includes/Revision.php

   1 <?php
   2 /**
   3  * Representation of a page version.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * @todo document
  25  */
  26 class Revision implements IDBAccessObject {
  27         protected $mId;
  28         protected $mPage;
  29         protected $mUserText;
  30         protected $mOrigUserText;
  31         protected $mUser;
  32         protected $mMinorEdit;
  33         protected $mTimestamp;
  34         protected $mDeleted;
  35         protected $mSize;
  36         protected $mSha1;
  37         protected $mParentId;
  38         protected $mComment;
  39         protected $mText;
  40         protected $mTextRow;
  41         protected $mTitle;
  42         protected $mCurrent;
  43         protected $mContentModel;
  44         protected $mContentFormat;
  45         protected $mContent;
  46         protected $mContentHandler;
  47
  48         // Revision deletion constants
  49         const DELETED_TEXT = 1;
  50         const DELETED_COMMENT = 2;
  51         const DELETED_USER = 4;
  52         const DELETED_RESTRICTED = 8;
  53         const SUPPRESSED_USER = 12; // convenience
  54
  55         // Audience options for accessors
  56         const FOR_PUBLIC = 1;
  57         const FOR_THIS_USER = 2;
  58         const RAW = 3;
  59
  60         /**
  61          * Load a page revision from a given revision ID number.
  62          * Returns null if no such revision can be found.
  63          *
  64          * $flags include:
  65          *      Revision::READ_LATEST  : Select the data from the master
  66          *      Revision::READ_LOCKING : Select & lock the data from the master
  67          *
  68          * @param $id Integer
  69          * @param $flags Integer (optional)
  70          * @return Revision or null
  71          */
  72         public static function newFromId( $id, $flags = 0 ) {
  73                 return self::newFromConds( array( 'rev_id' => intval( $id ) ), $flags );
  74         }
  75
  76         /**
  77          * Load either the current, or a specified, revision
  78          * that's attached to a given title. If not attached
  79          * to that title, will return null.
  80          *
  81          * $flags include:
  82          *      Revision::READ_LATEST  : Select the data from the master
  83          *      Revision::READ_LOCKING : Select & lock the data from the master
  84          *
  85          * @param $title Title
  86          * @param $id Integer (optional)
  87          * @param $flags Integer Bitfield (optional)
  88          * @return Revision or null
  89          */
  90         public static function newFromTitle( $title, $id = 0, $flags = null ) {
  91                 $conds = array(
  92                         'page_namespace' => $title->getNamespace(),
  93                         'page_title'     => $title->getDBkey()
  94                 );
  95                 if ( $id ) {
  96                         // Use the specified ID
  97                         $conds['rev_id'] = $id;
  98                 } else {
  99                         // Use a join to get the latest revision
 100                         $conds[] = 'rev_id=page_latest';
 101                         // Callers assume this will be up-to-date
 102                         $flags = is_int( $flags ) ? $flags : self::READ_LATEST; // b/c
 103                 }
 104                 return self::newFromConds( $conds, (int)$flags );
 105         }
 106
 107         /**
 108          * Load either the current, or a specified, revision
 109          * that's attached to a given page ID.
 110          * Returns null if no such revision can be found.
 111          *
 112          * $flags include:
 113          *      Revision::READ_LATEST  : Select the data from the master
 114          *      Revision::READ_LOCKING : Select & lock the data from the master
 115          *
 116          * @param $revId Integer
 117          * @param $pageId Integer (optional)
 118          * @param $flags Integer Bitfield (optional)
 119          * @return Revision or null
 120          */
 121         public static function newFromPageId( $pageId, $revId = 0, $flags = null ) {
 122                 $conds = array( 'page_id' => $pageId );
 123                 if ( $revId ) {
 124                         $conds['rev_id'] = $revId;
 125                 } else {
 126                         // Use a join to get the latest revision
 127                         $conds[] = 'rev_id = page_latest';
 128                         // Callers assume this will be up-to-date
 129                         $flags = is_int( $flags ) ? $flags : self::READ_LATEST; // b/c
 130                 }
 131                 return self::newFromConds( $conds, (int)$flags );
 132         }
 133
 134         /**
 135          * Make a fake revision object from an archive table row. This is queried
 136          * for permissions or even inserted (as in Special:Undelete)
 137          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
 138          *
 139          * @param $row
 140          * @param $overrides array
 141          *
 142          * @return Revision
 143          */
 144         public static function newFromArchiveRow( $row, $overrides = array() ) {
 145                 global $wgContentHandlerUseDB;
 146
 147                 $attribs = $overrides + array(
 148                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 149                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 150                         'comment'    => $row->ar_comment,
 151                         'user'       => $row->ar_user,
 152                         'user_text'  => $row->ar_user_text,
 153                         'timestamp'  => $row->ar_timestamp,
 154                         'minor_edit' => $row->ar_minor_edit,
 155                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 156                         'deleted'    => $row->ar_deleted,
 157                         'len'        => $row->ar_len,
 158                         'sha1'       => isset( $row->ar_sha1 ) ? $row->ar_sha1 : null,
 159                         'content_model' => isset( $row->ar_content_model ) ? $row->ar_content_model : null,
 160                         'content_format'  => isset( $row->ar_content_format ) ? $row->ar_content_format : null,
 161                 );
 162
 163                 if ( !$wgContentHandlerUseDB ) {
 164                         unset( $attribs['content_model'] );
 165                         unset( $attribs['content_format'] );
 166                 }
 167
 168                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 169                         // Pre-1.5 ar_text row
 170                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 171                         if ( $attribs['text'] === false ) {
 172                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 173                         }
 174                 }
 175                 return new self( $attribs );
 176         }
 177
 178         /**
 179          * @since 1.19
 180          *
 181          * @param $row
 182          * @return Revision
 183          */
 184         public static function newFromRow( $row ) {
 185                 return new self( $row );
 186         }
 187
 188         /**
 189          * Load a page revision from a given revision ID number.
 190          * Returns null if no such revision can be found.
 191          *
 192          * @param $db DatabaseBase
 193          * @param $id Integer
 194          * @return Revision or null
 195          */
 196         public static function loadFromId( $db, $id ) {
 197                 return self::loadFromConds( $db, array( 'rev_id' => intval( $id ) ) );
 198         }
 199
 200         /**
 201          * Load either the current, or a specified, revision
 202          * that's attached to a given page. If not attached
 203          * to that page, will return null.
 204          *
 205          * @param $db DatabaseBase
 206          * @param $pageid Integer
 207          * @param $id Integer
 208          * @return Revision or null
 209          */
 210         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 211                 $conds = array( 'rev_page' => intval( $pageid ), 'page_id'  => intval( $pageid ) );
 212                 if( $id ) {
 213                         $conds['rev_id'] = intval( $id );
 214                 } else {
 215                         $conds[] = 'rev_id=page_latest';
 216                 }
 217                 return self::loadFromConds( $db, $conds );
 218         }
 219
 220         /**
 221          * Load either the current, or a specified, revision
 222          * that's attached to a given page. If not attached
 223          * to that page, will return null.
 224          *
 225          * @param $db DatabaseBase
 226          * @param $title Title
 227          * @param $id Integer
 228          * @return Revision or null
 229          */
 230         public static function loadFromTitle( $db, $title, $id = 0 ) {
 231                 if( $id ) {
 232                         $matchId = intval( $id );
 233                 } else {
 234                         $matchId = 'page_latest';
 235                 }
 236                 return self::loadFromConds( $db,
 237                         array( "rev_id=$matchId",
 238                                    'page_namespace' => $title->getNamespace(),
 239                                    'page_title'     => $title->getDBkey() )
 240                 );
 241         }
 242
 243         /**
 244          * Load the revision for the given title with the given timestamp.
 245          * WARNING: Timestamps may in some circumstances not be unique,
 246          * so this isn't the best key to use.
 247          *
 248          * @param $db DatabaseBase
 249          * @param $title Title
 250          * @param $timestamp String
 251          * @return Revision or null
 252          */
 253         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 254                 return self::loadFromConds( $db,
 255                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 256                                    'page_namespace' => $title->getNamespace(),
 257                                    'page_title'     => $title->getDBkey() )
 258                 );
 259         }
 260
 261         /**
 262          * Given a set of conditions, fetch a revision.
 263          *
 264          * @param $conditions Array
 265          * @param $flags integer (optional)
 266          * @return Revision or null
 267          */
 268         private static function newFromConds( $conditions, $flags = 0 ) {
 269                 $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_SLAVE );
 270                 $rev = self::loadFromConds( $db, $conditions, $flags );
 271                 if ( is_null( $rev ) && wfGetLB()->getServerCount() > 1 ) {
 272                         if ( !( $flags & self::READ_LATEST ) ) {
 273                                 $dbw = wfGetDB( DB_MASTER );
 274                                 $rev = self::loadFromConds( $dbw, $conditions, $flags );
 275                         }
 276                 }
 277                 return $rev;
 278         }
 279
 280         /**
 281          * Given a set of conditions, fetch a revision from
 282          * the given database connection.
 283          *
 284          * @param $db DatabaseBase
 285          * @param $conditions Array
 286          * @param $flags integer (optional)
 287          * @return Revision or null
 288          */
 289         private static function loadFromConds( $db, $conditions, $flags = 0 ) {
 290                 $res = self::fetchFromConds( $db, $conditions, $flags );
 291                 if( $res ) {
 292                         $row = $res->fetchObject();
 293                         if( $row ) {
 294                                 $ret = new Revision( $row );
 295                                 return $ret;
 296                         }
 297                 }
 298                 $ret = null;
 299                 return $ret;
 300         }
 301
 302         /**
 303          * Return a wrapper for a series of database rows to
 304          * fetch all of a given page's revisions in turn.
 305          * Each row can be fed to the constructor to get objects.
 306          *
 307          * @param $title Title
 308          * @return ResultWrapper
 309          */
 310         public static function fetchRevision( $title ) {
 311                 return self::fetchFromConds(
 312                         wfGetDB( DB_SLAVE ),
 313                         array( 'rev_id=page_latest',
 314                                    'page_namespace' => $title->getNamespace(),
 315                                    'page_title'     => $title->getDBkey() )
 316                 );
 317         }
 318
 319         /**
 320          * Given a set of conditions, return a ResultWrapper
 321          * which will return matching database rows with the
 322          * fields necessary to build Revision objects.
 323          *
 324          * @param $db DatabaseBase
 325          * @param $conditions Array
 326          * @param $flags integer (optional)
 327          * @return ResultWrapper
 328          */
 329         private static function fetchFromConds( $db, $conditions, $flags = 0 ) {
 330                 $fields = array_merge(
 331                         self::selectFields(),
 332                         self::selectPageFields(),
 333                         self::selectUserFields()
 334                 );
 335                 $options = array( 'LIMIT' => 1 );
 336                 if ( $flags & self::READ_LOCKING ) {
 337                         $options[] = 'FOR UPDATE';
 338                 }
 339                 return $db->select(
 340                         array( 'revision', 'page', 'user' ),
 341                         $fields,
 342                         $conditions,
 343                         __METHOD__,
 344                         $options,
 345                         array( 'page' => self::pageJoinCond(), 'user' => self::userJoinCond() )
 346                 );
 347         }
 348
 349         /**
 350          * Return the value of a select() JOIN conds array for the user table.
 351          * This will get user table rows for logged-in users.
 352          * @since 1.19
 353          * @return Array
 354          */
 355         public static function userJoinCond() {
 356                 return array( 'LEFT JOIN', array( 'rev_user != 0', 'user_id = rev_user' ) );
 357         }
 358
 359         /**
 360          * Return the value of a select() page conds array for the paeg table.
 361          * This will assure that the revision(s) are not orphaned from live pages.
 362          * @since 1.19
 363          * @return Array
 364          */
 365         public static function pageJoinCond() {
 366                 return array( 'INNER JOIN', array( 'page_id = rev_page' ) );
 367         }
 368
 369         /**
 370          * Return the list of revision fields that should be selected to create
 371          * a new revision.
 372          * @return array
 373          */
 374         public static function selectFields() {
 375                 global $wgContentHandlerUseDB;
 376
 377                 $fields = array(
 378                         'rev_id',
 379                         'rev_page',
 380                         'rev_text_id',
 381                         'rev_timestamp',
 382                         'rev_comment',
 383                         'rev_user_text',
 384                         'rev_user',
 385                         'rev_minor_edit',
 386                         'rev_deleted',
 387                         'rev_len',
 388                         'rev_parent_id',
 389                         'rev_sha1',
 390                 );
 391
 392                 if ( $wgContentHandlerUseDB ) {
 393                         $fields[] = 'rev_content_format';
 394                         $fields[] = 'rev_content_model';
 395                 }
 396
 397                 return $fields;
 398         }
 399
 400         /**
 401          * Return the list of text fields that should be selected to read the
 402          * revision text
 403          * @return array
 404          */
 405         public static function selectTextFields() {
 406                 return array(
 407                         'old_text',
 408                         'old_flags'
 409                 );
 410         }
 411
 412         /**
 413          * Return the list of page fields that should be selected from page table
 414          * @return array
 415          */
 416         public static function selectPageFields() {
 417                 return array(
 418                         'page_namespace',
 419                         'page_title',
 420                         'page_id',
 421                         'page_latest',
 422                         'page_is_redirect',
 423                         'page_len',
 424                 );
 425         }
 426
 427         /**
 428          * Return the list of user fields that should be selected from user table
 429          * @return array
 430          */
 431         public static function selectUserFields() {
 432                 return array( 'user_name' );
 433         }
 434
 435         /**
 436          * Do a batched query to get the parent revision lengths
 437          * @param $db DatabaseBase
 438          * @param $revIds Array
 439          * @return array
 440          */
 441         public static function getParentLengths( $db, array $revIds ) {
 442                 $revLens = array();
 443                 if ( !$revIds ) {
 444                         return $revLens; // empty
 445                 }
 446                 wfProfileIn( __METHOD__ );
 447                 $res = $db->select( 'revision',
 448                         array( 'rev_id', 'rev_len' ),
 449                         array( 'rev_id' => $revIds ),
 450                         __METHOD__ );
 451                 foreach ( $res as $row ) {
 452                         $revLens[$row->rev_id] = $row->rev_len;
 453                 }
 454                 wfProfileOut( __METHOD__ );
 455                 return $revLens;
 456         }
 457
 458         /**
 459          * Constructor
 460          *
 461          * @param $row Mixed: either a database row or an array
 462          * @access private
 463          */
 464         function __construct( $row ) {
 465                 if( is_object( $row ) ) {
 466                         $this->mId        = intval( $row->rev_id );
 467                         $this->mPage      = intval( $row->rev_page );
 468                         $this->mTextId    = intval( $row->rev_text_id );
 469                         $this->mComment   =         $row->rev_comment;
 470                         $this->mUser      = intval( $row->rev_user );
 471                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 472                         $this->mTimestamp =         $row->rev_timestamp;
 473                         $this->mDeleted   = intval( $row->rev_deleted );
 474
 475                         if( !isset( $row->rev_parent_id ) ) {
 476                                 $this->mParentId = is_null( $row->rev_parent_id ) ? null : 0;
 477                         } else {
 478                                 $this->mParentId  = intval( $row->rev_parent_id );
 479                         }
 480
 481                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 482                                 $this->mSize = null;
 483                         } else {
 484                                 $this->mSize = intval( $row->rev_len );
 485                         }
 486
 487                         if ( !isset( $row->rev_sha1 ) ) {
 488                                 $this->mSha1 = null;
 489                         } else {
 490                                 $this->mSha1 = $row->rev_sha1;
 491                         }
 492
 493                         if( isset( $row->page_latest ) ) {
 494                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 495                                 $this->mTitle = Title::newFromRow( $row );
 496                         } else {
 497                                 $this->mCurrent = false;
 498                                 $this->mTitle = null;
 499                         }
 500
 501                         if( !isset( $row->rev_content_model ) || is_null( $row->rev_content_model ) ) {
 502                                 $this->mContentModel = null; # determine on demand if needed
 503                         } else {
 504                                 $this->mContentModel = strval( $row->rev_content_model );
 505                         }
 506
 507                         if( !isset( $row->rev_content_format ) || is_null( $row->rev_content_format ) ) {
 508                                 $this->mContentFormat = null; # determine on demand if needed
 509                         } else {
 510                                 $this->mContentFormat = strval( $row->rev_content_format );
 511                         }
 512
 513                         // Lazy extraction...
 514                         $this->mText      = null;
 515                         if( isset( $row->old_text ) ) {
 516                                 $this->mTextRow = $row;
 517                         } else {
 518                                 // 'text' table row entry will be lazy-loaded
 519                                 $this->mTextRow = null;
 520                         }
 521
 522                         // Use user_name for users and rev_user_text for IPs...
 523                         $this->mUserText = null; // lazy load if left null
 524                         if ( $this->mUser == 0 ) {
 525                                 $this->mUserText = $row->rev_user_text; // IP user
 526                         } elseif ( isset( $row->user_name ) ) {
 527                                 $this->mUserText = $row->user_name; // logged-in user
 528                         }
 529                         $this->mOrigUserText = $row->rev_user_text;
 530                 } elseif( is_array( $row ) ) {
 531                         // Build a new revision to be saved...
 532                         global $wgUser; // ugh
 533
 534
 535                         # if we have a content object, use it to set the model and type
 536                         if ( !empty( $row['content'] ) ) {
 537                                 if ( !empty( $row['text_id'] ) ) { //@todo: when is that set? test with external store setup! check out insertOn() [dk]
 538                                         throw new MWException( "Text already stored in external store (id {$row['text_id']}), can't serialize content object" );
 539                                 }
 540
 541                                 $row['content_model'] = $row['content']->getModel();
 542                                 # note: mContentFormat is initializes later accordingly
 543                                 # note: content is serialized later in this method!
 544                                 # also set text to null?
 545                         }
 546
 547                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 548                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 549                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 550                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 551                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 552                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 553                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestampNow();
 554                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 555                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 556                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 557                         $this->mSha1      = isset( $row['sha1']  )      ? strval( $row['sha1']  )      : null;
 558
 559                         $this->mContentModel = isset( $row['content_model']  )  ? strval( $row['content_model'] )  : null;
 560                         $this->mContentFormat    = isset( $row['content_format']  ) ? strval( $row['content_format'] ) : null;
 561
 562                         // Enforce spacing trimming on supplied text
 563                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 564                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 565                         $this->mTextRow   = null;
 566
 567                         $this->mTitle     = isset( $row['title']      ) ? $row['title'] : null;
 568
 569                         // if we have a Content object, override mText and mContentModel
 570                         if ( !empty( $row['content'] ) ) {
 571                                 $handler = $this->getContentHandler();
 572                                 $this->mContent = $row['content'];
 573
 574                                 $this->mContentModel = $this->mContent->getModel();
 575                                 $this->mContentHandler = null;
 576
 577                                 $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
 578                         } elseif ( !is_null( $this->mText ) ) {
 579                                 $handler = $this->getContentHandler();
 580                                 $this->mContent = $handler->unserializeContent( $this->mText );
 581                         }
 582
 583                         // if we have a Title object, override mPage. Useful for testing and convenience.
 584                         if ( isset( $row['title'] ) ) {
 585                                 $this->mTitle     = $row['title'];
 586                                 $this->mPage      = $this->mTitle->getArticleID();
 587                         } else {
 588                                 $this->mTitle     = null; // Load on demand if needed
 589                         }
 590
 591                         $this->mCurrent   = false; // @todo: XXX: really? we are about to create a revision. it will usually then be the current one.
 592
 593                         // If we still have no length, see it we have the text to figure it out
 594                         if ( !$this->mSize ) {
 595                                 if ( !is_null( $this->mContent ) ) {
 596                                         $this->mSize = $this->mContent->getSize();
 597                                 } else {
 598                                         #NOTE: this should never happen if we have either text or content object!
 599                                         $this->mSize = null;
 600                                 }
 601                         }
 602
 603                         // Same for sha1
 604                         if ( $this->mSha1 === null ) {
 605                                 $this->mSha1 = is_null( $this->mText ) ? null : self::base36Sha1( $this->mText );
 606                         }
 607
 608                         // force lazy init
 609                         $this->getContentModel();
 610                         $this->getContentFormat();
 611                 } else {
 612                         throw new MWException( 'Revision constructor passed invalid row format.' );
 613                 }
 614                 $this->mUnpatrolled = null;
 615         }
 616
 617         /**
 618          * Get revision ID
 619          *
 620          * @return Integer|null
 621          */
 622         public function getId() {
 623                 return $this->mId;
 624         }
 625
 626         /**
 627          * Set the revision ID
 628          *
 629          * @since 1.19
 630          * @param $id Integer
 631          */
 632         public function setId( $id ) {
 633                 $this->mId = $id;
 634         }
 635
 636         /**
 637          * Get text row ID
 638          *
 639          * @return Integer|null
 640          */
 641         public function getTextId() {
 642                 return $this->mTextId;
 643         }
 644
 645         /**
 646          * Get parent revision ID (the original previous page revision)
 647          *
 648          * @return Integer|null
 649          */
 650         public function getParentId() {
 651                 return $this->mParentId;
 652         }
 653
 654         /**
 655          * Returns the length of the text in this revision, or null if unknown.
 656          *
 657          * @return Integer|null
 658          */
 659         public function getSize() {
 660                 return $this->mSize;
 661         }
 662
 663         /**
 664          * Returns the base36 sha1 of the text in this revision, or null if unknown.
 665          *
 666          * @return String|null
 667          */
 668         public function getSha1() {
 669                 return $this->mSha1;
 670         }
 671
 672         /**
 673          * Returns the title of the page associated with this entry or null.
 674          *
 675          * Will do a query, when title is not set and id is given.
 676          *
 677          * @return Title|null
 678          */
 679         public function getTitle() {
 680                 if( isset( $this->mTitle ) ) {
 681                         return $this->mTitle;
 682                 }
 683                 if( !is_null( $this->mId ) ) { //rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
 684                         $dbr = wfGetDB( DB_SLAVE );
 685                         $row = $dbr->selectRow(
 686                                 array( 'page', 'revision' ),
 687                                 self::selectPageFields(),
 688                                 array( 'page_id=rev_page',
 689                                            'rev_id' => $this->mId ),
 690                                 __METHOD__ );
 691                         if ( $row ) {
 692                                 $this->mTitle = Title::newFromRow( $row );
 693                         }
 694                 }
 695
 696                 if ( !$this->mTitle && !is_null( $this->mPage ) && $this->mPage > 0 ) {
 697                         $this->mTitle = Title::newFromID( $this->mPage );
 698                 }
 699
 700                 return $this->mTitle;
 701         }
 702
 703         /**
 704          * Set the title of the revision
 705          *
 706          * @param $title Title
 707          */
 708         public function setTitle( $title ) {
 709                 $this->mTitle = $title;
 710         }
 711
 712         /**
 713          * Get the page ID
 714          *
 715          * @return Integer|null
 716          */
 717         public function getPage() {
 718                 return $this->mPage;
 719         }
 720
 721         /**
 722          * Fetch revision's user id if it's available to the specified audience.
 723          * If the specified audience does not have access to it, zero will be
 724          * returned.
 725          *
 726          * @param $audience Integer: one of:
 727          *      Revision::FOR_PUBLIC       to be displayed to all users
 728          *      Revision::FOR_THIS_USER    to be displayed to the given user
 729          *      Revision::RAW              get the ID regardless of permissions
 730          * @param $user User object to check for, only if FOR_THIS_USER is passed
 731          *              to the $audience parameter
 732          * @return Integer
 733          */
 734         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
 735                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 736                         return 0;
 737                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 738                         return 0;
 739                 } else {
 740                         return $this->mUser;
 741                 }
 742         }
 743
 744         /**
 745          * Fetch revision's user id without regard for the current user's permissions
 746          *
 747          * @return String
 748          */
 749         public function getRawUser() {
 750                 return $this->mUser;
 751         }
 752
 753         /**
 754          * Fetch revision's username if it's available to the specified audience.
 755          * If the specified audience does not have access to the username, an
 756          * empty string will be returned.
 757          *
 758          * @param $audience Integer: one of:
 759          *      Revision::FOR_PUBLIC       to be displayed to all users
 760          *      Revision::FOR_THIS_USER    to be displayed to the given user
 761          *      Revision::RAW              get the text regardless of permissions
 762          * @param $user User object to check for, only if FOR_THIS_USER is passed
 763          *              to the $audience parameter
 764          * @return string
 765          */
 766         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
 767                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 768                         return '';
 769                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 770                         return '';
 771                 } else {
 772                         return $this->getRawUserText();
 773                 }
 774         }
 775
 776         /**
 777          * Fetch revision's username without regard for view restrictions
 778          *
 779          * @return String
 780          */
 781         public function getRawUserText() {
 782                 if ( $this->mUserText === null ) {
 783                         $this->mUserText = User::whoIs( $this->mUser ); // load on demand
 784                         if ( $this->mUserText === false ) {
 785                                 # This shouldn't happen, but it can if the wiki was recovered
 786                                 # via importing revs and there is no user table entry yet.
 787                                 $this->mUserText = $this->mOrigUserText;
 788                         }
 789                 }
 790                 return $this->mUserText;
 791         }
 792
 793         /**
 794          * Fetch revision comment if it's available to the specified audience.
 795          * If the specified audience does not have access to the comment, an
 796          * empty string will be returned.
 797          *
 798          * @param $audience Integer: one of:
 799          *      Revision::FOR_PUBLIC       to be displayed to all users
 800          *      Revision::FOR_THIS_USER    to be displayed to the given user
 801          *      Revision::RAW              get the text regardless of permissions
 802          * @param $user User object to check for, only if FOR_THIS_USER is passed
 803          *              to the $audience parameter
 804          * @return String
 805          */
 806         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
 807                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 808                         return '';
 809                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
 810                         return '';
 811                 } else {
 812                         return $this->mComment;
 813                 }
 814         }
 815
 816         /**
 817          * Fetch revision comment without regard for the current user's permissions
 818          *
 819          * @return String
 820          */
 821         public function getRawComment() {
 822                 return $this->mComment;
 823         }
 824
 825         /**
 826          * @return Boolean
 827          */
 828         public function isMinor() {
 829                 return (bool)$this->mMinorEdit;
 830         }
 831
 832         /**
 833          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 834          */
 835         public function isUnpatrolled() {
 836                 if( $this->mUnpatrolled !== null ) {
 837                         return $this->mUnpatrolled;
 838                 }
 839                 $dbr = wfGetDB( DB_SLAVE );
 840                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 841                         'rc_id',
 842                         array( // Add redundant user,timestamp condition so we can use the existing index
 843                                 'rc_user_text'  => $this->getRawUserText(),
 844                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 845                                 'rc_this_oldid' => $this->getId(),
 846                                 'rc_patrolled'  => 0
 847                         ),
 848                         __METHOD__
 849                 );
 850                 return (int)$this->mUnpatrolled;
 851         }
 852
 853         /**
 854          * @param $field int one of DELETED_* bitfield constants
 855          *
 856          * @return Boolean
 857          */
 858         public function isDeleted( $field ) {
 859                 return ( $this->mDeleted & $field ) == $field;
 860         }
 861
 862         /**
 863          * Get the deletion bitfield of the revision
 864          *
 865          * @return int
 866          */
 867         public function getVisibility() {
 868                 return (int)$this->mDeleted;
 869         }
 870
 871         /**
 872          * Fetch revision text if it's available to the specified audience.
 873          * If the specified audience does not have the ability to view this
 874          * revision, an empty string will be returned.
 875          *
 876          * @param $audience Integer: one of:
 877          *      Revision::FOR_PUBLIC       to be displayed to all users
 878          *      Revision::FOR_THIS_USER    to be displayed to the given user
 879          *      Revision::RAW              get the text regardless of permissions
 880          * @param $user User object to check for, only if FOR_THIS_USER is passed
 881          *              to the $audience parameter
 882          * @return String
 883          * @deprecated in 1.WD, use getContent() instead
 884          * @todo: replace usage in core
 885          */
 886         public function getText( $audience = self::FOR_PUBLIC, User $user = null ) {
 887                 wfDeprecated( __METHOD__, '1.WD' );
 888
 889                 $content = $this->getContent( $audience, $user );
 890                 return ContentHandler::getContentText( $content ); # returns the raw content text, if applicable
 891         }
 892
 893         /**
 894          * Fetch revision content if it's available to the specified audience.
 895          * If the specified audience does not have the ability to view this
 896          * revision, null will be returned.
 897          *
 898          * @param $audience Integer: one of:
 899          *      Revision::FOR_PUBLIC       to be displayed to all users
 900          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 901          *      Revision::RAW              get the text regardless of permissions
 902          * @param $user User object to check for, only if FOR_THIS_USER is passed
 903          *              to the $audience parameter
 904          * @return Content
 905          *
 906          * @since 1.WD
 907          */
 908         public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
 909                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 910                         return null;
 911                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
 912                         return null;
 913                 } else {
 914                         return $this->getContentInternal();
 915                 }
 916         }
 917
 918         /**
 919          * Alias for getText(Revision::FOR_THIS_USER)
 920          *
 921          * @deprecated since 1.17
 922          * @return String
 923          */
 924         public function revText() {
 925                 wfDeprecated( __METHOD__, '1.17' );
 926                 return $this->getText( self::FOR_THIS_USER );
 927         }
 928
 929         /**
 930          * Fetch revision text without regard for view restrictions
 931          *
 932          * @return String
 933          *
 934          * @deprecated since 1.WD. Instead, use Revision::getContent( Revision::RAW ) or Revision::getSerializedData() as appropriate.
 935          */
 936         public function getRawText() {
 937                 wfDeprecated( __METHOD__, "1.WD" );
 938
 939                 return $this->getText( self::RAW );
 940         }
 941
 942         /**
 943          * Fetch original serialized data without regard for view restrictions
 944          *
 945          * @return String
 946          *
 947          * @since 1.WD
 948          */
 949         public function getSerializedData() {
 950                 return $this->mText;
 951         }
 952
 953         protected function getContentInternal() {
 954                 if( is_null( $this->mContent ) ) {
 955                         // Revision is immutable. Load on demand:
 956
 957                         $handler = $this->getContentHandler();
 958                         $format = $this->getContentFormat();
 959                         $title = $this->getTitle();
 960
 961                         if( is_null( $this->mText ) ) {
 962                                 // Load text on demand:
 963                                 $this->mText = $this->loadText();
 964                         }
 965
 966                         $this->mContent = is_null( $this->mText ) ? null : $handler->unserializeContent( $this->mText, $format );
 967                 }
 968
 969                 return $this->mContent;
 970         }
 971
 972         /**
 973          * Returns the content model for this revision.
 974          *
 975          * If no content model was stored in the database, $this->getTitle()->getContentModel() is
 976          * used to determine the content model to use. If no title is know, CONTENT_MODEL_WIKITEXT
 977          * is used as a last resort.
 978          *
 979          * @return String the content model id associated with this revision, see the CONTENT_MODEL_XXX constants.
 980          **/
 981         public function getContentModel() {
 982                 if ( !$this->mContentModel ) {
 983                         $title = $this->getTitle();
 984                         $this->mContentModel = ( $title ? $title->getContentModel() : CONTENT_MODEL_WIKITEXT );
 985
 986                         assert( !empty( $this->mContentModel ) );
 987                 }
 988
 989                 return $this->mContentModel;
 990         }
 991
 992         /**
 993          * Returns the content format for this revision.
 994          *
 995          * If no content format was stored in the database, the default format for this
 996          * revision's content model is returned.
 997          *
 998          * @return String the content format id associated with this revision, see the CONTENT_FORMAT_XXX constants.
 999          **/
1000         public function getContentFormat() {
1001                 if ( !$this->mContentFormat ) {
1002                         $handler = $this->getContentHandler();
1003                         $this->mContentFormat = $handler->getDefaultFormat();
1004
1005                         assert( !empty( $this->mContentFormat ) );
1006                 }
1007
1008                 return $this->mContentFormat;
1009         }
1010
1011         /**
1012          * Returns the content handler appropriate for this revision's content model.
1013          *
1014          * @return ContentHandler
1015          */
1016         public function getContentHandler() {
1017                 if ( !$this->mContentHandler ) {
1018                         $model = $this->getContentModel();
1019                         $this->mContentHandler = ContentHandler::getForModelID( $model );
1020
1021                         $format = $this->getContentFormat();
1022
1023                         if ( !$this->mContentHandler->isSupportedFormat( $format ) ) {
1024                                 throw new MWException( "Oops, the content format $format is not supported for this content model, $model" );
1025                         }
1026                 }
1027
1028                 return $this->mContentHandler;
1029         }
1030
1031         /**
1032          * @return String
1033          */
1034         public function getTimestamp() {
1035                 return wfTimestamp( TS_MW, $this->mTimestamp );
1036         }
1037
1038         /**
1039          * @return Boolean
1040          */
1041         public function isCurrent() {
1042                 return $this->mCurrent;
1043         }
1044
1045         /**
1046          * Get previous revision for this title
1047          *
1048          * @return Revision or null
1049          */
1050         public function getPrevious() {
1051                 if( $this->getTitle() ) {
1052                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
1053                         if( $prev ) {
1054                                 return self::newFromTitle( $this->getTitle(), $prev );
1055                         }
1056                 }
1057                 return null;
1058         }
1059
1060         /**
1061          * Get next revision for this title
1062          *
1063          * @return Revision or null
1064          */
1065         public function getNext() {
1066                 if( $this->getTitle() ) {
1067                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
1068                         if ( $next ) {
1069                                 return self::newFromTitle( $this->getTitle(), $next );
1070                         }
1071                 }
1072                 return null;
1073         }
1074
1075         /**
1076          * Get previous revision Id for this page_id
1077          * This is used to populate rev_parent_id on save
1078          *
1079          * @param $db DatabaseBase
1080          * @return Integer
1081          */
1082         private function getPreviousRevisionId( $db ) {
1083                 if( is_null( $this->mPage ) ) {
1084                         return 0;
1085                 }
1086                 # Use page_latest if ID is not given
1087                 if( !$this->mId ) {
1088                         $prevId = $db->selectField( 'page', 'page_latest',
1089                                 array( 'page_id' => $this->mPage ),
1090                                 __METHOD__ );
1091                 } else {
1092                         $prevId = $db->selectField( 'revision', 'rev_id',
1093                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
1094                                 __METHOD__,
1095                                 array( 'ORDER BY' => 'rev_id DESC' ) );
1096                 }
1097                 return intval( $prevId );
1098         }
1099
1100         /**
1101           * Get revision text associated with an old or archive row
1102           * $row is usually an object from wfFetchRow(), both the flags and the text
1103           * field must be included
1104           *
1105           * @param $row Object: the text data
1106           * @param $prefix String: table prefix (default 'old_')
1107           * @return String: text the text requested or false on failure
1108           */
1109         public static function getRevisionText( $row, $prefix = 'old_' ) {
1110                 wfProfileIn( __METHOD__ );
1111
1112                 # Get data
1113                 $textField = $prefix . 'text';
1114                 $flagsField = $prefix . 'flags';
1115
1116                 if( isset( $row->$flagsField ) ) {
1117                         $flags = explode( ',', $row->$flagsField );
1118                 } else {
1119                         $flags = array();
1120                 }
1121
1122                 if( isset( $row->$textField ) ) {
1123                         $text = $row->$textField;
1124                 } else {
1125                         wfProfileOut( __METHOD__ );
1126                         return false;
1127                 }
1128
1129                 # Use external methods for external objects, text in table is URL-only then
1130                 if ( in_array( 'external', $flags ) ) {
1131                         $url = $text;
1132                         $parts = explode( '://', $url, 2 );
1133                         if( count( $parts ) == 1 || $parts[1] == '' ) {
1134                                 wfProfileOut( __METHOD__ );
1135                                 return false;
1136                         }
1137                         $text = ExternalStore::fetchFromURL( $url );
1138                 }
1139
1140                 // If the text was fetched without an error, convert it
1141                 if ( $text !== false ) {
1142                         if( in_array( 'gzip', $flags ) ) {
1143                                 # Deal with optional compression of archived pages.
1144                                 # This can be done periodically via maintenance/compressOld.php, and
1145                                 # as pages are saved if $wgCompressRevisions is set.
1146                                 $text = gzinflate( $text );
1147                         }
1148
1149                         if( in_array( 'object', $flags ) ) {
1150                                 # Generic compressed storage
1151                                 $obj = unserialize( $text );
1152                                 if ( !is_object( $obj ) ) {
1153                                         // Invalid object
1154                                         wfProfileOut( __METHOD__ );
1155                                         return false;
1156                                 }
1157                                 $text = $obj->getText();
1158                         }
1159
1160                         global $wgLegacyEncoding;
1161                         if( $text !== false && $wgLegacyEncoding
1162                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
1163                         {
1164                                 # Old revisions kept around in a legacy encoding?
1165                                 # Upconvert on demand.
1166                                 # ("utf8" checked for compatibility with some broken
1167                                 #  conversion scripts 2008-12-30)
1168                                 global $wgContLang;
1169                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
1170                         }
1171                 }
1172                 wfProfileOut( __METHOD__ );
1173                 return $text;
1174         }
1175
1176         /**
1177          * If $wgCompressRevisions is enabled, we will compress data.
1178          * The input string is modified in place.
1179          * Return value is the flags field: contains 'gzip' if the
1180          * data is compressed, and 'utf-8' if we're saving in UTF-8
1181          * mode.
1182          *
1183          * @param $text Mixed: reference to a text
1184          * @return String
1185          */
1186         public static function compressRevisionText( &$text ) {
1187                 global $wgCompressRevisions;
1188                 $flags = array();
1189
1190                 # Revisions not marked this way will be converted
1191                 # on load if $wgLegacyCharset is set in the future.
1192                 $flags[] = 'utf-8';
1193
1194                 if( $wgCompressRevisions ) {
1195                         if( function_exists( 'gzdeflate' ) ) {
1196                                 $text = gzdeflate( $text );
1197                                 $flags[] = 'gzip';
1198                         } else {
1199                                 wfDebug( __METHOD__ . " -- no zlib support, not compressing\n" );
1200                         }
1201                 }
1202                 return implode( ',', $flags );
1203         }
1204
1205         /**
1206          * Insert a new revision into the database, returning the new revision ID
1207          * number on success and dies horribly on failure.
1208          *
1209          * @param $dbw DatabaseBase: (master connection)
1210          * @return Integer
1211          */
1212         public function insertOn( $dbw ) {
1213                 global $wgDefaultExternalStore, $wgContentHandlerUseDB;
1214
1215                 wfProfileIn( __METHOD__ );
1216
1217                 $this->checkContentModel();
1218
1219                 $data = $this->mText;
1220                 $flags = self::compressRevisionText( $data );
1221
1222                 # Write to external storage if required
1223                 if( $wgDefaultExternalStore ) {
1224                         // Store and get the URL
1225                         $data = ExternalStore::insertToDefault( $data );
1226                         if( !$data ) {
1227                                 throw new MWException( "Unable to store text to external storage" );
1228                         }
1229                         if( $flags ) {
1230                                 $flags .= ',';
1231                         }
1232                         $flags .= 'external';
1233                 }
1234
1235                 # Record the text (or external storage URL) to the text table
1236                 if( !isset( $this->mTextId ) ) {
1237                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
1238                         $dbw->insert( 'text',
1239                                 array(
1240                                         'old_id'    => $old_id,
1241                                         'old_text'  => $data,
1242                                         'old_flags' => $flags,
1243                                 ), __METHOD__
1244                         );
1245                         $this->mTextId = $dbw->insertId();
1246                 }
1247
1248                 if ( $this->mComment === null ) $this->mComment = "";
1249
1250                 # Record the edit in revisions
1251                 $rev_id = isset( $this->mId )
1252                         ? $this->mId
1253                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
1254                 $row = array(
1255                         'rev_id'         => $rev_id,
1256                         'rev_page'       => $this->mPage,
1257                         'rev_text_id'    => $this->mTextId,
1258                         'rev_comment'    => $this->mComment,
1259                         'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
1260                         'rev_user'       => $this->mUser,
1261                         'rev_user_text'  => $this->mUserText,
1262                         'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
1263                         'rev_deleted'    => $this->mDeleted,
1264                         'rev_len'        => $this->mSize,
1265                         'rev_parent_id'  => is_null( $this->mParentId )
1266                                 ? $this->getPreviousRevisionId( $dbw )
1267                                 : $this->mParentId,
1268                         'rev_sha1'       => is_null( $this->mSha1 )
1269                                 ? Revision::base36Sha1( $this->mText )
1270                                 : $this->mSha1,
1271                 );
1272
1273                 if ( $wgContentHandlerUseDB ) {
1274                         //NOTE: Store null for the default model and format, to save space.
1275                         //XXX: Makes the DB sensitive to changed defaults. Make this behaviour optional? Only in miser mode?
1276
1277                         $model = $this->getContentModel();
1278                         $format = $this->getContentFormat();
1279
1280                         $defaultModel = ContentHandler::getDefaultModelFor( $this->getTitle() );
1281                         $defaultFormat = ContentHandler::getForModelID( $defaultModel )->getDefaultFormat();
1282
1283                         $row[ 'rev_content_model' ] = ( $model === $defaultModel ) ? null : $model;
1284                         $row[ 'rev_content_format' ] = ( $format === $defaultFormat ) ? null : $format;
1285                 }
1286
1287                 $dbw->insert( 'revision', $row, __METHOD__ );
1288
1289                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
1290
1291                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
1292
1293                 wfProfileOut( __METHOD__ );
1294                 return $this->mId;
1295         }
1296
1297         protected function checkContentModel() {
1298                 global $wgContentHandlerUseDB;
1299
1300                 $title = $this->getTitle(); //note: may return null for revisions that have not yet been inserted.
1301
1302                 $model = $this->getContentModel();
1303                 $format = $this->getContentFormat();
1304                 $handler = $this->getContentHandler();
1305
1306                 if ( !$handler->isSupportedFormat( $format ) ) {
1307                         $t = $title->getPrefixedDBkey();
1308
1309                         throw new MWException( "Can't use format $format with content model $model on $t" );
1310                 }
1311
1312                 if ( !$wgContentHandlerUseDB && $title ) {
1313                         // if $wgContentHandlerUseDB is not set, all revisions must use the default content model and format.
1314
1315                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1316                         $defaultHandler = ContentHandler::getForModelID( $defaultModel );
1317                         $defaultFormat = $defaultHandler->getDefaultFormat();
1318
1319                         if ( $this->getContentModel() != $defaultModel ) {
1320                                 $t = $title->getPrefixedDBkey();
1321
1322                                 throw new MWException( "Can't save non-default content model with \$wgContentHandlerUseDB disabled: model is $model , default for $t is $defaultModel" );
1323                         }
1324
1325                         if ( $this->getContentFormat() != $defaultFormat ) {
1326                                 $t = $title->getPrefixedDBkey();
1327
1328                                 throw new MWException( "Can't use non-default content format with \$wgContentHandlerUseDB disabled: format is $format, default for $t is $defaultFormat" );
1329                         }
1330                 }
1331
1332                 $content = $this->getContent( Revision::RAW );
1333
1334                 if ( !$content->isValid() ) {
1335                         $t = $title->getPrefixedDBkey();
1336
1337                         throw new MWException( "Content of $t is not valid! Content model is $model" );
1338                 }
1339         }
1340
1341         /**
1342          * Get the base 36 SHA-1 value for a string of text
1343          * @param $text String
1344          * @return String
1345          */
1346         public static function base36Sha1( $text ) {
1347                 return wfBaseConvert( sha1( $text ), 16, 36, 31 );
1348         }
1349
1350         /**
1351          * Lazy-load the revision's text.
1352          * Currently hardcoded to the 'text' table storage engine.
1353          *
1354          * @return String
1355          */
1356         protected function loadText() {
1357                 wfProfileIn( __METHOD__ );
1358
1359                 // Caching may be beneficial for massive use of external storage
1360                 global $wgRevisionCacheExpiry, $wgMemc;
1361                 $textId = $this->getTextId();
1362                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
1363                 if( $wgRevisionCacheExpiry ) {
1364                         $text = $wgMemc->get( $key );
1365                         if( is_string( $text ) ) {
1366                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
1367                                 wfProfileOut( __METHOD__ );
1368                                 return $text;
1369                         }
1370                 }
1371
1372                 // If we kept data for lazy extraction, use it now...
1373                 if ( isset( $this->mTextRow ) ) {
1374                         $row = $this->mTextRow;
1375                         $this->mTextRow = null;
1376                 } else {
1377                         $row = null;
1378                 }
1379
1380                 if( !$row ) {
1381                         // Text data is immutable; check slaves first.
1382                         $dbr = wfGetDB( DB_SLAVE );
1383                         $row = $dbr->selectRow( 'text',
1384                                 array( 'old_text', 'old_flags' ),
1385                                 array( 'old_id' => $this->getTextId() ),
1386                                 __METHOD__ );
1387                 }
1388
1389                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
1390                         // Possible slave lag!
1391                         $dbw = wfGetDB( DB_MASTER );
1392                         $row = $dbw->selectRow( 'text',
1393                                 array( 'old_text', 'old_flags' ),
1394                                 array( 'old_id' => $this->getTextId() ),
1395                                 __METHOD__ );
1396                 }
1397
1398                 $text = self::getRevisionText( $row );
1399
1400                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
1401                 if( $wgRevisionCacheExpiry && $text !== false ) {
1402                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
1403                 }
1404
1405                 wfProfileOut( __METHOD__ );
1406
1407                 return $text;
1408         }
1409
1410         /**
1411          * Create a new null-revision for insertion into a page's
1412          * history. This will not re-save the text, but simply refer
1413          * to the text from the previous version.
1414          *
1415          * Such revisions can for instance identify page rename
1416          * operations and other such meta-modifications.
1417          *
1418          * @param $dbw DatabaseBase
1419          * @param $pageId Integer: ID number of the page to read from
1420          * @param $summary String: revision's summary
1421          * @param $minor Boolean: whether the revision should be considered as minor
1422          * @return Revision|null on error
1423          */
1424         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
1425                 global $wgContentHandlerUseDB;
1426
1427                 wfProfileIn( __METHOD__ );
1428
1429                 $fields = array( 'page_latest', 'page_namespace', 'page_title',
1430                                                 'rev_text_id', 'rev_len', 'rev_sha1' );
1431
1432                 if ( $wgContentHandlerUseDB ) {
1433                         $fields[] = 'rev_content_model';
1434                         $fields[] = 'rev_content_format';
1435                 }
1436
1437                 $current = $dbw->selectRow(
1438                         array( 'page', 'revision' ),
1439                         $fields,
1440                         array(
1441                                 'page_id' => $pageId,
1442                                 'page_latest=rev_id',
1443                                 ),
1444                         __METHOD__ );
1445
1446                 if( $current ) {
1447                         $row = array(
1448                                 'page'       => $pageId,
1449                                 'comment'    => $summary,
1450                                 'minor_edit' => $minor,
1451                                 'text_id'    => $current->rev_text_id,
1452                                 'parent_id'  => $current->page_latest,
1453                                 'len'        => $current->rev_len,
1454                                 'sha1'       => $current->rev_sha1
1455                         );
1456
1457                         if ( $wgContentHandlerUseDB ) {
1458                                 $row[ 'content_model' ] = $current->rev_content_model;
1459                                 $row[ 'content_format' ] = $current->rev_content_format;
1460                         }
1461
1462                         $revision = new Revision( $row );
1463                         $revision->setTitle( Title::makeTitle( $current->page_namespace, $current->page_title ) );
1464                 } else {
1465                         $revision = null;
1466                 }
1467
1468                 wfProfileOut( __METHOD__ );
1469                 return $revision;
1470         }
1471
1472         /**
1473          * Determine if the current user is allowed to view a particular
1474          * field of this revision, if it's marked as deleted.
1475          *
1476          * @param $field Integer:one of self::DELETED_TEXT,
1477          *                              self::DELETED_COMMENT,
1478          *                              self::DELETED_USER
1479          * @param $user User object to check, or null to use $wgUser
1480          * @return Boolean
1481          */
1482         public function userCan( $field, User $user = null ) {
1483                 return self::userCanBitfield( $this->mDeleted, $field, $user );
1484         }
1485
1486         /**
1487          * Determine if the current user is allowed to view a particular
1488          * field of this revision, if it's marked as deleted. This is used
1489          * by various classes to avoid duplication.
1490          *
1491          * @param $bitfield Integer: current field
1492          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1493          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1494          *                               self::DELETED_USER = File::DELETED_USER
1495          * @param $user User object to check, or null to use $wgUser
1496          * @return Boolean
1497          */
1498         public static function userCanBitfield( $bitfield, $field, User $user = null ) {
1499                 if( $bitfield & $field ) { // aspect is deleted
1500                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1501                                 $permission = 'suppressrevision';
1502                         } elseif ( $field & self::DELETED_TEXT ) {
1503                                 $permission = 'deletedtext';
1504                         } else {
1505                                 $permission = 'deletedhistory';
1506                         }
1507                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1508                         if ( $user === null ) {
1509                                 global $wgUser;
1510                                 $user = $wgUser;
1511                         }
1512                         return $user->isAllowed( $permission );
1513                 } else {
1514                         return true;
1515                 }
1516         }
1517
1518         /**
1519          * Get rev_timestamp from rev_id, without loading the rest of the row
1520          *
1521          * @param $title Title
1522          * @param $id Integer
1523          * @return String
1524          */
1525         static function getTimestampFromId( $title, $id ) {
1526                 $dbr = wfGetDB( DB_SLAVE );
1527                 // Casting fix for DB2
1528                 if ( $id == '' ) {
1529                         $id = 0;
1530                 }
1531                 $conds = array( 'rev_id' => $id );
1532                 $conds['rev_page'] = $title->getArticleID();
1533                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1534                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1535                         # Not in slave, try master
1536                         $dbw = wfGetDB( DB_MASTER );
1537                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1538                 }
1539                 return wfTimestamp( TS_MW, $timestamp );
1540         }
1541
1542         /**
1543          * Get count of revisions per page...not very efficient
1544          *
1545          * @param $db DatabaseBase
1546          * @param $id Integer: page id
1547          * @return Integer
1548          */
1549         static function countByPageId( $db, $id ) {
1550                 $row = $db->selectRow( 'revision', array( 'revCount' => 'COUNT(*)' ),
1551                         array( 'rev_page' => $id ), __METHOD__ );
1552                 if( $row ) {
1553                         return $row->revCount;
1554                 }
1555                 return 0;
1556         }
1557
1558         /**
1559          * Get count of revisions per page...not very efficient
1560          *
1561          * @param $db DatabaseBase
1562          * @param $title Title
1563          * @return Integer
1564          */
1565         static function countByTitle( $db, $title ) {
1566                 $id = $title->getArticleID();
1567                 if( $id ) {
1568                         return self::countByPageId( $db, $id );
1569                 }
1570                 return 0;
1571         }
1572 }