $title->getArticleID();
  56
  57                 $this->mParserOutput = $parserOutput;
  58                 $this->mLinks = $parserOutput->getLinks();
  59                 $this->mImages = $parserOutput->getImages();
  60                 $this->mTemplates = $parserOutput->getTemplates();
  61                 $this->mExternals = $parserOutput->getExternalLinks();
  62                 $this->mCategories = $parserOutput->getCategories();
  63                 $this->mProperties = $parserOutput->getProperties();
  64
  65                 # Convert the format of the interlanguage links
  66                 # I didn't want to change it in the ParserOutput, because that array is passed all
  67                 # the way back to the skin, so either a skin API break would be required, or an
  68                 # inefficient back-conversion.
  69                 $ill = $parserOutput->getLanguageLinks();
  70                 $this->mInterlangs = array();
  71                 foreach ( $ill as $link ) {
  72                         list( $key, $title ) = explode( ':', $link, 2 );
  73                         $this->mInterlangs[$key] = $title;
  74                 }
  75
  76                 $this->mRecursive = $recursive;
  77
  78                 wfRunHooks( 'LinksUpdateConstructed', array( &$this ) );
  79         }
  80
  81         /**
  82          * Update link tables with outgoing links from an updated article
  83          */
  84         function doUpdate() {
  85                 global $wgUseDumbLinkUpdate, $wgTrackLinkChanges;
  86
  87                 wfRunHooks( 'LinksUpdate', array( &$this ) );
  88                 if ( $wgUseDumbLinkUpdate ) {
  89                         $this->doDumbUpdate();
  90                 } else {
  91                         $this->doIncrementalUpdate();
  92                 }
  93                 if ( $wgTrackLinkChanges )
  94                         $this->makeRecentlinkchanges();
  95                 wfRunHooks( 'LinksUpdateComplete', array( &$this ) );
  96
  97         }
  98
  99         function doIncrementalUpdate() {
 100                 wfProfileIn( __METHOD__ );
 101
 102                 # Page links
 103                 $existing = $this->getExistingLinks();
 104                 $this->incrTableUpdate( 'pagelinks', 'pl', $this->getLinkDeletions( $existing ),
 105                         $this->getLinkInsertions( $existing ) );
 106
 107                 # Image links
 108                 $existing = $this->getExistingImages();
 109
 110                 $imageDeletes = $this->getImageDeletions( $existing );
 111                 $this->incrTableUpdate( 'imagelinks', 'il', $imageDeletes, $this->getImageInsertions( $existing ) );
 112
 113                 # Invalidate all image description pages which had links added or removed
 114                 $imageUpdates = $imageDeletes + array_diff_key( $this->mImages, $existing );
 115                 $this->invalidateImageDescriptions( $imageUpdates );
 116
 117                 # External links
 118                 $existing = $this->getExistingExternals();
 119                 $this->incrTableUpdate( 'externallinks', 'el', $this->getExternalDeletions( $existing ),
 120                 $this->getExternalInsertions( $existing ) );
 121
 122                 # Language links
 123                 $existing = $this->getExistingInterlangs();
 124                 $this->incrTableUpdate( 'langlinks', 'll', $this->getInterlangDeletions( $existing ),
 125                         $this->getInterlangInsertions( $existing ) );
 126
 127                 # Template links
 128                 $existing = $this->getExistingTemplates();
 129                 $this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
 130                         $this->getTemplateInsertions( $existing ) );
 131
 132                 # Category links
 133                 $existing = $this->getExistingCategories();
 134
 135                 $categoryDeletes = $this->getCategoryDeletions( $existing );
 136
 137                 $this->incrTableUpdate( 'categorylinks', 'cl', $categoryDeletes, $this->getCategoryInsertions( $existing ) );
 138
 139                 # Invalidate all categories which were added, deleted or changed (set symmetric difference)
 140                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 141                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 142                 $this->invalidateCategories( $categoryUpdates );
 143                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 144
 145                 # Page properties
 146                 $existing = $this->getExistingProperties();
 147
 148                 $propertiesDeletes = $this->getPropertyDeletions( $existing );
 149
 150                 $this->incrTableUpdate( 'page_props', 'pp', $propertiesDeletes, $this->getPropertyInsertions( $existing ) );
 151
 152                 # Invalidate the necessary pages
 153                 $changed = $propertiesDeletes + array_diff_assoc( $this->mProperties, $existing );
 154                 $this->invalidateProperties( $changed );
 155
 156                 # Refresh links of all pages including this page
 157                 # This will be in a separate transaction
 158                 if ( $this->mRecursive ) {
 159                         $this->queueRecursiveJobs();
 160                 }
 161
 162                 wfProfileOut( __METHOD__ );
 163         }
 164
 165         /**
 166          * Link update which clears the previous entries and inserts new ones
 167          * May be slower or faster depending on level of lock contention and write speed of DB
 168          * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
 169          */
 170         function doDumbUpdate() {
 171                 wfProfileIn( __METHOD__ );
 172
 173                 # Refresh category pages and image description pages
 174                 $existing = $this->getExistingCategories();
 175                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 176                 $categoryDeletes = array_diff_assoc( $existing, $this->mCategories );
 177                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 178                 $existing = $this->getExistingImages();
 179                 $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
 180
 181                 $this->dumbTableUpdate( 'pagelinks',     $this->getLinkInsertions(),     'pl_from' );
 182                 $this->dumbTableUpdate( 'imagelinks',    $this->getImageInsertions(),    'il_from' );
 183                 $this->dumbTableUpdate( 'categorylinks', $this->getCategoryInsertions(), 'cl_from' );
 184                 $this->dumbTableUpdate( 'templatelinks', $this->getTemplateInsertions(), 'tl_from' );
 185                 $this->dumbTableUpdate( 'externallinks', $this->getExternalInsertions(), 'el_from' );
 186                 $this->dumbTableUpdate( 'langlinks',     $this->getInterlangInsertions(),'ll_from' );
 187                 $this->dumbTableUpdate( 'page_props',    $this->getPropertyInsertions(), 'pp_page' );
 188
 189                 # Update the cache of all the category pages and image description
 190                 # pages which were changed, and fix the category table count
 191                 $this->invalidateCategories( $categoryUpdates );
 192                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 193                 $this->invalidateImageDescriptions( $imageUpdates );
 194
 195                 # Refresh links of all pages including this page
 196                 # This will be in a separate transaction
 197                 if ( $this->mRecursive ) {
 198                         $this->queueRecursiveJobs();
 199                 }
 200
 201                 wfProfileOut( __METHOD__ );
 202         }
 203
 204         function queueRecursiveJobs() {
 205                 wfProfileIn( __METHOD__ );
 206
 207                 $batchSize = 100;
 208                 $dbr = wfGetDB( DB_SLAVE );
 209                 $res = $dbr->select( array( 'templatelinks', 'page' ),
 210                         array( 'page_namespace', 'page_title' ),
 211                         array(
 212                                 'page_id=tl_from',
 213                                 'tl_namespace' => $this->mTitle->getNamespace(),
 214                                 'tl_title' => $this->mTitle->getDBkey()
 215                         ), __METHOD__
 216                 );
 217
 218                 $done = false;
 219                 while ( !$done ) {
 220                         $jobs = array();
 221                         for ( $i = 0; $i < $batchSize; $i++ ) {
 222                                 $row = $dbr->fetchObject( $res );
 223                                 if ( !$row ) {
 224                                         $done = true;
 225                                         break;
 226                                 }
 227                                 $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 228                                 $jobs[] = new RefreshLinksJob( $title, '' );
 229                         }
 230                         Job::batchInsert( $jobs );
 231                 }
 232                 $dbr->freeResult( $res );
 233                 wfProfileOut( __METHOD__ );
 234         }
 235
 236         /**
 237          * Invalidate the cache of a list of pages from a single namespace
 238          *
 239          * @param integer $namespace
 240          * @param array $dbkeys
 241          */
 242         function invalidatePages( $namespace, $dbkeys ) {
 243                 if ( !count( $dbkeys ) ) {
 244                         return;
 245                 }
 246
 247                 /**
 248                  * Determine which pages need to be updated
 249                  * This is necessary to prevent the job queue from smashing the DB with
 250                  * large numbers of concurrent invalidations of the same page
 251                  */
 252                 $now = $this->mDb->timestamp();
 253                 $ids = array();
 254                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 255                         array(
 256                                 'page_namespace' => $namespace,
 257                                 'page_title IN (' . $this->mDb->makeList( $dbkeys ) . ')',
 258                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 259                         ), __METHOD__
 260                 );
 261                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 262                         $ids[] = $row->page_id;
 263                 }
 264                 if ( !count( $ids ) ) {
 265                         return;
 266                 }
 267
 268                 /**
 269                  * Do the update
 270                  * We still need the page_touched condition, in case the row has changed since
 271                  * the non-locking select above.
 272                  */
 273                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 274                         array(
 275                                 'page_id IN (' . $this->mDb->makeList( $ids ) . ')',
 276                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 277                         ), __METHOD__
 278                 );
 279         }
 280
 281         function invalidateCategories( $cats ) {
 282                 $this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
 283         }
 284
 285         /**
 286          * Update all the appropriate counts in the category table.
 287          * @param $added associative array of category name => sort key
 288          * @param $deleted associative array of category name => sort key
 289          */
 290         function updateCategoryCounts( $added, $deleted ) {
 291                 $a = new Article($this->mTitle);
 292                 $a->updateCategoryCounts(
 293                         array_keys( $added ), array_keys( $deleted )
 294                 );
 295         }
 296
 297         function invalidateImageDescriptions( $images ) {
 298                 $this->invalidatePages( NS_IMAGE, array_keys( $images ) );
 299         }
 300
 301         function dumbTableUpdate( $table, $insertions, $fromField ) {
 302                 $this->mDb->delete( $table, array( $fromField => $this->mId ), __METHOD__ );
 303                 if ( count( $insertions ) ) {
 304                         # The link array was constructed without FOR UPDATE, so there may
 305                         # be collisions.  This may cause minor link table inconsistencies,
 306                         # which is better than crippling the site with lock contention.
 307                         $this->mDb->insert( $table, $insertions, __METHOD__, array( 'IGNORE' ) );
 308                 }
 309         }
 310
 311         /**
 312          * Make a WHERE clause from a 2-d NS/dbkey array
 313          *
 314          * @param array $arr 2-d array indexed by namespace and DB key
 315          * @param string $prefix Field name prefix, without the underscore
 316          */
 317         function makeWhereFrom2d( &$arr, $prefix ) {
 318                 $lb = new LinkBatch;
 319                 $lb->setArray( $arr );
 320                 return $lb->constructSet( $prefix, $this->mDb );
 321         }
 322
 323         /**
 324          * Update a table by doing a delete query then an insert query
 325          * @private
 326          */
 327         function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
 328                 if ( $table == 'page_props' ) {
 329                         $fromField = 'pp_page';
 330                 } else {
 331                         $fromField = "{$prefix}_from";
 332                 }
 333                 $where = array( $fromField => $this->mId );
 334                 if ( $table == 'pagelinks' || $table == 'templatelinks' ) {
 335                         $clause = $this->makeWhereFrom2d( $deletions, $prefix );
 336                         if ( $clause ) {
 337                                 $where[] = $clause;
 338                         } else {
 339                                 $where = false;
 340                         }
 341                 } else {
 342                         if ( $table == 'langlinks' ) {
 343                                 $toField = 'll_lang';
 344                         } elseif ( $table == 'page_props' ) {
 345                                 $toField = 'pp_propname';
 346                         } else {
 347                                 $toField = $prefix . '_to';
 348                         }
 349                         if ( count( $deletions ) ) {
 350                                 $where[] = "$toField IN (" . $this->mDb->makeList( array_keys( $deletions ) ) . ')';
 351                         } else {
 352                                 $where = false;
 353                         }
 354                 }
 355                 if ( $where ) {
 356                         $this->mDb->delete( $table, $where, __METHOD__ );
 357                 }
 358                 if ( count( $insertions ) ) {
 359                         $this->mDb->insert( $table, $insertions, __METHOD__, 'IGNORE' );
 360                 }
 361         }
 362
 363
 364         /**
 365          * Get an array of pagelinks insertions for passing to the DB
 366          * Skips the titles specified by the 2-D array $existing
 367          * @private
 368          */
 369         function getLinkInsertions( $existing = array() ) {
 370                 $arr = array();
 371                 foreach( $this->mLinks as $ns => $dbkeys ) {
 372                         # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
 373                         # in GlobalFunctions.php
 374                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 375                         foreach ( $diffs as $dbk => $id ) {
 376                                 $arr[] = array(
 377                                         'pl_from'      => $this->mId,
 378                                         'pl_namespace' => $ns,
 379                                         'pl_title'     => $dbk
 380                                 );
 381                         }
 382                 }
 383                 return $arr;
 384         }
 385
 386         /**
 387          * Get an array of template insertions. Like getLinkInsertions()
 388          * @private
 389          */
 390         function getTemplateInsertions( $existing = array() ) {
 391                 $arr = array();
 392                 foreach( $this->mTemplates as $ns => $dbkeys ) {
 393                         $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
 394                         foreach ( $diffs as $dbk => $id ) {
 395                                 $arr[] = array(
 396                                         'tl_from'      => $this->mId,
 397                                         'tl_namespace' => $ns,
 398                                         'tl_title'     => $dbk
 399                                 );
 400                         }
 401                 }
 402                 return $arr;
 403         }
 404
 405         /**
 406          * Get an array of image insertions
 407          * Skips the names specified in $existing
 408          * @private
 409          */
 410         function getImageInsertions( $existing = array() ) {
 411                 $arr = array();
 412                 $diffs = array_diff_key( $this->mImages, $existing );
 413                 foreach( $diffs as $iname => $dummy ) {
 414                         $arr[] = array(
 415                                 'il_from' => $this->mId,
 416                                 'il_to'   => $iname
 417                         );
 418                 }
 419                 return $arr;
 420         }
 421
 422         /**
 423          * Get an array of externallinks insertions. Skips the names specified in $existing
 424          * @private
 425          */
 426         function getExternalInsertions( $existing = array() ) {
 427                 $arr = array();
 428                 $diffs = array_diff_key( $this->mExternals, $existing );
 429                 foreach( $diffs as $url => $dummy ) {
 430                         $arr[] = array(
 431                                 'el_from'   => $this->mId,
 432                                 'el_to'     => $url,
 433                                 'el_index'  => wfMakeUrlIndex( $url ),
 434                         );
 435                 }
 436                 return $arr;
 437         }
 438
 439         /**
 440          * Get an array of category insertions
 441          * @param array $existing Array mapping existing category names to sort keys. If both
 442          * match a link in $this, the link will be omitted from the output
 443          * @private
 444          */
 445         function getCategoryInsertions( $existing = array() ) {
 446                 $diffs = array_diff_assoc( $this->mCategories, $existing );
 447                 $arr = array();
 448                 foreach ( $diffs as $name => $sortkey ) {
 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                 if ( is_array( $this->mExistingLinks ) )
 578                         return $this->mExistingLinks;
 579
 580                 $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
 581                         array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
 582                 $arr = array();
 583                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 584                         if ( !isset( $arr[$row->pl_namespace] ) ) {
 585                                 $arr[$row->pl_namespace] = array();
 586                         }
 587                         $arr[$row->pl_namespace][$row->pl_title] = 1;
 588                 }
 589                 $this->mDb->freeResult( $res );
 590                 return $this->mExistingLinks = $arr;
 591         }
 592
 593         /**
 594          * Get an array of existing templates, as a 2-D array
 595          * @private
 596          */
 597         function getExistingTemplates() {
 598                 if ( is_array( $this->mExistingTemplates ) )
 599                         return $this->mExistingTemplates;
 600
 601                 $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
 602                         array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
 603                 $arr = array();
 604                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 605                         if ( !isset( $arr[$row->tl_namespace] ) ) {
 606                                 $arr[$row->tl_namespace] = array();
 607                         }
 608                         $arr[$row->tl_namespace][$row->tl_title] = 1;
 609                 }
 610                 $this->mDb->freeResult( $res );
 611                 return $this->mExistingTemplates = $arr;
 612         }
 613
 614         /**
 615          * Get an array of existing images, image names in the keys
 616          * @private
 617          */
 618         function getExistingImages() {
 619                 if ( is_array( $this->mExistingImages ) )
 620                         return $this->mExistingImages;
 621
 622                 $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
 623                         array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
 624                 $arr = array();
 625                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 626                         $arr[$row->il_to] = 1;
 627                 }
 628                 $this->mDb->freeResult( $res );
 629                 return $this->mExistingImages = $arr;
 630         }
 631
 632         /**
 633          * Get an array of existing external links, URLs in the keys
 634          * @private
 635          */
 636         function getExistingExternals() {
 637                 if ( is_array( $this->mExistingExternals ) )
 638                         return $this->mExistingExternals;
 639
 640                 $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
 641                         array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
 642                 $arr = array();
 643                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 644                         $arr[$row->el_to] = 1;
 645                 }
 646                 $this->mDb->freeResult( $res );
 647                 return $this->mExistingExternals = $arr;
 648         }
 649
 650         /**
 651          * Get an array of existing categories, with the name in the key and sort key in the value.
 652          * @private
 653          */
 654         function getExistingCategories() {
 655                 if ( is_array( $this->mExistingCategories ) )
 656                         return $this->mExistingCategories;
 657
 658                 $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
 659                         array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
 660                 $arr = array();
 661                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 662                         $arr[$row->cl_to] = $row->cl_sortkey;
 663                 }
 664                 $this->mDb->freeResult( $res );
 665                 return $this->mExistingCategories = $arr;
 666         }
 667
 668         /**
 669          * Get an array of existing interlanguage links, with the language code in the key and the
 670          * title in the value.
 671          * @private
 672          */
 673         function getExistingInterlangs() {
 674                 if ( is_array( $this->mExistingInterlangs ) )
 675                         return $this->mExistingInterlangs;
 676
 677                 $res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
 678                         array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
 679                 $arr = array();
 680                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 681                         $arr[$row->ll_lang] = $row->ll_title;
 682                 }
 683                 return $this->mExistingInterlangs = $arr;
 684         }
 685
 686         /**
 687          * Get an array of existing categories, with the name in the key and sort key in the value.
 688          * @private
 689          */
 690         function getExistingProperties() {
 691                 if ( is_array( $this->mExistingProperties ) )
 692                         return $this->mExistingProperties;
 693
 694                 $res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
 695                         array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
 696                 $arr = array();
 697                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 698                         $arr[$row->pp_propname] = $row->pp_value;
 699                 }
 700                 $this->mDb->freeResult( $res );
 701                 return $this->mExistingProperties = $arr;
 702         }
 703
 704
 705         /**
 706          * Return the title object of the page being updated
 707          */
 708         function getTitle() {
 709                 return $this->mTitle;
 710         }
 711
 712         /**
 713          * Invalidate any necessary link lists related to page property changes
 714          */
 715         function invalidateProperties( $changed ) {
 716                 global $wgPagePropLinkInvalidations;
 717
 718                 foreach ( $changed as $name => $value ) {
 719                         if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
 720                                 $inv = $wgPagePropLinkInvalidations[$name];
 721                                 if ( !is_array( $inv ) ) {
 722                                         $inv = array( $inv );
 723                                 }
 724                                 foreach ( $inv as $table ) {
 725                                         $update = new HTMLCacheUpdate( $this->mTitle, $table );
 726                                         $update->doUpdate();
 727                                 }
 728                         }
 729                 }
 730         }
 731
 732         // Recentlinkchanges constants
 733         const INSERTION = 1;
 734         const DELETION = 2;
 735         private static $rlcFields = array(
 736                 'rlc_type',
 737                 'rlc_timestamp',
 738                 'rlc_action',
 739                 'rlc_from',
 740                 'rlc_to_namespace',
 741                 'rlc_to_title',
 742                 'rlc_to_blob'
 743         );
 744         /*
 745          * Insert items to recentlinkchanges
 746          */
 747         function makeRecentlinkchanges() {
 748                 $insert = array();
 749                 $now = $this->mDb->timestamp();
 750
 751                 // Category changes
 752                 $existing = array_keys( $this->getExistingCategories() );
 753                 $current = array_keys( $this->mCategories );
 754                 $this->simpleAddToLinkchanges( $insert, 'category', $now, $existing, $current, NS_CATEGORY );
 755
 756                 // External links
 757                 $existing = array_keys( $this->getExistingExternals() );
 758                 $current = array_keys( $this->mExternals );
 759                 $insertions = array_diff( $current, $existing );
 760                 foreach ( $insertions as $item )
 761                         $insert[] = array(
 762                                 'external', $now, self::INSERTION,
 763                                 $this->mId, null, null, $item );
 764                 $deletions = array_diff( $existing, $current );
 765                 foreach ( $deletions as $item )
 766                         $insert[] = array(
 767                                 'external', $now, self::DELETION,
 768                                 $this->mId, null, null, $item );
 769
 770                 // Image changes
 771                 $existing = array_keys( $this->getExistingImages() );
 772                 $current = array_keys( $this->mImages );
 773                 $this->simpleAddToLinkchanges( $insert, 'image', $now, $existing, $current, NS_IMAGE );
 774
 775                 // Interlangs
 776                 $existing = $this->getExistingInterlangs();
 777                 $current = $this->mInterlangs;
 778                 $this->assocAddToLinkchanges( $insert, 'interlang', $existing, $current );
 779
 780                 // Page links
 781                 $existing = $this->getExistingLinks();
 782                 $current = $this->mLinks;
 783                 $this->addToLinkChangesByNamespace( $insert, 'page', $now, $existing, $current);
 784
 785                 // Properties
 786                 $existing = $this->getExistingProperties();
 787                 $current = $this->mProperties;
 788                 $this->assocAddToLinkchanges( $insert, 'property', $existing, $current );
 789
 790                 // Templates
 791                 $existing = $this->getExistingTemplates();
 792                 $current = $this->mTemplates;
 793                 $this->addToLinkChangesByNamespace( $insert, 'template', $now, $existing, $current);
 794
 795                 $this->mDb->insert( 'recentlinkchanges', $insert, __METHOD__ );
 796
 797         }
 798
 799         /*
 800          * Compute the difference for arrays of titles with namespace $ns and add
 801          * them to $insert.
 802          */
 803         private function simpleAddToLinkchanges( &$insert, $type, $now, $existing, $current, $ns ) {
 804
 805                 $insertions = array_diff( $current, $existing );
 806                 foreach ( $insertions as $item )
 807                         $insert[] = array_combine(self::$rlcFields, array(
 808                                 $type, $now, self::INSERTION,
 809                                 $this->mId, $ns, $item, null
 810                         ) );
 811                 $deletions = array_diff( $existing, $current );
 812                 foreach ( $deletions as $item )
 813                         $insert[] = array_combine(self::$rlcFields, array(
 814                                 $type, $now, self::DELETION,
 815                                 $this->mId, $ns, $item, null
 816                         ) );
 817
 818         }
 819
 820         /*
 821          * Compute the difference for associative arrays and insert them to
 822          * $insert as title => blob.
 823          */
 824         function assocAddToLinkChanges( &$insert, $type, $now, $existing, $current ) {
 825                 $insertions = array_diff_assoc( $current, $existing );
 826                 foreach ( $insertions as $key => $value )
 827                         $insert[] = array_combine(self::$rlcFields, array(
 828                                 $type, $now, self::INSERTION,
 829                                 $this->mId, null, $key, $value
 830                         ) );
 831                 $deletions = array_diff_assoc( $existing, $current );
 832                 foreach ( $deletions as $key => $value )
 833                         $insert[] = array_combine(self::$rlcFields, array(
 834                                 $type, $now, self::DELETION,
 835                                 $this->mId, null, $key, $value
 836                         ) );
 837         }
 838
 839         /*
 840          * Format arrays in the form $namespace => $titleArray for use in
 841          * simpleAddLinkLinkChanges
 842          */
 843         function addToLinkChangesByNamespace( &$insert, $type, $now, $existing, $current ) {
 844                 $namespaces = array_merge( array_keys( $existing ), array_keys( $current ) );
 845                 foreach ( $namespaces as $ns )
 846                         $this->simpleAddToLinkchanges( $insert, $type, $now,
 847                                 isset( $existing[$ns] ) ? array_keys( $existing[$ns] ) : array(),
 848                                 isset( $current[$ns] ) ? array_keys( $current[$ns] ) : array(),
 849                                 $ns );
 850         }
 851 }