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                 $fields = self::selectFields();
 229                 $fields[] = 'page_namespace';
 230                 $fields[] = 'page_title';
 231                 $fields[] = 'page_latest';
 232                 $res = $db->select(
 233                         array( 'page', 'revision' ),
 234                         $fields,
 235                         $conditions,
 236                         'Revision::fetchRow',
 237                         array( 'LIMIT' => 1 ) );
 238                 $ret = $db->resultObject( $res );
 239                 return $ret;
 240         }
 241
 242         /**
 243          * Return the list of revision fields that should be selected to create
 244          * a new revision.
 245          */
 246         static function selectFields() {
 247                 return array(
 248                         'rev_id',
 249                         'rev_page',
 250                         'rev_text_id',
 251                         'rev_timestamp',
 252                         'rev_comment',
 253                         'rev_user_text,'.
 254                         'rev_user',
 255                         'rev_minor_edit',
 256                         'rev_deleted',
 257                         'rev_len',
 258                         'rev_parent_id'
 259                 );
 260         }
 261
 262         /**
 263          * @param object $row
 264          * @access private
 265          */
 266         function Revision( $row ) {
 267                 if( is_object( $row ) ) {
 268                         $this->mId        = intval( $row->rev_id );
 269                         $this->mPage      = intval( $row->rev_page );
 270                         $this->mTextId    = intval( $row->rev_text_id );
 271                         $this->mComment   =         $row->rev_comment;
 272                         $this->mUserText  =         $row->rev_user_text;
 273                         $this->mUser      = intval( $row->rev_user );
 274                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 275                         $this->mTimestamp =         $row->rev_timestamp;
 276                         $this->mDeleted   = intval( $row->rev_deleted );
 277
 278                         if( !isset( $row->rev_parent_id ) )
 279                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 280                         else
 281                                 $this->mParentId  = intval( $row->rev_parent_id );
 282
 283                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) )
 284                                 $this->mSize = null;
 285                         else
 286                                 $this->mSize = intval( $row->rev_len );
 287
 288                         if( isset( $row->page_latest ) ) {
 289                                 $this->mCurrent   = ( $row->rev_id == $row->page_latest );
 290                                 $this->mTitle     = Title::makeTitle( $row->page_namespace,
 291                                                                       $row->page_title );
 292                         } else {
 293                                 $this->mCurrent = false;
 294                                 $this->mTitle = null;
 295                         }
 296
 297                         // Lazy extraction...
 298                         $this->mText      = null;
 299                         if( isset( $row->old_text ) ) {
 300                                 $this->mTextRow = $row;
 301                         } else {
 302                                 // 'text' table row entry will be lazy-loaded
 303                                 $this->mTextRow = null;
 304                         }
 305                 } elseif( is_array( $row ) ) {
 306                         // Build a new revision to be saved...
 307                         global $wgUser;
 308
 309                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 310                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 311                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 312                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 313                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 314                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 315                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 316                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 317                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 318                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 319
 320                         // Enforce spacing trimming on supplied text
 321                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 322                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 323                         $this->mTextRow   = null;
 324
 325                         $this->mTitle     = null; # Load on demand if needed
 326                         $this->mCurrent   = false;
 327                         # If we still have no len_size, see it we have the text to figure it out
 328                         if ( !$this->mSize )
 329                                 $this->mSize      = is_null($this->mText) ? null : strlen($this->mText);
 330                 } else {
 331                         throw new MWException( 'Revision constructor passed invalid row format.' );
 332                 }
 333         }
 334
 335         /**#@+
 336          * @access public
 337          */
 338
 339         /**
 340          * Get revision ID
 341          * @return int
 342          */
 343         public function getId() {
 344                 return $this->mId;
 345         }
 346
 347         /**
 348          * Get text row ID
 349          * @return int
 350          */
 351         public function getTextId() {
 352                 return $this->mTextId;
 353         }
 354
 355         /**
 356          * Get parent revision ID (the original previous page revision)
 357          * @return int
 358          */
 359         public function getParentId() {
 360                 return $this->mParentId;
 361         }
 362
 363         /**
 364          * Returns the length of the text in this revision, or null if unknown.
 365          * @return int
 366          */
 367         public function getSize() {
 368                 return $this->mSize;
 369         }
 370
 371         /**
 372          * Returns the title of the page associated with this entry.
 373          * @return Title
 374          */
 375         public function getTitle() {
 376                 if( isset( $this->mTitle ) ) {
 377                         return $this->mTitle;
 378                 }
 379                 $dbr = wfGetDB( DB_SLAVE );
 380                 $row = $dbr->selectRow(
 381                         array( 'page', 'revision' ),
 382                         array( 'page_namespace', 'page_title' ),
 383                         array( 'page_id=rev_page',
 384                                'rev_id' => $this->mId ),
 385                         'Revision::getTitle' );
 386                 if( $row ) {
 387                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 388                                                            $row->page_title );
 389                 }
 390                 return $this->mTitle;
 391         }
 392
 393         /**
 394          * Set the title of the revision
 395          * @param Title $title
 396          */
 397         public function setTitle( $title ) {
 398                 $this->mTitle = $title;
 399         }
 400
 401         /**
 402          * Get the page ID
 403          * @return int
 404          */
 405         public function getPage() {
 406                 return $this->mPage;
 407         }
 408
 409         /**
 410          * Fetch revision's user id if it's available to all users
 411          * @return int
 412          */
 413         public function getUser() {
 414                 if( $this->isDeleted( self::DELETED_USER ) ) {
 415                         return 0;
 416                 } else {
 417                         return $this->mUser;
 418                 }
 419         }
 420
 421         /**
 422          * Fetch revision's user id without regard for the current user's permissions
 423          * @return string
 424          */
 425         public function getRawUser() {
 426                 return $this->mUser;
 427         }
 428
 429         /**
 430          * Fetch revision's username if it's available to all users
 431          * @return string
 432          */
 433         public function getUserText() {
 434                 if( $this->isDeleted( self::DELETED_USER ) ) {
 435                         return "";
 436                 } else {
 437                         return $this->mUserText;
 438                 }
 439         }
 440
 441         /**
 442          * Fetch revision's username without regard for view restrictions
 443          * @return string
 444          */
 445         public function getRawUserText() {
 446                 return $this->mUserText;
 447         }
 448
 449         /**
 450          * Fetch revision comment if it's available to all users
 451          * @return string
 452          */
 453         function getComment() {
 454                 if( $this->isDeleted( self::DELETED_COMMENT ) ) {
 455                         return "";
 456                 } else {
 457                         return $this->mComment;
 458                 }
 459         }
 460
 461         /**
 462          * Fetch revision comment without regard for the current user's permissions
 463          * @return string
 464          */
 465         public function getRawComment() {
 466                 return $this->mComment;
 467         }
 468
 469         /**
 470          * @return bool
 471          */
 472         public function isMinor() {
 473                 return (bool)$this->mMinorEdit;
 474         }
 475
 476         /**
 477          * int $field one of DELETED_* bitfield constants
 478          * @return bool
 479          */
 480         public function isDeleted( $field ) {
 481                 return ($this->mDeleted & $field) == $field;
 482         }
 483
 484         /**
 485          * Fetch revision text if it's available to all users
 486          * @return string
 487          */
 488         public function getText() {
 489                 if( $this->isDeleted( self::DELETED_TEXT ) ) {
 490                         return "";
 491                 } else {
 492                         return $this->getRawText();
 493                 }
 494         }
 495
 496         /**
 497          * Fetch revision text without regard for view restrictions
 498          * @return string
 499          */
 500         public function getRawText() {
 501                 if( is_null( $this->mText ) ) {
 502                         // Revision text is immutable. Load on demand:
 503                         $this->mText = $this->loadText();
 504                 }
 505                 return $this->mText;
 506         }
 507
 508         /**
 509          * Fetch revision text if it's available to THIS user
 510          * @return string
 511          */
 512         public function revText() {
 513                 if( !$this->userCan( self::DELETED_TEXT ) ) {
 514                         return "";
 515                 } else {
 516                         return $this->getRawText();
 517                 }
 518         }
 519
 520         /**
 521          * @return string
 522          */
 523         public function getTimestamp() {
 524                 return wfTimestamp(TS_MW, $this->mTimestamp);
 525         }
 526
 527         /**
 528          * @return bool
 529          */
 530         public function isCurrent() {
 531                 return $this->mCurrent;
 532         }
 533
 534         /**
 535          * Get previous revision for this title
 536          * @return Revision
 537          */
 538         public function getPrevious() {
 539                 $prev = $this->mTitle->getPreviousRevisionID( $this->mId );
 540                 if( $prev ) {
 541                         return Revision::newFromTitle( $this->mTitle, $prev );
 542                 } else {
 543                         return null;
 544                 }
 545         }
 546
 547         /**
 548          * @return Revision
 549          */
 550         public function getNext() {
 551                 $next = $this->mTitle->getNextRevisionID( $this->mId );
 552                 if ( $next ) {
 553                         return Revision::newFromTitle( $this->mTitle, $next );
 554                 } else {
 555                         return null;
 556                 }
 557         }
 558
 559         /**
 560          * Get previous revision Id for this page_id
 561          * This is used to populate rev_parent_id on save
 562          * @param Database $db
 563          * @return int
 564          */
 565         private function getPreviousRevisionId( $db ) {
 566                 if( is_null($this->mPage) ) {
 567                         return 0;
 568                 }
 569                 # Use page_latest if ID is not given
 570                 if( !$this->mId ) {
 571                         $prevId = $db->selectField( 'page', 'page_latest',
 572                                 array( 'page_id' => $this->mPage ),
 573                                 __METHOD__ );
 574                 } else {
 575                         $prevId = $db->selectField( 'revision', 'rev_id',
 576                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 577                                 __METHOD__,
 578                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 579                 }
 580                 return intval($prevId);
 581         }
 582
 583         /**
 584           * Get revision text associated with an old or archive row
 585           * $row is usually an object from wfFetchRow(), both the flags and the text
 586           * field must be included
 587           *
 588           * @param integer $row Id of a row
 589           * @param string $prefix table prefix (default 'old_')
 590           * @return string $text|false the text requested
 591           */
 592         public static function getRevisionText( $row, $prefix = 'old_' ) {
 593                 wfProfileIn( __METHOD__ );
 594
 595                 # Get data
 596                 $textField = $prefix . 'text';
 597                 $flagsField = $prefix . 'flags';
 598
 599                 if( isset( $row->$flagsField ) ) {
 600                         $flags = explode( ',', $row->$flagsField );
 601                 } else {
 602                         $flags = array();
 603                 }
 604
 605                 if( isset( $row->$textField ) ) {
 606                         $text = $row->$textField;
 607                 } else {
 608                         wfProfileOut( __METHOD__ );
 609                         return false;
 610                 }
 611
 612                 # Use external methods for external objects, text in table is URL-only then
 613                 if ( in_array( 'external', $flags ) ) {
 614                         $url=$text;
 615                         @list(/* $proto */,$path)=explode('://',$url,2);
 616                         if ($path=="") {
 617                                 wfProfileOut( __METHOD__ );
 618                                 return false;
 619                         }
 620                         $text=ExternalStore::fetchFromURL($url);
 621                 }
 622
 623                 // If the text was fetched without an error, convert it
 624                 if ( $text !== false ) {
 625                         if( in_array( 'gzip', $flags ) ) {
 626                                 # Deal with optional compression of archived pages.
 627                                 # This can be done periodically via maintenance/compressOld.php, and
 628                                 # as pages are saved if $wgCompressRevisions is set.
 629                                 $text = gzinflate( $text );
 630                         }
 631
 632                         if( in_array( 'object', $flags ) ) {
 633                                 # Generic compressed storage
 634                                 $obj = unserialize( $text );
 635                                 if ( !is_object( $obj ) ) {
 636                                         // Invalid object
 637                                         wfProfileOut( __METHOD__ );
 638                                         return false;
 639                                 }
 640                                 $text = $obj->getText();
 641                         }
 642
 643                         global $wgLegacyEncoding;
 644                         if( $wgLegacyEncoding && !in_array( 'utf-8', $flags ) ) {
 645                                 # Old revisions kept around in a legacy encoding?
 646                                 # Upconvert on demand.
 647                                 global $wgInputEncoding, $wgContLang;
 648                                 $text = $wgContLang->iconv( $wgLegacyEncoding, $wgInputEncoding, $text );
 649                         }
 650                 }
 651                 wfProfileOut( __METHOD__ );
 652                 return $text;
 653         }
 654
 655         /**
 656          * If $wgCompressRevisions is enabled, we will compress data.
 657          * The input string is modified in place.
 658          * Return value is the flags field: contains 'gzip' if the
 659          * data is compressed, and 'utf-8' if we're saving in UTF-8
 660          * mode.
 661          *
 662          * @param mixed $text reference to a text
 663          * @return string
 664          */
 665         public static function compressRevisionText( &$text ) {
 666                 global $wgCompressRevisions;
 667                 $flags = array();
 668
 669                 # Revisions not marked this way will be converted
 670                 # on load if $wgLegacyCharset is set in the future.
 671                 $flags[] = 'utf-8';
 672
 673                 if( $wgCompressRevisions ) {
 674                         if( function_exists( 'gzdeflate' ) ) {
 675                                 $text = gzdeflate( $text );
 676                                 $flags[] = 'gzip';
 677                         } else {
 678                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 679                         }
 680                 }
 681                 return implode( ',', $flags );
 682         }
 683
 684         /**
 685          * Insert a new revision into the database, returning the new revision ID
 686          * number on success and dies horribly on failure.
 687          *
 688          * @param Database $dbw
 689          * @return int
 690          */
 691         public function insertOn( &$dbw ) {
 692                 global $wgDefaultExternalStore;
 693
 694                 wfProfileIn( __METHOD__ );
 695
 696                 $data = $this->mText;
 697                 $flags = Revision::compressRevisionText( $data );
 698
 699                 # Write to external storage if required
 700                 if ( $wgDefaultExternalStore ) {
 701                         if ( is_array( $wgDefaultExternalStore ) ) {
 702                                 // Distribute storage across multiple clusters
 703                                 $store = $wgDefaultExternalStore[mt_rand(0, count( $wgDefaultExternalStore ) - 1)];
 704                         } else {
 705                                 $store = $wgDefaultExternalStore;
 706                         }
 707                         // Store and get the URL
 708                         $data = ExternalStore::insert( $store, $data );
 709                         if ( !$data ) {
 710                                 # This should only happen in the case of a configuration error, where the external store is not valid
 711                                 throw new MWException( "Unable to store text to external storage $store" );
 712                         }
 713                         if ( $flags ) {
 714                                 $flags .= ',';
 715                         }
 716                         $flags .= 'external';
 717                 }
 718
 719                 # Record the text (or external storage URL) to the text table
 720                 if( !isset( $this->mTextId ) ) {
 721                         $old_id = $dbw->nextSequenceValue( 'text_old_id_val' );
 722                         $dbw->insert( 'text',
 723                                 array(
 724                                         'old_id'    => $old_id,
 725                                         'old_text'  => $data,
 726                                         'old_flags' => $flags,
 727                                 ), __METHOD__
 728                         );
 729                         $this->mTextId = $dbw->insertId();
 730                 }
 731
 732                 # Record the edit in revisions
 733                 $rev_id = isset( $this->mId )
 734                         ? $this->mId
 735                         : $dbw->nextSequenceValue( 'rev_rev_id_val' );
 736                 $dbw->insert( 'revision',
 737                         array(
 738                                 'rev_id'         => $rev_id,
 739                                 'rev_page'       => $this->mPage,
 740                                 'rev_text_id'    => $this->mTextId,
 741                                 'rev_comment'    => $this->mComment,
 742                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 743                                 'rev_user'       => $this->mUser,
 744                                 'rev_user_text'  => $this->mUserText,
 745                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 746                                 'rev_deleted'    => $this->mDeleted,
 747                                 'rev_len'            => $this->mSize,
 748                                 'rev_parent_id'  => $this->mParentId ? $this->mParentId : $this->getPreviousRevisionId( $dbw )
 749                         ), __METHOD__
 750                 );
 751
 752                 $this->mId = !is_null($rev_id) ? $rev_id : $dbw->insertId();
 753
 754                 wfRunHooks( 'RevisionInsertComplete', array( &$this ) );
 755
 756                 wfProfileOut( __METHOD__ );
 757                 return $this->mId;
 758         }
 759
 760         /**
 761          * Lazy-load the revision's text.
 762          * Currently hardcoded to the 'text' table storage engine.
 763          *
 764          * @return string
 765          */
 766         private function loadText() {
 767                 wfProfileIn( __METHOD__ );
 768
 769                 // Caching may be beneficial for massive use of external storage
 770                 global $wgRevisionCacheExpiry, $wgMemc;
 771                 $key = wfMemcKey( 'revisiontext', 'textid', $this->getTextId() );
 772                 if( $wgRevisionCacheExpiry ) {
 773                         $text = $wgMemc->get( $key );
 774                         if( is_string( $text ) ) {
 775                                 wfProfileOut( __METHOD__ );
 776                                 return $text;
 777                         }
 778                 }
 779
 780                 // If we kept data for lazy extraction, use it now...
 781                 if ( isset( $this->mTextRow ) ) {
 782                         $row = $this->mTextRow;
 783                         $this->mTextRow = null;
 784                 } else {
 785                         $row = null;
 786                 }
 787
 788                 if( !$row ) {
 789                         // Text data is immutable; check slaves first.
 790                         $dbr = wfGetDB( DB_SLAVE );
 791                         $row = $dbr->selectRow( 'text',
 792                                 array( 'old_text', 'old_flags' ),
 793                                 array( 'old_id' => $this->getTextId() ),
 794                                 __METHOD__ );
 795                 }
 796
 797                 if( !$row ) {
 798                         // Possible slave lag!
 799                         $dbw = wfGetDB( DB_MASTER );
 800                         $row = $dbw->selectRow( 'text',
 801                                 array( 'old_text', 'old_flags' ),
 802                                 array( 'old_id' => $this->getTextId() ),
 803                                 __METHOD__ );
 804                 }
 805
 806                 $text = self::getRevisionText( $row );
 807
 808                 if( $wgRevisionCacheExpiry ) {
 809                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 810                 }
 811
 812                 wfProfileOut( __METHOD__ );
 813
 814                 return $text;
 815         }
 816
 817         /**
 818          * Create a new null-revision for insertion into a page's
 819          * history. This will not re-save the text, but simply refer
 820          * to the text from the previous version.
 821          *
 822          * Such revisions can for instance identify page rename
 823          * operations and other such meta-modifications.
 824          *
 825          * @param Database $dbw
 826          * @param int      $pageId ID number of the page to read from
 827          * @param string   $summary
 828          * @param bool     $minor
 829          * @return Revision
 830          */
 831         public static function newNullRevision( &$dbw, $pageId, $summary, $minor ) {
 832                 wfProfileIn( __METHOD__ );
 833
 834                 $current = $dbw->selectRow(
 835                         array( 'page', 'revision' ),
 836                         array( 'page_latest', 'rev_text_id' ),
 837                         array(
 838                                 'page_id' => $pageId,
 839                                 'page_latest=rev_id',
 840                                 ),
 841                         __METHOD__ );
 842
 843                 if( $current ) {
 844                         $revision = new Revision( array(
 845                                 'page'       => $pageId,
 846                                 'comment'    => $summary,
 847                                 'minor_edit' => $minor,
 848                                 'text_id'    => $current->rev_text_id,
 849                                 'parent_id'  => $current->page_latest
 850                                 ) );
 851                 } else {
 852                         $revision = null;
 853                 }
 854
 855                 wfProfileOut( __METHOD__ );
 856                 return $revision;
 857         }
 858
 859         /**
 860          * Determine if the current user is allowed to view a particular
 861          * field of this revision, if it's marked as deleted.
 862          * @param int $field one of self::DELETED_TEXT,
 863          *                          self::DELETED_COMMENT,
 864          *                          self::DELETED_USER
 865          * @return bool
 866          */
 867         public function userCan( $field ) {
 868                 if( ( $this->mDeleted & $field ) == $field ) {
 869                         global $wgUser;
 870                         $permission = ( $this->mDeleted & self::DELETED_RESTRICTED ) == self::DELETED_RESTRICTED
 871                                 ? 'hiderevision'
 872                                 : 'deleterevision';
 873                         wfDebug( "Checking for $permission due to $field match on $this->mDeleted\n" );
 874                         return $wgUser->isAllowed( $permission );
 875                 } else {
 876                         return true;
 877                 }
 878         }
 879
 880
 881         /**
 882          * Get rev_timestamp from rev_id, without loading the rest of the row
 883          * @param integer $id
 884          */
 885         static function getTimestampFromID( $id ) {
 886                 $dbr = wfGetDB( DB_SLAVE );
 887                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp',
 888                         array( 'rev_id' => $id ), __METHOD__ );
 889                 if ( $timestamp === false ) {
 890                         # Not in slave, try master
 891                         $dbw = wfGetDB( DB_MASTER );
 892                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp',
 893                                 array( 'rev_id' => $id ), __METHOD__ );
 894                 }
 895                 return $timestamp;
 896         }
 897
 898         /**
 899          * Get count of revisions per page...not very efficient
 900          * @param Database $db
 901          * @param int $id, page id
 902          */
 903         static function countByPageId( $db, $id ) {
 904                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
 905                         array( 'rev_page' => $id ), __METHOD__ );
 906                 if( $row ) {
 907                         return $row->revCount;
 908                 }
 909                 return 0;
 910         }
 911
 912         /**
 913          * Get count of revisions per page...not very efficient
 914          * @param Database $db
 915          * @param Title $title
 916          */
 917         static function countByTitle( $db, $title ) {
 918                 $id = $title->getArticleId();
 919                 if( $id ) {
 920                         return Revision::countByPageId( $db, $id );
 921                 }
 922                 return 0;
 923         }
 924 }
 925
 926 /**
 927  * Aliases for backwards compatibility with 1.6
 928  */
 929 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
 930 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
 931 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
 932 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );