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+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use MediaWiki\Logger\LoggerFactory;
+use MediaWiki\MediaWikiServices;
+use Wikimedia\ScopedCallback;
+
+/**
+ * Prepare an edit in shared cache so that it can be reused on edit
+ *
+ * This endpoint can be called via AJAX as the user focuses on the edit
+ * summary box. By the time of submission, the parse may have already
+ * finished, and can be immediately used on page save. Certain parser
+ * functions like {{REVISIONID}} or {{CURRENTTIME}} may cause the cache
+ * to not be used on edit. Template and files used are check for changes
+ * since the output was generated. The cache TTL is also kept low for sanity.
+ *
+ * @ingroup API
+ * @since 1.25
+ */
+class ApiStashEdit extends ApiBase {
+ const ERROR_NONE = 'stashed';
+ const ERROR_PARSE = 'error_parse';
+ const ERROR_CACHE = 'error_cache';
+ const ERROR_UNCACHEABLE = 'uncacheable';
+ const ERROR_BUSY = 'busy';
+
+ const PRESUME_FRESH_TTL_SEC = 30;
+ const MAX_CACHE_TTL = 300; // 5 minutes
+ const MAX_SIGNATURE_TTL = 60;
+
+ public function execute() {
+ $user = $this->getUser();
+ $params = $this->extractRequestParams();
+
+ if ( $user->isBot() ) { // sanity
+ $this->dieWithError( 'apierror-botsnotsupported' );
+ }
+
+ $cache = ObjectCache::getLocalClusterInstance();
+ $page = $this->getTitleOrPageId( $params );
+ $title = $page->getTitle();
+
+ if ( !ContentHandler::getForModelID( $params['contentmodel'] )
+ ->isSupportedFormat( $params['contentformat'] )
+ ) {
+ $this->dieWithError(
+ [ 'apierror-badformat-generic', $params['contentformat'], $params['contentmodel'] ],
+ 'badmodelformat'
+ );
+ }
+
+ $this->requireAtLeastOneParameter( $params, 'stashedtexthash', 'text' );
+
+ $text = null;
+ $textHash = null;
+ if ( strlen( $params['stashedtexthash'] ) ) {
+ // Load from cache since the client indicates the text is the same as last stash
+ $textHash = $params['stashedtexthash'];
+ if ( !preg_match( '/^[0-9a-f]{40}$/', $textHash ) ) {
+ $this->dieWithError( 'apierror-stashedit-missingtext', 'missingtext' );
+ }
+ $textKey = $cache->makeKey( 'stashedit', 'text', $textHash );
+ $text = $cache->get( $textKey );
+ if ( !is_string( $text ) ) {
+ $this->dieWithError( 'apierror-stashedit-missingtext', 'missingtext' );
+ }
+ } elseif ( $params['text'] !== null ) {
+ // Trim and fix newlines so the key SHA1's match (see WebRequest::getText())
+ $text = rtrim( str_replace( "\r\n", "\n", $params['text'] ) );
+ $textHash = sha1( $text );
+ } else {
+ $this->dieWithError( [
+ 'apierror-missingparam-at-least-one-of',
+ Message::listParam( [ '<var>stashedtexthash</var>', '<var>text</var>' ] ),
+ 2,
+ ], 'missingparam' );
+ }
+
+ $textContent = ContentHandler::makeContent(
+ $text, $title, $params['contentmodel'], $params['contentformat'] );
+
+ $page = WikiPage::factory( $title );
+ if ( $page->exists() ) {
+ // Page exists: get the merged content with the proposed change
+ $baseRev = Revision::newFromPageId( $page->getId(), $params['baserevid'] );
+ if ( !$baseRev ) {
+ $this->dieWithError( [ 'apierror-nosuchrevid', $params['baserevid'] ] );
+ }
+ $currentRev = $page->getRevision();
+ if ( !$currentRev ) {
+ $this->dieWithError( [ 'apierror-missingrev-pageid', $page->getId() ], 'missingrev' );
+ }
+ // Merge in the new version of the section to get the proposed version
+ $editContent = $page->replaceSectionAtRev(
+ $params['section'],
+ $textContent,
+ $params['sectiontitle'],
+ $baseRev->getId()
+ );
+ if ( !$editContent ) {
+ $this->dieWithError( 'apierror-sectionreplacefailed', 'replacefailed' );
+ }
+ if ( $currentRev->getId() == $baseRev->getId() ) {
+ // Base revision was still the latest; nothing to merge
+ $content = $editContent;
+ } else {
+ // Merge the edit into the current version
+ $baseContent = $baseRev->getContent();
+ $currentContent = $currentRev->getContent();
+ if ( !$baseContent || !$currentContent ) {
+ $this->dieWithError( [ 'apierror-missingcontent-pageid', $page->getId() ], 'missingrev' );
+ }
+ $handler = ContentHandler::getForModelID( $baseContent->getModel() );
+ $content = $handler->merge3( $baseContent, $editContent, $currentContent );
+ }
+ } else {
+ // New pages: use the user-provided content model
+ $content = $textContent;
+ }
+
+ if ( !$content ) { // merge3() failed
+ $this->getResult()->addValue( null,
+ $this->getModuleName(), [ 'status' => 'editconflict' ] );
+ return;
+ }
+
+ // The user will abort the AJAX request by pressing "save", so ignore that
+ ignore_user_abort( true );
+
+ if ( $user->pingLimiter( 'stashedit' ) ) {
+ $status = 'ratelimited';
+ } else {
+ $status = self::parseAndStash( $page, $content, $user, $params['summary'] );
+ $textKey = $cache->makeKey( 'stashedit', 'text', $textHash );
+ $cache->set( $textKey, $text, self::MAX_CACHE_TTL );
+ }
+
+ $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
+ $stats->increment( "editstash.cache_stores.$status" );
+
+ $this->getResult()->addValue(
+ null,
+ $this->getModuleName(),
+ [
+ 'status' => $status,
+ 'texthash' => $textHash
+ ]
+ );
+ }
+
+ /**
+ * @param WikiPage $page
+ * @param Content $content Edit content
+ * @param User $user
+ * @param string $summary Edit summary
+ * @return string ApiStashEdit::ERROR_* constant
+ * @since 1.25
+ */
+ public static function parseAndStash( WikiPage $page, Content $content, User $user, $summary ) {
+ $cache = ObjectCache::getLocalClusterInstance();
+ $logger = LoggerFactory::getInstance( 'StashEdit' );
+
+ $title = $page->getTitle();
+ $key = self::getStashKey( $title, self::getContentHash( $content ), $user );
+
+ // Use the master DB to allow for fast blocking locks on the "save path" where this
+ // value might actually be used to complete a page edit. If the edit submission request
+ // happens before this edit stash requests finishes, then the submission will block until
+ // the stash request finishes parsing. For the lock acquisition below, there is not much
+ // need to duplicate parsing of the same content/user/summary bundle, so try to avoid
+ // blocking at all here.
+ $dbw = wfGetDB( DB_MASTER );
+ if ( !$dbw->lock( $key, __METHOD__, 0 ) ) {
+ // De-duplicate requests on the same key
+ return self::ERROR_BUSY;
+ }
+ /** @noinspection PhpUnusedLocalVariableInspection */
+ $unlocker = new ScopedCallback( function () use ( $dbw, $key ) {
+ $dbw->unlock( $key, __METHOD__ );
+ } );
+
+ $cutoffTime = time() - self::PRESUME_FRESH_TTL_SEC;
+
+ // Reuse any freshly build matching edit stash cache
+ $editInfo = $cache->get( $key );
+ if ( $editInfo && wfTimestamp( TS_UNIX, $editInfo->timestamp ) >= $cutoffTime ) {
+ $alreadyCached = true;
+ } else {
+ $format = $content->getDefaultFormat();
+ $editInfo = $page->prepareContentForEdit( $content, null, $user, $format, false );
+ $alreadyCached = false;
+ }
+
+ if ( $editInfo && $editInfo->output ) {
+ // Let extensions add ParserOutput metadata or warm other caches
+ Hooks::run( 'ParserOutputStashForEdit',
+ [ $page, $content, $editInfo->output, $summary, $user ] );
+
+ $titleStr = (string)$title;
+ if ( $alreadyCached ) {
+ $logger->debug( "Already cached parser output for key '{cachekey}' ('{title}').",
+ [ 'cachekey' => $key, 'title' => $titleStr ] );
+ return self::ERROR_NONE;
+ }
+
+ list( $stashInfo, $ttl, $code ) = self::buildStashValue(
+ $editInfo->pstContent,
+ $editInfo->output,
+ $editInfo->timestamp,
+ $user
+ );
+
+ if ( $stashInfo ) {
+ $ok = $cache->set( $key, $stashInfo, $ttl );
+ if ( $ok ) {
+ $logger->debug( "Cached parser output for key '{cachekey}' ('{title}').",
+ [ 'cachekey' => $key, 'title' => $titleStr ] );
+ return self::ERROR_NONE;
+ } else {
+ $logger->error( "Failed to cache parser output for key '{cachekey}' ('{title}').",
+ [ 'cachekey' => $key, 'title' => $titleStr ] );
+ return self::ERROR_CACHE;
+ }
+ } else {
+ $logger->info( "Uncacheable parser output for key '{cachekey}' ('{title}') [{code}].",
+ [ 'cachekey' => $key, 'title' => $titleStr, 'code' => $code ] );
+ return self::ERROR_UNCACHEABLE;
+ }
+ }
+
+ return self::ERROR_PARSE;
+ }
+
+ /**
+ * Check that a prepared edit is in cache and still up-to-date
+ *
+ * This method blocks if the prepared edit is already being rendered,
+ * waiting until rendering finishes before doing final validity checks.
+ *
+ * The cache is rejected if template or file changes are detected.
+ * Note that foreign template or file transclusions are not checked.
+ *
+ * The result is a map (pstContent,output,timestamp) with fields
+ * extracted directly from WikiPage::prepareContentForEdit().
+ *
+ * @param Title $title
+ * @param Content $content
+ * @param User $user User to get parser options from
+ * @return stdClass|bool Returns false on cache miss
+ */
+ public static function checkCache( Title $title, Content $content, User $user ) {
+ if ( $user->isBot() ) {
+ return false; // bots never stash - don't pollute stats
+ }
+
+ $cache = ObjectCache::getLocalClusterInstance();
+ $logger = LoggerFactory::getInstance( 'StashEdit' );
+ $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
+
+ $key = self::getStashKey( $title, self::getContentHash( $content ), $user );
+ $editInfo = $cache->get( $key );
+ if ( !is_object( $editInfo ) ) {
+ $start = microtime( true );
+ // We ignore user aborts and keep parsing. Block on any prior parsing
+ // so as to use its results and make use of the time spent parsing.
+ // Skip this logic if there no master connection in case this method
+ // is called on an HTTP GET request for some reason.
+ $lb = MediaWikiServices::getInstance()->getDBLoadBalancer();
+ $dbw = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
+ if ( $dbw && $dbw->lock( $key, __METHOD__, 30 ) ) {
+ $editInfo = $cache->get( $key );
+ $dbw->unlock( $key, __METHOD__ );
+ }
+
+ $timeMs = 1000 * max( 0, microtime( true ) - $start );
+ $stats->timing( 'editstash.lock_wait_time', $timeMs );
+ }
+
+ if ( !is_object( $editInfo ) || !$editInfo->output ) {
+ $stats->increment( 'editstash.cache_misses.no_stash' );
+ $logger->debug( "Empty cache for key '$key' ('$title'); user '{$user->getName()}'." );
+ return false;
+ }
+
+ $age = time() - wfTimestamp( TS_UNIX, $editInfo->output->getCacheTime() );
+ if ( $age <= self::PRESUME_FRESH_TTL_SEC ) {
+ // Assume nothing changed in this time
+ $stats->increment( 'editstash.cache_hits.presumed_fresh' );
+ $logger->debug( "Timestamp-based cache hit for key '$key' (age: $age sec)." );
+ } elseif ( isset( $editInfo->edits ) && $editInfo->edits === $user->getEditCount() ) {
+ // Logged-in user made no local upload/template edits in the meantime
+ $stats->increment( 'editstash.cache_hits.presumed_fresh' );
+ $logger->debug( "Edit count based cache hit for key '$key' (age: $age sec)." );
+ } elseif ( $user->isAnon()
+ && self::lastEditTime( $user ) < $editInfo->output->getCacheTime()
+ ) {
+ // Logged-out user made no local upload/template edits in the meantime
+ $stats->increment( 'editstash.cache_hits.presumed_fresh' );
+ $logger->debug( "Edit check based cache hit for key '$key' (age: $age sec)." );
+ } else {
+ // User may have changed included content
+ $editInfo = false;
+ }
+
+ if ( !$editInfo ) {
+ $stats->increment( 'editstash.cache_misses.proven_stale' );
+ $logger->info( "Stale cache for key '$key'; old key with outside edits. (age: $age sec)" );
+ } elseif ( $editInfo->output->getFlag( 'vary-revision' ) ) {
+ // This can be used for the initial parse, e.g. for filters or doEditContent(),
+ // but a second parse will be triggered in doEditUpdates(). This is not optimal.
+ $logger->info( "Cache for key '$key' ('$title') has vary_revision." );
+ } elseif ( $editInfo->output->getFlag( 'vary-revision-id' ) ) {
+ // Similar to the above if we didn't guess the ID correctly.
+ $logger->info( "Cache for key '$key' ('$title') has vary_revision_id." );
+ }
+
+ return $editInfo;
+ }
+
+ /**
+ * @param User $user
+ * @return string|null TS_MW timestamp or null
+ */
+ private static function lastEditTime( User $user ) {
+ $db = wfGetDB( DB_REPLICA );
+ $actorQuery = ActorMigration::newMigration()->getWhere( $db, 'rc_user', $user, false );
+ $time = $db->selectField(
+ [ 'recentchanges' ] + $actorQuery['tables'],
+ 'MAX(rc_timestamp)',
+ [ $actorQuery['conds'] ],
+ __METHOD__,
+ [],
+ $actorQuery['joins']
+ );
+
+ return wfTimestampOrNull( TS_MW, $time );
+ }
+
+ /**
+ * Get hash of the content, factoring in model/format
+ *
+ * @param Content $content
+ * @return string
+ */
+ private static function getContentHash( Content $content ) {
+ return sha1( implode( "\n", [
+ $content->getModel(),
+ $content->getDefaultFormat(),
+ $content->serialize( $content->getDefaultFormat() )
+ ] ) );
+ }
+
+ /**
+ * Get the temporary prepared edit stash key for a user
+ *
+ * This key can be used for caching prepared edits provided:
+ * - a) The $user was used for PST options
+ * - b) The parser output was made from the PST using cannonical matching options
+ *
+ * @param Title $title
+ * @param string $contentHash Result of getContentHash()
+ * @param User $user User to get parser options from
+ * @return string
+ */
+ private static function getStashKey( Title $title, $contentHash, User $user ) {
+ return ObjectCache::getLocalClusterInstance()->makeKey(
+ 'prepared-edit',
+ md5( $title->getPrefixedDBkey() ),
+ // Account for the edit model/text
+ $contentHash,
+ // Account for user name related variables like signatures
+ md5( $user->getId() . "\n" . $user->getName() )
+ );
+ }
+
+ /**
+ * Build a value to store in memcached based on the PST content and parser output
+ *
+ * This makes a simple version of WikiPage::prepareContentForEdit() as stash info
+ *
+ * @param Content $pstContent Pre-Save transformed content
+ * @param ParserOutput $parserOutput
+ * @param string $timestamp TS_MW
+ * @param User $user
+ * @return array (stash info array, TTL in seconds, info code) or (null, 0, info code)
+ */
+ private static function buildStashValue(
+ Content $pstContent, ParserOutput $parserOutput, $timestamp, User $user
+ ) {
+ // If an item is renewed, mind the cache TTL determined by config and parser functions.
+ // Put an upper limit on the TTL for sanity to avoid extreme template/file staleness.
+ $since = time() - wfTimestamp( TS_UNIX, $parserOutput->getTimestamp() );
+ $ttl = min( $parserOutput->getCacheExpiry() - $since, self::MAX_CACHE_TTL );
+
+ // Avoid extremely stale user signature timestamps (T84843)
+ if ( $parserOutput->getFlag( 'user-signature' ) ) {
+ $ttl = min( $ttl, self::MAX_SIGNATURE_TTL );
+ }
+
+ if ( $ttl <= 0 ) {
+ return [ null, 0, 'no_ttl' ];
+ }
+
+ // Only store what is actually needed
+ $stashInfo = (object)[
+ 'pstContent' => $pstContent,
+ 'output' => $parserOutput,
+ 'timestamp' => $timestamp,
+ 'edits' => $user->getEditCount()
+ ];
+
+ return [ $stashInfo, $ttl, 'ok' ];
+ }
+
+ public function getAllowedParams() {
+ return [
+ 'title' => [
+ ApiBase::PARAM_TYPE => 'string',
+ ApiBase::PARAM_REQUIRED => true
+ ],
+ 'section' => [
+ ApiBase::PARAM_TYPE => 'string',
+ ],
+ 'sectiontitle' => [
+ ApiBase::PARAM_TYPE => 'string'
+ ],
+ 'text' => [
+ ApiBase::PARAM_TYPE => 'text',
+ ApiBase::PARAM_DFLT => null
+ ],
+ 'stashedtexthash' => [
+ ApiBase::PARAM_TYPE => 'string',
+ ApiBase::PARAM_DFLT => null
+ ],
+ 'summary' => [
+ ApiBase::PARAM_TYPE => 'string',
+ ],
+ 'contentmodel' => [
+ ApiBase::PARAM_TYPE => ContentHandler::getContentModels(),
+ ApiBase::PARAM_REQUIRED => true
+ ],
+ 'contentformat' => [
+ ApiBase::PARAM_TYPE => ContentHandler::getAllContentFormats(),
+ ApiBase::PARAM_REQUIRED => true
+ ],
+ 'baserevid' => [
+ ApiBase::PARAM_TYPE => 'integer',
+ ApiBase::PARAM_REQUIRED => true
+ ]
+ ];
+ }
+
+ public function needsToken() {
+ return 'csrf';
+ }
+
+ public function mustBePosted() {
+ return true;
+ }
+
+ public function isWriteMode() {
+ return true;
+ }
+
+ public function isInternal() {
+ return true;
+ }
+}
generated by cgit v1.2.1 (git 2.18.0) at 2024-05-04 23:22:02 +0000