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 of the page we're updating
  30          * @param $parserOutput ParserOutput: output from a full parse of this page
  31          * @param $recursive Boolean: queue jobs for recursive updates?
  32          */
  33         function __construct( $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                 $this->mInterwikis = $parserOutput->getInterwikiLinks();
  58
  59                 # Convert the format of the interlanguage links
  60                 # I didn't want to change it in the ParserOutput, because that array is passed all
  61                 # the way back to the skin, so either a skin API break would be required, or an
  62                 # inefficient back-conversion.
  63                 $ill = $parserOutput->getLanguageLinks();
  64                 $this->mInterlangs = array();
  65                 foreach ( $ill as $link ) {
  66                         list( $key, $title ) = explode( ':', $link, 2 );
  67                         $this->mInterlangs[$key] = $title;
  68                 }
  69
  70                 $this->mRecursive = $recursive;
  71
  72                 wfRunHooks( 'LinksUpdateConstructed', array( &$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                 # Inline interwiki links
 119                 $existing = $this->getExistingInterwikis();
 120                 $this->incrTableUpdate( 'iwlinks', 'iwl', $this->getInterwikiDeletions( $existing ),
 121                         $this->getInterwikiInsertions( $existing ) );
 122
 123                 # Template links
 124                 $existing = $this->getExistingTemplates();
 125                 $this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
 126                         $this->getTemplateInsertions( $existing ) );
 127
 128                 # Category links
 129                 $existing = $this->getExistingCategories();
 130
 131                 $categoryDeletes = $this->getCategoryDeletions( $existing );
 132
 133                 $this->incrTableUpdate( 'categorylinks', 'cl', $categoryDeletes, $this->getCategoryInsertions( $existing ) );
 134
 135                 # Invalidate all categories which were added, deleted or changed (set symmetric difference)
 136                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 137                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 138                 $this->invalidateCategories( $categoryUpdates );
 139                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 140
 141                 # Page properties
 142                 $existing = $this->getExistingProperties();
 143
 144                 $propertiesDeletes = $this->getPropertyDeletions( $existing );
 145
 146                 $this->incrTableUpdate( 'page_props', 'pp', $propertiesDeletes, $this->getPropertyInsertions( $existing ) );
 147
 148                 # Invalidate the necessary pages
 149                 $changed = $propertiesDeletes + array_diff_assoc( $this->mProperties, $existing );
 150                 $this->invalidateProperties( $changed );
 151
 152                 # Refresh links of all pages including this page
 153                 # This will be in a separate transaction
 154                 if ( $this->mRecursive ) {
 155                         $this->queueRecursiveJobs();
 156                 }
 157
 158                 wfProfileOut( __METHOD__ );
 159         }
 160
 161         /**
 162          * Link update which clears the previous entries and inserts new ones
 163          * May be slower or faster depending on level of lock contention and write speed of DB
 164          * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
 165          */
 166         protected function doDumbUpdate() {
 167                 wfProfileIn( __METHOD__ );
 168
 169                 # Refresh category pages and image description pages
 170                 $existing = $this->getExistingCategories();
 171                 $categoryInserts = array_diff_assoc( $this->mCategories, $existing );
 172                 $categoryDeletes = array_diff_assoc( $existing, $this->mCategories );
 173                 $categoryUpdates = $categoryInserts + $categoryDeletes;
 174                 $existing = $this->getExistingImages();
 175                 $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
 176
 177                 $this->dumbTableUpdate( 'pagelinks',     $this->getLinkInsertions(),     'pl_from' );
 178                 $this->dumbTableUpdate( 'imagelinks',    $this->getImageInsertions(),    'il_from' );
 179                 $this->dumbTableUpdate( 'categorylinks', $this->getCategoryInsertions(), 'cl_from' );
 180                 $this->dumbTableUpdate( 'templatelinks', $this->getTemplateInsertions(), 'tl_from' );
 181                 $this->dumbTableUpdate( 'externallinks', $this->getExternalInsertions(), 'el_from' );
 182                 $this->dumbTableUpdate( 'langlinks',     $this->getInterlangInsertions(),'ll_from' );
 183                 $this->dumbTableUpdate( 'iwlinks',       $this->getInterwikiInsertions(),'iwl_from' );
 184                 $this->dumbTableUpdate( 'page_props',    $this->getPropertyInsertions(), 'pp_page' );
 185
 186                 # Update the cache of all the category pages and image description
 187                 # pages which were changed, and fix the category table count
 188                 $this->invalidateCategories( $categoryUpdates );
 189                 $this->updateCategoryCounts( $categoryInserts, $categoryDeletes );
 190                 $this->invalidateImageDescriptions( $imageUpdates );
 191
 192                 # Refresh links of all pages including this page
 193                 # This will be in a separate transaction
 194                 if ( $this->mRecursive ) {
 195                         $this->queueRecursiveJobs();
 196                 }
 197
 198                 wfProfileOut( __METHOD__ );
 199         }
 200
 201         function queueRecursiveJobs() {
 202                 global $wgUpdateRowsPerJob;
 203                 wfProfileIn( __METHOD__ );
 204
 205                 $cache = $this->mTitle->getBacklinkCache();
 206                 $batches = $cache->partition( 'templatelinks', $wgUpdateRowsPerJob );
 207                 if ( !$batches ) {
 208                         wfProfileOut( __METHOD__ );
 209                         return;
 210                 }
 211                 $jobs = array();
 212                 foreach ( $batches as $batch ) {
 213                         list( $start, $end ) = $batch;
 214                         $params = array(
 215                                 'start' => $start,
 216                                 'end' => $end,
 217                         );
 218                         $jobs[] = new RefreshLinksJob2( $this->mTitle, $params );
 219                 }
 220                 Job::batchInsert( $jobs );
 221
 222                 wfProfileOut( __METHOD__ );
 223         }
 224
 225         /**
 226          * Invalidate the cache of a list of pages from a single namespace
 227          *
 228          * @param $namespace Integer
 229          * @param $dbkeys Array
 230          */
 231         function invalidatePages( $namespace, $dbkeys ) {
 232                 if ( !count( $dbkeys ) ) {
 233                         return;
 234                 }
 235
 236                 /**
 237                  * Determine which pages need to be updated
 238                  * This is necessary to prevent the job queue from smashing the DB with
 239                  * large numbers of concurrent invalidations of the same page
 240                  */
 241                 $now = $this->mDb->timestamp();
 242                 $ids = array();
 243                 $res = $this->mDb->select( 'page', array( 'page_id' ),
 244                         array(
 245                                 'page_namespace' => $namespace,
 246                                 'page_title IN (' . $this->mDb->makeList( $dbkeys ) . ')',
 247                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 248                         ), __METHOD__
 249                 );
 250                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 251                         $ids[] = $row->page_id;
 252                 }
 253                 if ( !count( $ids ) ) {
 254                         return;
 255                 }
 256
 257                 /**
 258                  * Do the update
 259                  * We still need the page_touched condition, in case the row has changed since
 260                  * the non-locking select above.
 261                  */
 262                 $this->mDb->update( 'page', array( 'page_touched' => $now ),
 263                         array(
 264                                 'page_id IN (' . $this->mDb->makeList( $ids ) . ')',
 265                                 'page_touched < ' . $this->mDb->addQuotes( $now )
 266                         ), __METHOD__
 267                 );
 268         }
 269
 270         function invalidateCategories( $cats ) {
 271                 $this->invalidatePages( NS_CATEGORY, array_keys( $cats ) );
 272         }
 273
 274         /**
 275          * Update all the appropriate counts in the category table.
 276          * @param $added associative array of category name => sort key
 277          * @param $deleted associative array of category name => sort key
 278          */
 279         function updateCategoryCounts( $added, $deleted ) {
 280                 $a = new Article($this->mTitle);
 281                 $a->updateCategoryCounts(
 282                         array_keys( $added ), array_keys( $deleted )
 283                 );
 284         }
 285
 286         function invalidateImageDescriptions( $images ) {
 287                 $this->invalidatePages( NS_FILE, array_keys( $images ) );
 288         }
 289
 290         function dumbTableUpdate( $table, $insertions, $fromField ) {
 291                 $this->mDb->delete( $table, array( $fromField => $this->mId ), __METHOD__ );
 292                 if ( count( $insertions ) ) {
 293                         # The link array was constructed without FOR UPDATE, so there may
 294                         # be collisions.  This may cause minor link table inconsistencies,
 295                         # which is better than crippling the site with lock contention.
 296                         $this->mDb->insert( $table, $insertions, __METHOD__, array( 'IGNORE' ) );
 297                 }
 298         }
 299
 300         /**
 301          * Update a table by doing a delete query then an insert query
 302          * @private
 303          */
 304         function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
 305                 if ( $table == 'page_props' ) {
 306                         $fromField = 'pp_page';
 307                 } else {
 308                         $fromField = "{$prefix}_from";
 309                 }
 310                 $where = array( $fromField => $this->mId );
 311                 if ( $table == 'pagelinks' || $table == 'templatelinks' || $table == 'iwlinks' ) {
 312                         if ( $table == 'iwlinks' ) {
 313                                 $baseKey = 'iwl_prefix';
 314                         } else {
 315                                 $baseKey = "{$prefix}_namespace";
 316                         }
 317                         $clause = $this->mDb->makeWhereFrom2d( $deletions, $baseKey, "{$prefix}_title" );
 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          *
 424          * @param $existing Array mapping existing category names to sort keys. If both
 425          * match a link in $this, the link will be omitted from the output
 426          * @private
 427          */
 428         function getCategoryInsertions( $existing = array() ) {
 429                 global $wgContLang, $wgCategoryCollation;
 430                 $diffs = array_diff_assoc( $this->mCategories, $existing );
 431                 $arr = array();
 432                 foreach ( $diffs as $name => $sortkey ) {
 433                         $nt = Title::makeTitleSafe( NS_CATEGORY, $name );
 434                         $wgContLang->findVariantLink( $name, $nt, true );
 435
 436                         if ( $this->mTitle->getNamespace() == NS_CATEGORY ) {
 437                                 $type = 'subcat';
 438                         } elseif ( $this->mTitle->getNamespace() == NS_FILE ) {
 439                                 $type = 'file';
 440                         } else {
 441                                 $type = 'page';
 442                         }
 443
 444                         # TODO: This is kind of wrong, because someone might set a sort
 445                         # key prefix that's the same as the default sortkey for the
 446                         # title.  This should be fixed by refactoring code to replace
 447                         # $sortkey in this array by a prefix, but it's basically harmless
 448                         # (Title::moveTo() has had the same issue for a long time).
 449                         if ( $this->mTitle->getCategorySortkey() == $sortkey ) {
 450                                 $prefix = '';
 451                                 $sortkey = $wgContLang->convertToSortkey( $sortkey );
 452                         } else {
 453                                 # Treat custom sortkeys as a prefix, so that if multiple
 454                                 # things are forced to sort as '*' or something, they'll
 455                                 # sort properly in the category rather than in page_id
 456                                 # order or such.
 457                                 $prefix = $sortkey;
 458                                 $sortkey = $wgContLang->convertToSortkey(
 459                                         $this->mTitle->getCategorySortkey( $prefix ) );
 460                         }
 461
 462                         $arr[] = array(
 463                                 'cl_from'    => $this->mId,
 464                                 'cl_to'      => $name,
 465                                 'cl_sortkey' => $sortkey,
 466                                 'cl_timestamp' => $this->mDb->timestamp(),
 467                                 'cl_sortkey_prefix' => $prefix,
 468                                 'cl_collation' => $wgCategoryCollation,
 469                                 'cl_type' => $type,
 470                         );
 471                 }
 472                 return $arr;
 473         }
 474
 475         /**
 476          * Get an array of interlanguage link insertions
 477          *
 478          * @param $existing Array mapping existing language codes to titles
 479          * @private
 480          */
 481         function getInterlangInsertions( $existing = array() ) {
 482             $diffs = array_diff_assoc( $this->mInterlangs, $existing );
 483             $arr = array();
 484             foreach( $diffs as $lang => $title ) {
 485                 $arr[] = array(
 486                     'll_from'  => $this->mId,
 487                     'll_lang'  => $lang,
 488                     'll_title' => $title
 489                 );
 490             }
 491             return $arr;
 492         }
 493
 494         /**
 495          * Get an array of page property insertions
 496          */
 497         function getPropertyInsertions( $existing = array() ) {
 498                 $diffs = array_diff_assoc( $this->mProperties, $existing );
 499                 $arr = array();
 500                 foreach ( $diffs as $name => $value ) {
 501                         $arr[] = array(
 502                                 'pp_page'      => $this->mId,
 503                                 'pp_propname'  => $name,
 504                                 'pp_value'     => $value,
 505                         );
 506                 }
 507                 return $arr;
 508         }
 509
 510         /**
 511          * Get an array of interwiki insertions for passing to the DB
 512          * Skips the titles specified by the 2-D array $existing
 513          * @private
 514          */
 515         function getInterwikiInsertions( $existing = array() ) {
 516                 $arr = array();
 517                 foreach( $this->mInterwikis as $prefix => $dbkeys ) {
 518                         # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
 519                         # in GlobalFunctions.php
 520                         $diffs = isset( $existing[$prefix] ) ? array_diff_key( $dbkeys, $existing[$prefix] ) : $dbkeys;
 521                         foreach ( $diffs as $dbk => $id ) {
 522                                 $arr[] = array(
 523                                         'iwl_from'   => $this->mId,
 524                                         'iwl_prefix' => $prefix,
 525                                         'iwl_title'  => $dbk
 526                                 );
 527                         }
 528                 }
 529                 return $arr;
 530         }
 531
 532
 533
 534         /**
 535          * Given an array of existing links, returns those links which are not in $this
 536          * and thus should be deleted.
 537          * @private
 538          */
 539         function getLinkDeletions( $existing ) {
 540                 $del = array();
 541                 foreach ( $existing as $ns => $dbkeys ) {
 542                         if ( isset( $this->mLinks[$ns] ) ) {
 543                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
 544                         } else {
 545                                 $del[$ns] = $existing[$ns];
 546                         }
 547                 }
 548                 return $del;
 549         }
 550
 551         /**
 552          * Given an array of existing templates, returns those templates which are not in $this
 553          * and thus should be deleted.
 554          * @private
 555          */
 556         function getTemplateDeletions( $existing ) {
 557                 $del = array();
 558                 foreach ( $existing as $ns => $dbkeys ) {
 559                         if ( isset( $this->mTemplates[$ns] ) ) {
 560                                 $del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
 561                         } else {
 562                                 $del[$ns] = $existing[$ns];
 563                         }
 564                 }
 565                 return $del;
 566         }
 567
 568         /**
 569          * Given an array of existing images, returns those images which are not in $this
 570          * and thus should be deleted.
 571          * @private
 572          */
 573         function getImageDeletions( $existing ) {
 574                 return array_diff_key( $existing, $this->mImages );
 575         }
 576
 577         /**
 578          * Given an array of existing external links, returns those links which are not
 579          * in $this and thus should be deleted.
 580          * @private
 581          */
 582         function getExternalDeletions( $existing ) {
 583                 return array_diff_key( $existing, $this->mExternals );
 584         }
 585
 586         /**
 587          * Given an array of existing categories, returns those categories which are not in $this
 588          * and thus should be deleted.
 589          * @private
 590          */
 591         function getCategoryDeletions( $existing ) {
 592                 return array_diff_assoc( $existing, $this->mCategories );
 593         }
 594
 595         /**
 596          * Given an array of existing interlanguage links, returns those links which are not
 597          * in $this and thus should be deleted.
 598          * @private
 599          */
 600         function getInterlangDeletions( $existing ) {
 601             return array_diff_assoc( $existing, $this->mInterlangs );
 602         }
 603
 604         /**
 605          * Get array of properties which should be deleted.
 606          * @private
 607          */
 608         function getPropertyDeletions( $existing ) {
 609                 return array_diff_assoc( $existing, $this->mProperties );
 610         }
 611
 612         /**
 613          * Given an array of existing interwiki links, returns those links which are not in $this
 614          * and thus should be deleted.
 615          * @private
 616          */
 617         function getInterwikiDeletions( $existing ) {
 618                 $del = array();
 619                 foreach ( $existing as $prefix => $dbkeys ) {
 620                         if ( isset( $this->mInterwikis[$prefix] ) ) {
 621                                 $del[$prefix] = array_diff_key( $existing[$prefix], $this->mInterwikis[$prefix] );
 622                         } else {
 623                                 $del[$prefix] = $existing[$prefix];
 624                         }
 625                 }
 626                 return $del;
 627         }
 628
 629         /**
 630          * Get an array of existing links, as a 2-D array
 631          * @private
 632          */
 633         function getExistingLinks() {
 634                 $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
 635                         array( 'pl_from' => $this->mId ), __METHOD__, $this->mOptions );
 636                 $arr = array();
 637                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 638                         if ( !isset( $arr[$row->pl_namespace] ) ) {
 639                                 $arr[$row->pl_namespace] = array();
 640                         }
 641                         $arr[$row->pl_namespace][$row->pl_title] = 1;
 642                 }
 643                 return $arr;
 644         }
 645
 646         /**
 647          * Get an array of existing templates, as a 2-D array
 648          * @private
 649          */
 650         function getExistingTemplates() {
 651                 $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
 652                         array( 'tl_from' => $this->mId ), __METHOD__, $this->mOptions );
 653                 $arr = array();
 654                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 655                         if ( !isset( $arr[$row->tl_namespace] ) ) {
 656                                 $arr[$row->tl_namespace] = array();
 657                         }
 658                         $arr[$row->tl_namespace][$row->tl_title] = 1;
 659                 }
 660                 return $arr;
 661         }
 662
 663         /**
 664          * Get an array of existing images, image names in the keys
 665          * @private
 666          */
 667         function getExistingImages() {
 668                 $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
 669                         array( 'il_from' => $this->mId ), __METHOD__, $this->mOptions );
 670                 $arr = array();
 671                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 672                         $arr[$row->il_to] = 1;
 673                 }
 674                 return $arr;
 675         }
 676
 677         /**
 678          * Get an array of existing external links, URLs in the keys
 679          * @private
 680          */
 681         function getExistingExternals() {
 682                 $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
 683                         array( 'el_from' => $this->mId ), __METHOD__, $this->mOptions );
 684                 $arr = array();
 685                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 686                         $arr[$row->el_to] = 1;
 687                 }
 688                 return $arr;
 689         }
 690
 691         /**
 692          * Get an array of existing categories, with the name in the key and sort key in the value.
 693          * @private
 694          */
 695         function getExistingCategories() {
 696                 $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
 697                         array( 'cl_from' => $this->mId ), __METHOD__, $this->mOptions );
 698                 $arr = array();
 699                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 700                         $arr[$row->cl_to] = $row->cl_sortkey;
 701                 }
 702                 return $arr;
 703         }
 704
 705         /**
 706          * Get an array of existing interlanguage links, with the language code in the key and the
 707          * title in the value.
 708          * @private
 709          */
 710         function getExistingInterlangs() {
 711                 $res = $this->mDb->select( 'langlinks', array( 'll_lang', 'll_title' ),
 712                         array( 'll_from' => $this->mId ), __METHOD__, $this->mOptions );
 713                 $arr = array();
 714                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 715                         $arr[$row->ll_lang] = $row->ll_title;
 716                 }
 717                 return $arr;
 718         }
 719
 720         /**
 721          * Get an array of existing inline interwiki links, as a 2-D array
 722          * @return array (prefix => array(dbkey => 1))
 723          */
 724         protected function getExistingInterwikis() {
 725                 $res = $this->mDb->select( 'iwlinks', array( 'iwl_prefix', 'iwl_title' ),
 726                         array( 'iwl_from' => $this->mId ), __METHOD__, $this->mOptions );
 727                 $arr = array();
 728                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 729                         if ( !isset( $arr[$row->iwl_prefix] ) ) {
 730                                 $arr[$row->iwl_prefix] = array();
 731                         }
 732                         $arr[$row->iwl_prefix][$row->iwl_title] = 1;
 733                 }
 734                 return $arr;
 735         }
 736
 737         /**
 738          * Get an array of existing categories, with the name in the key and sort key in the value.
 739          * @private
 740          */
 741         function getExistingProperties() {
 742                 $res = $this->mDb->select( 'page_props', array( 'pp_propname', 'pp_value' ),
 743                         array( 'pp_page' => $this->mId ), __METHOD__, $this->mOptions );
 744                 $arr = array();
 745                 while ( $row = $this->mDb->fetchObject( $res ) ) {
 746                         $arr[$row->pp_propname] = $row->pp_value;
 747                 }
 748                 return $arr;
 749         }
 750
 751
 752         /**
 753          * Return the title object of the page being updated
 754          */
 755         function getTitle() {
 756                 return $this->mTitle;
 757         }
 758
 759         /**
 760          * Return the list of images used as generated by the parser
 761          */
 762         public function getImages() {
 763                 return $this->mImages;
 764         }
 765
 766         /**
 767          * Invalidate any necessary link lists related to page property changes
 768          */
 769         function invalidateProperties( $changed ) {
 770                 global $wgPagePropLinkInvalidations;
 771
 772                 foreach ( $changed as $name => $value ) {
 773                         if ( isset( $wgPagePropLinkInvalidations[$name] ) ) {
 774                                 $inv = $wgPagePropLinkInvalidations[$name];
 775                                 if ( !is_array( $inv ) ) {
 776                                         $inv = array( $inv );
 777                                 }
 778                                 foreach ( $inv as $table ) {
 779                                         $update = new HTMLCacheUpdate( $this->mTitle, $table );
 780                                         $update->doUpdate();
 781                                 }
 782                         }
 783                 }
 784         }
 785 }