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                 // Trim and fix newlines so the key SHA1's match (see RequestContext::getText())
  52                 $text = rtrim( str_replace( "\r\n", "\n", $params['text'] ) );
  53                 $textContent = ContentHandler::makeContent(
  54                         $text, $title, $params['contentmodel'], $params['contentformat'] );
  55
  56                 $page = WikiPage::factory( $title );
  57                 if ( $page->exists() ) {
  58                         // Page exists: get the merged content with the proposed change
  59                         $baseRev = Revision::newFromPageId( $page->getId(), $params['baserevid'] );
  60                         if ( !$baseRev ) {
  61                                 $this->dieUsage( "No revision ID {$params['baserevid']}", 'missingrev' );
  62                         }
  63                         $currentRev = $page->getRevision();
  64                         if ( !$currentRev ) {
  65                                 $this->dieUsage( "No current revision of page ID {$page->getId()}", 'missingrev' );
  66                         }
  67                         // Merge in the new version of the section to get the proposed version
  68                         $editContent = $page->replaceSectionAtRev(
  69                                 $params['section'],
  70                                 $textContent,
  71                                 $params['sectiontitle'],
  72                                 $baseRev->getId()
  73                         );
  74                         if ( !$editContent ) {
  75                                 $this->dieUsage( "Could not merge updated section.", 'replacefailed' );
  76                         }
  77                         if ( $currentRev->getId() == $baseRev->getId() ) {
  78                                 // Base revision was still the latest; nothing to merge
  79                                 $content = $editContent;
  80                         } else {
  81                                 // Merge the edit into the current version
  82                                 $baseContent = $baseRev->getContent();
  83                                 $currentContent = $currentRev->getContent();
  84                                 if ( !$baseContent || !$currentContent ) {
  85                                         $this->dieUsage( "Missing content for page ID {$page->getId()}", 'missingrev' );
  86                                 }
  87                                 $handler = ContentHandler::getForModelID( $baseContent->getModel() );
  88                                 $content = $handler->merge3( $baseContent, $editContent, $currentContent );
  89                         }
  90                 } else {
  91                         // New pages: use the user-provided content model
  92                         $content = $textContent;
  93                 }
  94
  95                 if ( !$content ) { // merge3() failed
  96                         $this->getResult()->addValue( null,
  97                                 $this->getModuleName(), array( 'status' => 'editconflict' ) );
  98                         return;
  99                 }
 100
 101                 // The user will abort the AJAX request by pressing "save", so ignore that
 102                 ignore_user_abort( true );
 103
 104                 // Get a key based on the source text, format, and user preferences
 105                 $key = self::getStashKey( $title, $content, $user );
 106                 // De-duplicate requests on the same key
 107                 if ( $user->pingLimiter( 'stashedit' ) ) {
 108                         $editInfo = false;
 109                         $status = 'ratelimited';
 110                 } elseif ( $wgMemc->lock( $key, 0, 30 ) ) {
 111                         $contentFormat = $content->getDefaultFormat();
 112                         $editInfo = $page->prepareContentForEdit( $content, null, $user, $contentFormat );
 113                         $status = 'error'; // default
 114                         $unlocker = new ScopedCallback( function() use ( $key ) {
 115                                 global $wgMemc;
 116                                 $wgMemc->unlock( $key );
 117                         } );
 118                 } else {
 119                         $editInfo = false;
 120                         $status = 'busy';
 121                 }
 122
 123                 if ( $editInfo && $editInfo->output ) {
 124                         $parserOutput = $editInfo->output;
 125                         // If an item is renewed, mind the cache TTL determined by config and parser functions
 126                         $since = time() - wfTimestamp( TS_UNIX, $parserOutput->getTimestamp() );
 127                         $ttl = min( $parserOutput->getCacheExpiry() - $since, 5 * 60 );
 128                         if ( $ttl > 0 && !$parserOutput->getFlag( 'vary-revision' ) ) {
 129                                 // Only store what is actually needed
 130                                 $stashInfo = (object)array(
 131                                         'pstContent' => $editInfo->pstContent,
 132                                         'output' => $editInfo->output,
 133                                         'timestamp' => $editInfo->timestamp
 134                                 );
 135                                 $ok = $wgMemc->set( $key, $stashInfo, $ttl );
 136                                 if ( $ok ) {
 137                                         $status = 'stashed';
 138                                         wfDebugLog( 'StashEdit', "Cached parser output for key '$key'." );
 139                                 } else {
 140                                         $status = 'error';
 141                                         wfDebugLog( 'StashEdit', "Failed to cache parser output for key '$key'." );
 142                                 }
 143                         } else {
 144                                 $status = 'uncacheable';
 145                                 wfDebugLog( 'StashEdit', "Uncacheable parser output for key '$key'." );
 146                         }
 147                 }
 148
 149                 $this->getResult()->addValue( null, $this->getModuleName(), array( 'status' => $status ) );
 150         }
 151
 152         /**
 153          * Get the temporary prepared edit stash key for a user
 154          *
 155          * @param Title $title
 156          * @param Content $content
 157          * @param User $user User to get parser options from
 158          * @return string
 159          */
 160         protected static function getStashKey(
 161                 Title $title, Content $content, User $user
 162         ) {
 163                 return wfMemcKey( 'prepared-edit',
 164                         md5( $title->getPrefixedDBkey() ), // handle rename races
 165                         $content->getModel(),
 166                         $content->getDefaultFormat(),
 167                         sha1( $content->serialize( $content->getDefaultFormat() ) ),
 168                         $user->getId() ?: md5( $user->getName() ), // account for user parser options
 169                         $user->getId() ? $user->getTouched() : '-' // handle preference change races
 170                 );
 171         }
 172
 173         /**
 174          * Check that a prepared edit is in cache and still up-to-date
 175          *
 176          * This method blocks if the prepared edit is already being rendered,
 177          * waiting until rendering finishes before doing final validity checks.
 178          *
 179          * The cache is rejected if template or file changes are detected.
 180          * Note that foreign template or file transclusions are not checked.
 181          *
 182          * The result is a map (pstContent,output,timestamp) with fields
 183          * extracted directly from WikiPage::prepareContentForEdit().
 184          *
 185          * @param Title $title
 186          * @param Content $content
 187          * @param User $user User to get parser options from
 188          * @return stdClass|bool Returns false on cache miss
 189          */
 190         public static function checkCache( Title $title, Content $content, User $user ) {
 191                 global $wgMemc;
 192
 193                 $key = self::getStashKey( $title, $content, $user );
 194                 $editInfo = $wgMemc->get( $key );
 195                 if ( !is_object( $editInfo ) ) {
 196                         $start = microtime( true );
 197                         // We ignore user aborts and keep parsing. Block on any prior parsing
 198                         // so as to use it's results and make use of the time spent parsing.
 199                         if ( $wgMemc->lock( $key, 30, 30 ) ) {
 200                                 $editInfo = $wgMemc->get( $key );
 201                                 $wgMemc->unlock( $key );
 202                         }
 203                         $sec = microtime( true ) - $start;
 204                         wfDebugLog( 'StashEdit', "Waited $sec seconds on '$key'." );
 205                 }
 206
 207                 if ( !is_object( $editInfo ) || !$editInfo->output ) {
 208                         wfDebugLog( 'StashEdit', "No cache value for key '$key'." );
 209                         return false;
 210                 }
 211
 212                 $time = wfTimestamp( TS_UNIX, $editInfo->output->getTimestamp() );
 213                 if ( ( time() - $time ) <= 3 ) {
 214                         wfDebugLog( 'StashEdit', "Timestamp-based cache hit for key '$key'." );
 215                         return $editInfo; // assume nothing changed
 216                 }
 217
 218                 $dbr = wfGetDB( DB_SLAVE );
 219                 // Check that no templates used in the output changed...
 220                 $cWhr = array(); // conditions to find changes/creations
 221                 $dWhr = array(); // conditions to find deletions
 222                 foreach ( $editInfo->output->getTemplateIds() as $ns => $stuff ) {
 223                         foreach ( $stuff as $dbkey => $revId ) {
 224                                 $cWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey,
 225                                         'page_latest != ' . intval( $revId ) );
 226                                 $dWhr[] = array( 'page_namespace' => $ns, 'page_title' => $dbkey );
 227                         }
 228                 }
 229                 $change = $dbr->selectField( 'page', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
 230                 $n = $dbr->selectField( 'page', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
 231                 if ( $change || $n != count( $dWhr ) ) {
 232                         wfDebugLog( 'StashEdit', "Stale cache for key '$key'; template changed." );
 233                         return false;
 234                 }
 235
 236                 // Check that no files used in the output changed...
 237                 $cWhr = array(); // conditions to find changes/creations
 238                 $dWhr = array(); // conditions to find deletions
 239                 foreach ( $editInfo->output->getFileSearchOptions() as $name => $options ) {
 240                         $cWhr[] = array( 'img_name' => $dbkey,
 241                                 'img_sha1 != ' . $dbr->addQuotes( strval( $options['sha1'] ) ) );
 242                         $dWhr[] = array( 'img_name' => $dbkey );
 243                 }
 244                 $change = $dbr->selectField( 'image', '1', $dbr->makeList( $cWhr, LIST_OR ), __METHOD__ );
 245                 $n = $dbr->selectField( 'image', 'COUNT(*)', $dbr->makeList( $dWhr, LIST_OR ), __METHOD__ );
 246                 if ( $change || $n != count( $dWhr ) ) {
 247                         wfDebugLog( 'StashEdit', "Stale cache for key '$key'; file changed." );
 248                         return false;
 249                 }
 250
 251                 wfDebugLog( 'StashEdit', "Cache hit for key '$key'." );
 252
 253                 return $editInfo;
 254         }
 255
 256         public function getAllowedParams() {
 257                 return array(
 258                         'title' => array(
 259                                 ApiBase::PARAM_TYPE => 'string',
 260                                 ApiBase::PARAM_REQUIRED => true
 261                         ),
 262                         'section' => array(
 263                                 ApiBase::PARAM_TYPE => 'string',
 264                         ),
 265                         'sectiontitle' => array(
 266                                 ApiBase::PARAM_TYPE => 'string'
 267                         ),
 268                         'text' => array(
 269                                 ApiBase::PARAM_TYPE => 'string',
 270                                 ApiBase::PARAM_REQUIRED => true
 271                         ),
 272                         'contentmodel' => array(
 273                                 ApiBase::PARAM_TYPE => ContentHandler::getContentModels(),
 274                                 ApiBase::PARAM_REQUIRED => true
 275                         ),
 276                         'contentformat' => array(
 277                                 ApiBase::PARAM_TYPE => ContentHandler::getAllContentFormats(),
 278                                 ApiBase::PARAM_REQUIRED => true
 279                         ),
 280                         'baserevid' => array(
 281                                 ApiBase::PARAM_TYPE => 'integer',
 282                                 ApiBase::PARAM_REQUIRED => true
 283                         )
 284                 );
 285         }
 286
 287         function needsToken() {
 288                 return 'csrf';
 289         }
 290
 291         function mustBePosted() {
 292                 return true;
 293         }
 294
 295         function isInternal() {
 296                 return true;
 297         }
 298 }