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                                'rev_len' ),
 243                         $conditions,
 244                         'Revision::fetchRow',
 245                         array( 'LIMIT' => 1 ) );
 246                 $ret = $db->resultObject( $res );
 247                 return $ret;
 248         }
 249
 250         /**
 251          * Return the list of revision fields that should be selected to create
 252          * a new revision.
 253          */
 254         static function selectFields() {
 255                 return array(
 256                         'rev_id',
 257                         'rev_page',
 258                         'rev_text_id',
 259                         'rev_timestamp',
 260                         'rev_comment',
 261                         'rev_minor_edit',
 262                         'rev_user',
 263                         'rev_user_text,'.
 264                         'rev_deleted',
 265                         'rev_len'
 266                 );
 267         }
 268
 269         /**
 270          * @param object $row
 271          * @access private
 272          */
 273         function Revision( $row ) {
 274                 if( is_object( $row ) ) {
 275                         $this->mId        = intval( $row->rev_id );
 276                         $this->mPage      = intval( $row->rev_page );
 277                         $this->mTextId    = intval( $row->rev_text_id );
 278                         $this->mComment   =         $row->rev_comment;
 279                         $this->mUserText  =         $row->rev_user_text;
 280                         $this->mUser      = intval( $row->rev_user );
 281                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 282                         $this->mTimestamp =         $row->rev_timestamp;
 283                         $this->mDeleted   = intval( $row->rev_deleted );
 284
 285                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) )
 286                                 $this->mSize = null;
 287                         else
 288                                 $this->mSize = intval( $row->rev_len );
 289
 290                         if( isset( $row->page_latest ) ) {
 291                                 $this->mCurrent   = ( $row->rev_id == $row->page_latest );
 292                                 $this->mTitle     = Title::makeTitle( $row->page_namespace,
 293                                                                       $row->page_title );
 294                         } else {
 295                                 $this->mCurrent = false;
 296                                 $this->mTitle = null;
 297                         }
 298
 299                         // Lazy extraction...
 300                         $this->mText      = null;
 301                         if( isset( $row->old_text ) ) {
 302                                 $this->mTextRow = $row;
 303                         } else {
 304                                 // 'text' table row entry will be lazy-loaded
 305                                 $this->mTextRow = null;
 306                         }
 307                 } elseif( is_array( $row ) ) {
 308                         // Build a new revision to be saved...
 309                         global $wgUser;
 310
 311                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 312                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 313                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 314                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 315                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 316                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 317                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 318                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 319                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 320
 321                         // Enforce spacing trimming on supplied text
 322                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 323                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 324                         $this->mTextRow   = null;
 325
 326                         $this->mTitle     = null; # Load on demand if needed
 327                         $this->mCurrent   = false;
 328                         # If we still have no len_size, see it we have the text to figure it out
 329                         if ( !$this->mSize )
 330                                 $this->mSize      = is_null($this->mText) ? null : strlen($this->mText);
 331                 } else {
 332                         throw new MWException( 'Revision constructor passed invalid row format.' );
 333                 }
 334         }
 335
 336         /**#@+
 337          * @access public
 338          */
 339
 340         /**
 341          * @return int
 342          */
 343         function getId() {
 344                 return $this->mId;
 345         }
 346
 347         /**
 348          * @return int
 349          */
 350         function getTextId() {
 351                 return $this->mTextId;
 352         }
 353
 354         /**
 355          * Returns the length of the text in this revision, or null if unknown.
 356          */
 357         function getSize() {
 358                 return $this->mSize;
 359         }
 360
 361         /**
 362          * Returns the title of the page associated with this entry.
 363          * @return Title
 364          */
 365         function getTitle() {
 366                 if( isset( $this->mTitle ) ) {
 367                         return $this->mTitle;
 368                 }
 369                 $dbr = wfGetDB( DB_SLAVE );
 370                 $row = $dbr->selectRow(
 371                         array( 'page', 'revision' ),
 372                         array( 'page_namespace', 'page_title' ),
 373                         array( 'page_id=rev_page',
 374                                'rev_id' => $this->mId ),
 375                         'Revision::getTitle' );
 376                 if( $row ) {
 377                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 378                                                            $row->page_title );
 379                 }
 380                 return $this->mTitle;
 381         }
 382
 383         /**
 384          * Set the title of the revision
 385          * @param Title $title
 386          */
 387         function setTitle( $title ) {
 388                 $this->mTitle = $title;
 389         }
 390
 391         /**
 392          * @return int
 393          */
 394         function getPage() {
 395                 return $this->mPage;
 396         }
 397
 398         /**
 399          * Fetch revision's user id if it's available to all users
 400          * @return int
 401          */
 402         function getUser() {
 403                 if( $this->isDeleted( self::DELETED_USER ) ) {
 404                         return 0;
 405                 } else {
 406                         return $this->mUser;
 407                 }
 408         }
 409
 410         /**
 411          * Fetch revision's user id without regard for the current user's permissions
 412          * @return string
 413          */
 414         function getRawUser() {
 415                 return $this->mUser;
 416         }
 417
 418         /**
 419          * Fetch revision's username if it's available to all users
 420          * @return string
 421          */
 422         function getUserText() {
 423                 if( $this->isDeleted( self::DELETED_USER ) ) {
 424                         return "";
 425                 } else {
 426                         return $this->mUserText;
 427                 }
 428         }
 429
 430         /**
 431          * Fetch revision's username without regard for view restrictions
 432          * @return string
 433          */
 434         function getRawUserText() {
 435                 return $this->mUserText;
 436         }
 437
 438         /**
 439          * Fetch revision comment if it's available to all users
 440          * @return string
 441          */
 442         function getComment() {
 443                 if( $this->isDeleted( self::DELETED_COMMENT ) ) {
 444                         return "";
 445                 } else {
 446                         return $this->mComment;
 447                 }
 448         }
 449
 450         /**
 451          * Fetch revision comment without regard for the current user's permissions
 452          * @return string
 453          */
 454         function getRawComment() {
 455                 return $this->mComment;
 456         }
 457
 458         /**
 459          * @return bool
 460          */
 461         function isMinor() {
 462                 return (bool)$this->mMinorEdit;
 463         }
 464
 465         /**
 466          * int $field one of DELETED_* bitfield constants
 467          * @return bool
 468          */
 469         function isDeleted( $field ) {
 470                 return ($this->mDeleted & $field) == $field;
 471         }
 472
 473         /**
 474          * Fetch revision text if it's available to all users
 475          * @return string
 476          */
 477         function getText() {
 478                 if( $this->isDeleted( self::DELETED_TEXT ) ) {
 479                         return "";
 480                 } else {
 481                         return $this->getRawText();
 482                 }
 483         }
 484
 485         /**
 486          * Fetch revision text without regard for view restrictions
 487          * @return string
 488          */
 489         function getRawText() {
 490                 if( is_null( $this->mText ) ) {
 491                         // Revision text is immutable. Load on demand:
 492                         $this->mText = $this->loadText();
 493                 }
 494                 return $this->mText;
 495         }
 496
 497         /**
 498          * Fetch revision text if it's available to THIS user
 499          * @return string
 500          */
 501         function revText() {
 502                 if( !$this->userCan( self::DELETED_TEXT ) ) {
 503                         return "";
 504                 } else {
 505                         return $this->getRawText();
 506                 }
 507         }
 508
 509         /**
 510          * @return string
 511          */
 512         function getTimestamp() {
 513                 return wfTimestamp(TS_MW, $this->mTimestamp);
 514         }
 515
 516         /**
 517          * @return bool
 518          */
 519         function isCurrent() {
 520                 return $this->mCurrent;
 521         }
 522
 523         /**
 524          * @return Revision
 525          */
 526         function getPrevious() {
 527                 $prev = $this->mTitle->getPreviousRevisionID( $this->mId );
 528                 if ( $prev ) {
 529                         return Revision::newFromTitle( $this->mTitle, $prev );
 530                 } else {
 531                         return null;
 532                 }
 533         }
 534
 535         /**
 536          * @return Revision
 537          */
 538         function getNext() {
 539                 $next = $this->mTitle->getNextRevisionID( $this->mId );
 540                 if ( $next ) {
 541                         return Revision::newFromTitle( $this->mTitle, $next );
 542                 } else {
 543                         return null;
 544                 }
 545         }
 546         /**#@-*/
 547
 548         /**
 549           * Get revision text associated with an old or archive row
 550           * $row is usually an object from wfFetchRow(), both the flags and the text
 551           * field must be included
 552           *
 553           * @param integer $row Id of a row
 554           * @param string $prefix table prefix (default 'old_')
 555           * @return string $text|false the text requested
 556           */
 557         public static function getRevisionText( $row, $prefix = 'old_' ) {
 558                 wfProfileIn( __METHOD__ );
 559
 560                 # Get data
 561                 $textField = $prefix . 'text';
 562                 $flagsField = $prefix . 'flags';
 563
 564                 if( isset( $row->$flagsField ) ) {
 565                         $flags = explode( ',', $row->$flagsField );
 566                 } else {
 567                         $flags = array();
 568                 }
 569
 570                 if( isset( $row->$textField ) ) {
 571                         $text = $row->$textField;
 572                 } else {
 573                         wfProfileOut( __METHOD__ );
 574                         return false;
 575                 }
 576
 577                 # Use external methods for external objects, text in table is URL-only then
 578                 if ( in_array( 'external', $flags ) ) {
 579                         $url=$text;
 580                         @list(/* $proto */,$path)=explode('://',$url,2);
 581                         if ($path=="") {
 582                                 wfProfileOut( __METHOD__ );
 583                                 return false;
 584                         }
 585                         $text=ExternalStore::fetchFromURL($url);
 586                 }
 587
 588                 // If the text was fetched without an error, convert it
 589                 if ( $text !== false ) {
 590                         if( in_array( 'gzip', $flags ) ) {
 591                                 # Deal with optional compression of archived pages.
 592                                 # This can be done periodically via maintenance/compressOld.php, and
 593                                 # as pages are saved if $wgCompressRevisions is set.
 594                                 $text = gzinflate( $text );
 595                         }
 596
 597                         if( in_array( 'object', $flags ) ) {
 598                                 # Generic compressed storage
 599                                 $obj = unserialize( $text );
 600                                 if ( !is_object( $obj ) ) {
 601                                         // Invalid object
 602                                         wfProfileOut( __METHOD__ );
 603                                         return false;
 604                                 }
 605                                 $text = $obj->getText();
 606                         }
 607
 608                         global $wgLegacyEncoding;
 609                         if( $wgLegacyEncoding && !in_array( 'utf-8', $flags ) ) {
 610                                 # Old revisions kept around in a legacy encoding?
 611                                 # Upconvert on demand.
 612                                 global $wgInputEncoding, $wgContLang;
 613                                 $text = $wgContLang->iconv( $wgLegacyEncoding, $wgInputEncoding, $text );
 614                         }
 615                 }
 616                 wfProfileOut( __METHOD__ );
 617                 return $text;
 618         }
 619
 620         /**
 621          * If $wgCompressRevisions is enabled, we will compress data.
 622          * The input string is modified in place.
 623          * Return value is the flags field: contains 'gzip' if the
 624          * data is compressed, and 'utf-8' if we're saving in UTF-8
 625          * mode.
 626          *
 627          * @param mixed $text reference to a text
 628          * @return string
 629          */
 630         static function compressRevisionText( &$text ) {
 631                 global $wgCompressRevisions;
 632                 $flags = array();
 633
 634                 # Revisions not marked this way will be converted
 635                 # on load if $wgLegacyCharset is set in the future.
 636                 $flags[] = 'utf-8';
 637
 638                 if( $wgCompressRevisions ) {
 639                         if( function_exists( 'gzdeflate' ) ) {
 640                                 $text = gzdeflate( $text );
 641                                 $flags[] = 'gzip';
 642                         } else {
 643                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 644                         }
 645                 }
 646                 return implode( ',', $flags );
 647         }
 648
 649         /**
 650          * Insert a new revision into the database, returning the new revision ID
 651          * number on success and dies horribly on failure.
 652          *
 653          * @param Database $dbw
 654          * @return int
 655          */
 656         function insertOn( &$dbw ) {
 657                 global $wgDefaultExternalStore;
 658
 659                 wfProfileIn( __METHOD__ );
 660
 661                 $data = $this->mText;
 662                 $flags = Revision::compressRevisionText( $data );
 663
 664                 # Write to external storage if required
 665                 if ( $wgDefaultExternalStore ) {
 666                         if ( is_array( $wgDefaultExternalStore ) ) {
 667                                 // Distribute storage across multiple clusters
 668                                 $store = $wgDefaultExternalStore[mt_rand(0, count( $wgDefaultExternalStore ) - 1)];
 669                         } else {
 670                                 $store = $wgDefaultExternalStore;
 671                         }
 672                         // Store and get the URL
 673                         $data = ExternalStore::insert( $store, $data );
 674                         if ( !$data ) {
 675                                 # This should only happen in the case of a configuration error, where the external store is not valid
 676                                 throw new MWException( "Unable to store text to external storage $store" );
 677                         }
 678                         if ( $flags ) {
 679                                 $flags .= ',';
 680                         }
 681                         $flags .= 'external';
 682                 }
 683
 684                 # Record the text (or external storage URL) to the text table
 685                 if( !isset( $this->mTextId ) ) {
 686                         $old_id = $dbw->nextSequenceValue( 'text_old_id_val' );
 687                         $dbw->insert( 'text',
 688                                 array(
 689                                         'old_id'    => $old_id,
 690                                         'old_text'  => $data,
 691                                         'old_flags' => $flags,
 692                                 ), __METHOD__
 693                         );
 694                         $this->mTextId = $dbw->insertId();
 695                 }
 696
 697                 # Record the edit in revisions
 698                 $rev_id = isset( $this->mId )
 699                         ? $this->mId
 700                         : $dbw->nextSequenceValue( 'rev_rev_id_val' );
 701                 $dbw->insert( 'revision',
 702                         array(
 703                                 'rev_id'         => $rev_id,
 704                                 'rev_page'       => $this->mPage,
 705                                 'rev_text_id'    => $this->mTextId,
 706                                 'rev_comment'    => $this->mComment,
 707                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 708                                 'rev_user'       => $this->mUser,
 709                                 'rev_user_text'  => $this->mUserText,
 710                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 711                                 'rev_deleted'    => $this->mDeleted,
 712                                 'rev_len'            => $this->mSize,
 713                         ), __METHOD__
 714                 );
 715
 716                 $this->mId = !is_null($rev_id) ? $rev_id : $dbw->insertId();
 717                 wfProfileOut( __METHOD__ );
 718                 return $this->mId;
 719         }
 720
 721         /**
 722          * Lazy-load the revision's text.
 723          * Currently hardcoded to the 'text' table storage engine.
 724          *
 725          * @return string
 726          * @access private
 727          */
 728         function loadText() {
 729                 wfProfileIn( __METHOD__ );
 730
 731                 // Caching may be beneficial for massive use of external storage
 732                 global $wgRevisionCacheExpiry, $wgMemc;
 733                 $key = wfMemcKey( 'revisiontext', 'textid', $this->getTextId() );
 734                 if( $wgRevisionCacheExpiry ) {
 735                         $text = $wgMemc->get( $key );
 736                         if( is_string( $text ) ) {
 737                                 wfProfileOut( __METHOD__ );
 738                                 return $text;
 739                         }
 740                 }
 741
 742                 // If we kept data for lazy extraction, use it now...
 743                 if ( isset( $this->mTextRow ) ) {
 744                         $row = $this->mTextRow;
 745                         $this->mTextRow = null;
 746                 } else {
 747                         $row = null;
 748                 }
 749
 750                 if( !$row ) {
 751                         // Text data is immutable; check slaves first.
 752                         $dbr = wfGetDB( DB_SLAVE );
 753                         $row = $dbr->selectRow( 'text',
 754                                 array( 'old_text', 'old_flags' ),
 755                                 array( 'old_id' => $this->getTextId() ),
 756                                 __METHOD__ );
 757                 }
 758
 759                 if( !$row ) {
 760                         // Possible slave lag!
 761                         $dbw = wfGetDB( DB_MASTER );
 762                         $row = $dbw->selectRow( 'text',
 763                                 array( 'old_text', 'old_flags' ),
 764                                 array( 'old_id' => $this->getTextId() ),
 765                                 __METHOD__ );
 766                 }
 767
 768                 $text = self::getRevisionText( $row );
 769
 770                 if( $wgRevisionCacheExpiry ) {
 771                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 772                 }
 773
 774                 wfProfileOut( __METHOD__ );
 775
 776                 return $text;
 777         }
 778
 779         /**
 780          * Create a new null-revision for insertion into a page's
 781          * history. This will not re-save the text, but simply refer
 782          * to the text from the previous version.
 783          *
 784          * Such revisions can for instance identify page rename
 785          * operations and other such meta-modifications.
 786          *
 787          * @param Database $dbw
 788          * @param int      $pageId ID number of the page to read from
 789          * @param string   $summary
 790          * @param bool     $minor
 791          * @return Revision
 792          */
 793         public static function newNullRevision( &$dbw, $pageId, $summary, $minor ) {
 794                 wfProfileIn( __METHOD__ );
 795
 796                 $current = $dbw->selectRow(
 797                         array( 'page', 'revision' ),
 798                         array( 'page_latest', 'rev_text_id' ),
 799                         array(
 800                                 'page_id' => $pageId,
 801                                 'page_latest=rev_id',
 802                                 ),
 803                         __METHOD__ );
 804
 805                 if( $current ) {
 806                         $revision = new Revision( array(
 807                                 'page'       => $pageId,
 808                                 'comment'    => $summary,
 809                                 'minor_edit' => $minor,
 810                                 'text_id'    => $current->rev_text_id,
 811                                 ) );
 812                 } else {
 813                         $revision = null;
 814                 }
 815
 816                 wfProfileOut( __METHOD__ );
 817                 return $revision;
 818         }
 819
 820         /**
 821          * Determine if the current user is allowed to view a particular
 822          * field of this revision, if it's marked as deleted.
 823          * @param int $field one of self::DELETED_TEXT,
 824          *                          self::DELETED_COMMENT,
 825          *                          self::DELETED_USER
 826          * @return bool
 827          */
 828         function userCan( $field ) {
 829                 if( ( $this->mDeleted & $field ) == $field ) {
 830                         global $wgUser;
 831                         $permission = ( $this->mDeleted & self::DELETED_RESTRICTED ) == self::DELETED_RESTRICTED
 832                                 ? 'hiderevision'
 833                                 : 'deleterevision';
 834                         wfDebug( "Checking for $permission due to $field match on $this->mDeleted\n" );
 835                         return $wgUser->isAllowed( $permission );
 836                 } else {
 837                         return true;
 838                 }
 839         }
 840
 841
 842         /**
 843          * Get rev_timestamp from rev_id, without loading the rest of the row
 844          * @param integer $id
 845          */
 846         static function getTimestampFromID( $id ) {
 847                 $dbr = wfGetDB( DB_SLAVE );
 848                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp',
 849                         array( 'rev_id' => $id ), __METHOD__ );
 850                 if ( $timestamp === false ) {
 851                         # Not in slave, try master
 852                         $dbw = wfGetDB( DB_MASTER );
 853                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp',
 854                                 array( 'rev_id' => $id ), __METHOD__ );
 855                 }
 856                 return $timestamp;
 857         }
 858
 859         static function countByPageId( $db, $id ) {
 860                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
 861                         array( 'rev_page' => $id ), __METHOD__ );
 862                 if( $row ) {
 863                         return $row->revCount;
 864                 }
 865                 return 0;
 866         }
 867
 868         static function countByTitle( $db, $title ) {
 869                 $id = $title->getArticleId();
 870                 if( $id ) {
 871                         return Revision::countByPageId( $db, $id );
 872                 }
 873                 return 0;
 874         }
 875 }
 876
 877 /**
 878  * Aliases for backwards compatibility with 1.6
 879  */
 880 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
 881 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
 882 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
 883 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );
 884
 885
 886