replace TYPE= with ENGINE=, (supported since 4.0, TYPE deprecated since 4.1)
[lhc/web/wiklou.git] / includes / LinksUpdate.php
index 435d610..46dc1ca 100644 (file)
 <?php
-# See deferred.doc
+/**
+ * See deferred.txt
+ * @package MediaWiki
+ */
 
+/**
+ * @todo document
+ * @package MediaWiki
+ */
 class LinksUpdate {
 
-       /* private */ var $mId, $mTitle;
+       /**#@+
+        * @access private
+        */
+       var $mId,            # Page ID of the article linked from
+               $mTitle,         # Title object of the article linked from
+               $mLinks,         # Map of title strings to IDs for the links in the document
+               $mImages,        # DB keys of the images used, in the array key only
+               $mTemplates,     # Map of title strings to IDs for the template references, including broken ones
+               $mExternals,     # URLs of external links, array key only
+               $mCategories,    # Map of category names to sort keys
+               $mDb,            # Database connection reference
+               $mOptions,       # SELECT options to be used (array)
+               $mRecursive;     # Whether to queue jobs for recursive updates
+       /**#@-*/
 
-       function LinksUpdate( $id, $title )
-       {
-               $this->mId = $id;
+       /**
+        * Constructor
+        * Initialize private variables
+        * @param integer $id
+        * @param string $title
+        */
+       function LinksUpdate( $title, $parserOutput, $recursive = true ) {
+               global $wgAntiLockFlags;
+
+               if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
+                       $this->mOptions = array();
+               } else {
+                       $this->mOptions = array( 'FOR UPDATE' );
+               }
+               $this->mDb =& wfGetDB( DB_MASTER );
+
+               if ( !is_object( $title ) ) {
+                       wfDebugDieBacktrace( "The calling convention to LinksUpdate::LinksUpdate() has changed. " .
+                               "Please see Article::editUpdates() for an invocation example.\n" );
+               }
                $this->mTitle = $title;
+               $this->mId = $title->getArticleID();
+
+               $this->mLinks = $parserOutput->getLinks();
+               $this->mImages = $parserOutput->getImages();
+               $this->mTemplates = $parserOutput->getTemplates();
+               $this->mExternals = $parserOutput->getExternalLinks();
+               $this->mCategories = $parserOutput->getCategories();
+               $this->mRecursive = $recursive;
+
+       }
+
+       /**
+        * Update link tables with outgoing links from an updated article
+        */
+       function doUpdate() {
+               global $wgUseDumbLinkUpdate;
+               if ( $wgUseDumbLinkUpdate ) {
+                       $this->doDumbUpdate();
+               } else {
+                       $this->doIncrementalUpdate();
+               }
        }
 
-       
-       function doUpdate()
-       {
-               global $wgUseBetterLinksUpdate, $wgLinkCache, $wgDBtransactions;
-               global $wgEnablePersistentLC, $wgUseCategoryMagic;
+       function doIncrementalUpdate() {
+               $fname = 'LinksUpdate::doIncrementalUpdate';
+               wfProfileIn( $fname );
+
+               # Page links
+               $existing = $this->getExistingLinks();
+               $this->incrTableUpdate( 'pagelinks', 'pl', $this->getLinkDeletions( $existing ),
+                       $this->getLinkInsertions( $existing ) );
+
+               # Image links
+               $existing = $this->getExistingImages();
+               $this->incrTableUpdate( 'imagelinks', 'il', $this->getImageDeletions( $existing ),
+                       $this->getImageInsertions( $existing ) );
+
+               # Invalidate all image description pages which had links added or removed
+               $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
+               $this->invalidateImageDescriptions( $imageUpdates );
+
+               # External links
+               $existing = $this->getExistingExternals();
+               $this->incrTableUpdate( 'externallinks', 'el', $this->getExternalDeletions( $existing ),
+                       $this->getExternalInsertions( $existing ) );
+
+               # Template links
+               $existing = $this->getExistingTemplates();
+               $this->incrTableUpdate( 'templatelinks', 'tl', $this->getTemplateDeletions( $existing ),
+                       $this->getTemplateInsertions( $existing ) );
+
+               # Refresh links of all pages including this page
+               if ( $this->mRecursive ) {
+                       $tlto = $this->mTitle->getTemplateLinksTo();
+                       if ( count( $tlto ) ) {
+                               require_once( 'JobQueue.php' );
+                               Job::queueLinksJobs( $tlto );
+                       }
+               }
+
+               # Category links
+               $existing = $this->getExistingCategories();
+               $this->incrTableUpdate( 'categorylinks', 'cl', $this->getCategoryDeletions( $existing ),
+                       $this->getCategoryInsertions( $existing ) );
+
+               # Invalidate all categories which were added, deleted or changed (set symmetric difference)
+               $categoryUpdates = array_diff_assoc( $existing, $this->mCategories ) + array_diff_assoc( $this->mCategories, $existing );
+               $this->invalidateCategories( $categoryUpdates );
 
-               /* Update link tables with outgoing links from an updated article */
-               /* Relies on the 'link cache' to be filled out */
+               wfProfileOut( $fname );
+       }
 
-               $fname = "LinksUpdate::doUpdate";
+       /**
+         * Link update which clears the previous entries and inserts new ones
+         * May be slower or faster depending on level of lock contention and write speed of DB
+         * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
+        */
+       function doDumbUpdate() {
+               $fname = 'LinksUpdate::doDumbUpdate';
                wfProfileIn( $fname );
 
-               $del = array();
-               $add = array();
-
-               $dbw =& wfGetDB( DB_MASTER );
-               $links = $dbw->tableName( 'links' );
-               $brokenlinks = $dbw->tableName( 'brokenlinks' );
-               $imagelinks = $dbw->tableName( 'imagelinks' );
-               $categorylinks = $dbw->tableName( 'categorylinks' );
-               
-               #------------------------------------------------------------------------------
-               # Good links
-
-               if ( $wgLinkCache->incrementalSetup( LINKCACHE_GOOD, $del, $add ) ) {
-                       # Delete where necessary
-                       if ( count( $del ) ) {
-                               $sql = "DELETE FROM $links WHERE l_from={$this->mId} AND l_to IN(".
-                                       implode( ",", $del ) . ")";
-                               $dbw->query( $sql, $fname );
+               # Refresh category pages and image description pages
+               $existing = $this->getExistingCategories();
+               $categoryUpdates = array_diff_assoc( $existing, $this->mCategories ) + array_diff_assoc( $this->mCategories, $existing );
+               $existing = $this->getExistingImages();
+               $imageUpdates = array_diff_key( $existing, $this->mImages ) + array_diff_key( $this->mImages, $existing );
+
+               # Refresh links of all pages including this page
+               if ( $this->mRecursive ) {
+                       $tlto = $this->mTitle->getTemplateLinksTo();
+                       if ( count( $tlto ) ) {
+                               require_once( 'JobQueue.php' );
+                               Job::queueLinksJobs( $tlto );
                        }
-               } else {
-                       # Delete everything
-                       $dbw->delete( 'links', array( 'l_from' => $this->mId ), $fname );
-                                               
-                       # Get the addition list
-                       $add = $wgLinkCache->getGoodLinks();
                }
 
-               # Do the insertion
-               $sql = "";
-               if ( 0 != count( $add ) ) {
-                       $arr=array();
-                       foreach($add as $lt=>$lid) 
-                               array_push($arr,array(
-                                       'l_from'=>$this->mId,
-                                       'l_to'=>$lid));
-                        # The link cache was constructed without FOR UPDATE, so there may be collisions
-                        # Ignoring for now, I'm not sure if that causes problems or not, but I'm fairly
-                        # sure it's better than without IGNORE
-                       $dbw->insertArray($links,$arr,array('IGNORE'));
+               $this->dumbTableUpdate( 'pagelinks',     $this->getLinkInsertions(),     'pl_from' );
+               $this->dumbTableUpdate( 'imagelinks',    $this->getImageInsertions(),    'il_from' );
+               $this->dumbTableUpdate( 'categorylinks', $this->getCategoryInsertions(), 'cl_from' );
+               $this->dumbTableUpdate( 'templatelinks', $this->getTemplateInsertions(), 'tl_from' );
+               $this->dumbTableUpdate( 'externallinks', $this->getExternalInsertions(), 'el_from' );
+
+               # Update the cache of all the category pages and image description pages which were changed
+               $this->invalidateCategories( $categoryUpdates );
+               $this->invalidateImageDescriptions( $imageUpdates );
+
+               wfProfileOut( $fname );
+       }
+
+       function invalidateCategories( $cats ) {
+               $fname = 'LinksUpdate::invalidateCategories';
+               if ( count( $cats ) ) {
+                       $this->mDb->update( 'page', array( 'page_touched' => $this->mDb->timestamp() ),
+                               array(
+                                       'page_namespace' => NS_CATEGORY,
+                                       'page_title IN (' . $this->mDb->makeList( array_keys( $cats ) ) . ')'
+                               ), $fname
+                       );
+               }
+       }
+
+       function invalidateImageDescriptions( $images ) {
+               $fname = 'LinksUpdate::invalidateImageDescriptions';
+               if ( count( $images ) ) {
+                       $this->mDb->update( 'page', array( 'page_touched' => $this->mDb->timestamp() ),
+                               array(
+                                       'page_namespace' => NS_IMAGE,
+                                       'page_title IN (' . $this->mDb->makeList( array_keys( $images ) ) . ')'
+                               ), $fname
+                       );
                }
+       }
 
-               #------------------------------------------------------------------------------
-               # Bad links
-
-               if ( $wgLinkCache->incrementalSetup( LINKCACHE_BAD, $del, $add ) ) {
-                       # Delete where necessary
-                       if ( count( $del ) ) {
-                               $sql = "DELETE FROM $brokenlinks WHERE bl_from={$this->mId} AND bl_to IN(";
-                               $first = true;
-                               foreach( $del as $badTitle ) {
-                                       if ( $first ) {
-                                               $first = false;
-                                       } else {
-                                               $sql .= ",";
-                                       }
-                                       $sql .= $dbw->addQuotes( $badTitle );
-                               }
-                               $sql .= ")";
-                               $dbw->query( $sql, $fname );
+       function dumbTableUpdate( $table, $insertions, $fromField ) {
+               $fname = 'LinksUpdate::dumbTableUpdate';
+               $this->mDb->delete( $table, array( $fromField => $this->mId ), $fname );
+               if ( count( $insertions ) ) {
+                       # The link array was constructed without FOR UPDATE, so there may be collisions
+                       # This may cause minor link table inconsistencies, which is better than
+                       # crippling the site with lock contention.
+                       $this->mDb->insert( $table, $insertions, $fname, array( 'IGNORE' ) );
+               }
+       }
+
+       /**
+        * Make a WHERE clause from a 2-d NS/dbkey array
+        *
+        * @param array $arr 2-d array indexed by namespace and DB key
+        * @param string $prefix Field name prefix, without the underscore
+        */
+       function makeWhereFrom2d( &$arr, $prefix ) {
+               $lb = new LinkBatch;
+               $lb->setArray( $arr );
+               return $lb->constructSet( $prefix, $this->mDb );
+       }
+
+       /**
+        * Update a table by doing a delete query then an insert query
+        * @access private
+        */
+       function incrTableUpdate( $table, $prefix, $deletions, $insertions ) {
+               $fname = 'LinksUpdate::incrTableUpdate';
+               $where = array( "{$prefix}_from" => $this->mId );
+               if ( $table == 'pagelinks' || $table == 'templatelinks' ) {
+                       $clause = $this->makeWhereFrom2d( $deletions, $prefix );
+                       if ( $clause ) {
+                               $where[] = $clause;
+                       } else {
+                               $where = false;
                        }
                } else {
-                       # Delete all
-                       $dbw->delete( 'brokenlinks', array( 'bl_from' => $this->mId ) );
-                       
-                       # Get addition list
-                       $add = $wgLinkCache->getBadLinks();
+                       if ( count( $deletions ) ) {
+                               $where[] = "{$prefix}_to IN (" . $this->mDb->makeList( array_keys( $deletions ) ) . ')';
+                       } else {
+                               $where = false;
+                       }
+               }
+               if ( $where ) {
+                       $this->mDb->delete( $table, $where, $fname );
                }
+               if ( count( $insertions ) ) {
+                       $this->mDb->insert( $table, $insertions, $fname, 'IGNORE' );
+               }
+       }
+
 
-               # Do additions
-               $sql = "";
-               if ( 0 != count ( $add ) ) {
-                       $arr=array();
-                       foreach( $add as $blt ) {
-                               $blt = $dbw->strencode( $blt );
-                               array_push($arr,array(
-                                       'bl_from'=>$this->mId,
-                                       'bl_to'=>$blt));
+       /**
+        * Get an array of pagelinks insertions for passing to the DB
+        * Skips the titles specified by the 2-D array $existing
+        * @access private
+        */
+       function getLinkInsertions( $existing = array() ) {
+               $arr = array();
+               foreach( $this->mLinks as $ns => $dbkeys ) {
+                       # array_diff_key() was introduced in PHP 5.1, there is a compatibility function
+                       # in GlobalFunctions.php
+                       $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
+                       foreach ( $diffs as $dbk => $id ) {
+                               $arr[] = array(
+                                       'pl_from'      => $this->mId,
+                                       'pl_namespace' => $ns,
+                                       'pl_title'     => $dbk
+                               );
                        }
-                       $dbw->insertArray($brokenlinks,$arr,array('IGNORE'));
-                       $dbw->query( $sql, $fname );
                }
+               return $arr;
+       }
 
-               #------------------------------------------------------------------------------
-               # Image links
-               $sql = "DELETE FROM $imagelinks WHERE il_from='{$this->mId}'";
-               $dbw->query( $sql, $fname );
-               
-               # Get addition list
-               $add = $wgLinkCache->getImageLinks();
-               
-               # Do the insertion
-               $sql = "";
-               $image = Namespace::getImage();
-               if ( 0 != count ( $add ) ) {
-                       $sql = "INSERT IGNORE INTO $imagelinks (il_from,il_to) VALUES ";
-                       $first = true;
-                       foreach( $add as $iname => $val ) {
-                               # FIXME: Change all this to avoid unnecessary duplication
-                               $nt = Title::makeTitle( $image, $iname );
-                               if( !$nt ) continue;
-                               $nt->invalidateCache();
-
-                               $iname = $dbw->strencode( $iname );
-                               if ( ! $first ) { $sql .= ","; }
-                               $first = false;
-
-                               $sql .= "({$this->mId},'{$iname}')";
+       /**
+        * Get an array of template insertions. Like getLinkInsertions()
+        * @access private
+        */
+       function getTemplateInsertions( $existing = array() ) {
+               $arr = array();
+               foreach( $this->mTemplates as $ns => $dbkeys ) {
+                       $diffs = isset( $existing[$ns] ) ? array_diff_key( $dbkeys, $existing[$ns] ) : $dbkeys;
+                       foreach ( $diffs as $dbk => $id ) {
+                               $arr[] = array(
+                                       'tl_from'      => $this->mId,
+                                       'tl_namespace' => $ns,
+                                       'tl_title'     => $dbk
+                               );
                        }
                }
-               if ( "" != $sql ) { 
-                       $dbw->query( $sql, $fname ); 
+               return $arr;
+       }
+
+       /**
+        * Get an array of image insertions
+        * Skips the names specified in $existing
+        * @access private
+        */
+       function getImageInsertions( $existing = array() ) {
+               $arr = array();
+               $diffs = array_diff_key( $this->mImages, $existing );
+               foreach( $diffs as $iname => $dummy ) {
+                       $arr[] = array(
+                               'il_from' => $this->mId,
+                               'il_to'   => $iname
+                       );
                }
+               return $arr;
+       }
 
-               #------------------------------------------------------------------------------
-               # Category links
-               if( $wgUseCategoryMagic ) {
-                       $sql = "DELETE FROM $categorylinks WHERE cl_from='{$this->mId}'";
-                       $dbw->query( $sql, $fname );
-                       
-                       # Get addition list
-                       $add = $wgLinkCache->getCategoryLinks();
-                       
-                       # Do the insertion
-                       $sql = "";
-                       if ( 0 != count ( $add ) ) {
-                               $sql = "INSERT IGNORE INTO $categorylinks (cl_from,cl_to,cl_sortkey) VALUES ";
-                               $first = true;
-                               foreach( $add as $cname => $sortkey ) {
-                                       # FIXME: Change all this to avoid unnecessary duplication
-                                       $nt = Title::makeTitle( NS_CATEGORY, $cname );
-                                       if( !$nt ) continue;
-                                       $nt->invalidateCache();
-       
-                                       if ( ! $first ) { $sql .= ","; }
-                                       $first = false;
-       
-                                       $sql .= "({$this->mId},'" . $dbw->strencode( $cname ) .
-                                               "','" . $dbw->strencode( $sortkey ) . "')";
-                               }
-                       }
-                       if ( "" != $sql ) { 
-                               $dbw->query( $sql, $fname ); 
-                       }
+       /**
+        * Get an array of externallinks insertions. Skips the names specified in $existing
+        * @access private
+        */
+       function getExternalInsertions( $existing = array() ) {
+               $arr = array();
+               $diffs = array_diff_key( $this->mExternals, $existing );
+               foreach( $diffs as $url => $dummy ) {
+                       $arr[] = array(
+                               'el_from'   => $this->mId,
+                               'el_to'     => $url,
+                               'el_index'  => wfMakeUrlIndex( $url ),
+                       );
                }
-               
-               $this->fixBrokenLinks();
+               return $arr;
+       }
 
-               wfProfileOut( $fname );
+       /**
+        * Get an array of category insertions
+        * @param array $existing Array mapping existing category names to sort keys. If both
+        * match a link in $this, the link will be omitted from the output
+        * @access private
+        */
+       function getCategoryInsertions( $existing = array() ) {
+               $diffs = array_diff_assoc( $this->mCategories, $existing );
+               $arr = array();
+               foreach ( $diffs as $name => $sortkey ) {
+                       $arr[] = array(
+                               'cl_from'    => $this->mId,
+                               'cl_to'      => $name,
+                               'cl_sortkey' => $sortkey,
+                               'cl_timestamp' => $this->mDb->timestamp()
+                       );
+               }
+               return $arr;
        }
-       
-       function doDumbUpdate()
-       {
-               # Old inefficient update function
-               # Used for rebuilding the link table
-               global $wgLinkCache, $wgDBtransactions, $wgUseCategoryMagic;
-               $fname = "LinksUpdate::doDumbUpdate";
-               wfProfileIn( $fname );
-               
-               
-               $dbw =& wfGetDB( DB_MASTER );
-               $links = $dbw->tableName( 'links' );
-               $brokenlinks = $dbw->tableName( 'brokenlinks' );
-               $imagelinks = $dbw->tableName( 'imagelinks' );
-               $categorylinks = $dbw->tableName( 'categorylinks' );
-               
-               $sql = "DELETE FROM $links WHERE l_from={$this->mId}";
-               $dbw->query( $sql, $fname );
-
-               $a = $wgLinkCache->getGoodLinks();
-               $sql = "";
-               if ( 0 != count( $a ) ) {
-                       $sql = "INSERT IGNORE INTO $links (l_from,l_to) VALUES ";
-                       $first = true;
-                       foreach( $a as $lt => $lid ) {
-                               if ( ! $first ) { $sql .= ","; }
-                               $first = false;
-
-                               $sql .= "({$this->mId},{$lid})";
+
+       /**
+        * Given an array of existing links, returns those links which are not in $this
+        * and thus should be deleted.
+        * @access private
+        */
+       function getLinkDeletions( $existing ) {
+               $del = array();
+               foreach ( $existing as $ns => $dbkeys ) {
+                       if ( isset( $this->mLinks[$ns] ) ) {
+                               $del[$ns] = array_diff_key( $existing[$ns], $this->mLinks[$ns] );
+                       } else {
+                               $del[$ns] = $existing[$ns];
                        }
                }
-               if ( "" != $sql ) { 
-                       $dbw->query( $sql, $fname ); 
+               return $del;
+       }
+
+       /**
+        * Given an array of existing templates, returns those templates which are not in $this
+        * and thus should be deleted.
+        * @access private
+        */
+       function getTemplateDeletions( $existing ) {
+               $del = array();
+               foreach ( $existing as $ns => $dbkeys ) {
+                       if ( isset( $this->mTemplates[$ns] ) ) {
+                               $del[$ns] = array_diff_key( $existing[$ns], $this->mTemplates[$ns] );
+                       } else {
+                               $del[$ns] = $existing[$ns];
+                       }
                }
+               return $del;
+       }
+
+       /**
+        * Given an array of existing images, returns those images which are not in $this
+        * and thus should be deleted.
+        * @access private
+        */
+       function getImageDeletions( $existing ) {
+               return array_diff_key( $existing, $this->mImages );
+       }
 
-               $sql = "DELETE FROM $brokenlinks WHERE bl_from={$this->mId}";
-               $dbw->query( $sql, $fname );
+       /** 
+        * Given an array of existing external links, returns those links which are not
+        * in $this and thus should be deleted.
+        * @access private
+        */
+       function getExternalDeletions( $existing ) {
+               return array_diff_key( $existing, $this->mExternals );
+       }
 
-               $a = $wgLinkCache->getBadLinks();
-               $sql = "";
-               if ( 0 != count ( $a ) ) {
-                       $sql = "INSERT IGNORE INTO $brokenlinks (bl_from,bl_to) VALUES ";
-                       $first = true;
-                       foreach( $a as $blt ) {
-                               $blt = $dbw->strencode( $blt );
-                               if ( ! $first ) { $sql .= ","; }
-                               $first = false;
+       /**
+        * Given an array of existing categories, returns those categories which are not in $this
+        * and thus should be deleted.
+        * @access private
+        */
+       function getCategoryDeletions( $existing ) {
+               return array_diff_assoc( $existing, $this->mCategories );
+       }
 
-                               $sql .= "({$this->mId},'{$blt}')";
+       /**
+        * Get an array of existing links, as a 2-D array
+        * @access private
+        */
+       function getExistingLinks() {
+               $fname = 'LinksUpdate::getExistingLinks';
+               $res = $this->mDb->select( 'pagelinks', array( 'pl_namespace', 'pl_title' ),
+                       array( 'pl_from' => $this->mId ), $fname, $this->mOptions );
+               $arr = array();
+               while ( $row = $this->mDb->fetchObject( $res ) ) {
+                       if ( !isset( $arr[$row->pl_namespace] ) ) {
+                               $arr[$row->pl_namespace] = array();
                        }
+                       $arr[$row->pl_namespace][$row->pl_title] = 1;
                }
-               if ( "" != $sql ) { 
-                       $dbw->query( $sql, $fname ); 
-               }
-               
-               $sql = "DELETE FROM $imagelinks WHERE il_from={$this->mId}";
-               $dbw->query( $sql, $fname );
-
-               $a = $wgLinkCache->getImageLinks();
-               $sql = "";
-               if ( 0 != count ( $a ) ) {
-                       $sql = "INSERT IGNORE INTO $imagelinks (il_from,il_to) VALUES ";
-                       $first = true;
-                       foreach( $a as $iname => $val ) {
-                               $iname = $dbw->strencode( $iname );
-                               if ( ! $first ) { $sql .= ","; }
-                               $first = false;
-
-                               $sql .= "({$this->mId},'{$iname}')";
+               $this->mDb->freeResult( $res );
+               return $arr;
+       }
+
+       /**
+        * Get an array of existing templates, as a 2-D array
+        * @access private
+        */
+       function getExistingTemplates() {
+               $fname = 'LinksUpdate::getExistingTemplates';
+               $res = $this->mDb->select( 'templatelinks', array( 'tl_namespace', 'tl_title' ),
+                       array( 'tl_from' => $this->mId ), $fname, $this->mOptions );
+               $arr = array();
+               while ( $row = $this->mDb->fetchObject( $res ) ) {
+                       if ( !isset( $arr[$row->tl_namespace] ) ) {
+                               $arr[$row->tl_namespace] = array();
                        }
+                       $arr[$row->tl_namespace][$row->tl_title] = 1;
                }
-               if ( "" != $sql ) { 
-                       $dbw->query( $sql, $fname ); 
-               }
+               $this->mDb->freeResult( $res );
+               return $arr;
+       }
 
-               if( $wgUseCategoryMagic ) {
-                       $sql = "DELETE FROM $categorylinks WHERE cl_from='{$this->mId}'";
-                       $dbw->query( $sql, $fname );
-                       
-                       # Get addition list
-                       $add = $wgLinkCache->getCategoryLinks();
-                       
-                       # Do the insertion
-                       $sql = "";
-                       if ( 0 != count ( $add ) ) {
-                               $sql = "INSERT IGNORE INTO $categorylinks (cl_from,cl_to,cl_sortkey) VALUES ";
-                               $first = true;
-                               foreach( $add as $cname => $sortkey ) {
-                                       # FIXME: Change all this to avoid unnecessary duplication
-                                       $nt = Title::makeTitle( NS_CATEGORY, $cname );
-                                       if( !$nt ) continue;
-                                       $nt->invalidateCache();
-       
-                                       if ( ! $first ) { $sql .= ","; }
-                                       $first = false;
-       
-                                       $sql .= "({$this->mId},'" . $dbw->strencode( $cname ) .
-                                               "','" . $dbw->strencode( $sortkey ) . "')";
-                               }
-                       }
-                       if ( "" != $sql ) { 
-                               $dbw->query( $sql, $fname ); 
-                       }
+       /**
+        * Get an array of existing images, image names in the keys
+        * @access private
+        */
+       function getExistingImages() {
+               $fname = 'LinksUpdate::getExistingImages';
+               $res = $this->mDb->select( 'imagelinks', array( 'il_to' ),
+                       array( 'il_from' => $this->mId ), $fname, $this->mOptions );
+               $arr = array();
+               while ( $row = $this->mDb->fetchObject( $res ) ) {
+                       $arr[$row->il_to] = 1;
                }
-               $this->fixBrokenLinks();
-               wfProfileOut( $fname );
+               $this->mDb->freeResult( $res );
+               return $arr;
        }
-       
-       function fixBrokenLinks() {
-               /* Update any brokenlinks *to* this page */
-               /* Call for a newly created page, or just to make sure state is consistent */
-               $fname = "LinksUpdate::fixBrokenLinks";
-
-               $dbw =& wfGetDB( DB_MASTER );
-               $cur = $dbw->tableName( 'cur' );
-               $links = $dbw->tableName( 'links' );
-               
-               $res = $dbw->select( 'brokenlinks', array( 'bl_from' ), array( 'bl_to' => $this->mTitle ), 
-                 $fname, 'FOR UPDATE' );
-               if ( 0 == $dbw->numRows( $res ) ) { return; }
-
-               # Ignore errors. If a link existed in both the brokenlinks table and the links 
-               # table, that's an error which can be fixed at this stage by simply ignoring collisions
-               $sql = "INSERT IGNORE INTO $links (l_from,l_to) VALUES ";
-               $now = wfTimestampNow();
-               $sql2 = "UPDATE $cur SET cur_touched='{$now}' WHERE cur_id IN (";
-               $first = true;
-               while ( $row = $dbw->fetchObject( $res ) ) {
-                       if ( ! $first ) { $sql .= ","; $sql2 .= ","; }
-                       $first = false;
-
-                       $sql .= "({$row->bl_from},{$this->mId})";
-                       $sql2 .= $row->bl_from;
+
+       /**
+        * Get an array of existing external links, URLs in the keys
+        * @access private
+        */
+       function getExistingExternals() {
+               $fname = 'LinksUpdate::getExistingExternals';
+               $res = $this->mDb->select( 'externallinks', array( 'el_to' ),
+                       array( 'el_from' => $this->mId ), $fname, $this->mOptions );
+               $arr = array();
+               while ( $row = $this->mDb->fetchObject( $res ) ) {
+                       $arr[$row->el_to] = 1;
                }
-               $sql2 .= ")";
-               $dbw->query( $sql, $fname );
-               $dbw->query( $sql2, $fname );
+               $this->mDb->freeResult( $res );
+               return $arr;
+       }
 
-               $dbw->delete( 'brokenlinks', array( 'bl_to' => $this->mTitle ), $fname );
+       /**
+        * Get an array of existing categories, with the name in the key and sort key in the value.
+        * @access private
+        */
+       function getExistingCategories() {
+               $fname = 'LinksUpdate::getExistingCategories';
+               $res = $this->mDb->select( 'categorylinks', array( 'cl_to', 'cl_sortkey' ),
+                       array( 'cl_from' => $this->mId ), $fname, $this->mOptions );
+               $arr = array();
+               while ( $row = $this->mDb->fetchObject( $res ) ) {
+                       $arr[$row->cl_to] = $row->cl_sortkey;
+               }
+               $this->mDb->freeResult( $res );
+               return $arr;
        }
 }
-
 ?>