+++ /dev/null
-<?php
-
-/**
- * Class to invalidate the HTML cache of all the pages linking to a given title.
- * Small numbers of links will be done immediately, large numbers are pushed onto
- * the job queue.
- *
- * This class is designed to work efficiently with small numbers of links, and
- * to work reasonably well with up to ~10^5 links. Above ~10^6 links, the memory
- * and time requirements of loading all backlinked IDs in doUpdate() might become
- * prohibitive. The requirements measured at Wikimedia are approximately:
- *
- * memory: 48 bytes per row
- * time: 16us per row for the query plus processing
- *
- * The reason this query is done is to support partitioning of the job
- * by backlinked ID. The memory issue could be allieviated by doing this query in
- * batches, but of course LIMIT with an offset is inefficient on the DB side.
- *
- * The class is nevertheless a vast improvement on the previous method of using
- * Image::getLinksTo() and Title::touchArray(), which uses about 2KB of memory per
- * link.
- *
- * @ingroup Cache
- */
-class HTMLCacheUpdate
-{
- public $mTitle, $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 );
- }
- }
- }
-
- /**
- * Update some of the backlinks, defined by a page ID range
- */
- 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 );
- }
- }
-
- /**
- * Partition the current range given by $this->mStart and $this->mEnd,
- * using a pre-calculated title array which gives the links in that range.
- * Queue the resulting jobs.
- */
- 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 );
- }
-
- /**
- * Invalidate a range of pages, right now
- * @deprecated
- */
- public function invalidate( $startId = false, $endId = false ) {
- $titleArray = $this->mCache->getLinks( $this->mTable, $startId, $endId );
- $this->invalidateTitles( $titleArray );
- }
-
- /**
- * Invalidate an array (or iterator) of Title objects, right now
- */
- 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 IN (' . $dbw->makeList( $batch ) . ')' ),
- __METHOD__
- );
- }
-
- # Update squid
- if ( $wgUseSquid ) {
- $u = SquidUpdate::newFromTitles( $titleArray );
- $u->doUpdate();
- }
-
- # Update file cache
- if ( $wgUseFileCache ) {
- foreach ( $titleArray as $title ) {
- HTMLFileCache::clearFileCache( $title );
- }
- }
- }
-
-}
-
-/**
- * Job wrapper for HTMLCacheUpdate. Gets run whenever a related
- * job gets called from the queue.
- *
- * @ingroup JobQueue
- */
-class HTMLCacheUpdateJob extends Job {
- var $table, $start, $end;
-
- /**
- * Construct a job
- * @param $title Title: the title linked to
- * @param $params Array: job parameters (table, start and end page_ids)
- * @param $id Integer: job id
- */
- 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;
- }
-}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff