includes/Revision.php

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