includes/api/ApiStashEdit.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  * @author Aaron Schulz
  20  */
  21
  22 /**
  23  * Prepare and edit in shared cache so that it can be reused on edit
  24  *
  25  * This endpoint can be called via AJAX as the user focuses on the edit
  26  * summary box. By the time of submission, the parse may have already
  27  * finished, and can be immediately used on page save. Certain parser
  28  * functions like {{REVISIONID}} or {{CURRENTTIME}} may cause the cache
  29  * to not be used on edit. Template and files used are check for changes
  30  * since the output was generated. The cache TTL is also kept low for sanity.
  31  *
  32  * @ingroup API
  33  * @since 1.25
  34  */
  35 class ApiStashEdit extends ApiBase {
  36         public function execute() {
  37                 global $wgMemc;
  38
  39                 $user = $this->getUser();
  40                 $params = $this->extractRequestParams();
  41
  42                 $page = $this->getTitleOrPageId( $params );
  43                 $title = $page->getTitle();
  44
  45                 if ( !ContentHandler::getForModelID( $params['contentmodel'] )
  46                         ->isSupportedFormat( $params['contentformat'] )
  47                 ) {
  48                         $this->dieUsage( "Unsupported content model/format", 'badmodelformat' );
  49                 }
  50
  51                 $text = trim( $params['text'] ); // needed so the key SHA1's match
  52                 $textContent = ContentHandler::makeContent(
  53                         $text, $title, $params['contentmodel'], $params['contentformat'] );
  54
  55                 $page = WikiPage::factory( $title );
  56                 if ( $page->exists() ) {
  57                         // Page exists: get the merged content with the proposed change
  58                         $baseRev = Revision::newFromPageId( $page->getId(), $params['baserevid'] );
  59                         if ( !$baseRev ) {
  60                                 $this->dieUsage( "No revision ID {$params['baserevid']}", 'missingrev' );
  61                         }
  62                         $currentRev = $page->getRevision();
  63                         if ( !$currentRev ) {
  64                                 $this->dieUsage( "No current revision of page ID {$page->getId()}", 'missingrev' );
  65                         }
  66                         // Merge in the new version of the section to get the proposed version
  67                         $editContent = $page->replaceSectionAtRev(
  68                                 $params['section'],
  69                                 $textContent,
  70                                 $params['sectiontitle'],
  71                                 $baseRev->getId()
  72                         );
  73                         if ( !$editContent ) {
  74                                 $this->dieUsage( "Could not merge updated section.", 'replacefailed' );
  75                         }
  76                         if ( $currentRev->getId() == $baseRev->getId() ) {
  77                                 // Base revision was still the latest; nothing to merge
  78                                 $content = $editContent;
  79                         } else {
  80                                 // Merge the edit into the current version
  81                                 $baseContent = $baseRev->getContent();
  82                                 $currentContent = $currentRev->getContent();
  83                                 if ( !$baseContent || !$currentContent ) {
  84                                         $this->dieUsage( "Missing content for page ID {$page->getId()}", 'missingrev' );
  85                                 }
  86                                 $handler = ContentHandler::getForModelID( $baseContent->getModel() );
  87                                 $content = $handler->merge3( $baseContent, $editContent, $currentContent );
  88                         }
  89                 } else {
  90                         // New pages: use the user-provided content model
  91                         $content = $textContent;
  92                 }
  93
  94                 if ( !$content ) { // merge3() failed
  95                         $this->getResult()->addValue( null,
  96                                 $this->getModuleName(), array( 'status' => 'editconflict' ) );
  97                         return;
  98                 }
  99
 100                 // The user will abort the AJAX request by pressing "save", so ignore that
 101                 ignore_user_abort( true );
 102
 103                 // Get a key based on the source text, format, and user preferences
 104                 $key = self::getStashKey( $title, $content, $user );
 105                 // De-duplicate requests on the same key
 106                 if ( $user->pingLimiter( 'stashedit' ) ) {
 107                         $editInfo = false;
 108                         $status = 'ratelimited';
 109                 } elseif ( $wgMemc->lock( $key, 0, 30 ) ) {
 110                         $contentFormat = $content->getDefaultFormat();
 111                         $editInfo = $page->prepareContentForEdit( $content, null, $user, $contentFormat );
 112                         $wgMemc->unlock( $key );
 113                         $status = 'error'; // default
 114                 } else {
 115                         $editInfo = false;
 116                         $status = 'busy';
 117                 }
 118
 119                 if ( $editInfo && $editInfo->output ) {
 120                         $parserOutput = $editInfo->output;
 121                         // If an item is renewed, mind the cache TTL determined by config and parser functions
 122                         $since = time() - wfTimestamp( TS_UNIX, $parserOutput->getTimestamp() );
 123                         $ttl = min( $parserOutput->getCacheExpiry() - $since, 5 * 60 );
 124                         if ( $ttl > 0 && !$parserOutput->getFlag( 'vary-revision' ) ) {
 125                                 // Only store what is actually needed
 126                                 $stashInfo = (object)array(
 127                                         'pstContent' => $editInfo->pstContent,
 128                                         'output' => $editInfo->output,
 129                                         'timestamp' => $editInfo->timestamp
 130                                 );
 131                                 $ok = $wgMemc->set( $key, $stashInfo, $ttl );
 132                                 if ( $ok ) {
 133                                         $status = 'stashed';
 134                                         wfDebugLog( 'StashEdit', "Cached parser output for key '$key'." );
 135                                 } else {
 136                                         $status = 'error';
 137                                         wfDebugLog( 'StashEdit', "Failed to cache parser output for key '$key'." );
 138                                 }
 139                         } else {
 140                                 $status = 'uncacheable';
 141                                 wfDebugLog( 'StashEdit', "Uncacheable parser output for key '$key'." );
 142                         }
 143                 }
 144
 145                 $this->getResult()->addValue( null, $this->getModuleName(), array( 'status' => $status ) );
 146         }
 147
 148         /**
 149          * Get the temporary prepared edit stash key for a user
 150          *
 151          * @param Title $title
 152          * @param Content $content
 153          * @param User $user User to get parser options from
 154          * @return string
 155          */
 156         protected static function getStashKey(
 157                 Title $title, Content $content, User $user
 158         ) {
 159                 return wfMemcKey( 'prepared-edit',
 160                         md5( $title->getPrefixedDBkey() ), // handle rename races
 161                         $content->getModel(),
 162                         $content->getDefaultFormat(),
 163                         sha1( $content->serialize( $content->getDefaultFormat() ) ),
 164                         $user->getId() ?: md5( $user->getName() ), // account for user parser options
 165                         $user->getId() ? $user->getTouched() : '-' // handle preference change races
 166                 );
 167         }
 168
 169         /**
 170          * Check that a prepared edit is in cache and still up-to-date
 171          *
 172          * This method blocks if the prepared edit is already being rendered,
 173          * waiting until rendering finishes before doing final validity checks.
 174          *
 175          * The cache is rejected if template or file changes are detected.
 176          * Note that foreign template or file transclusions are not checked.
 177          *
 178          * The result is a map (pstContent,output,timestamp) with fields
 179          * extracted directly from WikiPage::prepareContentForEdit().
 180          *
 181          * @param Title $title
 182          * @param Content $content
 183          * @param User $user User to get parser options from
 184          * @return stdClass|bool Returns false on cache miss
 185          */
 186         public static function checkCache( Title $title, Content $content, User $user ) {
 187                 global $wgMemc;
 188
 189                 $key = self::getStashKey( $title, $content, $user );
 190                 $editInfo = $wgMemc->get( $key );
 191                 if ( !is_object( $editInfo ) ) {
 192                         $start = microtime( true );
 193                         // We ignore user aborts and keep parsing. Block on any prior parsing
 194                         // so as to use it's results and make use of the time spent parsing.
 195                         if ( $wgMemc->lock( $key, 30, 30 ) ) {
 196                                 $editInfo = $wgMemc->get( $key );
 197                                 $wgMemc->unlock( $key );
 198                                 $sec = microtime( true ) - $start;
 199                                 wfDebugLog( 'StashEdit', "Waited $sec seconds on '$key'." );
 200                         }
 201                 }
 202
 203                 if ( !is_object( $editInfo ) || !$editInfo->output ) {
 204                         return false;
 205                 }
 206
 207                 $time = wfTimestamp( TS_UNIX, $editInfo->output->getTimestamp() );
 208                 if ( ( time() - $time ) <= 3 ) {
 209                         wfDebugLog( 'StashEdit', "Timestamp-based cache hit for key '$key'." );
 210                         return $editInfo; // assume nothing changed
 211                 }
 212
 213                 $dbr = wfGetDB( DB_SLAVE );
 214                 // Check that no templates used in the output changed...
 215                 $cWhr = array(); // conditions to find changes/creations
 216                 $dWhr = array(); // conditions to find deletions
 217                 foreach ( $editInfo->output->getTemplateIds() as $ns => $stuff ) {
 218                         foreach ( $stuff as $dbkey => $revId ) {
 219                                 $cWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey,
 220                                         'page_latest != ' . intval( $revId ) );
 221                                 $dWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey );
 222                         }
 223                 }
 224                 $change = $dbr->selectField( 'page', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
 225                 $n = $dbr->selectField( 'page', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
 226                 if ( $change || $n != count( $dWhr ) ) {
 227                         wfDebugLog( 'StashEdit', "Stale cache for key '$key'; template changed." );
 228                         return false;
 229                 }
 230
 231                 // Check that no files used in the output changed...
 232                 $cWhr = array(); // conditions to find changes/creations
 233                 $dWhr = array(); // conditions to find deletions
 234                 foreach ( $editInfo->output->getFileSearchOptions() as $name => $options ) {
 235                         $cWhr[] = array( 'img_name' => $dbkey,
 236                                 'img_sha1 != ' . $dbr->addQuotes( strval( $options['sha1'] ) ) );
 237                         $dWhr[] = array( 'img_name' => $dbkey );
 238                 }
 239                 $change = $dbr->selectField( 'image', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
 240                 $n = $dbr->selectField( 'image', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
 241                 if ( $change || $n != count( $dWhr ) ) {
 242                         wfDebugLog( 'StashEdit', "Stale cache for key '$key'; file changed." );
 243                         return false;
 244                 }
 245
 246                 wfDebugLog( 'StashEdit', "Cache hit for key '$key'." );
 247
 248                 return $editInfo;
 249         }
 250
 251         public function getAllowedParams() {
 252                 return array(
 253                         'title' => array(
 254                                 ApiBase::PARAM_TYPE => 'string',
 255                                 ApiBase::PARAM_REQUIRED => true
 256                         ),
 257                         'section' => array(
 258                                 ApiBase::PARAM_TYPE => 'string',
 259                         ),
 260                         'sectiontitle' => array(
 261                                 ApiBase::PARAM_TYPE => 'string'
 262                         ),
 263                         'text' => array(
 264                                 ApiBase::PARAM_TYPE => 'string',
 265                                 ApiBase::PARAM_REQUIRED => true
 266                         ),
 267                         'contentmodel' => array(
 268                                 ApiBase::PARAM_TYPE => ContentHandler::getContentModels(),
 269                                 ApiBase::PARAM_REQUIRED => true
 270                         ),
 271                         'contentformat' => array(
 272                                 ApiBase::PARAM_TYPE => ContentHandler::getAllContentFormats(),
 273                                 ApiBase::PARAM_REQUIRED => true
 274                         ),
 275                         'baserevid' => array(
 276                                 ApiBase::PARAM_TYPE => 'integer',
 277                                 ApiBase::PARAM_REQUIRED => true
 278                         )
 279                 );
 280         }
 281
 282         function needsToken() {
 283                 return 'csrf';
 284         }
 285
 286         function mustBePosted() {
 287                 return true;
 288         }
 289
 290         function isInternal() {
 291                 return true;
 292         }
 293 }