includes/Revision.php

   1 <?php
   2 /**
   3  * @todo document
   4  */
   5
   6 /**
   7  * @todo document
   8  */
   9 class Revision {
  10         const DELETED_TEXT      = 1;
  11         const DELETED_COMMENT   = 2;
  12         const DELETED_USER      = 4;
  13         const DELETED_RESTRICTED = 8;
  14
  15         /**
  16          * Load a page revision from a given revision ID number.
  17          * Returns null if no such revision can be found.
  18          *
  19          * @param int $id
  20          * @access public
  21          * @static
  22          */
  23         public static function newFromId( $id ) {
  24                 return Revision::newFromConds(
  25                         array( 'page_id=rev_page',
  26                                'rev_id' => intval( $id ) ) );
  27         }
  28
  29         /**
  30          * Load either the current, or a specified, revision
  31          * that's attached to a given title. If not attached
  32          * to that title, will return null.
  33          *
  34          * @param Title $title
  35          * @param int $id
  36          * @return Revision
  37          * @access public
  38          * @static
  39          */
  40         public static function newFromTitle( &$title, $id = 0 ) {
  41                 if( $id ) {
  42                         $matchId = intval( $id );
  43                 } else {
  44                         $matchId = 'page_latest';
  45                 }
  46                 return Revision::newFromConds(
  47                         array( "rev_id=$matchId",
  48                                'page_id=rev_page',
  49                                'page_namespace' => $title->getNamespace(),
  50                                'page_title'     => $title->getDbkey() ) );
  51         }
  52
  53         /**
  54          * Load a page revision from a given revision ID number.
  55          * Returns null if no such revision can be found.
  56          *
  57          * @param Database $db
  58          * @param int $id
  59          * @access public
  60          * @static
  61          */
  62         public static function loadFromId( &$db, $id ) {
  63                 return Revision::loadFromConds( $db,
  64                         array( 'page_id=rev_page',
  65                                'rev_id' => intval( $id ) ) );
  66         }
  67
  68         /**
  69          * Load either the current, or a specified, revision
  70          * that's attached to a given page. If not attached
  71          * to that page, will return null.
  72          *
  73          * @param Database $db
  74          * @param int $pageid
  75          * @param int $id
  76          * @return Revision
  77          * @access public
  78          * @static
  79          */
  80         public static function loadFromPageId( &$db, $pageid, $id = 0 ) {
  81                 $conds=array('page_id=rev_page','rev_page'=>intval( $pageid ), 'page_id'=>intval( $pageid ));
  82                 if( $id ) {
  83                         $conds['rev_id']=intval($id);
  84                 } else {
  85                         $conds[]='rev_id=page_latest';
  86                 }
  87                 return Revision::loadFromConds( $db, $conds );
  88         }
  89
  90         /**
  91          * Load either the current, or a specified, revision
  92          * that's attached to a given page. If not attached
  93          * to that page, will return null.
  94          *
  95          * @param Database $db
  96          * @param Title $title
  97          * @param int $id
  98          * @return Revision
  99          * @access public
 100          * @static
 101          */
 102         public static function loadFromTitle( &$db, $title, $id = 0 ) {
 103                 if( $id ) {
 104                         $matchId = intval( $id );
 105                 } else {
 106                         $matchId = 'page_latest';
 107                 }
 108                 return Revision::loadFromConds(
 109                         $db,
 110                         array( "rev_id=$matchId",
 111                                'page_id=rev_page',
 112                                'page_namespace' => $title->getNamespace(),
 113                                'page_title'     => $title->getDbkey() ) );
 114         }
 115
 116         /**
 117          * Load the revision for the given title with the given timestamp.
 118          * WARNING: Timestamps may in some circumstances not be unique,
 119          * so this isn't the best key to use.
 120          *
 121          * @param Database $db
 122          * @param Title $title
 123          * @param string $timestamp
 124          * @return Revision
 125          * @access public
 126          * @static
 127          */
 128         public static function loadFromTimestamp( &$db, &$title, $timestamp ) {
 129                 return Revision::loadFromConds(
 130                         $db,
 131                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 132                                'page_id=rev_page',
 133                                'page_namespace' => $title->getNamespace(),
 134                                'page_title'     => $title->getDbkey() ) );
 135         }
 136
 137         /**
 138          * Given a set of conditions, fetch a revision.
 139          *
 140          * @param array $conditions
 141          * @return Revision
 142          * @access private
 143          * @static
 144          */
 145         private static function newFromConds( $conditions ) {
 146                 $db =& wfGetDB( DB_SLAVE );
 147                 $row = Revision::loadFromConds( $db, $conditions );
 148                 if( is_null( $row ) ) {
 149                         $dbw =& wfGetDB( DB_MASTER );
 150                         $row = Revision::loadFromConds( $dbw, $conditions );
 151                 }
 152                 return $row;
 153         }
 154
 155         /**
 156          * Given a set of conditions, fetch a revision from
 157          * the given database connection.
 158          *
 159          * @param Database $db
 160          * @param array $conditions
 161          * @return Revision
 162          * @access private
 163          * @static
 164          */
 165         private static function loadFromConds( &$db, $conditions ) {
 166                 $res = Revision::fetchFromConds( $db, $conditions );
 167                 if( $res ) {
 168                         $row = $res->fetchObject();
 169                         $res->free();
 170                         if( $row ) {
 171                                 $ret = new Revision( $row );
 172                                 return $ret;
 173                         }
 174                 }
 175                 $ret = null;
 176                 return $ret;
 177         }
 178
 179         /**
 180          * Return a wrapper for a series of database rows to
 181          * fetch all of a given page's revisions in turn.
 182          * Each row can be fed to the constructor to get objects.
 183          *
 184          * @param Title $title
 185          * @return ResultWrapper
 186          * @access public
 187          * @static
 188          */
 189         public static function fetchAllRevisions( &$title ) {
 190                 return Revision::fetchFromConds(
 191                         wfGetDB( DB_SLAVE ),
 192                         array( 'page_namespace' => $title->getNamespace(),
 193                                'page_title'     => $title->getDbkey(),
 194                                'page_id=rev_page' ) );
 195         }
 196
 197         /**
 198          * Return a wrapper for a series of database rows to
 199          * fetch all of a given page's revisions in turn.
 200          * Each row can be fed to the constructor to get objects.
 201          *
 202          * @param Title $title
 203          * @return ResultWrapper
 204          * @access public
 205          * @static
 206          */
 207         public static function fetchRevision( &$title ) {
 208                 return Revision::fetchFromConds(
 209                         wfGetDB( DB_SLAVE ),
 210                         array( 'rev_id=page_latest',
 211                                'page_namespace' => $title->getNamespace(),
 212                                'page_title'     => $title->getDbkey(),
 213                                'page_id=rev_page' ) );
 214         }
 215
 216         /**
 217          * Given a set of conditions, return a ResultWrapper
 218          * which will return matching database rows with the
 219          * fields necessary to build Revision objects.
 220          *
 221          * @param Database $db
 222          * @param array $conditions
 223          * @return ResultWrapper
 224          * @access private
 225          * @static
 226          */
 227         private static function fetchFromConds( &$db, $conditions ) {
 228                 $res = $db->select(
 229                         array( 'page', 'revision' ),
 230                         array( 'page_namespace',
 231                                'page_title',
 232                                'page_latest',
 233                                'rev_id',
 234                                'rev_page',
 235                                'rev_text_id',
 236                                'rev_comment',
 237                                'rev_user_text',
 238                                'rev_user',
 239                                'rev_minor_edit',
 240                                'rev_timestamp',
 241                                'rev_deleted' ),
 242                         $conditions,
 243                         'Revision::fetchRow',
 244                         array( 'LIMIT' => 1 ) );
 245                 $ret = $db->resultObject( $res );
 246                 return $ret;
 247         }
 248
 249         /**
 250          * @param object $row
 251          * @access private
 252          */
 253         function Revision( $row ) {
 254                 if( is_object( $row ) ) {
 255                         $this->mId        = intval( $row->rev_id );
 256                         $this->mPage      = intval( $row->rev_page );
 257                         $this->mTextId    = intval( $row->rev_text_id );
 258                         $this->mComment   =         $row->rev_comment;
 259                         $this->mUserText  =         $row->rev_user_text;
 260                         $this->mUser      = intval( $row->rev_user );
 261                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 262                         $this->mTimestamp =         $row->rev_timestamp;
 263                         $this->mDeleted   = intval( $row->rev_deleted );
 264
 265                         if( isset( $row->page_latest ) ) {
 266                                 $this->mCurrent   = ( $row->rev_id == $row->page_latest );
 267                                 $this->mTitle     = Title::makeTitle( $row->page_namespace,
 268                                                                       $row->page_title );
 269                         } else {
 270                                 $this->mCurrent = false;
 271                                 $this->mTitle = null;
 272                         }
 273
 274                         // Lazy extraction...
 275                         $this->mText      = null;
 276                         if( isset( $row->old_text ) ) {
 277                                 $this->mTextRow = $row;
 278                         } else {
 279                                 // 'text' table row entry will be lazy-loaded
 280                                 $this->mTextRow = null;
 281                         }
 282                 } elseif( is_array( $row ) ) {
 283                         // Build a new revision to be saved...
 284                         global $wgUser;
 285
 286                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 287                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 288                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 289                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 290                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 291                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 292                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 293                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 294
 295                         // Enforce spacing trimming on supplied text
 296                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 297                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 298                         $this->mTextRow   = null;
 299
 300                         $this->mTitle     = null; # Load on demand if needed
 301                         $this->mCurrent   = false;
 302                 } else {
 303                         throw new MWException( 'Revision constructor passed invalid row format.' );
 304                 }
 305         }
 306
 307         /**#@+
 308          * @access public
 309          */
 310
 311         /**
 312          * @return int
 313          */
 314         function getId() {
 315                 return $this->mId;
 316         }
 317
 318         /**
 319          * @return int
 320          */
 321         function getTextId() {
 322                 return $this->mTextId;
 323         }
 324
 325         /**
 326          * Returns the title of the page associated with this entry.
 327          * @return Title
 328          */
 329         function getTitle() {
 330                 if( isset( $this->mTitle ) ) {
 331                         return $this->mTitle;
 332                 }
 333                 $dbr =& wfGetDB( DB_SLAVE );
 334                 $row = $dbr->selectRow(
 335                         array( 'page', 'revision' ),
 336                         array( 'page_namespace', 'page_title' ),
 337                         array( 'page_id=rev_page',
 338                                'rev_id' => $this->mId ),
 339                         'Revision::getTitle' );
 340                 if( $row ) {
 341                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 342                                                            $row->page_title );
 343                 }
 344                 return $this->mTitle;
 345         }
 346
 347         /**
 348          * Set the title of the revision
 349          * @param Title $title
 350          */
 351         function setTitle( $title ) {
 352                 $this->mTitle = $title;
 353         }
 354
 355         /**
 356          * @return int
 357          */
 358         function getPage() {
 359                 return $this->mPage;
 360         }
 361
 362         /**
 363          * Fetch revision's user id if it's available to all users
 364          * @return int
 365          */
 366         function getUser() {
 367                 if( $this->isDeleted( self::DELETED_USER ) ) {
 368                         return 0;
 369                 } else {
 370                         return $this->mUser;
 371                 }
 372         }
 373
 374         /**
 375          * Fetch revision's user id without regard for the current user's permissions
 376          * @return string
 377          */
 378         function getRawUser() {
 379                 return $this->mUser;
 380         }
 381
 382         /**
 383          * Fetch revision's username if it's available to all users
 384          * @return string
 385          */
 386         function getUserText() {
 387                 if( $this->isDeleted( self::DELETED_USER ) ) {
 388                         return "";
 389                 } else {
 390                         return $this->mUserText;
 391                 }
 392         }
 393
 394         /**
 395          * Fetch revision's username without regard for view restrictions
 396          * @return string
 397          */
 398         function getRawUserText() {
 399                 return $this->mUserText;
 400         }
 401
 402         /**
 403          * Fetch revision comment if it's available to all users
 404          * @return string
 405          */
 406         function getComment() {
 407                 if( $this->isDeleted( self::DELETED_COMMENT ) ) {
 408                         return "";
 409                 } else {
 410                         return $this->mComment;
 411                 }
 412         }
 413
 414         /**
 415          * Fetch revision comment without regard for the current user's permissions
 416          * @return string
 417          */
 418         function getRawComment() {
 419                 return $this->mComment;
 420         }
 421
 422         /**
 423          * @return bool
 424          */
 425         function isMinor() {
 426                 return (bool)$this->mMinorEdit;
 427         }
 428
 429         /**
 430          * int $field one of DELETED_* bitfield constants
 431          * @return bool
 432          */
 433         function isDeleted( $field ) {
 434                 return ($this->mDeleted & $field) == $field;
 435         }
 436
 437         /**
 438          * Fetch revision text if it's available to all users
 439          * @return string
 440          */
 441         function getText() {
 442                 if( $this->isDeleted( self::DELETED_TEXT ) ) {
 443                         return "";
 444                 } else {
 445                         return $this->getRawText();
 446                 }
 447         }
 448
 449         /**
 450          * Fetch revision text without regard for view restrictions
 451          * @return string
 452          */
 453         function getRawText() {
 454                 if( is_null( $this->mText ) ) {
 455                         // Revision text is immutable. Load on demand:
 456                         $this->mText = $this->loadText();
 457                 }
 458                 return $this->mText;
 459         }
 460
 461         /**
 462          * @return string
 463          */
 464         function getTimestamp() {
 465                 return wfTimestamp(TS_MW, $this->mTimestamp);
 466         }
 467
 468         /**
 469          * @return bool
 470          */
 471         function isCurrent() {
 472                 return $this->mCurrent;
 473         }
 474
 475         /**
 476          * @return Revision
 477          */
 478         function getPrevious() {
 479                 $prev = $this->mTitle->getPreviousRevisionID( $this->mId );
 480                 if ( $prev ) {
 481                         return Revision::newFromTitle( $this->mTitle, $prev );
 482                 } else {
 483                         return null;
 484                 }
 485         }
 486
 487         /**
 488          * @return Revision
 489          */
 490         function getNext() {
 491                 $next = $this->mTitle->getNextRevisionID( $this->mId );
 492                 if ( $next ) {
 493                         return Revision::newFromTitle( $this->mTitle, $next );
 494                 } else {
 495                         return null;
 496                 }
 497         }
 498         /**#@-*/
 499
 500         /**
 501           * Get revision text associated with an old or archive row
 502           * $row is usually an object from wfFetchRow(), both the flags and the text
 503           * field must be included
 504           * @static
 505           * @param integer $row Id of a row
 506           * @param string $prefix table prefix (default 'old_')
 507           * @return string $text|false the text requested
 508           */
 509         public static function getRevisionText( $row, $prefix = 'old_' ) {
 510                 $fname = 'Revision::getRevisionText';
 511                 wfProfileIn( $fname );
 512
 513                 # Get data
 514                 $textField = $prefix . 'text';
 515                 $flagsField = $prefix . 'flags';
 516
 517                 if( isset( $row->$flagsField ) ) {
 518                         $flags = explode( ',', $row->$flagsField );
 519                 } else {
 520                         $flags = array();
 521                 }
 522
 523                 if( isset( $row->$textField ) ) {
 524                         $text = $row->$textField;
 525                 } else {
 526                         wfProfileOut( $fname );
 527                         return false;
 528                 }
 529
 530                 # Use external methods for external objects, text in table is URL-only then
 531                 if ( in_array( 'external', $flags ) ) {
 532                         $url=$text;
 533                         @list(/* $proto */,$path)=explode('://',$url,2);
 534                         if ($path=="") {
 535                                 wfProfileOut( $fname );
 536                                 return false;
 537                         }
 538                         $text=ExternalStore::fetchFromURL($url);
 539                 }
 540
 541                 // If the text was fetched without an error, convert it
 542                 if ( $text !== false ) {
 543                         if( in_array( 'gzip', $flags ) ) {
 544                                 # Deal with optional compression of archived pages.
 545                                 # This can be done periodically via maintenance/compressOld.php, and
 546                                 # as pages are saved if $wgCompressRevisions is set.
 547                                 $text = gzinflate( $text );
 548                         }
 549
 550                         if( in_array( 'object', $flags ) ) {
 551                                 # Generic compressed storage
 552                                 $obj = unserialize( $text );
 553                                 if ( !is_object( $obj ) ) {
 554                                         // Invalid object
 555                                         wfProfileOut( $fname );
 556                                         return false;
 557                                 }
 558                                 $text = $obj->getText();
 559                         }
 560
 561                         global $wgLegacyEncoding;
 562                         if( $wgLegacyEncoding && !in_array( 'utf-8', $flags ) ) {
 563                                 # Old revisions kept around in a legacy encoding?
 564                                 # Upconvert on demand.
 565                                 global $wgInputEncoding, $wgContLang;
 566                                 $text = $wgContLang->iconv( $wgLegacyEncoding, $wgInputEncoding . '//IGNORE', $text );
 567                         }
 568                 }
 569                 wfProfileOut( $fname );
 570                 return $text;
 571         }
 572
 573         /**
 574          * If $wgCompressRevisions is enabled, we will compress data.
 575          * The input string is modified in place.
 576          * Return value is the flags field: contains 'gzip' if the
 577          * data is compressed, and 'utf-8' if we're saving in UTF-8
 578          * mode.
 579          *
 580          * @static
 581          * @param mixed $text reference to a text
 582          * @return string
 583          */
 584         function compressRevisionText( &$text ) {
 585                 global $wgCompressRevisions;
 586                 $flags = array();
 587
 588                 # Revisions not marked this way will be converted
 589                 # on load if $wgLegacyCharset is set in the future.
 590                 $flags[] = 'utf-8';
 591
 592                 if( $wgCompressRevisions ) {
 593                         if( function_exists( 'gzdeflate' ) ) {
 594                                 $text = gzdeflate( $text );
 595                                 $flags[] = 'gzip';
 596                         } else {
 597                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 598                         }
 599                 }
 600                 return implode( ',', $flags );
 601         }
 602
 603         /**
 604          * Insert a new revision into the database, returning the new revision ID
 605          * number on success and dies horribly on failure.
 606          *
 607          * @param Database $dbw
 608          * @return int
 609          */
 610         function insertOn( &$dbw ) {
 611                 global $wgDefaultExternalStore;
 612
 613                 $fname = 'Revision::insertOn';
 614                 wfProfileIn( $fname );
 615
 616                 $data = $this->mText;
 617                 $flags = Revision::compressRevisionText( $data );
 618
 619                 # Write to external storage if required
 620                 if ( $wgDefaultExternalStore ) {
 621                         if ( is_array( $wgDefaultExternalStore ) ) {
 622                                 // Distribute storage across multiple clusters
 623                                 $store = $wgDefaultExternalStore[mt_rand(0, count( $wgDefaultExternalStore ) - 1)];
 624                         } else {
 625                                 $store = $wgDefaultExternalStore;
 626                         }
 627                         // Store and get the URL
 628                         $data = ExternalStore::insert( $store, $data );
 629                         if ( !$data ) {
 630                                 # This should only happen in the case of a configuration error, where the external store is not valid
 631                                 throw new MWException( "Unable to store text to external storage $store" );
 632                         }
 633                         if ( $flags ) {
 634                                 $flags .= ',';
 635                         }
 636                         $flags .= 'external';
 637                 }
 638
 639                 # Record the text (or external storage URL) to the text table
 640                 if( !isset( $this->mTextId ) ) {
 641                         $old_id = $dbw->nextSequenceValue( 'text_old_id_val' );
 642                         $dbw->insert( 'text',
 643                                 array(
 644                                         'old_id'    => $old_id,
 645                                         'old_text'  => $data,
 646                                         'old_flags' => $flags,
 647                                 ), $fname
 648                         );
 649                         $this->mTextId = $dbw->insertId();
 650                 }
 651
 652                 # Record the edit in revisions
 653                 $rev_id = isset( $this->mId )
 654                         ? $this->mId
 655                         : $dbw->nextSequenceValue( 'rev_rev_id_val' );
 656                 $dbw->insert( 'revision',
 657                         array(
 658                                 'rev_id'         => $rev_id,
 659                                 'rev_page'       => $this->mPage,
 660                                 'rev_text_id'    => $this->mTextId,
 661                                 'rev_comment'    => $this->mComment,
 662                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 663                                 'rev_user'       => $this->mUser,
 664                                 'rev_user_text'  => $this->mUserText,
 665                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 666                                 'rev_deleted'    => $this->mDeleted,
 667                         ), $fname
 668                 );
 669
 670                 $this->mId = !is_null($rev_id) ? $rev_id : $dbw->insertId();
 671                 wfProfileOut( $fname );
 672                 return $this->mId;
 673         }
 674
 675         /**
 676          * Lazy-load the revision's text.
 677          * Currently hardcoded to the 'text' table storage engine.
 678          *
 679          * @return string
 680          * @access private
 681          */
 682         function loadText() {
 683                 $fname = 'Revision::loadText';
 684                 wfProfileIn( $fname );
 685
 686                 // Caching may be beneficial for massive use of external storage
 687                 global $wgRevisionCacheExpiry, $wgMemc;
 688                 $key = wfMemcKey( 'revisiontext', 'textid', $this->getTextId() );
 689                 if( $wgRevisionCacheExpiry ) {
 690                         $text = $wgMemc->get( $key );
 691                         if( is_string( $text ) ) {
 692                                 wfProfileOut( $fname );
 693                                 return $text;
 694                         }
 695                 }
 696
 697                 // If we kept data for lazy extraction, use it now...
 698                 if ( isset( $this->mTextRow ) ) {
 699                         $row = $this->mTextRow;
 700                         $this->mTextRow = null;
 701                 } else {
 702                         $row = null;
 703                 }
 704
 705                 if( !$row ) {
 706                         // Text data is immutable; check slaves first.
 707                         $dbr =& wfGetDB( DB_SLAVE );
 708                         $row = $dbr->selectRow( 'text',
 709                                 array( 'old_text', 'old_flags' ),
 710                                 array( 'old_id' => $this->getTextId() ),
 711                                 $fname);
 712                 }
 713
 714                 if( !$row ) {
 715                         // Possible slave lag!
 716                         $dbw =& wfGetDB( DB_MASTER );
 717                         $row = $dbw->selectRow( 'text',
 718                                 array( 'old_text', 'old_flags' ),
 719                                 array( 'old_id' => $this->getTextId() ),
 720                                 $fname);
 721                 }
 722
 723                 $text = Revision::getRevisionText( $row );
 724
 725                 if( $wgRevisionCacheExpiry ) {
 726                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 727                 }
 728
 729                 wfProfileOut( $fname );
 730
 731                 return $text;
 732         }
 733
 734         /**
 735          * Create a new null-revision for insertion into a page's
 736          * history. This will not re-save the text, but simply refer
 737          * to the text from the previous version.
 738          *
 739          * Such revisions can for instance identify page rename
 740          * operations and other such meta-modifications.
 741          *
 742          * @param Database $dbw
 743          * @param int      $pageId ID number of the page to read from
 744          * @param string   $summary
 745          * @param bool     $minor
 746          * @return Revision
 747          */
 748         function newNullRevision( &$dbw, $pageId, $summary, $minor ) {
 749                 $fname = 'Revision::newNullRevision';
 750                 wfProfileIn( $fname );
 751
 752                 $current = $dbw->selectRow(
 753                         array( 'page', 'revision' ),
 754                         array( 'page_latest', 'rev_text_id' ),
 755                         array(
 756                                 'page_id' => $pageId,
 757                                 'page_latest=rev_id',
 758                                 ),
 759                         $fname );
 760
 761                 if( $current ) {
 762                         $revision = new Revision( array(
 763                                 'page'       => $pageId,
 764                                 'comment'    => $summary,
 765                                 'minor_edit' => $minor,
 766                                 'text_id'    => $current->rev_text_id,
 767                                 ) );
 768                 } else {
 769                         $revision = null;
 770                 }
 771
 772                 wfProfileOut( $fname );
 773                 return $revision;
 774         }
 775
 776         /**
 777          * Determine if the current user is allowed to view a particular
 778          * field of this revision, if it's marked as deleted.
 779          * @param int $field one of self::DELETED_TEXT,
 780          *                          self::DELETED_COMMENT,
 781          *                          self::DELETED_USER
 782          * @return bool
 783          */
 784         function userCan( $field ) {
 785                 if( ( $this->mDeleted & $field ) == $field ) {
 786                         global $wgUser;
 787                         $permission = ( $this->mDeleted & self::DELETED_RESTRICTED ) == self::DELETED_RESTRICTED
 788                                 ? 'hiderevision'
 789                                 : 'deleterevision';
 790                         wfDebug( "Checking for $permission due to $field match on $this->mDeleted\n" );
 791                         return $wgUser->isAllowed( $permission );
 792                 } else {
 793                         return true;
 794                 }
 795         }
 796
 797
 798         /**
 799          * Get rev_timestamp from rev_id, without loading the rest of the row
 800          * @param integer $id
 801          */
 802         static function getTimestampFromID( $id ) {
 803                 $dbr =& wfGetDB( DB_SLAVE );
 804                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp',
 805                         array( 'rev_id' => $id ), __METHOD__ );
 806                 if ( $timestamp === false ) {
 807                         # Not in slave, try master
 808                         $dbw =& wfGetDB( DB_MASTER );
 809                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp',
 810                                 array( 'rev_id' => $id ), __METHOD__ );
 811                 }
 812                 return $timestamp;
 813         }
 814
 815         static function countByPageId( $db, $id ) {
 816                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
 817                         array( 'rev_page' => $id ), __METHOD__ );
 818                 if( $row ) {
 819                         return $row->revCount;
 820                 }
 821                 return 0;
 822         }
 823
 824         static function countByTitle( $db, $title ) {
 825                 $id = $title->getArticleId();
 826                 if( $id ) {
 827                         return Revision::countByPageId( $db, $id );
 828                 }
 829                 return 0;
 830         }
 831 }
 832
 833 /**
 834  * Aliases for backwards compatibility with 1.6
 835  */
 836 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
 837 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
 838 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
 839 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );
 840
 841
 842 ?>