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     const DELETED_NAME = 16;
  15
  16         /**
  17          * Load a page revision from a given revision ID number.
  18          * Returns null if no such revision can be found.
  19          *
  20          * @param int $id
  21          * @access public
  22          * @static
  23          */
  24         public static function newFromId( $id ) {
  25                 return Revision::newFromConds(
  26                         array( 'page_id=rev_page',
  27                                'rev_id' => intval( $id ) ) );
  28         }
  29
  30         /**
  31          * Load either the current, or a specified, revision
  32          * that's attached to a given title. If not attached
  33          * to that title, will return null.
  34          *
  35          * @param Title $title
  36          * @param int $id
  37          * @return Revision
  38          * @access public
  39          * @static
  40          */
  41         public static function newFromTitle( &$title, $id = 0 ) {
  42                 if( $id ) {
  43                         $matchId = intval( $id );
  44                 } else {
  45                         $matchId = 'page_latest';
  46                 }
  47                 return Revision::newFromConds(
  48                         array( "rev_id=$matchId",
  49                                'page_id=rev_page',
  50                                'page_namespace' => $title->getNamespace(),
  51                                'page_title'     => $title->getDbkey() ) );
  52         }
  53
  54         /**
  55          * Load a page revision from a given revision ID number.
  56          * Returns null if no such revision can be found.
  57          *
  58          * @param Database $db
  59          * @param int $id
  60          * @access public
  61          * @static
  62          */
  63         public static function loadFromId( &$db, $id ) {
  64                 return Revision::loadFromConds( $db,
  65                         array( 'page_id=rev_page',
  66                                'rev_id' => intval( $id ) ) );
  67         }
  68
  69         /**
  70          * Load either the current, or a specified, revision
  71          * that's attached to a given page. If not attached
  72          * to that page, will return null.
  73          *
  74          * @param Database $db
  75          * @param int $pageid
  76          * @param int $id
  77          * @return Revision
  78          * @access public
  79          * @static
  80          */
  81         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
  82                 $conds=array('page_id=rev_page','rev_page'=>intval( $pageid ), 'page_id'=>intval( $pageid ));
  83                 if( $id ) {
  84                         $conds['rev_id']=intval($id);
  85                 } else {
  86                         $conds[]='rev_id=page_latest';
  87                 }
  88                 return Revision::loadFromConds( $db, $conds );
  89         }
  90
  91         /**
  92          * Load either the current, or a specified, revision
  93          * that's attached to a given page. If not attached
  94          * to that page, will return null.
  95          *
  96          * @param Database $db
  97          * @param Title $title
  98          * @param int $id
  99          * @return Revision
 100          * @access public
 101          * @static
 102          */
 103         public static function loadFromTitle( &$db, $title, $id = 0 ) {
 104                 if( $id ) {
 105                         $matchId = intval( $id );
 106                 } else {
 107                         $matchId = 'page_latest';
 108                 }
 109                 return Revision::loadFromConds(
 110                         $db,
 111                         array( "rev_id=$matchId",
 112                                'page_id=rev_page',
 113                                'page_namespace' => $title->getNamespace(),
 114                                'page_title'     => $title->getDbkey() ) );
 115         }
 116
 117         /**
 118          * Load the revision for the given title with the given timestamp.
 119          * WARNING: Timestamps may in some circumstances not be unique,
 120          * so this isn't the best key to use.
 121          *
 122          * @param Database $db
 123          * @param Title $title
 124          * @param string $timestamp
 125          * @return Revision
 126          * @access public
 127          * @static
 128          */
 129         public static function loadFromTimestamp( &$db, &$title, $timestamp ) {
 130                 return Revision::loadFromConds(
 131                         $db,
 132                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 133                                'page_id=rev_page',
 134                                'page_namespace' => $title->getNamespace(),
 135                                'page_title'     => $title->getDbkey() ) );
 136         }
 137
 138         /**
 139          * Given a set of conditions, fetch a revision.
 140          *
 141          * @param array $conditions
 142          * @return Revision
 143          * @access private
 144          * @static
 145          */
 146         private static function newFromConds( $conditions ) {
 147                 $db = wfGetDB( DB_SLAVE );
 148                 $row = Revision::loadFromConds( $db, $conditions );
 149                 if( is_null( $row ) ) {
 150                         $dbw = wfGetDB( DB_MASTER );
 151                         $row = Revision::loadFromConds( $dbw, $conditions );
 152                 }
 153                 return $row;
 154         }
 155
 156         /**
 157          * Given a set of conditions, fetch a revision from
 158          * the given database connection.
 159          *
 160          * @param Database $db
 161          * @param array $conditions
 162          * @return Revision
 163          * @access private
 164          * @static
 165          */
 166         private static function loadFromConds( $db, $conditions ) {
 167                 $res = Revision::fetchFromConds( $db, $conditions );
 168                 if( $res ) {
 169                         $row = $res->fetchObject();
 170                         $res->free();
 171                         if( $row ) {
 172                                 $ret = new Revision( $row );
 173                                 return $ret;
 174                         }
 175                 }
 176                 $ret = null;
 177                 return $ret;
 178         }
 179
 180         /**
 181          * Return a wrapper for a series of database rows to
 182          * fetch all of a given page's revisions in turn.
 183          * Each row can be fed to the constructor to get objects.
 184          *
 185          * @param Title $title
 186          * @return ResultWrapper
 187          * @access public
 188          * @static
 189          */
 190         public static function fetchAllRevisions( &$title ) {
 191                 return Revision::fetchFromConds(
 192                         wfGetDB( DB_SLAVE ),
 193                         array( 'page_namespace' => $title->getNamespace(),
 194                                'page_title'     => $title->getDbkey(),
 195                                'page_id=rev_page' ) );
 196         }
 197
 198         /**
 199          * Return a wrapper for a series of database rows to
 200          * fetch all of a given page's revisions in turn.
 201          * Each row can be fed to the constructor to get objects.
 202          *
 203          * @param Title $title
 204          * @return ResultWrapper
 205          * @access public
 206          * @static
 207          */
 208         public static function fetchRevision( &$title ) {
 209                 return Revision::fetchFromConds(
 210                         wfGetDB( DB_SLAVE ),
 211                         array( 'rev_id=page_latest',
 212                                'page_namespace' => $title->getNamespace(),
 213                                'page_title'     => $title->getDbkey(),
 214                                'page_id=rev_page' ) );
 215         }
 216
 217         /**
 218          * Given a set of conditions, return a ResultWrapper
 219          * which will return matching database rows with the
 220          * fields necessary to build Revision objects.
 221          *
 222          * @param Database $db
 223          * @param array $conditions
 224          * @return ResultWrapper
 225          * @access private
 226          * @static
 227          */
 228         private static function fetchFromConds( $db, $conditions ) {
 229                 $res = $db->select(
 230                         array( 'page', 'revision' ),
 231                         array( 'page_namespace',
 232                                'page_title',
 233                                'page_latest',
 234                                'rev_id',
 235                                'rev_page',
 236                                'rev_text_id',
 237                                'rev_comment',
 238                                'rev_user_text',
 239                                'rev_user',
 240                                'rev_minor_edit',
 241                                'rev_timestamp',
 242                                'rev_deleted',
 243                                'rev_len' ),
 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( $row->rev_deleted );
 266
 267                         if (is_null($row->rev_len))
 268                                 $this->mSize = null;
 269                         else
 270                                 $this->mSize = intval( $row->rev_len );
 271
 272                         if( isset( $row->page_latest ) ) {
 273                                 $this->mCurrent   = ( $row->rev_id == $row->page_latest );
 274                                 $this->mTitle     = Title::makeTitle( $row->page_namespace,
 275                                                                       $row->page_title );
 276                         } else {
 277                                 $this->mCurrent = false;
 278                                 $this->mTitle = null;
 279                         }
 280
 281                         // Lazy extraction...
 282                         $this->mText      = null;
 283                         if( isset( $row->old_text ) ) {
 284                                 $this->mTextRow = $row;
 285                         } else {
 286                                 // 'text' table row entry will be lazy-loaded
 287                                 $this->mTextRow = null;
 288                         }
 289                 } elseif( is_array( $row ) ) {
 290                         // Build a new revision to be saved...
 291                         global $wgUser;
 292
 293                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 294                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 295                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 296                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 297                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 298                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 299                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 300                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 301
 302                         // Enforce spacing trimming on supplied text
 303                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 304                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 305                         $this->mTextRow   = null;
 306
 307                         $this->mTitle     = null; # Load on demand if needed
 308                         $this->mCurrent   = false;
 309
 310                         $this->mSize      = is_null($this->mText) ? null : strlen($this->mText);
 311                 } else {
 312                         throw new MWException( 'Revision constructor passed invalid row format.' );
 313                 }
 314         }
 315
 316         /**#@+
 317          * @access public
 318          */
 319
 320         /**
 321          * @return int
 322          */
 323         function getId() {
 324                 return $this->mId;
 325         }
 326
 327         /**
 328          * @return int
 329          */
 330         function getTextId() {
 331                 return $this->mTextId;
 332         }
 333
 334         /**
 335          * Returns the length of the text in this revision, or null if unknown.
 336          */
 337         function getSize() {
 338                 return $this->mSize;
 339         }
 340
 341         /**
 342          * Returns the title of the page associated with this entry.
 343          * @return Title
 344          */
 345         function getTitle() {
 346                 if( isset( $this->mTitle ) ) {
 347                         return $this->mTitle;
 348                 }
 349                 $dbr = wfGetDB( DB_SLAVE );
 350                 $row = $dbr->selectRow(
 351                         array( 'page', 'revision' ),
 352                         array( 'page_namespace', 'page_title' ),
 353                         array( 'page_id=rev_page',
 354                                'rev_id' => $this->mId ),
 355                         'Revision::getTitle' );
 356                 if( $row ) {
 357                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 358                                                            $row->page_title );
 359                 }
 360                 return $this->mTitle;
 361         }
 362
 363         /**
 364          * Set the title of the revision
 365          * @param Title $title
 366          */
 367         function setTitle( $title ) {
 368                 $this->mTitle = $title;
 369         }
 370
 371         /**
 372          * @return int
 373          */
 374         function getPage() {
 375                 return $this->mPage;
 376         }
 377
 378         /**
 379          * Fetch revision's user id if it's available to all users
 380          * @return int
 381          */
 382         function getUser() {
 383                 if( $this->isDeleted( self::DELETED_USER ) ) {
 384                         return 0;
 385                 } else {
 386                         return $this->mUser;
 387                 }
 388         }
 389
 390         /**
 391          * Fetch revision's user id without regard for the current user's permissions
 392          * @return string
 393          */
 394         function getRawUser() {
 395                 return $this->mUser;
 396         }
 397
 398         /**
 399          * Fetch revision's username if it's available to all users
 400          * @return string
 401          */
 402         function getUserText() {
 403                 if( $this->isDeleted( self::DELETED_USER ) ) {
 404                         return "";
 405                 } else {
 406                         return $this->mUserText;
 407                 }
 408         }
 409
 410         /**
 411          * Fetch revision's username without regard for view restrictions
 412          * @return string
 413          */
 414         function getRawUserText() {
 415                 return $this->mUserText;
 416         }
 417
 418         /**
 419          * Fetch revision comment if it's available to all users
 420          * @return string
 421          */
 422         function getComment() {
 423                 if( $this->isDeleted( self::DELETED_COMMENT ) ) {
 424                         return "";
 425                 } else {
 426                         return $this->mComment;
 427                 }
 428         }
 429
 430         /**
 431          * Fetch revision comment without regard for the current user's permissions
 432          * @return string
 433          */
 434         function getRawComment() {
 435                 return $this->mComment;
 436         }
 437
 438         /**
 439          * @return bool
 440          */
 441         function isMinor() {
 442                 return (bool)$this->mMinorEdit;
 443         }
 444
 445         /**
 446          * int $field one of DELETED_* bitfield constants
 447          * @return bool
 448          */
 449         function isDeleted( $field ) {
 450                 return ($this->mDeleted & $field) == $field;
 451         }
 452
 453         /**
 454          * Fetch revision text if it's available to all users
 455          * @return string
 456          */
 457         function getText() {
 458                 if( $this->isDeleted( self::DELETED_TEXT ) ) {
 459                         return "";
 460                 } else {
 461                         return $this->getRawText();
 462                 }
 463         }
 464
 465         /**
 466          * Fetch revision text without regard for view restrictions
 467          * @return string
 468          */
 469         function getRawText() {
 470                 if( is_null( $this->mText ) ) {
 471                         // Revision text is immutable. Load on demand:
 472                         $this->mText = $this->loadText();
 473                 }
 474                 return $this->mText;
 475         }
 476
 477         /**
 478          * Fetch revision text if it's available to THIS user
 479          * @return string
 480          */
 481         function revText() {
 482                 if( !$this->userCan( self::DELETED_TEXT ) ) {
 483                         return "";
 484                 } else {
 485                         return $this->getRawText();
 486                 }
 487         }
 488
 489         /**
 490          * @return string
 491          */
 492         function getTimestamp() {
 493                 return wfTimestamp(TS_MW, $this->mTimestamp);
 494         }
 495
 496         /**
 497          * @return bool
 498          */
 499         function isCurrent() {
 500                 return $this->mCurrent;
 501         }
 502
 503         /**
 504          * @return Revision
 505          */
 506         function getPrevious() {
 507                 $prev = $this->mTitle->getPreviousRevisionID( $this->mId );
 508                 if ( $prev ) {
 509                         return Revision::newFromTitle( $this->mTitle, $prev );
 510                 } else {
 511                         return null;
 512                 }
 513         }
 514
 515         /**
 516          * @return Revision
 517          */
 518         function getNext() {
 519                 $next = $this->mTitle->getNextRevisionID( $this->mId );
 520                 if ( $next ) {
 521                         return Revision::newFromTitle( $this->mTitle, $next );
 522                 } else {
 523                         return null;
 524                 }
 525         }
 526         /**#@-*/
 527
 528         /**
 529           * Get revision text associated with an old or archive row
 530           * $row is usually an object from wfFetchRow(), both the flags and the text
 531           * field must be included
 532           * @static
 533           * @param integer $row Id of a row
 534           * @param string $prefix table prefix (default 'old_')
 535           * @return string $text|false the text requested
 536           */
 537         public static function getRevisionText( $row, $prefix = 'old_' ) {
 538                 $fname = 'Revision::getRevisionText';
 539                 wfProfileIn( $fname );
 540
 541                 # Get data
 542                 $textField = $prefix . 'text';
 543                 $flagsField = $prefix . 'flags';
 544
 545                 if( isset( $row->$flagsField ) ) {
 546                         $flags = explode( ',', $row->$flagsField );
 547                 } else {
 548                         $flags = array();
 549                 }
 550
 551                 if( isset( $row->$textField ) ) {
 552                         $text = $row->$textField;
 553                 } else {
 554                         wfProfileOut( $fname );
 555                         return false;
 556                 }
 557
 558                 # Use external methods for external objects, text in table is URL-only then
 559                 if ( in_array( 'external', $flags ) ) {
 560                         $url=$text;
 561                         @list(/* $proto */,$path)=explode('://',$url,2);
 562                         if ($path=="") {
 563                                 wfProfileOut( $fname );
 564                                 return false;
 565                         }
 566                         $text=ExternalStore::fetchFromURL($url);
 567                 }
 568
 569                 // If the text was fetched without an error, convert it
 570                 if ( $text !== false ) {
 571                         if( in_array( 'gzip', $flags ) ) {
 572                                 # Deal with optional compression of archived pages.
 573                                 # This can be done periodically via maintenance/compressOld.php, and
 574                                 # as pages are saved if $wgCompressRevisions is set.
 575                                 $text = gzinflate( $text );
 576                         }
 577
 578                         if( in_array( 'object', $flags ) ) {
 579                                 # Generic compressed storage
 580                                 $obj = unserialize( $text );
 581                                 if ( !is_object( $obj ) ) {
 582                                         // Invalid object
 583                                         wfProfileOut( $fname );
 584                                         return false;
 585                                 }
 586                                 $text = $obj->getText();
 587                         }
 588
 589                         global $wgLegacyEncoding;
 590                         if( $wgLegacyEncoding && !in_array( 'utf-8', $flags ) ) {
 591                                 # Old revisions kept around in a legacy encoding?
 592                                 # Upconvert on demand.
 593                                 global $wgInputEncoding, $wgContLang;
 594                                 $text = $wgContLang->iconv( $wgLegacyEncoding, $wgInputEncoding . '//IGNORE', $text );
 595                         }
 596                 }
 597                 wfProfileOut( $fname );
 598                 return $text;
 599         }
 600
 601         /**
 602          * If $wgCompressRevisions is enabled, we will compress data.
 603          * The input string is modified in place.
 604          * Return value is the flags field: contains 'gzip' if the
 605          * data is compressed, and 'utf-8' if we're saving in UTF-8
 606          * mode.
 607          *
 608          * @static
 609          * @param mixed $text reference to a text
 610          * @return string
 611          */
 612         function compressRevisionText( &$text ) {
 613                 global $wgCompressRevisions;
 614                 $flags = array();
 615
 616                 # Revisions not marked this way will be converted
 617                 # on load if $wgLegacyCharset is set in the future.
 618                 $flags[] = 'utf-8';
 619
 620                 if( $wgCompressRevisions ) {
 621                         if( function_exists( 'gzdeflate' ) ) {
 622                                 $text = gzdeflate( $text );
 623                                 $flags[] = 'gzip';
 624                         } else {
 625                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 626                         }
 627                 }
 628                 return implode( ',', $flags );
 629         }
 630
 631         /**
 632          * Insert a new revision into the database, returning the new revision ID
 633          * number on success and dies horribly on failure.
 634          *
 635          * @param Database $dbw
 636          * @return int
 637          */
 638         function insertOn( &$dbw ) {
 639                 global $wgDefaultExternalStore;
 640
 641                 $fname = 'Revision::insertOn';
 642                 wfProfileIn( $fname );
 643
 644                 $data = $this->mText;
 645                 $flags = Revision::compressRevisionText( $data );
 646
 647                 # Write to external storage if required
 648                 if ( $wgDefaultExternalStore ) {
 649                         if ( is_array( $wgDefaultExternalStore ) ) {
 650                                 // Distribute storage across multiple clusters
 651                                 $store = $wgDefaultExternalStore[mt_rand(0, count( $wgDefaultExternalStore ) - 1)];
 652                         } else {
 653                                 $store = $wgDefaultExternalStore;
 654                         }
 655                         // Store and get the URL
 656                         $data = ExternalStore::insert( $store, $data );
 657                         if ( !$data ) {
 658                                 # This should only happen in the case of a configuration error, where the external store is not valid
 659                                 throw new MWException( "Unable to store text to external storage $store" );
 660                         }
 661                         if ( $flags ) {
 662                                 $flags .= ',';
 663                         }
 664                         $flags .= 'external';
 665                 }
 666
 667                 # Record the text (or external storage URL) to the text table
 668                 if( !isset( $this->mTextId ) ) {
 669                         $old_id = $dbw->nextSequenceValue( 'text_old_id_val' );
 670                         $dbw->insert( 'text',
 671                                 array(
 672                                         'old_id'    => $old_id,
 673                                         'old_text'  => $data,
 674                                         'old_flags' => $flags,
 675                                 ), $fname
 676                         );
 677                         $this->mTextId = $dbw->insertId();
 678                 }
 679
 680                 # Record the edit in revisions
 681                 $rev_id = isset( $this->mId )
 682                         ? $this->mId
 683                         : $dbw->nextSequenceValue( 'rev_rev_id_val' );
 684                 $dbw->insert( 'revision',
 685                         array(
 686                                 'rev_id'         => $rev_id,
 687                                 'rev_page'       => $this->mPage,
 688                                 'rev_text_id'    => $this->mTextId,
 689                                 'rev_comment'    => $this->mComment,
 690                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 691                                 'rev_user'       => $this->mUser,
 692                                 'rev_user_text'  => $this->mUserText,
 693                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 694                                 'rev_deleted'    => $this->mDeleted,
 695                                 'rev_len'        => strlen($this->mText),
 696                         ), $fname
 697                 );
 698
 699                 $this->mId = !is_null($rev_id) ? $rev_id : $dbw->insertId();
 700                 wfProfileOut( $fname );
 701                 return $this->mId;
 702         }
 703
 704         /**
 705          * Lazy-load the revision's text.
 706          * Currently hardcoded to the 'text' table storage engine.
 707          *
 708          * @return string
 709          * @access private
 710          */
 711         function loadText() {
 712                 $fname = 'Revision::loadText';
 713                 wfProfileIn( $fname );
 714
 715                 // Caching may be beneficial for massive use of external storage
 716                 global $wgRevisionCacheExpiry, $wgMemc;
 717                 $key = wfMemcKey( 'revisiontext', 'textid', $this->getTextId() );
 718                 if( $wgRevisionCacheExpiry ) {
 719                         $text = $wgMemc->get( $key );
 720                         if( is_string( $text ) ) {
 721                                 wfProfileOut( $fname );
 722                                 return $text;
 723                         }
 724                 }
 725
 726                 // If we kept data for lazy extraction, use it now...
 727                 if ( isset( $this->mTextRow ) ) {
 728                         $row = $this->mTextRow;
 729                         $this->mTextRow = null;
 730                 } else {
 731                         $row = null;
 732                 }
 733
 734                 if( !$row ) {
 735                         // Text data is immutable; check slaves first.
 736                         $dbr = wfGetDB( DB_SLAVE );
 737                         $row = $dbr->selectRow( 'text',
 738                                 array( 'old_text', 'old_flags' ),
 739                                 array( 'old_id' => $this->getTextId() ),
 740                                 $fname);
 741                 }
 742
 743                 if( !$row ) {
 744                         // Possible slave lag!
 745                         $dbw = wfGetDB( DB_MASTER );
 746                         $row = $dbw->selectRow( 'text',
 747                                 array( 'old_text', 'old_flags' ),
 748                                 array( 'old_id' => $this->getTextId() ),
 749                                 $fname);
 750                 }
 751
 752                 $text = Revision::getRevisionText( $row );
 753
 754                 if( $wgRevisionCacheExpiry ) {
 755                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 756                 }
 757
 758                 wfProfileOut( $fname );
 759
 760                 return $text;
 761         }
 762
 763         /**
 764          * Create a new null-revision for insertion into a page's
 765          * history. This will not re-save the text, but simply refer
 766          * to the text from the previous version.
 767          *
 768          * Such revisions can for instance identify page rename
 769          * operations and other such meta-modifications.
 770          *
 771          * @param Database $dbw
 772          * @param int      $pageId ID number of the page to read from
 773          * @param string   $summary
 774          * @param bool     $minor
 775          * @return Revision
 776          */
 777         function newNullRevision( &$dbw, $pageId, $summary, $minor ) {
 778                 $fname = 'Revision::newNullRevision';
 779                 wfProfileIn( $fname );
 780
 781                 $current = $dbw->selectRow(
 782                         array( 'page', 'revision' ),
 783                         array( 'page_latest', 'rev_text_id' ),
 784                         array(
 785                                 'page_id' => $pageId,
 786                                 'page_latest=rev_id',
 787                                 ),
 788                         $fname );
 789
 790                 if( $current ) {
 791                         $revision = new Revision( array(
 792                                 'page'       => $pageId,
 793                                 'comment'    => $summary,
 794                                 'minor_edit' => $minor,
 795                                 'text_id'    => $current->rev_text_id,
 796                                 ) );
 797                 } else {
 798                         $revision = null;
 799                 }
 800
 801                 wfProfileOut( $fname );
 802                 return $revision;
 803         }
 804
 805         /**
 806          * Determine if the current user is allowed to view a particular
 807          * field of this revision, if it's marked as deleted.
 808          * @param int $field one of self::DELETED_TEXT,
 809          *                          self::DELETED_COMMENT,
 810          *                          self::DELETED_USER
 811          * @return bool
 812          */
 813         function userCan( $field ) {
 814                 if( ( $this->mDeleted & $field ) == $field ) {
 815                         global $wgUser;
 816                         $permission = ( $this->mDeleted & self::DELETED_RESTRICTED ) == self::DELETED_RESTRICTED
 817                                 ? 'hiderevision'
 818                                 : 'deleterevision';
 819                         wfDebug( "Checking for $permission due to $field match on $this->mDeleted\n" );
 820                         return $wgUser->isAllowed( $permission );
 821                 } else {
 822                         return true;
 823                 }
 824         }
 825
 826
 827         /**
 828          * Get rev_timestamp from rev_id, without loading the rest of the row
 829          * @param integer $id
 830          */
 831         static function getTimestampFromID( $id ) {
 832                 $dbr = wfGetDB( DB_SLAVE );
 833                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp',
 834                         array( 'rev_id' => $id ), __METHOD__ );
 835                 if ( $timestamp === false ) {
 836                         # Not in slave, try master
 837                         $dbw = wfGetDB( DB_MASTER );
 838                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp',
 839                                 array( 'rev_id' => $id ), __METHOD__ );
 840                 }
 841                 return $timestamp;
 842         }
 843
 844         static function countByPageId( $db, $id ) {
 845                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
 846                         array( 'rev_page' => $id ), __METHOD__ );
 847                 if( $row ) {
 848                         return $row->revCount;
 849                 }
 850                 return 0;
 851         }
 852
 853         static function countByTitle( $db, $title ) {
 854                 $id = $title->getArticleId();
 855                 if( $id ) {
 856                         return Revision::countByPageId( $db, $id );
 857                 }
 858                 return 0;
 859         }
 860 }
 861
 862 /**
 863  * Aliases for backwards compatibility with 1.6
 864  */
 865 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
 866 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
 867 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
 868 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );
 869
 870
 871 ?>