577 lines
18 KiB
PHP
577 lines
18 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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namespace MediaWiki\Storage;
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use MediaWiki\Content\Content;
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use MediaWiki\HookContainer\HookContainer;
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use MediaWiki\HookContainer\HookRunner;
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use MediaWiki\Page\PageIdentity;
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use MediaWiki\Page\WikiPageFactory;
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use MediaWiki\Parser\ParserOutput;
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use MediaWiki\Parser\ParserOutputFlags;
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use MediaWiki\Revision\SlotRecord;
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use MediaWiki\Storage\Hook\ParserOutputStashForEditHook;
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use MediaWiki\User\UserEditTracker;
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use MediaWiki\User\UserFactory;
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use MediaWiki\User\UserIdentity;
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use Psr\Log\LoggerInterface;
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use stdClass;
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use Wikimedia\ObjectCache\BagOStuff;
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use Wikimedia\Rdbms\IConnectionProvider;
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use Wikimedia\ScopedCallback;
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use Wikimedia\Stats\StatsFactory;
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use WikiPage;
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/**
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* Manage the pre-emptive page parsing for edits to wiki pages.
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*
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* This is written to by ApiStashEdit, and consumed by ApiEditPage
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* and EditPage (via PageUpdaterFactory and DerivedPageDataUpdater).
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*
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* See also mediawiki.action.edit/stash.js.
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*
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* @since 1.34
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* @ingroup Page
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*/
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class PageEditStash {
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/** @var BagOStuff */
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private $cache;
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/** @var IConnectionProvider */
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private $dbProvider;
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/** @var LoggerInterface */
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private $logger;
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/** @var StatsFactory */
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private $stats;
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/** @var ParserOutputStashForEditHook */
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private $hookRunner;
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/** @var UserEditTracker */
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private $userEditTracker;
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/** @var UserFactory */
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private $userFactory;
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/** @var WikiPageFactory */
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private $wikiPageFactory;
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/** @var int */
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private $initiator;
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public const ERROR_NONE = 'stashed';
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public const ERROR_PARSE = 'error_parse';
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public const ERROR_CACHE = 'error_cache';
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public const ERROR_UNCACHEABLE = 'uncacheable';
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public const ERROR_BUSY = 'busy';
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public const PRESUME_FRESH_TTL_SEC = 30;
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public const MAX_CACHE_TTL = 300; // 5 minutes
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public const MAX_SIGNATURE_TTL = 60;
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private const MAX_CACHE_RECENT = 2;
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public const INITIATOR_USER = 1;
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public const INITIATOR_JOB_OR_CLI = 2;
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/**
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* @param BagOStuff $cache
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* @param IConnectionProvider $dbProvider
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* @param LoggerInterface $logger
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* @param StatsFactory $stats
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* @param UserEditTracker $userEditTracker
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* @param UserFactory $userFactory
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* @param WikiPageFactory $wikiPageFactory
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* @param HookContainer $hookContainer
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* @param int $initiator Class INITIATOR__* constant
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*/
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public function __construct(
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BagOStuff $cache,
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IConnectionProvider $dbProvider,
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LoggerInterface $logger,
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StatsFactory $stats,
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UserEditTracker $userEditTracker,
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UserFactory $userFactory,
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WikiPageFactory $wikiPageFactory,
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HookContainer $hookContainer,
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$initiator
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) {
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$this->cache = $cache;
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$this->dbProvider = $dbProvider;
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$this->logger = $logger;
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$this->stats = $stats;
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$this->userEditTracker = $userEditTracker;
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$this->userFactory = $userFactory;
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$this->wikiPageFactory = $wikiPageFactory;
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$this->hookRunner = new HookRunner( $hookContainer );
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$this->initiator = $initiator;
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}
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/**
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* @param PageUpdater $pageUpdater (a WikiPage instance is also supported but deprecated)
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* @param Content $content Edit content
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* @param UserIdentity $user
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* @param string $summary Edit summary
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* @return string Class ERROR_* constant
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*/
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public function parseAndCache( $pageUpdater, Content $content, UserIdentity $user, string $summary ) {
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$logger = $this->logger;
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if ( $pageUpdater instanceof WikiPage ) {
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wfDeprecated( __METHOD__ . ' with WikiPage instance', '1.42' );
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$pageUpdater = $pageUpdater->newPageUpdater( $user );
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}
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$page = $pageUpdater->getPage();
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$key = $this->getStashKey( $page, $this->getContentHash( $content ), $user );
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$fname = __METHOD__;
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// Use the primary DB to allow for fast blocking locks on the "save path" where this
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// value might actually be used to complete a page edit. If the edit submission request
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// happens before this edit stash requests finishes, then the submission will block until
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// the stash request finishes parsing. For the lock acquisition below, there is not much
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// need to duplicate parsing of the same content/user/summary bundle, so try to avoid
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// blocking at all here.
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$dbw = $this->dbProvider->getPrimaryDatabase();
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if ( !$dbw->lock( $key, $fname, 0 ) ) {
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// De-duplicate requests on the same key
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return self::ERROR_BUSY;
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}
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/** @noinspection PhpUnusedLocalVariableInspection */
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$unlocker = new ScopedCallback( static function () use ( $dbw, $key, $fname ) {
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$dbw->unlock( $key, $fname );
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} );
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$cutoffTime = time() - self::PRESUME_FRESH_TTL_SEC;
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// Reuse any freshly build matching edit stash cache
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$editInfo = $this->getStashValue( $key );
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if ( $editInfo && (int)wfTimestamp( TS_UNIX, $editInfo->timestamp ) >= $cutoffTime ) {
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$alreadyCached = true;
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} else {
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$pageUpdater->setContent( SlotRecord::MAIN, $content );
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$update = $pageUpdater->prepareUpdate( EDIT_INTERNAL ); // applies pre-safe transform
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$output = $update->getCanonicalParserOutput(); // causes content to be parsed
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$output->setCacheTime( $update->getRevision()->getTimestamp() );
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// emulate a cache value that kind of looks like a PreparedEdit, for use below
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$editInfo = (object)[
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'pstContent' => $update->getRawContent( SlotRecord::MAIN ),
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'output' => $output,
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'timestamp' => $output->getCacheTime()
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];
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$alreadyCached = false;
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}
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$logContext = [ 'cachekey' => $key, 'title' => (string)$page ];
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if ( $editInfo->output ) {
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// Let extensions add ParserOutput metadata or warm other caches
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$legacyUser = $this->userFactory->newFromUserIdentity( $user );
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$legacyPage = $this->wikiPageFactory->newFromTitle( $page );
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$this->hookRunner->onParserOutputStashForEdit(
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$legacyPage, $content, $editInfo->output, $summary, $legacyUser );
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if ( $alreadyCached ) {
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$logger->debug( "Parser output for key '{cachekey}' already cached.", $logContext );
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return self::ERROR_NONE;
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}
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$code = $this->storeStashValue(
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$key,
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$editInfo->pstContent,
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$editInfo->output,
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$editInfo->timestamp,
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$user
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);
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if ( $code === true ) {
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$logger->debug( "Cached parser output for key '{cachekey}'.", $logContext );
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return self::ERROR_NONE;
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} elseif ( $code === 'uncacheable' ) {
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$logger->info(
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"Uncacheable parser output for key '{cachekey}' [{code}].",
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$logContext + [ 'code' => $code ]
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);
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return self::ERROR_UNCACHEABLE;
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} else {
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$logger->error(
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"Failed to cache parser output for key '{cachekey}'.",
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$logContext + [ 'code' => $code ]
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);
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return self::ERROR_CACHE;
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}
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}
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return self::ERROR_PARSE;
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}
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/**
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* Check that a prepared edit is in cache and still up-to-date
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*
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* This method blocks if the prepared edit is already being rendered,
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* waiting until rendering finishes before doing final validity checks.
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*
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* The cache is rejected if template or file changes are detected.
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* Note that foreign template or file transclusions are not checked.
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*
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* This returns an object with the following fields:
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* - pstContent: the Content after pre-save-transform
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* - output: the ParserOutput instance
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* - timestamp: the timestamp of the parse
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* - edits: author edit count if they are logged in or NULL otherwise
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*
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* @param PageIdentity $page
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* @param Content $content
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* @param UserIdentity $user to get parser options from
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* @return stdClass|false Returns edit stash object or false on cache miss
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*/
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public function checkCache( PageIdentity $page, Content $content, UserIdentity $user ) {
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$legacyUser = $this->userFactory->newFromUserIdentity( $user );
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if (
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// The context is not an HTTP POST request
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!$legacyUser->getRequest()->wasPosted() ||
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// The context is a CLI script or a job runner HTTP POST request
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$this->initiator !== self::INITIATOR_USER ||
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// The editor account is a known bot
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$legacyUser->isBot()
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) {
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// Avoid wasted queries and statsd pollution
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return false;
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}
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$logger = $this->logger;
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$key = $this->getStashKey( $page, $this->getContentHash( $content ), $user );
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$logContext = [
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'key' => $key,
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'title' => (string)$page,
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'user' => $user->getName()
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];
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$editInfo = $this->getAndWaitForStashValue( $key );
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if ( !is_object( $editInfo ) || !$editInfo->output ) {
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$this->incrCacheReadStats( 'miss', 'no_stash', $content );
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if ( $this->recentStashEntryCount( $user ) > 0 ) {
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$logger->info( "Empty cache for key '{key}' but not for user.", $logContext );
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} else {
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$logger->debug( "Empty cache for key '{key}'.", $logContext );
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}
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return false;
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}
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$age = time() - (int)wfTimestamp( TS_UNIX, $editInfo->output->getCacheTime() );
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$logContext['age'] = $age;
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$isCacheUsable = true;
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if ( $age <= self::PRESUME_FRESH_TTL_SEC ) {
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// Assume nothing changed in this time
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$this->incrCacheReadStats( 'hit', 'presumed_fresh', $content );
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$logger->debug( "Timestamp-based cache hit for key '{key}'.", $logContext );
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} elseif ( !$user->isRegistered() ) {
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$lastEdit = $this->lastEditTime( $user );
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$cacheTime = $editInfo->output->getCacheTime();
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if ( $lastEdit < $cacheTime ) {
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// Logged-out user made no local upload/template edits in the meantime
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$this->incrCacheReadStats( 'hit', 'presumed_fresh', $content );
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$logger->debug( "Edit check based cache hit for key '{key}'.", $logContext );
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} else {
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$isCacheUsable = false;
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$this->incrCacheReadStats( 'miss', 'proven_stale', $content );
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$logger->info( "Stale cache for key '{key}' due to outside edits.", $logContext );
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}
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} else {
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if ( $editInfo->edits === $this->userEditTracker->getUserEditCount( $user ) ) {
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// Logged-in user made no local upload/template edits in the meantime
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$this->incrCacheReadStats( 'hit', 'presumed_fresh', $content );
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$logger->debug( "Edit count based cache hit for key '{key}'.", $logContext );
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} else {
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$isCacheUsable = false;
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$this->incrCacheReadStats( 'miss', 'proven_stale', $content );
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$logger->info( "Stale cache for key '{key}'due to outside edits.", $logContext );
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}
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}
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if ( !$isCacheUsable ) {
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return false;
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}
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if ( $editInfo->output->getOutputFlag( ParserOutputFlags::VARY_REVISION ) ) {
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// This can be used for the initial parse, e.g. for filters or doUserEditContent(),
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// but a second parse will be triggered in doEditUpdates() no matter what
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$logger->info(
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"Cache for key '{key}' has vary-revision; post-insertion parse inevitable.",
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$logContext
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);
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} else {
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static $flagsMaybeReparse = [
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// Similar to the above if we didn't guess the ID correctly
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ParserOutputFlags::VARY_REVISION_ID,
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// Similar to the above if we didn't guess the timestamp correctly
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ParserOutputFlags::VARY_REVISION_TIMESTAMP,
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// Similar to the above if we didn't guess the content correctly
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ParserOutputFlags::VARY_REVISION_SHA1,
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// Similar to the above if we didn't guess page ID correctly
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ParserOutputFlags::VARY_PAGE_ID,
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];
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foreach ( $flagsMaybeReparse as $flag ) {
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if ( $editInfo->output->getOutputFlag( $flag ) ) {
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$logger->debug(
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"Cache for key '{key}' has $flag; post-insertion parse possible.",
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$logContext
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);
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}
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}
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}
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return $editInfo;
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}
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/**
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* @param string $result
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* @param string $reason
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* @param Content $content
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*/
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private function incrCacheReadStats( $result, $reason, Content $content ) {
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static $subtypeByResult = [ 'miss' => 'cache_misses', 'hit' => 'cache_hits' ];
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$this->stats->getCounter( "editstash_cache_checks_total" )
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->setLabel( 'reason', $reason )
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->setLabel( 'result', $result )
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->setLabel( 'model', $content->getModel() )
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->copyToStatsdAt( [
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'editstash.' . $subtypeByResult[ $result ] . '.' . $reason,
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'editstash_by_model.' . $content->getModel() . '.' . $subtypeByResult[ $result ] . '.' . $reason ] )
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->increment();
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}
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/**
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* @param string $key
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* @return bool|stdClass
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*/
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private function getAndWaitForStashValue( $key ) {
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$editInfo = $this->getStashValue( $key );
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if ( !$editInfo ) {
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$start = microtime( true );
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// We ignore user aborts and keep parsing. Block on any prior parsing
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// so as to use its results and make use of the time spent parsing.
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$dbw = $this->dbProvider->getPrimaryDatabase();
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if ( $dbw->lock( $key, __METHOD__, 30 ) ) {
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$editInfo = $this->getStashValue( $key );
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$dbw->unlock( $key, __METHOD__ );
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}
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$timeMs = 1000 * max( 0, microtime( true ) - $start );
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$this->stats->getTiming( 'editstash_lock_wait_seconds' )
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->copyToStatsdAt( 'editstash.lock_wait_time' )
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->observe( $timeMs );
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}
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return $editInfo;
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}
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/**
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* @param string $textHash
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* @return string|bool Text or false if missing
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*/
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public function fetchInputText( $textHash ) {
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$textKey = $this->cache->makeKey( 'stashedit', 'text', $textHash );
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return $this->cache->get( $textKey );
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}
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/**
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* @param string $text
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* @param string $textHash
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* @return bool Success
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*/
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public function stashInputText( $text, $textHash ) {
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$textKey = $this->cache->makeKey( 'stashedit', 'text', $textHash );
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return $this->cache->set(
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$textKey,
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$text,
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self::MAX_CACHE_TTL,
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BagOStuff::WRITE_ALLOW_SEGMENTS
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);
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}
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/**
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* @param UserIdentity $user
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* @return string|null TS_MW timestamp or null
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*/
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private function lastEditTime( UserIdentity $user ) {
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$time = $this->dbProvider->getReplicaDatabase()->newSelectQueryBuilder()
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->select( 'MAX(rc_timestamp)' )
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->from( 'recentchanges' )
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->join( 'actor', null, 'actor_id=rc_actor' )
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->where( [ 'actor_name' => $user->getName() ] )
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->caller( __METHOD__ )
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->fetchField();
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return wfTimestampOrNull( TS_MW, $time );
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}
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/**
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* Get hash of the content, factoring in model/format
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*
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* @param Content $content
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* @return string
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*/
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private function getContentHash( Content $content ) {
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return sha1( implode( "\n", [
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$content->getModel(),
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$content->getDefaultFormat(),
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$content->serialize( $content->getDefaultFormat() )
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] ) );
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}
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/**
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* Get the temporary prepared edit stash key for a user
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*
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* This key can be used for caching prepared edits provided:
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* - a) The $user was used for PST options
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* - b) The parser output was made from the PST using cannonical matching options
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*
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* @param PageIdentity $page
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* @param string $contentHash Result of getContentHash()
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* @param UserIdentity $user User to get parser options from
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* @return string
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*/
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private function getStashKey( PageIdentity $page, $contentHash, UserIdentity $user ) {
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return $this->cache->makeKey(
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'stashedit-info-v2',
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md5( "{$page->getNamespace()}\n{$page->getDBkey()}" ),
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// Account for the edit model/text
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$contentHash,
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// Account for user name related variables like signatures
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md5( "{$user->getId()}\n{$user->getName()}" )
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);
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}
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/**
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* @param string $key
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* @return stdClass|bool Object map (pstContent,output,outputID,timestamp,edits) or false
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*/
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private function getStashValue( $key ) {
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$serial = $this->cache->get( $key );
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return $this->unserializeStashInfo( $serial );
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}
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/**
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* Build a value to store in memcached based on the PST content and parser output
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*
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* This makes a simple version of WikiPage::prepareContentForEdit() as stash info
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*
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* @param string $key
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* @param Content $pstContent Pre-Save transformed content
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* @param ParserOutput $parserOutput
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* @param string $timestamp TS_MW
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* @param UserIdentity $user
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* @return string|bool True or an error code
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*/
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private function storeStashValue(
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$key,
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Content $pstContent,
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ParserOutput $parserOutput,
|
|
$timestamp,
|
|
UserIdentity $user
|
|
) {
|
|
// If an item is renewed, mind the cache TTL determined by config and parser functions.
|
|
// Put an upper limit on the TTL to avoid extreme template/file staleness.
|
|
$age = time() - (int)wfTimestamp( TS_UNIX, $parserOutput->getCacheTime() );
|
|
$ttl = min( $parserOutput->getCacheExpiry() - $age, self::MAX_CACHE_TTL );
|
|
// Avoid extremely stale user signature timestamps (T84843)
|
|
if ( $parserOutput->getOutputFlag( ParserOutputFlags::USER_SIGNATURE ) ) {
|
|
$ttl = min( $ttl, self::MAX_SIGNATURE_TTL );
|
|
}
|
|
|
|
if ( $ttl <= 0 ) {
|
|
return 'uncacheable'; // low TTL due to a tag, magic word, or signature?
|
|
}
|
|
|
|
// Store what is actually needed and split the output into another key (T204742)
|
|
$stashInfo = (object)[
|
|
'pstContent' => $pstContent,
|
|
'output' => $parserOutput,
|
|
'timestamp' => $timestamp,
|
|
'edits' => $this->userEditTracker->getUserEditCount( $user ),
|
|
];
|
|
$serial = $this->serializeStashInfo( $stashInfo );
|
|
if ( $serial === false ) {
|
|
return 'store_error';
|
|
}
|
|
|
|
$ok = $this->cache->set( $key, $serial, $ttl, BagOStuff::WRITE_ALLOW_SEGMENTS );
|
|
if ( $ok ) {
|
|
// These blobs can waste slots in low cardinality memcached slabs
|
|
$this->pruneExcessStashedEntries( $user, $key );
|
|
}
|
|
|
|
return $ok ? true : 'store_error';
|
|
}
|
|
|
|
/**
|
|
* @param UserIdentity $user
|
|
* @param string $newKey
|
|
*/
|
|
private function pruneExcessStashedEntries( UserIdentity $user, $newKey ) {
|
|
$key = $this->cache->makeKey( 'stash-edit-recent', sha1( $user->getName() ) );
|
|
|
|
$keyList = $this->cache->get( $key ) ?: [];
|
|
if ( count( $keyList ) >= self::MAX_CACHE_RECENT ) {
|
|
$oldestKey = array_shift( $keyList );
|
|
$this->cache->delete( $oldestKey, BagOStuff::WRITE_ALLOW_SEGMENTS );
|
|
}
|
|
|
|
$keyList[] = $newKey;
|
|
$this->cache->set( $key, $keyList, 2 * self::MAX_CACHE_TTL );
|
|
}
|
|
|
|
/**
|
|
* @param UserIdentity $user
|
|
* @return int
|
|
*/
|
|
private function recentStashEntryCount( UserIdentity $user ) {
|
|
$key = $this->cache->makeKey( 'stash-edit-recent', sha1( $user->getName() ) );
|
|
|
|
return count( $this->cache->get( $key ) ?: [] );
|
|
}
|
|
|
|
private function serializeStashInfo( stdClass $stashInfo ) {
|
|
// @todo: use JSON with ParserOutput and Content
|
|
return serialize( $stashInfo );
|
|
}
|
|
|
|
private function unserializeStashInfo( $serial ) {
|
|
if ( is_string( $serial ) ) {
|
|
// @todo: use JSON with ParserOutput and Content
|
|
$stashInfo = unserialize( $serial );
|
|
if ( is_object( $stashInfo ) && $stashInfo->output instanceof ParserOutput ) {
|
|
return $stashInfo;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
}
|