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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
+ * @author Aaron Schulz
+ */
+
+/**
+ * Prepare and 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';
+
+ public function execute() {
+ global $wgMemc;
+
+ $user = $this->getUser();
+ $params = $this->extractRequestParams();
+
+ $page = $this->getTitleOrPageId( $params );
+ $title = $page->getTitle();
+
+ if ( !ContentHandler::getForModelID( $params['contentmodel'] )
+ ->isSupportedFormat( $params['contentformat'] )
+ ) {
+ $this->dieUsage( "Unsupported content model/format", 'badmodelformat' );
+ }
+
+ // Trim and fix newlines so the key SHA1's match (see RequestContext::getText())
+ $text = rtrim( str_replace( "\r\n", "\n", $params['text'] ) );
+ $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 ) {
+ $this->dieUsage( "No revision ID {$params['baserevid']}", 'missingrev' );
+ }
+ $currentRev = $page->getRevision();
+ if ( !$currentRev ) {
+ $this->dieUsage( "No current revision of page ID {$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->dieUsage( "Could not merge updated section.", '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 ) {
+ $this->dieUsage( "Missing content for page ID {$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(), array( 'status' => 'editconflict' ) );
+ return;
+ }
+
+ // The user will abort the AJAX request by pressing "save", so ignore that
+ ignore_user_abort( true );
+
+ // Get a key based on the source text, format, and user preferences
+ $key = self::getStashKey( $title, $content, $user );
+ // De-duplicate requests on the same key
+ if ( $user->pingLimiter( 'stashedit' ) ) {
+ $status = 'ratelimited';
+ } elseif ( $wgMemc->lock( $key, 0, 30 ) ) {
+ $unlocker = new ScopedCallback( function() use ( $key ) {
+ global $wgMemc;
+ $wgMemc->unlock( $key );
+ } );
+ $status = self::parseAndStash( $page, $content, $user );
+ } else {
+ $status = 'busy';
+ }
+
+ $this->getResult()->addValue( null, $this->getModuleName(), array( 'status' => $status ) );
+ }
+
+ /**
+ * @param WikiPage $page
+ * @param Content $content
+ * @param User $user
+ * @return integer ApiStashEdit::ERROR_* constant
+ * @since 1.25
+ */
+ public static function parseAndStash( WikiPage $page, Content $content, User $user ) {
+ global $wgMemc;
+
+ $format = $content->getDefaultFormat();
+ $editInfo = $page->prepareContentForEdit( $content, null, $user, $format, false );
+
+ if ( $editInfo && $editInfo->output ) {
+ $key = self::getStashKey( $page->getTitle(), $content, $user );
+
+ list( $stashInfo, $ttl ) = self::buildStashValue(
+ $editInfo->pstContent, $editInfo->output, $editInfo->timestamp
+ );
+
+ if ( $stashInfo ) {
+ $ok = $wgMemc->set( $key, $stashInfo, $ttl );
+ if ( $ok ) {
+ wfDebugLog( 'StashEdit', "Cached parser output for key '$key'." );
+ return self::ERROR_NONE;
+ } else {
+ wfDebugLog( 'StashEdit', "Failed to cache parser output for key '$key'." );
+ return self::ERROR_CACHE;
+ }
+ } else {
+ wfDebugLog( 'StashEdit', "Uncacheable parser output for key '$key'." );
+ return self::ERROR_UNCACHEABLE;
+ }
+ }
+
+ return self::ERROR_PARSE;
+ }
+
+ /**
+ * Attempt to cache PST content and corresponding parser output in passing
+ *
+ * This method can be called when the output was already generated for other
+ * reasons. Parsing should not be done just to call this method, however.
+ * $pstOpts must be that of the user doing the edit preview. If $pOpts does
+ * not match the options of WikiPage::makeParserOptions( 'canonical' ), this
+ * will do nothing. Provided the values are cacheable, they will be stored
+ * in memcached so that final edit submission might make use of them.
+ *
+ * @param Article|WikiPage $page Page title
+ * @param Content $content Proposed page content
+ * @param Content $pstContent The result of preSaveTransform() on $content
+ * @param ParserOutput $pOut The result of getParserOutput() on $pstContent
+ * @param ParserOptions $pstOpts Options for $pstContent (MUST be for prospective author)
+ * @param ParserOptions $pOpts Options for $pOut
+ * @param string $timestamp TS_MW timestamp of parser output generation
+ * @return bool Success
+ */
+ public static function stashEditFromPreview(
+ Page $page, Content $content, Content $pstContent, ParserOutput $pOut,
+ ParserOptions $pstOpts, ParserOptions $pOpts, $timestamp
+ ) {
+ global $wgMemc;
+
+ // getIsPreview() controls parser function behavior that references things
+ // like user/revision that don't exists yet. The user/text should already
+ // be set correctly by callers, just double check the preview flag.
+ if ( !$pOpts->getIsPreview() ) {
+ return false; // sanity
+ } elseif ( $pOpts->getIsSectionPreview() ) {
+ return false; // short-circuit (need the full content)
+ }
+
+ // PST parser options are for the user (handles signatures, etc...)
+ $user = $pstOpts->getUser();
+ // Get a key based on the source text, format, and user preferences
+ $key = self::getStashKey( $page->getTitle(), $content, $user );
+
+ // Parser output options must match cannonical options.
+ // Treat some options as matching that are different but don't matter.
+ $canonicalPOpts = $page->makeParserOptions( 'canonical' );
+ $canonicalPOpts->setIsPreview( true ); // force match
+ $canonicalPOpts->setTimestamp( $pOpts->getTimestamp() ); // force match
+ if ( !$pOpts->matches( $canonicalPOpts ) ) {
+ wfDebugLog( 'StashEdit', "Uncacheable preview output for key '$key' (options)." );
+ return false;
+ }
+
+ // Build a value to cache with a proper TTL
+ list( $stashInfo, $ttl ) = self::buildStashValue( $pstContent, $pOut, $timestamp );
+ if ( !$stashInfo ) {
+ wfDebugLog( 'StashEdit', "Uncacheable parser output for key '$key' (rev/TTL)." );
+ return false;
+ }
+
+ $ok = $wgMemc->set( $key, $stashInfo, $ttl );
+ if ( !$ok ) {
+ wfDebugLog( 'StashEdit', "Failed to cache preview parser output for key '$key'." );
+ } else {
+ wfDebugLog( 'StashEdit', "Cached preview output for key '$key'." );
+ }
+
+ return $ok;
+ }
+
+ /**
+ * 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 ) {
+ global $wgMemc;
+
+ $key = self::getStashKey( $title, $content, $user );
+ $editInfo = $wgMemc->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 it's results and make use of the time spent parsing.
+ if ( $wgMemc->lock( $key, 30, 30 ) ) {
+ $editInfo = $wgMemc->get( $key );
+ $wgMemc->unlock( $key );
+ }
+ $sec = microtime( true ) - $start;
+ if ( $sec > .01 ) {
+ wfDebugLog( 'StashEdit', "Waited $sec seconds on '$key'." );
+ }
+ }
+
+ if ( !is_object( $editInfo ) || !$editInfo->output ) {
+ wfDebugLog( 'StashEdit', "No cache value for key '$key'." );
+ return false;
+ }
+
+ $time = wfTimestamp( TS_UNIX, $editInfo->output->getTimestamp() );
+ if ( ( time() - $time ) <= 3 ) {
+ wfDebugLog( 'StashEdit', "Timestamp-based cache hit for key '$key'." );
+ return $editInfo; // assume nothing changed
+ }
+
+ $dbr = wfGetDB( DB_SLAVE );
+ // Check that no templates used in the output changed...
+ $cWhr = array(); // conditions to find changes/creations
+ $dWhr = array(); // conditions to find deletions
+ foreach ( $editInfo->output->getTemplateIds() as $ns => $stuff ) {
+ foreach ( $stuff as $dbkey => $revId ) {
+ $cWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey,
+ 'page_latest != ' . intval( $revId ) );
+ $dWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey );
+ }
+ }
+ $change = $dbr->selectField( 'page', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
+ $n = $dbr->selectField( 'page', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
+ if ( $change || $n != count( $dWhr ) ) {
+ wfDebugLog( 'StashEdit', "Stale cache for key '$key'; template changed." );
+ return false;
+ }
+
+ // Check that no files used in the output changed...
+ $cWhr = array(); // conditions to find changes/creations
+ $dWhr = array(); // conditions to find deletions
+ foreach ( $editInfo->output->getFileSearchOptions() as $name => $options ) {
+ $cWhr[] = array( 'img_name' => $dbkey,
+ 'img_sha1 != ' . $dbr->addQuotes( strval( $options['sha1'] ) ) );
+ $dWhr[] = array( 'img_name' => $dbkey );
+ }
+ $change = $dbr->selectField( 'image', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
+ $n = $dbr->selectField( 'image', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
+ if ( $change || $n != count( $dWhr ) ) {
+ wfDebugLog( 'StashEdit', "Stale cache for key '$key'; file changed." );
+ return false;
+ }
+
+ wfDebugLog( 'StashEdit', "Cache hit for key '$key'." );
+
+ return $editInfo;
+ }
+
+ /**
+ * 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 Content $content
+ * @param User $user User to get parser options from
+ * @return string
+ */
+ protected static function getStashKey( Title $title, Content $content, User $user ) {
+ $hash = sha1( implode( ':', array(
+ $content->getModel(),
+ $content->getDefaultFormat(),
+ sha1( $content->serialize( $content->getDefaultFormat() ) ),
+ $user->getId() ?: md5( $user->getName() ), // account for user parser options
+ $user->getId() ? $user->getTouched() : '-' // handle preference change races
+ ) ) );
+
+ return wfMemcKey( 'prepared-edit', md5( $title->getPrefixedDBkey() ), $hash );
+ }
+
+ /**
+ * 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
+ * @param ParserOutput $parserOutput
+ * @param string $timestamp TS_MW
+ * @return array (stash info array, TTL in seconds) or (null, 0)
+ */
+ protected static function buildStashValue(
+ Content $pstContent, ParserOutput $parserOutput, $timestamp
+ ) {
+ // If an item is renewed, mind the cache TTL determined by config and parser functions
+ $since = time() - wfTimestamp( TS_UNIX, $parserOutput->getTimestamp() );
+ $ttl = min( $parserOutput->getCacheExpiry() - $since, 5 * 60 );
+
+ if ( $ttl > 0 && !$parserOutput->getFlag( 'vary-revision' ) ) {
+ // Only store what is actually needed
+ $stashInfo = (object)array(
+ 'pstContent' => $pstContent,
+ 'output' => $parserOutput,
+ 'timestamp' => $timestamp
+ );
+ return array( $stashInfo, $ttl );
+ }
+
+ return array( null, 0 );
+ }
+
+ public function getAllowedParams() {
+ return array(
+ 'title' => array(
+ ApiBase::PARAM_TYPE => 'string',
+ ApiBase::PARAM_REQUIRED => true
+ ),
+ 'section' => array(
+ ApiBase::PARAM_TYPE => 'string',
+ ),
+ 'sectiontitle' => array(
+ ApiBase::PARAM_TYPE => 'string'
+ ),
+ 'text' => array(
+ ApiBase::PARAM_TYPE => 'string',
+ ApiBase::PARAM_REQUIRED => true
+ ),
+ 'contentmodel' => array(
+ ApiBase::PARAM_TYPE => ContentHandler::getContentModels(),
+ ApiBase::PARAM_REQUIRED => true
+ ),
+ 'contentformat' => array(
+ ApiBase::PARAM_TYPE => ContentHandler::getAllContentFormats(),
+ ApiBase::PARAM_REQUIRED => true
+ ),
+ 'baserevid' => array(
+ ApiBase::PARAM_TYPE => 'integer',
+ ApiBase::PARAM_REQUIRED => true
+ )
+ );
+ }
+
+ function needsToken() {
+ return 'csrf';
+ }
+
+ function mustBePosted() {
+ return true;
+ }
+
+ function isInternal() {
+ return true;
+ }
+}
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