HTMLCacheUpdate.php

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<?php

class HTMLCacheUpdate implements DeferrableUpdate {
        public $mTitle;

        public $mTable, $mPrefix, $mStart, $mEnd;
        public $mRowsPerJob, $mRowsPerQuery;

        function __construct( $titleTo, $table, $start = false, $end = false ) {
                global $wgUpdateRowsPerJob, $wgUpdateRowsPerQuery;

                $this->mTitle = $titleTo;
                $this->mTable = $table;
                $this->mStart = $start;
                $this->mEnd = $end;
                $this->mRowsPerJob = $wgUpdateRowsPerJob;
                $this->mRowsPerQuery = $wgUpdateRowsPerQuery;
                $this->mCache = $this->mTitle->getBacklinkCache();
        }

        public function doUpdate() {
                if ( $this->mStart || $this->mEnd ) {
                        $this->doPartialUpdate();
                        return;
                }

                # Get an estimate of the number of rows from the BacklinkCache
                $numRows = $this->mCache->getNumLinks( $this->mTable );
                if ( $numRows > $this->mRowsPerJob * 2 ) {
                        # Do fast cached partition
                        $this->insertJobs();
                } else {
                        # Get the links from the DB
                        $titleArray = $this->mCache->getLinks( $this->mTable );
                        # Check if the row count estimate was correct
                        if ( $titleArray->count() > $this->mRowsPerJob * 2 ) {
                                # Not correct, do accurate partition
                                wfDebug( __METHOD__.": row count estimate was incorrect, repartitioning\n" );
                                $this->insertJobsFromTitles( $titleArray );
                        } else {
                                $this->invalidateTitles( $titleArray );
                        }
                }
        }

        protected function doPartialUpdate() {
                $titleArray = $this->mCache->getLinks( $this->mTable, $this->mStart, $this->mEnd );
                if ( $titleArray->count() <= $this->mRowsPerJob * 2 ) {
                        # This partition is small enough, do the update
                        $this->invalidateTitles( $titleArray );
                } else {
                        # Partitioning was excessively inaccurate. Divide the job further.
                        # This can occur when a large number of links are added in a short
                        # period of time, say by updating a heavily-used template.
                        $this->insertJobsFromTitles( $titleArray );
                }
        }

        protected function insertJobsFromTitles( $titleArray ) {
                # We make subpartitions in the sense that the start of the first job
                # will be the start of the parent partition, and the end of the last
                # job will be the end of the parent partition.
                $jobs = array();
                $start = $this->mStart; # start of the current job
                $numTitles = 0;
                foreach ( $titleArray as $title ) {
                        $id = $title->getArticleID();
                        # $numTitles is now the number of titles in the current job not
                        # including the current ID
                        if ( $numTitles >= $this->mRowsPerJob ) {
                                # Add a job up to but not including the current ID
                                $params = array(
                                        'table' => $this->mTable,
                                        'start' => $start,
                                        'end' => $id - 1
                                );
                                $jobs[] = new HTMLCacheUpdateJob( $this->mTitle, $params );
                                $start = $id;
                                $numTitles = 0;
                        }
                        $numTitles++;
                }
                # Last job
                $params = array(
                        'table' => $this->mTable,
                        'start' => $start,
                        'end' => $this->mEnd
                );
                $jobs[] = new HTMLCacheUpdateJob( $this->mTitle, $params );
                wfDebug( __METHOD__.": repartitioning into " . count( $jobs ) . " jobs\n" );

                if ( count( $jobs ) < 2 ) {
                        # I don't think this is possible at present, but handling this case
                        # makes the code a bit more robust against future code updates and
                        # avoids a potential infinite loop of repartitioning
                        wfDebug( __METHOD__.": repartitioning failed!\n" );
                        $this->invalidateTitles( $titleArray );
                        return;
                }

                Job::batchInsert( $jobs );
        }

        protected function insertJobs() {
                $batches = $this->mCache->partition( $this->mTable, $this->mRowsPerJob );
                if ( !$batches ) {
                        return;
                }
                $jobs = array();
                foreach ( $batches as $batch ) {
                        $params = array(
                                'table' => $this->mTable,
                                'start' => $batch[0],
                                'end' => $batch[1],
                        );
                        $jobs[] = new HTMLCacheUpdateJob( $this->mTitle, $params );
                }
                Job::batchInsert( $jobs );
        }

        protected function invalidateTitles( $titleArray ) {
                global $wgUseFileCache, $wgUseSquid;

                $dbw = wfGetDB( DB_MASTER );
                $timestamp = $dbw->timestamp();

                # Get all IDs in this query into an array
                $ids = array();
                foreach ( $titleArray as $title ) {
                        $ids[] = $title->getArticleID();
                }

                if ( !$ids ) {
                        return;
                }

                # Update page_touched
                $batches = array_chunk( $ids, $this->mRowsPerQuery );
                foreach ( $batches as $batch ) {
                        $dbw->update( 'page',
                                array( 'page_touched' => $timestamp ),
                                array( 'page_id' => $batch ),
                                __METHOD__
                        );
                }

                # Update squid
                if ( $wgUseSquid ) {
                        $u = SquidUpdate::newFromTitles( $titleArray );
                        $u->doUpdate();
                }

                # Update file cache
                if  ( $wgUseFileCache ) {
                        foreach ( $titleArray as $title ) {
                                HTMLFileCache::clearFileCache( $title );
                        }
                }
        }
}


class HTMLCacheUpdateJob extends Job {
        var $table, $start, $end;

        function __construct( $title, $params, $id = 0 ) {
                parent::__construct( 'htmlCacheUpdate', $title, $params, $id );
                $this->table = $params['table'];
                $this->start = $params['start'];
                $this->end = $params['end'];
        }

        public function run() {
                $update = new HTMLCacheUpdate( $this->title, $this->table, $this->start, $this->end );
                $update->doUpdate();
                return true;
        }
}