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