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 use Wikimedia\Rdbms\Database;
  24 use Wikimedia\Rdbms\IDatabase;
  25 use MediaWiki\Linker\LinkTarget;
  26 use MediaWiki\MediaWikiServices;
  27 use Wikimedia\Rdbms\ResultWrapper;
  28 use Wikimedia\Rdbms\FakeResultWrapper;
  29
  30 /**
  31  * @todo document
  32  */
  33 class Revision implements IDBAccessObject {
  34         /** @var int|null */
  35         protected $mId;
  36         /** @var int|null */
  37         protected $mPage;
  38         /** @var string */
  39         protected $mUserText;
  40         /** @var string */
  41         protected $mOrigUserText;
  42         /** @var int */
  43         protected $mUser;
  44         /** @var bool */
  45         protected $mMinorEdit;
  46         /** @var string */
  47         protected $mTimestamp;
  48         /** @var int */
  49         protected $mDeleted;
  50         /** @var int */
  51         protected $mSize;
  52         /** @var string */
  53         protected $mSha1;
  54         /** @var int */
  55         protected $mParentId;
  56         /** @var string */
  57         protected $mComment;
  58         /** @var string */
  59         protected $mText;
  60         /** @var int */
  61         protected $mTextId;
  62         /** @var int */
  63         protected $mUnpatrolled;
  64
  65         /** @var stdClass|null */
  66         protected $mTextRow;
  67
  68         /**  @var null|Title */
  69         protected $mTitle;
  70         /** @var bool */
  71         protected $mCurrent;
  72         /** @var string */
  73         protected $mContentModel;
  74         /** @var string */
  75         protected $mContentFormat;
  76
  77         /** @var Content|null|bool */
  78         protected $mContent;
  79         /** @var null|ContentHandler */
  80         protected $mContentHandler;
  81
  82         /** @var int */
  83         protected $mQueryFlags = 0;
  84         /** @var bool Used for cached values to reload user text and rev_deleted */
  85         protected $mRefreshMutableFields = false;
  86         /** @var string Wiki ID; false means the current wiki */
  87         protected $mWiki = false;
  88
  89         // Revision deletion constants
  90         const DELETED_TEXT = 1;
  91         const DELETED_COMMENT = 2;
  92         const DELETED_USER = 4;
  93         const DELETED_RESTRICTED = 8;
  94         const SUPPRESSED_USER = 12; // convenience
  95         const SUPPRESSED_ALL = 15; // convenience
  96
  97         // Audience options for accessors
  98         const FOR_PUBLIC = 1;
  99         const FOR_THIS_USER = 2;
 100         const RAW = 3;
 101
 102         const TEXT_CACHE_GROUP = 'revisiontext:10'; // process cache name and max key count
 103
 104         /**
 105          * Load a page revision from a given revision ID number.
 106          * Returns null if no such revision can be found.
 107          *
 108          * $flags include:
 109          *      Revision::READ_LATEST  : Select the data from the master
 110          *      Revision::READ_LOCKING : Select & lock the data from the master
 111          *
 112          * @param int $id
 113          * @param int $flags (optional)
 114          * @return Revision|null
 115          */
 116         public static function newFromId( $id, $flags = 0 ) {
 117                 return self::newFromConds( [ 'rev_id' => intval( $id ) ], $flags );
 118         }
 119
 120         /**
 121          * Load either the current, or a specified, revision
 122          * that's attached to a given link target. If not attached
 123          * to that link target, will return null.
 124          *
 125          * $flags include:
 126          *      Revision::READ_LATEST  : Select the data from the master
 127          *      Revision::READ_LOCKING : Select & lock the data from the master
 128          *
 129          * @param LinkTarget $linkTarget
 130          * @param int $id (optional)
 131          * @param int $flags Bitfield (optional)
 132          * @return Revision|null
 133          */
 134         public static function newFromTitle( LinkTarget $linkTarget, $id = 0, $flags = 0 ) {
 135                 $conds = [
 136                         'page_namespace' => $linkTarget->getNamespace(),
 137                         'page_title' => $linkTarget->getDBkey()
 138                 ];
 139                 if ( $id ) {
 140                         // Use the specified ID
 141                         $conds['rev_id'] = $id;
 142                         return self::newFromConds( $conds, $flags );
 143                 } else {
 144                         // Use a join to get the latest revision
 145                         $conds[] = 'rev_id=page_latest';
 146                         $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 147                         return self::loadFromConds( $db, $conds, $flags );
 148                 }
 149         }
 150
 151         /**
 152          * Load either the current, or a specified, revision
 153          * that's attached to a given page ID.
 154          * Returns null if no such revision can be found.
 155          *
 156          * $flags include:
 157          *      Revision::READ_LATEST  : Select the data from the master (since 1.20)
 158          *      Revision::READ_LOCKING : Select & lock the data from the master
 159          *
 160          * @param int $pageId
 161          * @param int $revId (optional)
 162          * @param int $flags Bitfield (optional)
 163          * @return Revision|null
 164          */
 165         public static function newFromPageId( $pageId, $revId = 0, $flags = 0 ) {
 166                 $conds = [ 'page_id' => $pageId ];
 167                 if ( $revId ) {
 168                         $conds['rev_id'] = $revId;
 169                         return self::newFromConds( $conds, $flags );
 170                 } else {
 171                         // Use a join to get the latest revision
 172                         $conds[] = 'rev_id = page_latest';
 173                         $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 174                         return self::loadFromConds( $db, $conds, $flags );
 175                 }
 176         }
 177
 178         /**
 179          * Make a fake revision object from an archive table row. This is queried
 180          * for permissions or even inserted (as in Special:Undelete)
 181          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
 182          *
 183          * @param object $row
 184          * @param array $overrides
 185          *
 186          * @throws MWException
 187          * @return Revision
 188          */
 189         public static function newFromArchiveRow( $row, $overrides = [] ) {
 190                 global $wgContentHandlerUseDB;
 191
 192                 $attribs = $overrides + [
 193                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 194                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 195                         'comment'    => CommentStore::newKey( 'ar_comment' )
 196                                 // Legacy because $row may have come from self::selectArchiveFields()
 197                                 ->getCommentLegacy( wfGetDB( DB_REPLICA ), $row, true )->text,
 198                         'user'       => $row->ar_user,
 199                         'user_text'  => $row->ar_user_text,
 200                         'timestamp'  => $row->ar_timestamp,
 201                         'minor_edit' => $row->ar_minor_edit,
 202                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 203                         'deleted'    => $row->ar_deleted,
 204                         'len'        => $row->ar_len,
 205                         'sha1'       => isset( $row->ar_sha1 ) ? $row->ar_sha1 : null,
 206                         'content_model'   => isset( $row->ar_content_model ) ? $row->ar_content_model : null,
 207                         'content_format'  => isset( $row->ar_content_format ) ? $row->ar_content_format : null,
 208                 ];
 209
 210                 if ( !$wgContentHandlerUseDB ) {
 211                         unset( $attribs['content_model'] );
 212                         unset( $attribs['content_format'] );
 213                 }
 214
 215                 if ( !isset( $attribs['title'] )
 216                         && isset( $row->ar_namespace )
 217                         && isset( $row->ar_title )
 218                 ) {
 219                         $attribs['title'] = Title::makeTitle( $row->ar_namespace, $row->ar_title );
 220                 }
 221
 222                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 223                         // Pre-1.5 ar_text row
 224                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 225                         if ( $attribs['text'] === false ) {
 226                                 throw new MWException( 'Unable to load text from archive row (possibly T24624)' );
 227                         }
 228                 }
 229                 return new self( $attribs );
 230         }
 231
 232         /**
 233          * @since 1.19
 234          *
 235          * @param object $row
 236          * @return Revision
 237          */
 238         public static function newFromRow( $row ) {
 239                 return new self( $row );
 240         }
 241
 242         /**
 243          * Load a page revision from a given revision ID number.
 244          * Returns null if no such revision can be found.
 245          *
 246          * @param IDatabase $db
 247          * @param int $id
 248          * @return Revision|null
 249          */
 250         public static function loadFromId( $db, $id ) {
 251                 return self::loadFromConds( $db, [ 'rev_id' => intval( $id ) ] );
 252         }
 253
 254         /**
 255          * Load either the current, or a specified, revision
 256          * that's attached to a given page. If not attached
 257          * to that page, will return null.
 258          *
 259          * @param IDatabase $db
 260          * @param int $pageid
 261          * @param int $id
 262          * @return Revision|null
 263          */
 264         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 265                 $conds = [ 'rev_page' => intval( $pageid ), 'page_id' => intval( $pageid ) ];
 266                 if ( $id ) {
 267                         $conds['rev_id'] = intval( $id );
 268                 } else {
 269                         $conds[] = 'rev_id=page_latest';
 270                 }
 271                 return self::loadFromConds( $db, $conds );
 272         }
 273
 274         /**
 275          * Load either the current, or a specified, revision
 276          * that's attached to a given page. If not attached
 277          * to that page, will return null.
 278          *
 279          * @param IDatabase $db
 280          * @param Title $title
 281          * @param int $id
 282          * @return Revision|null
 283          */
 284         public static function loadFromTitle( $db, $title, $id = 0 ) {
 285                 if ( $id ) {
 286                         $matchId = intval( $id );
 287                 } else {
 288                         $matchId = 'page_latest';
 289                 }
 290                 return self::loadFromConds( $db,
 291                         [
 292                                 "rev_id=$matchId",
 293                                 'page_namespace' => $title->getNamespace(),
 294                                 'page_title' => $title->getDBkey()
 295                         ]
 296                 );
 297         }
 298
 299         /**
 300          * Load the revision for the given title with the given timestamp.
 301          * WARNING: Timestamps may in some circumstances not be unique,
 302          * so this isn't the best key to use.
 303          *
 304          * @param IDatabase $db
 305          * @param Title $title
 306          * @param string $timestamp
 307          * @return Revision|null
 308          */
 309         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 310                 return self::loadFromConds( $db,
 311                         [
 312                                 'rev_timestamp' => $db->timestamp( $timestamp ),
 313                                 'page_namespace' => $title->getNamespace(),
 314                                 'page_title' => $title->getDBkey()
 315                         ]
 316                 );
 317         }
 318
 319         /**
 320          * Given a set of conditions, fetch a revision
 321          *
 322          * This method is used then a revision ID is qualified and
 323          * will incorporate some basic replica DB/master fallback logic
 324          *
 325          * @param array $conditions
 326          * @param int $flags (optional)
 327          * @return Revision|null
 328          */
 329         private static function newFromConds( $conditions, $flags = 0 ) {
 330                 $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 331
 332                 $rev = self::loadFromConds( $db, $conditions, $flags );
 333                 // Make sure new pending/committed revision are visibile later on
 334                 // within web requests to certain avoid bugs like T93866 and T94407.
 335                 if ( !$rev
 336                         && !( $flags & self::READ_LATEST )
 337                         && wfGetLB()->getServerCount() > 1
 338                         && wfGetLB()->hasOrMadeRecentMasterChanges()
 339                 ) {
 340                         $flags = self::READ_LATEST;
 341                         $db = wfGetDB( DB_MASTER );
 342                         $rev = self::loadFromConds( $db, $conditions, $flags );
 343                 }
 344
 345                 if ( $rev ) {
 346                         $rev->mQueryFlags = $flags;
 347                 }
 348
 349                 return $rev;
 350         }
 351
 352         /**
 353          * Given a set of conditions, fetch a revision from
 354          * the given database connection.
 355          *
 356          * @param IDatabase $db
 357          * @param array $conditions
 358          * @param int $flags (optional)
 359          * @return Revision|null
 360          */
 361         private static function loadFromConds( $db, $conditions, $flags = 0 ) {
 362                 $row = self::fetchFromConds( $db, $conditions, $flags );
 363                 if ( $row ) {
 364                         $rev = new Revision( $row );
 365                         $rev->mWiki = $db->getDomainID();
 366
 367                         return $rev;
 368                 }
 369
 370                 return null;
 371         }
 372
 373         /**
 374          * Return a wrapper for a series of database rows to
 375          * fetch all of a given page's revisions in turn.
 376          * Each row can be fed to the constructor to get objects.
 377          *
 378          * @param LinkTarget $title
 379          * @return ResultWrapper
 380          * @deprecated Since 1.28
 381          */
 382         public static function fetchRevision( LinkTarget $title ) {
 383                 $row = self::fetchFromConds(
 384                         wfGetDB( DB_REPLICA ),
 385                         [
 386                                 'rev_id=page_latest',
 387                                 'page_namespace' => $title->getNamespace(),
 388                                 'page_title' => $title->getDBkey()
 389                         ]
 390                 );
 391
 392                 return new FakeResultWrapper( $row ? [ $row ] : [] );
 393         }
 394
 395         /**
 396          * Given a set of conditions, return a ResultWrapper
 397          * which will return matching database rows with the
 398          * fields necessary to build Revision objects.
 399          *
 400          * @param IDatabase $db
 401          * @param array $conditions
 402          * @param int $flags (optional)
 403          * @return stdClass
 404          */
 405         private static function fetchFromConds( $db, $conditions, $flags = 0 ) {
 406                 $revQuery = self::getQueryInfo( [ 'page', 'user' ] );
 407                 $options = [];
 408                 if ( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING ) {
 409                         $options[] = 'FOR UPDATE';
 410                 }
 411                 return $db->selectRow(
 412                         $revQuery['tables'],
 413                         $revQuery['fields'],
 414                         $conditions,
 415                         __METHOD__,
 416                         $options,
 417                         $revQuery['joins']
 418                 );
 419         }
 420
 421         /**
 422          * Return the value of a select() JOIN conds array for the user table.
 423          * This will get user table rows for logged-in users.
 424          * @since 1.19
 425          * @deprecated since 1.31, use self::getQueryInfo( [ 'user' ] ) instead.
 426          * @return array
 427          */
 428         public static function userJoinCond() {
 429                 return [ 'LEFT JOIN', [ 'rev_user != 0', 'user_id = rev_user' ] ];
 430         }
 431
 432         /**
 433          * Return the value of a select() page conds array for the page table.
 434          * This will assure that the revision(s) are not orphaned from live pages.
 435          * @since 1.19
 436          * @deprecated since 1.31, use self::getQueryInfo( [ 'page' ] ) instead.
 437          * @return array
 438          */
 439         public static function pageJoinCond() {
 440                 return [ 'INNER JOIN', [ 'page_id = rev_page' ] ];
 441         }
 442
 443         /**
 444          * Return the list of revision fields that should be selected to create
 445          * a new revision.
 446          * @deprecated since 1.31, use self::getQueryInfo() instead.
 447          * @return array
 448          */
 449         public static function selectFields() {
 450                 global $wgContentHandlerUseDB;
 451
 452                 $fields = [
 453                         'rev_id',
 454                         'rev_page',
 455                         'rev_text_id',
 456                         'rev_timestamp',
 457                         'rev_user_text',
 458                         'rev_user',
 459                         'rev_minor_edit',
 460                         'rev_deleted',
 461                         'rev_len',
 462                         'rev_parent_id',
 463                         'rev_sha1',
 464                 ];
 465
 466                 $fields += CommentStore::newKey( 'rev_comment' )->getFields();
 467
 468                 if ( $wgContentHandlerUseDB ) {
 469                         $fields[] = 'rev_content_format';
 470                         $fields[] = 'rev_content_model';
 471                 }
 472
 473                 return $fields;
 474         }
 475
 476         /**
 477          * Return the list of revision fields that should be selected to create
 478          * a new revision from an archive row.
 479          * @deprecated since 1.31, use self::getArchiveQueryInfo() instead.
 480          * @return array
 481          */
 482         public static function selectArchiveFields() {
 483                 global $wgContentHandlerUseDB;
 484                 $fields = [
 485                         'ar_id',
 486                         'ar_page_id',
 487                         'ar_rev_id',
 488                         'ar_text',
 489                         'ar_text_id',
 490                         'ar_timestamp',
 491                         'ar_user_text',
 492                         'ar_user',
 493                         'ar_minor_edit',
 494                         'ar_deleted',
 495                         'ar_len',
 496                         'ar_parent_id',
 497                         'ar_sha1',
 498                 ];
 499
 500                 $fields += CommentStore::newKey( 'ar_comment' )->getFields();
 501
 502                 if ( $wgContentHandlerUseDB ) {
 503                         $fields[] = 'ar_content_format';
 504                         $fields[] = 'ar_content_model';
 505                 }
 506                 return $fields;
 507         }
 508
 509         /**
 510          * Return the list of text fields that should be selected to read the
 511          * revision text
 512          * @deprecated since 1.31, use self::getQueryInfo( [ 'text' ] ) instead.
 513          * @return array
 514          */
 515         public static function selectTextFields() {
 516                 return [
 517                         'old_text',
 518                         'old_flags'
 519                 ];
 520         }
 521
 522         /**
 523          * Return the list of page fields that should be selected from page table
 524          * @deprecated since 1.31, use self::getQueryInfo( [ 'page' ] ) instead.
 525          * @return array
 526          */
 527         public static function selectPageFields() {
 528                 return [
 529                         'page_namespace',
 530                         'page_title',
 531                         'page_id',
 532                         'page_latest',
 533                         'page_is_redirect',
 534                         'page_len',
 535                 ];
 536         }
 537
 538         /**
 539          * Return the list of user fields that should be selected from user table
 540          * @deprecated since 1.31, use self::getQueryInfo( [ 'user' ] ) instead.
 541          * @return array
 542          */
 543         public static function selectUserFields() {
 544                 return [ 'user_name' ];
 545         }
 546
 547         /**
 548          * Return the tables, fields, and join conditions to be selected to create
 549          * a new revision object.
 550          * @since 1.31
 551          * @param array $options Any combination of the following strings
 552          *  - 'page': Join with the page table, and select fields to identify the page
 553          *  - 'user': Join with the user table, and select the user name
 554          *  - 'text': Join with the text table, and select fields to load page text
 555          * @return array With three keys:
 556          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
 557          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
 558          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
 559          */
 560         public static function getQueryInfo( $options = [] ) {
 561                 global $wgContentHandlerUseDB;
 562
 563                 $commentQuery = CommentStore::newKey( 'rev_comment' )->getJoin();
 564                 $ret = [
 565                         'tables' => [ 'revision' ] + $commentQuery['tables'],
 566                         'fields' => [
 567                                 'rev_id',
 568                                 'rev_page',
 569                                 'rev_text_id',
 570                                 'rev_timestamp',
 571                                 'rev_user_text',
 572                                 'rev_user',
 573                                 'rev_minor_edit',
 574                                 'rev_deleted',
 575                                 'rev_len',
 576                                 'rev_parent_id',
 577                                 'rev_sha1',
 578                         ] + $commentQuery['fields'],
 579                         'joins' => $commentQuery['joins'],
 580                 ];
 581
 582                 if ( $wgContentHandlerUseDB ) {
 583                         $ret['fields'][] = 'rev_content_format';
 584                         $ret['fields'][] = 'rev_content_model';
 585                 }
 586
 587                 if ( in_array( 'page', $options, true ) ) {
 588                         $ret['tables'][] = 'page';
 589                         $ret['fields'] = array_merge( $ret['fields'], [
 590                                 'page_namespace',
 591                                 'page_title',
 592                                 'page_id',
 593                                 'page_latest',
 594                                 'page_is_redirect',
 595                                 'page_len',
 596                         ] );
 597                         $ret['joins']['page'] = [ 'INNER JOIN', [ 'page_id = rev_page' ] ];
 598                 }
 599
 600                 if ( in_array( 'user', $options, true ) ) {
 601                         $ret['tables'][] = 'user';
 602                         $ret['fields'] = array_merge( $ret['fields'], [
 603                                 'user_name',
 604                         ] );
 605                         $ret['joins']['user'] = [ 'LEFT JOIN', [ 'rev_user != 0', 'user_id = rev_user' ] ];
 606                 }
 607
 608                 if ( in_array( 'text', $options, true ) ) {
 609                         $ret['tables'][] = 'text';
 610                         $ret['fields'] = array_merge( $ret['fields'], [
 611                                 'old_text',
 612                                 'old_flags'
 613                         ] );
 614                         $ret['joins']['text'] = [ 'INNER JOIN', [ 'rev_text_id=old_id' ] ];
 615                 }
 616
 617                 return $ret;
 618         }
 619
 620         /**
 621          * Return the tables, fields, and join conditions to be selected to create
 622          * a new archived revision object.
 623          * @since 1.31
 624          * @return array With three keys:
 625          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
 626          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
 627          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
 628          */
 629         public static function getArchiveQueryInfo() {
 630                 global $wgContentHandlerUseDB;
 631
 632                 $commentQuery = CommentStore::newKey( 'ar_comment' )->getJoin();
 633                 $ret = [
 634                         'tables' => [ 'archive' ] + $commentQuery['tables'],
 635                         'fields' => [
 636                                 'ar_id',
 637                                 'ar_page_id',
 638                                 'ar_rev_id',
 639                                 'ar_text',
 640                                 'ar_text_id',
 641                                 'ar_timestamp',
 642                                 'ar_user_text',
 643                                 'ar_user',
 644                                 'ar_minor_edit',
 645                                 'ar_deleted',
 646                                 'ar_len',
 647                                 'ar_parent_id',
 648                                 'ar_sha1',
 649                         ] + $commentQuery['fields'],
 650                         'joins' => $commentQuery['joins'],
 651                 ];
 652
 653                 if ( $wgContentHandlerUseDB ) {
 654                         $ret['fields'][] = 'ar_content_format';
 655                         $ret['fields'][] = 'ar_content_model';
 656                 }
 657
 658                 return $ret;
 659         }
 660
 661         /**
 662          * Do a batched query to get the parent revision lengths
 663          * @param IDatabase $db
 664          * @param array $revIds
 665          * @return array
 666          */
 667         public static function getParentLengths( $db, array $revIds ) {
 668                 $revLens = [];
 669                 if ( !$revIds ) {
 670                         return $revLens; // empty
 671                 }
 672                 $res = $db->select( 'revision',
 673                         [ 'rev_id', 'rev_len' ],
 674                         [ 'rev_id' => $revIds ],
 675                         __METHOD__ );
 676                 foreach ( $res as $row ) {
 677                         $revLens[$row->rev_id] = $row->rev_len;
 678                 }
 679                 return $revLens;
 680         }
 681
 682         /**
 683          * @param object|array $row Either a database row or an array
 684          * @throws MWException
 685          * @access private
 686          */
 687         public function __construct( $row ) {
 688                 if ( is_object( $row ) ) {
 689                         $this->constructFromDbRowObject( $row );
 690                 } elseif ( is_array( $row ) ) {
 691                         $this->constructFromRowArray( $row );
 692                 } else {
 693                         throw new MWException( 'Revision constructor passed invalid row format.' );
 694                 }
 695                 $this->mUnpatrolled = null;
 696         }
 697
 698         /**
 699          * @param object $row
 700          */
 701         private function constructFromDbRowObject( $row ) {
 702                 $this->mId = intval( $row->rev_id );
 703                 $this->mPage = intval( $row->rev_page );
 704                 $this->mTextId = intval( $row->rev_text_id );
 705                 $this->mComment = CommentStore::newKey( 'rev_comment' )
 706                         // Legacy because $row may have come from self::selectFields()
 707                         ->getCommentLegacy( wfGetDB( DB_REPLICA ), $row, true )->text;
 708                 $this->mUser = intval( $row->rev_user );
 709                 $this->mMinorEdit = intval( $row->rev_minor_edit );
 710                 $this->mTimestamp = $row->rev_timestamp;
 711                 $this->mDeleted = intval( $row->rev_deleted );
 712
 713                 if ( !isset( $row->rev_parent_id ) ) {
 714                         $this->mParentId = null;
 715                 } else {
 716                         $this->mParentId = intval( $row->rev_parent_id );
 717                 }
 718
 719                 if ( !isset( $row->rev_len ) ) {
 720                         $this->mSize = null;
 721                 } else {
 722                         $this->mSize = intval( $row->rev_len );
 723                 }
 724
 725                 if ( !isset( $row->rev_sha1 ) ) {
 726                         $this->mSha1 = null;
 727                 } else {
 728                         $this->mSha1 = $row->rev_sha1;
 729                 }
 730
 731                 if ( isset( $row->page_latest ) ) {
 732                         $this->mCurrent = ( $row->rev_id == $row->page_latest );
 733                         $this->mTitle = Title::newFromRow( $row );
 734                 } else {
 735                         $this->mCurrent = false;
 736                         $this->mTitle = null;
 737                 }
 738
 739                 if ( !isset( $row->rev_content_model ) ) {
 740                         $this->mContentModel = null; # determine on demand if needed
 741                 } else {
 742                         $this->mContentModel = strval( $row->rev_content_model );
 743                 }
 744
 745                 if ( !isset( $row->rev_content_format ) ) {
 746                         $this->mContentFormat = null; # determine on demand if needed
 747                 } else {
 748                         $this->mContentFormat = strval( $row->rev_content_format );
 749                 }
 750
 751                 // Lazy extraction...
 752                 $this->mText = null;
 753                 if ( isset( $row->old_text ) ) {
 754                         $this->mTextRow = $row;
 755                 } else {
 756                         // 'text' table row entry will be lazy-loaded
 757                         $this->mTextRow = null;
 758                 }
 759
 760                 // Use user_name for users and rev_user_text for IPs...
 761                 $this->mUserText = null; // lazy load if left null
 762                 if ( $this->mUser == 0 ) {
 763                         $this->mUserText = $row->rev_user_text; // IP user
 764                 } elseif ( isset( $row->user_name ) ) {
 765                         $this->mUserText = $row->user_name; // logged-in user
 766                 }
 767                 $this->mOrigUserText = $row->rev_user_text;
 768         }
 769
 770         /**
 771          * @param array $row
 772          *
 773          * @throws MWException
 774          */
 775         private function constructFromRowArray( array $row ) {
 776                 // Build a new revision to be saved...
 777                 global $wgUser; // ugh
 778
 779                 # if we have a content object, use it to set the model and type
 780                 if ( !empty( $row['content'] ) ) {
 781                         if ( !( $row['content'] instanceof Content ) ) {
 782                                 throw new MWException( '`content` field must contain a Content object.' );
 783                         }
 784
 785                         // @todo when is that set? test with external store setup! check out insertOn() [dk]
 786                         if ( !empty( $row['text_id'] ) ) {
 787                                 throw new MWException( "Text already stored in external store (id {$row['text_id']}), " .
 788                                         "can't serialize content object" );
 789                         }
 790
 791                         $row['content_model'] = $row['content']->getModel();
 792                         # note: mContentFormat is initializes later accordingly
 793                         # note: content is serialized later in this method!
 794                         # also set text to null?
 795                 }
 796
 797                 $this->mId = isset( $row['id'] ) ? intval( $row['id'] ) : null;
 798                 $this->mPage = isset( $row['page'] ) ? intval( $row['page'] ) : null;
 799                 $this->mTextId = isset( $row['text_id'] ) ? intval( $row['text_id'] ) : null;
 800                 $this->mUserText = isset( $row['user_text'] )
 801                         ? strval( $row['user_text'] ) : $wgUser->getName();
 802                 $this->mUser = isset( $row['user'] ) ? intval( $row['user'] ) : $wgUser->getId();
 803                 $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 804                 $this->mTimestamp = isset( $row['timestamp'] )
 805                         ? strval( $row['timestamp'] ) : wfTimestampNow();
 806                 $this->mDeleted = isset( $row['deleted'] ) ? intval( $row['deleted'] ) : 0;
 807                 $this->mSize = isset( $row['len'] ) ? intval( $row['len'] ) : null;
 808                 $this->mParentId = isset( $row['parent_id'] ) ? intval( $row['parent_id'] ) : null;
 809                 $this->mSha1 = isset( $row['sha1'] ) ? strval( $row['sha1'] ) : null;
 810
 811                 $this->mContentModel = isset( $row['content_model'] )
 812                         ? strval( $row['content_model'] ) : null;
 813                 $this->mContentFormat = isset( $row['content_format'] )
 814                         ? strval( $row['content_format'] ) : null;
 815
 816                 // Enforce spacing trimming on supplied text
 817                 $this->mComment = isset( $row['comment'] ) ? trim( strval( $row['comment'] ) ) : null;
 818                 $this->mText = isset( $row['text'] ) ? rtrim( strval( $row['text'] ) ) : null;
 819                 $this->mTextRow = null;
 820
 821                 $this->mTitle = isset( $row['title'] ) ? $row['title'] : null;
 822
 823                 // if we have a Content object, override mText and mContentModel
 824                 if ( !empty( $row['content'] ) ) {
 825                         $handler = $this->getContentHandler();
 826                         $this->mContent = $row['content'];
 827
 828                         $this->mContentModel = $this->mContent->getModel();
 829                         $this->mContentHandler = null;
 830
 831                         $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
 832                 } elseif ( $this->mText !== null ) {
 833                         $handler = $this->getContentHandler();
 834                         $this->mContent = $handler->unserializeContent( $this->mText );
 835                 }
 836
 837                 // If we have a Title object, make sure it is consistent with mPage.
 838                 if ( $this->mTitle && $this->mTitle->exists() ) {
 839                         if ( $this->mPage === null ) {
 840                                 // if the page ID wasn't known, set it now
 841                                 $this->mPage = $this->mTitle->getArticleID();
 842                         } elseif ( $this->mTitle->getArticleID() !== $this->mPage ) {
 843                                 // Got different page IDs. This may be legit (e.g. during undeletion),
 844                                 // but it seems worth mentioning it in the log.
 845                                 wfDebug( "Page ID " . $this->mPage . " mismatches the ID " .
 846                                         $this->mTitle->getArticleID() . " provided by the Title object." );
 847                         }
 848                 }
 849
 850                 $this->mCurrent = false;
 851
 852                 // If we still have no length, see it we have the text to figure it out
 853                 if ( !$this->mSize && $this->mContent !== null ) {
 854                         $this->mSize = $this->mContent->getSize();
 855                 }
 856
 857                 // Same for sha1
 858                 if ( $this->mSha1 === null ) {
 859                         $this->mSha1 = $this->mText === null ? null : self::base36Sha1( $this->mText );
 860                 }
 861
 862                 // force lazy init
 863                 $this->getContentModel();
 864                 $this->getContentFormat();
 865         }
 866
 867         /**
 868          * Get revision ID
 869          *
 870          * @return int|null
 871          */
 872         public function getId() {
 873                 return $this->mId;
 874         }
 875
 876         /**
 877          * Set the revision ID
 878          *
 879          * This should only be used for proposed revisions that turn out to be null edits
 880          *
 881          * @since 1.19
 882          * @param int $id
 883          */
 884         public function setId( $id ) {
 885                 $this->mId = (int)$id;
 886         }
 887
 888         /**
 889          * Set the user ID/name
 890          *
 891          * This should only be used for proposed revisions that turn out to be null edits
 892          *
 893          * @since 1.28
 894          * @param int $id User ID
 895          * @param string $name User name
 896          */
 897         public function setUserIdAndName( $id, $name ) {
 898                 $this->mUser = (int)$id;
 899                 $this->mUserText = $name;
 900                 $this->mOrigUserText = $name;
 901         }
 902
 903         /**
 904          * Get text row ID
 905          *
 906          * @return int|null
 907          */
 908         public function getTextId() {
 909                 return $this->mTextId;
 910         }
 911
 912         /**
 913          * Get parent revision ID (the original previous page revision)
 914          *
 915          * @return int|null
 916          */
 917         public function getParentId() {
 918                 return $this->mParentId;
 919         }
 920
 921         /**
 922          * Returns the length of the text in this revision, or null if unknown.
 923          *
 924          * @return int|null
 925          */
 926         public function getSize() {
 927                 return $this->mSize;
 928         }
 929
 930         /**
 931          * Returns the base36 sha1 of the text in this revision, or null if unknown.
 932          *
 933          * @return string|null
 934          */
 935         public function getSha1() {
 936                 return $this->mSha1;
 937         }
 938
 939         /**
 940          * Returns the title of the page associated with this entry or null.
 941          *
 942          * Will do a query, when title is not set and id is given.
 943          *
 944          * @return Title|null
 945          */
 946         public function getTitle() {
 947                 if ( $this->mTitle !== null ) {
 948                         return $this->mTitle;
 949                 }
 950                 // rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
 951                 if ( $this->mId !== null ) {
 952                         $dbr = wfGetLB( $this->mWiki )->getConnectionRef( DB_REPLICA, [], $this->mWiki );
 953                         // @todo: Title::getSelectFields(), or Title::getQueryInfo(), or something like that
 954                         $row = $dbr->selectRow(
 955                                 [ 'revision', 'page' ],
 956                                 [
 957                                         'page_namespace',
 958                                         'page_title',
 959                                         'page_id',
 960                                         'page_latest',
 961                                         'page_is_redirect',
 962                                         'page_len',
 963                                 ],
 964                                 [ 'rev_id' => $this->mId ],
 965                                 __METHOD__,
 966                                 [],
 967                                 [ 'page' => [ 'JOIN', 'page_id=rev_page' ] ]
 968                         );
 969                         if ( $row ) {
 970                                 // @TODO: better foreign title handling
 971                                 $this->mTitle = Title::newFromRow( $row );
 972                         }
 973                 }
 974
 975                 if ( $this->mWiki === false || $this->mWiki === wfWikiID() ) {
 976                         // Loading by ID is best, though not possible for foreign titles
 977                         if ( !$this->mTitle && $this->mPage !== null && $this->mPage > 0 ) {
 978                                 $this->mTitle = Title::newFromID( $this->mPage );
 979                         }
 980                 }
 981
 982                 return $this->mTitle;
 983         }
 984
 985         /**
 986          * Set the title of the revision
 987          *
 988          * @param Title $title
 989          */
 990         public function setTitle( $title ) {
 991                 $this->mTitle = $title;
 992         }
 993
 994         /**
 995          * Get the page ID
 996          *
 997          * @return int|null
 998          */
 999         public function getPage() {
1000                 return $this->mPage;
1001         }
1002
1003         /**
1004          * Fetch revision's user id if it's available to the specified audience.
1005          * If the specified audience does not have access to it, zero will be
1006          * returned.
1007          *
1008          * @param int $audience One of:
1009          *   Revision::FOR_PUBLIC       to be displayed to all users
1010          *   Revision::FOR_THIS_USER    to be displayed to the given user
1011          *   Revision::RAW              get the ID regardless of permissions
1012          * @param User|null $user User object to check for, only if FOR_THIS_USER is passed
1013          *   to the $audience parameter
1014          * @return int
1015          */
1016         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
1017                 if ( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
1018                         return 0;
1019                 } elseif ( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
1020                         return 0;
1021                 } else {
1022                         return $this->mUser;
1023                 }
1024         }
1025
1026         /**
1027          * Fetch revision's user id without regard for the current user's permissions
1028          *
1029          * @return int
1030          * @deprecated since 1.25, use getUser( Revision::RAW )
1031          */
1032         public function getRawUser() {
1033                 wfDeprecated( __METHOD__, '1.25' );
1034                 return $this->getUser( self::RAW );
1035         }
1036
1037         /**
1038          * Fetch revision's username if it's available to the specified audience.
1039          * If the specified audience does not have access to the username, an
1040          * empty string will be returned.
1041          *
1042          * @param int $audience One of:
1043          *   Revision::FOR_PUBLIC       to be displayed to all users
1044          *   Revision::FOR_THIS_USER    to be displayed to the given user
1045          *   Revision::RAW              get the text regardless of permissions
1046          * @param User|null $user User object to check for, only if FOR_THIS_USER is passed
1047          *   to the $audience parameter
1048          * @return string
1049          */
1050         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
1051                 $this->loadMutableFields();
1052
1053                 if ( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
1054                         return '';
1055                 } elseif ( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
1056                         return '';
1057                 } else {
1058                         if ( $this->mUserText === null ) {
1059                                 $this->mUserText = User::whoIs( $this->mUser ); // load on demand
1060                                 if ( $this->mUserText === false ) {
1061                                         # This shouldn't happen, but it can if the wiki was recovered
1062                                         # via importing revs and there is no user table entry yet.
1063                                         $this->mUserText = $this->mOrigUserText;
1064                                 }
1065                         }
1066                         return $this->mUserText;
1067                 }
1068         }
1069
1070         /**
1071          * Fetch revision's username without regard for view restrictions
1072          *
1073          * @return string
1074          * @deprecated since 1.25, use getUserText( Revision::RAW )
1075          */
1076         public function getRawUserText() {
1077                 wfDeprecated( __METHOD__, '1.25' );
1078                 return $this->getUserText( self::RAW );
1079         }
1080
1081         /**
1082          * Fetch revision comment if it's available to the specified audience.
1083          * If the specified audience does not have access to the comment, an
1084          * empty string will be returned.
1085          *
1086          * @param int $audience One of:
1087          *   Revision::FOR_PUBLIC       to be displayed to all users
1088          *   Revision::FOR_THIS_USER    to be displayed to the given user
1089          *   Revision::RAW              get the text regardless of permissions
1090          * @param User|null $user User object to check for, only if FOR_THIS_USER is passed
1091          *   to the $audience parameter
1092          * @return string
1093          */
1094         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
1095                 if ( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
1096                         return '';
1097                 } elseif ( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
1098                         return '';
1099                 } else {
1100                         return $this->mComment;
1101                 }
1102         }
1103
1104         /**
1105          * Fetch revision comment without regard for the current user's permissions
1106          *
1107          * @return string
1108          * @deprecated since 1.25, use getComment( Revision::RAW )
1109          */
1110         public function getRawComment() {
1111                 wfDeprecated( __METHOD__, '1.25' );
1112                 return $this->getComment( self::RAW );
1113         }
1114
1115         /**
1116          * @return bool
1117          */
1118         public function isMinor() {
1119                 return (bool)$this->mMinorEdit;
1120         }
1121
1122         /**
1123          * @return int Rcid of the unpatrolled row, zero if there isn't one
1124          */
1125         public function isUnpatrolled() {
1126                 if ( $this->mUnpatrolled !== null ) {
1127                         return $this->mUnpatrolled;
1128                 }
1129                 $rc = $this->getRecentChange();
1130                 if ( $rc && $rc->getAttribute( 'rc_patrolled' ) == 0 ) {
1131                         $this->mUnpatrolled = $rc->getAttribute( 'rc_id' );
1132                 } else {
1133                         $this->mUnpatrolled = 0;
1134                 }
1135                 return $this->mUnpatrolled;
1136         }
1137
1138         /**
1139          * Get the RC object belonging to the current revision, if there's one
1140          *
1141          * @param int $flags (optional) $flags include:
1142          *      Revision::READ_LATEST  : Select the data from the master
1143          *
1144          * @since 1.22
1145          * @return RecentChange|null
1146          */
1147         public function getRecentChange( $flags = 0 ) {
1148                 $dbr = wfGetDB( DB_REPLICA );
1149
1150                 list( $dbType, ) = DBAccessObjectUtils::getDBOptions( $flags );
1151
1152                 return RecentChange::newFromConds(
1153                         [
1154                                 'rc_user_text' => $this->getUserText( self::RAW ),
1155                                 'rc_timestamp' => $dbr->timestamp( $this->getTimestamp() ),
1156                                 'rc_this_oldid' => $this->getId()
1157                         ],
1158                         __METHOD__,
1159                         $dbType
1160                 );
1161         }
1162
1163         /**
1164          * @param int $field One of DELETED_* bitfield constants
1165          *
1166          * @return bool
1167          */
1168         public function isDeleted( $field ) {
1169                 if ( $this->isCurrent() && $field === self::DELETED_TEXT ) {
1170                         // Current revisions of pages cannot have the content hidden. Skipping this
1171                         // check is very useful for Parser as it fetches templates using newKnownCurrent().
1172                         // Calling getVisibility() in that case triggers a verification database query.
1173                         return false; // no need to check
1174                 }
1175
1176                 return ( $this->getVisibility() & $field ) == $field;
1177         }
1178
1179         /**
1180          * Get the deletion bitfield of the revision
1181          *
1182          * @return int
1183          */
1184         public function getVisibility() {
1185                 $this->loadMutableFields();
1186
1187                 return (int)$this->mDeleted;
1188         }
1189
1190         /**
1191          * Fetch revision content if it's available to the specified audience.
1192          * If the specified audience does not have the ability to view this
1193          * revision, null will be returned.
1194          *
1195          * @param int $audience One of:
1196          *   Revision::FOR_PUBLIC       to be displayed to all users
1197          *   Revision::FOR_THIS_USER    to be displayed to $wgUser
1198          *   Revision::RAW              get the text regardless of permissions
1199          * @param User $user User object to check for, only if FOR_THIS_USER is passed
1200          *   to the $audience parameter
1201          * @since 1.21
1202          * @return Content|null
1203          */
1204         public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
1205                 if ( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
1206                         return null;
1207                 } elseif ( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
1208                         return null;
1209                 } else {
1210                         return $this->getContentInternal();
1211                 }
1212         }
1213
1214         /**
1215          * Get original serialized data (without checking view restrictions)
1216          *
1217          * @since 1.21
1218          * @return string
1219          */
1220         public function getSerializedData() {
1221                 if ( $this->mText === null ) {
1222                         // Revision is immutable. Load on demand.
1223                         $this->mText = $this->loadText();
1224                 }
1225
1226                 return $this->mText;
1227         }
1228
1229         /**
1230          * Gets the content object for the revision (or null on failure).
1231          *
1232          * Note that for mutable Content objects, each call to this method will return a
1233          * fresh clone.
1234          *
1235          * @since 1.21
1236          * @return Content|null The Revision's content, or null on failure.
1237          */
1238         protected function getContentInternal() {
1239                 if ( $this->mContent === null ) {
1240                         $text = $this->getSerializedData();
1241
1242                         if ( $text !== null && $text !== false ) {
1243                                 // Unserialize content
1244                                 $handler = $this->getContentHandler();
1245                                 $format = $this->getContentFormat();
1246
1247                                 $this->mContent = $handler->unserializeContent( $text, $format );
1248                         }
1249                 }
1250
1251                 // NOTE: copy() will return $this for immutable content objects
1252                 return $this->mContent ? $this->mContent->copy() : null;
1253         }
1254
1255         /**
1256          * Returns the content model for this revision.
1257          *
1258          * If no content model was stored in the database, the default content model for the title is
1259          * used to determine the content model to use. If no title is know, CONTENT_MODEL_WIKITEXT
1260          * is used as a last resort.
1261          *
1262          * @return string The content model id associated with this revision,
1263          *     see the CONTENT_MODEL_XXX constants.
1264          */
1265         public function getContentModel() {
1266                 if ( !$this->mContentModel ) {
1267                         $title = $this->getTitle();
1268                         if ( $title ) {
1269                                 $this->mContentModel = ContentHandler::getDefaultModelFor( $title );
1270                         } else {
1271                                 $this->mContentModel = CONTENT_MODEL_WIKITEXT;
1272                         }
1273
1274                         assert( !empty( $this->mContentModel ) );
1275                 }
1276
1277                 return $this->mContentModel;
1278         }
1279
1280         /**
1281          * Returns the content format for this revision.
1282          *
1283          * If no content format was stored in the database, the default format for this
1284          * revision's content model is returned.
1285          *
1286          * @return string The content format id associated with this revision,
1287          *     see the CONTENT_FORMAT_XXX constants.
1288          */
1289         public function getContentFormat() {
1290                 if ( !$this->mContentFormat ) {
1291                         $handler = $this->getContentHandler();
1292                         $this->mContentFormat = $handler->getDefaultFormat();
1293
1294                         assert( !empty( $this->mContentFormat ) );
1295                 }
1296
1297                 return $this->mContentFormat;
1298         }
1299
1300         /**
1301          * Returns the content handler appropriate for this revision's content model.
1302          *
1303          * @throws MWException
1304          * @return ContentHandler
1305          */
1306         public function getContentHandler() {
1307                 if ( !$this->mContentHandler ) {
1308                         $model = $this->getContentModel();
1309                         $this->mContentHandler = ContentHandler::getForModelID( $model );
1310
1311                         $format = $this->getContentFormat();
1312
1313                         if ( !$this->mContentHandler->isSupportedFormat( $format ) ) {
1314                                 throw new MWException( "Oops, the content format $format is not supported for "
1315                                         . "this content model, $model" );
1316                         }
1317                 }
1318
1319                 return $this->mContentHandler;
1320         }
1321
1322         /**
1323          * @return string
1324          */
1325         public function getTimestamp() {
1326                 return wfTimestamp( TS_MW, $this->mTimestamp );
1327         }
1328
1329         /**
1330          * @return bool
1331          */
1332         public function isCurrent() {
1333                 return $this->mCurrent;
1334         }
1335
1336         /**
1337          * Get previous revision for this title
1338          *
1339          * @return Revision|null
1340          */
1341         public function getPrevious() {
1342                 if ( $this->getTitle() ) {
1343                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
1344                         if ( $prev ) {
1345                                 return self::newFromTitle( $this->getTitle(), $prev );
1346                         }
1347                 }
1348                 return null;
1349         }
1350
1351         /**
1352          * Get next revision for this title
1353          *
1354          * @return Revision|null
1355          */
1356         public function getNext() {
1357                 if ( $this->getTitle() ) {
1358                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
1359                         if ( $next ) {
1360                                 return self::newFromTitle( $this->getTitle(), $next );
1361                         }
1362                 }
1363                 return null;
1364         }
1365
1366         /**
1367          * Get previous revision Id for this page_id
1368          * This is used to populate rev_parent_id on save
1369          *
1370          * @param IDatabase $db
1371          * @return int
1372          */
1373         private function getPreviousRevisionId( $db ) {
1374                 if ( $this->mPage === null ) {
1375                         return 0;
1376                 }
1377                 # Use page_latest if ID is not given
1378                 if ( !$this->mId ) {
1379                         $prevId = $db->selectField( 'page', 'page_latest',
1380                                 [ 'page_id' => $this->mPage ],
1381                                 __METHOD__ );
1382                 } else {
1383                         $prevId = $db->selectField( 'revision', 'rev_id',
1384                                 [ 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ],
1385                                 __METHOD__,
1386                                 [ 'ORDER BY' => 'rev_id DESC' ] );
1387                 }
1388                 return intval( $prevId );
1389         }
1390
1391         /**
1392          * Get revision text associated with an old or archive row
1393          *
1394          * Both the flags and the text field must be included. Including the old_id
1395          * field will activate cache usage as long as the $wiki parameter is not set.
1396          *
1397          * @param stdClass $row The text data
1398          * @param string $prefix Table prefix (default 'old_')
1399          * @param string|bool $wiki The name of the wiki to load the revision text from
1400          *   (same as the the wiki $row was loaded from) or false to indicate the local
1401          *   wiki (this is the default). Otherwise, it must be a symbolic wiki database
1402          *   identifier as understood by the LoadBalancer class.
1403          * @return string|false Text the text requested or false on failure
1404          */
1405         public static function getRevisionText( $row, $prefix = 'old_', $wiki = false ) {
1406                 $textField = $prefix . 'text';
1407                 $flagsField = $prefix . 'flags';
1408
1409                 if ( isset( $row->$flagsField ) ) {
1410                         $flags = explode( ',', $row->$flagsField );
1411                 } else {
1412                         $flags = [];
1413                 }
1414
1415                 if ( isset( $row->$textField ) ) {
1416                         $text = $row->$textField;
1417                 } else {
1418                         return false;
1419                 }
1420
1421                 // Use external methods for external objects, text in table is URL-only then
1422                 if ( in_array( 'external', $flags ) ) {
1423                         $url = $text;
1424                         $parts = explode( '://', $url, 2 );
1425                         if ( count( $parts ) == 1 || $parts[1] == '' ) {
1426                                 return false;
1427                         }
1428
1429                         if ( isset( $row->old_id ) && $wiki === false ) {
1430                                 // Make use of the wiki-local revision text cache
1431                                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
1432                                 // The cached value should be decompressed, so handle that and return here
1433                                 return $cache->getWithSetCallback(
1434                                         $cache->makeKey( 'revisiontext', 'textid', $row->old_id ),
1435                                         self::getCacheTTL( $cache ),
1436                                         function () use ( $url, $wiki, $flags ) {
1437                                                 // No negative caching per Revision::loadText()
1438                                                 $text = ExternalStore::fetchFromURL( $url, [ 'wiki' => $wiki ] );
1439
1440                                                 return self::decompressRevisionText( $text, $flags );
1441                                         },
1442                                         [ 'pcGroup' => self::TEXT_CACHE_GROUP, 'pcTTL' => $cache::TTL_PROC_LONG ]
1443                                 );
1444                         } else {
1445                                 $text = ExternalStore::fetchFromURL( $url, [ 'wiki' => $wiki ] );
1446                         }
1447                 }
1448
1449                 return self::decompressRevisionText( $text, $flags );
1450         }
1451
1452         /**
1453          * If $wgCompressRevisions is enabled, we will compress data.
1454          * The input string is modified in place.
1455          * Return value is the flags field: contains 'gzip' if the
1456          * data is compressed, and 'utf-8' if we're saving in UTF-8
1457          * mode.
1458          *
1459          * @param mixed &$text Reference to a text
1460          * @return string
1461          */
1462         public static function compressRevisionText( &$text ) {
1463                 global $wgCompressRevisions;
1464                 $flags = [];
1465
1466                 # Revisions not marked this way will be converted
1467                 # on load if $wgLegacyCharset is set in the future.
1468                 $flags[] = 'utf-8';
1469
1470                 if ( $wgCompressRevisions ) {
1471                         if ( function_exists( 'gzdeflate' ) ) {
1472                                 $deflated = gzdeflate( $text );
1473
1474                                 if ( $deflated === false ) {
1475                                         wfLogWarning( __METHOD__ . ': gzdeflate() failed' );
1476                                 } else {
1477                                         $text = $deflated;
1478                                         $flags[] = 'gzip';
1479                                 }
1480                         } else {
1481                                 wfDebug( __METHOD__ . " -- no zlib support, not compressing\n" );
1482                         }
1483                 }
1484                 return implode( ',', $flags );
1485         }
1486
1487         /**
1488          * Re-converts revision text according to it's flags.
1489          *
1490          * @param mixed $text Reference to a text
1491          * @param array $flags Compression flags
1492          * @return string|bool Decompressed text, or false on failure
1493          */
1494         public static function decompressRevisionText( $text, $flags ) {
1495                 global $wgLegacyEncoding, $wgContLang;
1496
1497                 if ( $text === false ) {
1498                         // Text failed to be fetched; nothing to do
1499                         return false;
1500                 }
1501
1502                 if ( in_array( 'gzip', $flags ) ) {
1503                         # Deal with optional compression of archived pages.
1504                         # This can be done periodically via maintenance/compressOld.php, and
1505                         # as pages are saved if $wgCompressRevisions is set.
1506                         $text = gzinflate( $text );
1507
1508                         if ( $text === false ) {
1509                                 wfLogWarning( __METHOD__ . ': gzinflate() failed' );
1510                                 return false;
1511                         }
1512                 }
1513
1514                 if ( in_array( 'object', $flags ) ) {
1515                         # Generic compressed storage
1516                         $obj = unserialize( $text );
1517                         if ( !is_object( $obj ) ) {
1518                                 // Invalid object
1519                                 return false;
1520                         }
1521                         $text = $obj->getText();
1522                 }
1523
1524                 if ( $text !== false && $wgLegacyEncoding
1525                         && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags )
1526                 ) {
1527                         # Old revisions kept around in a legacy encoding?
1528                         # Upconvert on demand.
1529                         # ("utf8" checked for compatibility with some broken
1530                         #  conversion scripts 2008-12-30)
1531                         $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
1532                 }
1533
1534                 return $text;
1535         }
1536
1537         /**
1538          * Insert a new revision into the database, returning the new revision ID
1539          * number on success and dies horribly on failure.
1540          *
1541          * @param IDatabase $dbw (master connection)
1542          * @throws MWException
1543          * @return int The revision ID
1544          */
1545         public function insertOn( $dbw ) {
1546                 global $wgDefaultExternalStore, $wgContentHandlerUseDB;
1547
1548                 // We're inserting a new revision, so we have to use master anyway.
1549                 // If it's a null revision, it may have references to rows that
1550                 // are not in the replica yet (the text row).
1551                 $this->mQueryFlags |= self::READ_LATEST;
1552
1553                 // Not allowed to have rev_page equal to 0, false, etc.
1554                 if ( !$this->mPage ) {
1555                         $title = $this->getTitle();
1556                         if ( $title instanceof Title ) {
1557                                 $titleText = ' for page ' . $title->getPrefixedText();
1558                         } else {
1559                                 $titleText = '';
1560                         }
1561                         throw new MWException( "Cannot insert revision$titleText: page ID must be nonzero" );
1562                 }
1563
1564                 $this->checkContentModel();
1565
1566                 $data = $this->mText;
1567                 $flags = self::compressRevisionText( $data );
1568
1569                 # Write to external storage if required
1570                 if ( $wgDefaultExternalStore ) {
1571                         // Store and get the URL
1572                         $data = ExternalStore::insertToDefault( $data );
1573                         if ( !$data ) {
1574                                 throw new MWException( "Unable to store text to external storage" );
1575                         }
1576                         if ( $flags ) {
1577                                 $flags .= ',';
1578                         }
1579                         $flags .= 'external';
1580                 }
1581
1582                 # Record the text (or external storage URL) to the text table
1583                 if ( $this->mTextId === null ) {
1584                         $dbw->insert( 'text',
1585                                 [
1586                                         'old_text' => $data,
1587                                         'old_flags' => $flags,
1588                                 ], __METHOD__
1589                         );
1590                         $this->mTextId = $dbw->insertId();
1591                 }
1592
1593                 if ( $this->mComment === null ) {
1594                         $this->mComment = "";
1595                 }
1596
1597                 # Record the edit in revisions
1598                 $row = [
1599                         'rev_page'       => $this->mPage,
1600                         'rev_text_id'    => $this->mTextId,
1601                         'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
1602                         'rev_user'       => $this->mUser,
1603                         'rev_user_text'  => $this->mUserText,
1604                         'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
1605                         'rev_deleted'    => $this->mDeleted,
1606                         'rev_len'        => $this->mSize,
1607                         'rev_parent_id'  => $this->mParentId === null
1608                                 ? $this->getPreviousRevisionId( $dbw )
1609                                 : $this->mParentId,
1610                         'rev_sha1'       => $this->mSha1 === null
1611                                 ? self::base36Sha1( $this->mText )
1612                                 : $this->mSha1,
1613                 ];
1614                 if ( $this->mId !== null ) {
1615                         $row['rev_id'] = $this->mId;
1616                 }
1617
1618                 list( $commentFields, $commentCallback ) =
1619                         CommentStore::newKey( 'rev_comment' )->insertWithTempTable( $dbw, $this->mComment );
1620                 $row += $commentFields;
1621
1622                 if ( $wgContentHandlerUseDB ) {
1623                         // NOTE: Store null for the default model and format, to save space.
1624                         // XXX: Makes the DB sensitive to changed defaults.
1625                         // Make this behavior optional? Only in miser mode?
1626
1627                         $model = $this->getContentModel();
1628                         $format = $this->getContentFormat();
1629
1630                         $title = $this->getTitle();
1631
1632                         if ( $title === null ) {
1633                                 throw new MWException( "Insufficient information to determine the title of the "
1634                                         . "revision's page!" );
1635                         }
1636
1637                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1638                         $defaultFormat = ContentHandler::getForModelID( $defaultModel )->getDefaultFormat();
1639
1640                         $row['rev_content_model'] = ( $model === $defaultModel ) ? null : $model;
1641                         $row['rev_content_format'] = ( $format === $defaultFormat ) ? null : $format;
1642                 }
1643
1644                 $dbw->insert( 'revision', $row, __METHOD__ );
1645
1646                 if ( $this->mId === null ) {
1647                         // Only if auto-increment was used
1648                         $this->mId = $dbw->insertId();
1649                 }
1650                 $commentCallback( $this->mId );
1651
1652                 // Assertion to try to catch T92046
1653                 if ( (int)$this->mId === 0 ) {
1654                         throw new UnexpectedValueException(
1655                                 'After insert, Revision mId is ' . var_export( $this->mId, 1 ) . ': ' .
1656                                         var_export( $row, 1 )
1657                         );
1658                 }
1659
1660                 // Insert IP revision into ip_changes for use when querying for a range.
1661                 if ( $this->mUser === 0 && IP::isValid( $this->mUserText ) ) {
1662                         $ipcRow = [
1663                                 'ipc_rev_id'        => $this->mId,
1664                                 'ipc_rev_timestamp' => $row['rev_timestamp'],
1665                                 'ipc_hex'           => IP::toHex( $row['rev_user_text'] ),
1666                         ];
1667                         $dbw->insert( 'ip_changes', $ipcRow, __METHOD__ );
1668                 }
1669
1670                 // Avoid PHP 7.1 warning of passing $this by reference
1671                 $revision = $this;
1672                 Hooks::run( 'RevisionInsertComplete', [ &$revision, $data, $flags ] );
1673
1674                 return $this->mId;
1675         }
1676
1677         protected function checkContentModel() {
1678                 global $wgContentHandlerUseDB;
1679
1680                 // Note: may return null for revisions that have not yet been inserted
1681                 $title = $this->getTitle();
1682
1683                 $model = $this->getContentModel();
1684                 $format = $this->getContentFormat();
1685                 $handler = $this->getContentHandler();
1686
1687                 if ( !$handler->isSupportedFormat( $format ) ) {
1688                         $t = $title->getPrefixedDBkey();
1689
1690                         throw new MWException( "Can't use format $format with content model $model on $t" );
1691                 }
1692
1693                 if ( !$wgContentHandlerUseDB && $title ) {
1694                         // if $wgContentHandlerUseDB is not set,
1695                         // all revisions must use the default content model and format.
1696
1697                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1698                         $defaultHandler = ContentHandler::getForModelID( $defaultModel );
1699                         $defaultFormat = $defaultHandler->getDefaultFormat();
1700
1701                         if ( $this->getContentModel() != $defaultModel ) {
1702                                 $t = $title->getPrefixedDBkey();
1703
1704                                 throw new MWException( "Can't save non-default content model with "
1705                                         . "\$wgContentHandlerUseDB disabled: model is $model, "
1706                                         . "default for $t is $defaultModel" );
1707                         }
1708
1709                         if ( $this->getContentFormat() != $defaultFormat ) {
1710                                 $t = $title->getPrefixedDBkey();
1711
1712                                 throw new MWException( "Can't use non-default content format with "
1713                                         . "\$wgContentHandlerUseDB disabled: format is $format, "
1714                                         . "default for $t is $defaultFormat" );
1715                         }
1716                 }
1717
1718                 $content = $this->getContent( self::RAW );
1719                 $prefixedDBkey = $title->getPrefixedDBkey();
1720                 $revId = $this->mId;
1721
1722                 if ( !$content ) {
1723                         throw new MWException(
1724                                 "Content of revision $revId ($prefixedDBkey) could not be loaded for validation!"
1725                         );
1726                 }
1727                 if ( !$content->isValid() ) {
1728                         throw new MWException(
1729                                 "Content of revision $revId ($prefixedDBkey) is not valid! Content model is $model"
1730                         );
1731                 }
1732         }
1733
1734         /**
1735          * Get the base 36 SHA-1 value for a string of text
1736          * @param string $text
1737          * @return string
1738          */
1739         public static function base36Sha1( $text ) {
1740                 return Wikimedia\base_convert( sha1( $text ), 16, 36, 31 );
1741         }
1742
1743         /**
1744          * Get the text cache TTL
1745          *
1746          * @param WANObjectCache $cache
1747          * @return int
1748          */
1749         private static function getCacheTTL( WANObjectCache $cache ) {
1750                 global $wgRevisionCacheExpiry;
1751
1752                 if ( $cache->getQoS( $cache::ATTR_EMULATION ) <= $cache::QOS_EMULATION_SQL ) {
1753                         // Do not cache RDBMs blobs in...the RDBMs store
1754                         $ttl = $cache::TTL_UNCACHEABLE;
1755                 } else {
1756                         $ttl = $wgRevisionCacheExpiry ?: $cache::TTL_UNCACHEABLE;
1757                 }
1758
1759                 return $ttl;
1760         }
1761
1762         /**
1763          * Lazy-load the revision's text.
1764          * Currently hardcoded to the 'text' table storage engine.
1765          *
1766          * @return string|bool The revision's text, or false on failure
1767          */
1768         private function loadText() {
1769                 $cache = ObjectCache::getMainWANInstance();
1770
1771                 // No negative caching; negative hits on text rows may be due to corrupted replica DBs
1772                 return $cache->getWithSetCallback(
1773                         $cache->makeKey( 'revisiontext', 'textid', $this->getTextId() ),
1774                         self::getCacheTTL( $cache ),
1775                         function () {
1776                                 return $this->fetchText();
1777                         },
1778                         [ 'pcGroup' => self::TEXT_CACHE_GROUP, 'pcTTL' => $cache::TTL_PROC_LONG ]
1779                 );
1780         }
1781
1782         private function fetchText() {
1783                 $textId = $this->getTextId();
1784
1785                 // If we kept data for lazy extraction, use it now...
1786                 if ( $this->mTextRow !== null ) {
1787                         $row = $this->mTextRow;
1788                         $this->mTextRow = null;
1789                 } else {
1790                         $row = null;
1791                 }
1792
1793                 // Callers doing updates will pass in READ_LATEST as usual. Since the text/blob tables
1794                 // do not normally get rows changed around, set READ_LATEST_IMMUTABLE in those cases.
1795                 $flags = $this->mQueryFlags;
1796                 $flags |= DBAccessObjectUtils::hasFlags( $flags, self::READ_LATEST )
1797                         ? self::READ_LATEST_IMMUTABLE
1798                         : 0;
1799
1800                 list( $index, $options, $fallbackIndex, $fallbackOptions ) =
1801                         DBAccessObjectUtils::getDBOptions( $flags );
1802
1803                 if ( !$row ) {
1804                         // Text data is immutable; check replica DBs first.
1805                         $row = wfGetDB( $index )->selectRow(
1806                                 'text',
1807                                 [ 'old_text', 'old_flags' ],
1808                                 [ 'old_id' => $textId ],
1809                                 __METHOD__,
1810                                 $options
1811                         );
1812                 }
1813
1814                 // Fallback to DB_MASTER in some cases if the row was not found
1815                 if ( !$row && $fallbackIndex !== null ) {
1816                         // Use FOR UPDATE if it was used to fetch this revision. This avoids missing the row
1817                         // due to REPEATABLE-READ. Also fallback to the master if READ_LATEST is provided.
1818                         $row = wfGetDB( $fallbackIndex )->selectRow(
1819                                 'text',
1820                                 [ 'old_text', 'old_flags' ],
1821                                 [ 'old_id' => $textId ],
1822                                 __METHOD__,
1823                                 $fallbackOptions
1824                         );
1825                 }
1826
1827                 if ( !$row ) {
1828                         wfDebugLog( 'Revision', "No text row with ID '$textId' (revision {$this->getId()})." );
1829                 }
1830
1831                 $text = self::getRevisionText( $row );
1832                 if ( $row && $text === false ) {
1833                         wfDebugLog( 'Revision', "No blob for text row '$textId' (revision {$this->getId()})." );
1834                 }
1835
1836                 return is_string( $text ) ? $text : false;
1837         }
1838
1839         /**
1840          * Create a new null-revision for insertion into a page's
1841          * history. This will not re-save the text, but simply refer
1842          * to the text from the previous version.
1843          *
1844          * Such revisions can for instance identify page rename
1845          * operations and other such meta-modifications.
1846          *
1847          * @param IDatabase $dbw
1848          * @param int $pageId ID number of the page to read from
1849          * @param string $summary Revision's summary
1850          * @param bool $minor Whether the revision should be considered as minor
1851          * @param User|null $user User object to use or null for $wgUser
1852          * @return Revision|null Revision or null on error
1853          */
1854         public static function newNullRevision( $dbw, $pageId, $summary, $minor, $user = null ) {
1855                 global $wgContentHandlerUseDB;
1856
1857                 $fields = [ 'page_latest', 'page_namespace', 'page_title',
1858                                                 'rev_text_id', 'rev_len', 'rev_sha1' ];
1859
1860                 if ( $wgContentHandlerUseDB ) {
1861                         $fields[] = 'rev_content_model';
1862                         $fields[] = 'rev_content_format';
1863                 }
1864
1865                 $current = $dbw->selectRow(
1866                         [ 'page', 'revision' ],
1867                         $fields,
1868                         [
1869                                 'page_id' => $pageId,
1870                                 'page_latest=rev_id',
1871                         ],
1872                         __METHOD__,
1873                         [ 'FOR UPDATE' ] // T51581
1874                 );
1875
1876                 if ( $current ) {
1877                         if ( !$user ) {
1878                                 global $wgUser;
1879                                 $user = $wgUser;
1880                         }
1881
1882                         $row = [
1883                                 'page'       => $pageId,
1884                                 'user_text'  => $user->getName(),
1885                                 'user'       => $user->getId(),
1886                                 'comment'    => $summary,
1887                                 'minor_edit' => $minor,
1888                                 'text_id'    => $current->rev_text_id,
1889                                 'parent_id'  => $current->page_latest,
1890                                 'len'        => $current->rev_len,
1891                                 'sha1'       => $current->rev_sha1
1892                         ];
1893
1894                         if ( $wgContentHandlerUseDB ) {
1895                                 $row['content_model'] = $current->rev_content_model;
1896                                 $row['content_format'] = $current->rev_content_format;
1897                         }
1898
1899                         $row['title'] = Title::makeTitle( $current->page_namespace, $current->page_title );
1900
1901                         $revision = new Revision( $row );
1902                 } else {
1903                         $revision = null;
1904                 }
1905
1906                 return $revision;
1907         }
1908
1909         /**
1910          * Determine if the current user is allowed to view a particular
1911          * field of this revision, if it's marked as deleted.
1912          *
1913          * @param int $field One of self::DELETED_TEXT,
1914          *                              self::DELETED_COMMENT,
1915          *                              self::DELETED_USER
1916          * @param User|null $user User object to check, or null to use $wgUser
1917          * @return bool
1918          */
1919         public function userCan( $field, User $user = null ) {
1920                 return self::userCanBitfield( $this->getVisibility(), $field, $user );
1921         }
1922
1923         /**
1924          * Determine if the current user is allowed to view a particular
1925          * field of this revision, if it's marked as deleted. This is used
1926          * by various classes to avoid duplication.
1927          *
1928          * @param int $bitfield Current field
1929          * @param int $field One of self::DELETED_TEXT = File::DELETED_FILE,
1930          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1931          *                               self::DELETED_USER = File::DELETED_USER
1932          * @param User|null $user User object to check, or null to use $wgUser
1933          * @param Title|null $title A Title object to check for per-page restrictions on,
1934          *                          instead of just plain userrights
1935          * @return bool
1936          */
1937         public static function userCanBitfield( $bitfield, $field, User $user = null,
1938                 Title $title = null
1939         ) {
1940                 if ( $bitfield & $field ) { // aspect is deleted
1941                         if ( $user === null ) {
1942                                 global $wgUser;
1943                                 $user = $wgUser;
1944                         }
1945                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1946                                 $permissions = [ 'suppressrevision', 'viewsuppressed' ];
1947                         } elseif ( $field & self::DELETED_TEXT ) {
1948                                 $permissions = [ 'deletedtext' ];
1949                         } else {
1950                                 $permissions = [ 'deletedhistory' ];
1951                         }
1952                         $permissionlist = implode( ', ', $permissions );
1953                         if ( $title === null ) {
1954                                 wfDebug( "Checking for $permissionlist due to $field match on $bitfield\n" );
1955                                 return call_user_func_array( [ $user, 'isAllowedAny' ], $permissions );
1956                         } else {
1957                                 $text = $title->getPrefixedText();
1958                                 wfDebug( "Checking for $permissionlist on $text due to $field match on $bitfield\n" );
1959                                 foreach ( $permissions as $perm ) {
1960                                         if ( $title->userCan( $perm, $user ) ) {
1961                                                 return true;
1962                                         }
1963                                 }
1964                                 return false;
1965                         }
1966                 } else {
1967                         return true;
1968                 }
1969         }
1970
1971         /**
1972          * Get rev_timestamp from rev_id, without loading the rest of the row
1973          *
1974          * @param Title $title
1975          * @param int $id
1976          * @param int $flags
1977          * @return string|bool False if not found
1978          */
1979         static function getTimestampFromId( $title, $id, $flags = 0 ) {
1980                 $db = ( $flags & self::READ_LATEST )
1981                         ? wfGetDB( DB_MASTER )
1982                         : wfGetDB( DB_REPLICA );
1983                 // Casting fix for databases that can't take '' for rev_id
1984                 if ( $id == '' ) {
1985                         $id = 0;
1986                 }
1987                 $conds = [ 'rev_id' => $id ];
1988                 $conds['rev_page'] = $title->getArticleID();
1989                 $timestamp = $db->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1990
1991                 return ( $timestamp !== false ) ? wfTimestamp( TS_MW, $timestamp ) : false;
1992         }
1993
1994         /**
1995          * Get count of revisions per page...not very efficient
1996          *
1997          * @param IDatabase $db
1998          * @param int $id Page id
1999          * @return int
2000          */
2001         static function countByPageId( $db, $id ) {
2002                 $row = $db->selectRow( 'revision', [ 'revCount' => 'COUNT(*)' ],
2003                         [ 'rev_page' => $id ], __METHOD__ );
2004                 if ( $row ) {
2005                         return $row->revCount;
2006                 }
2007                 return 0;
2008         }
2009
2010         /**
2011          * Get count of revisions per page...not very efficient
2012          *
2013          * @param IDatabase $db
2014          * @param Title $title
2015          * @return int
2016          */
2017         static function countByTitle( $db, $title ) {
2018                 $id = $title->getArticleID();
2019                 if ( $id ) {
2020                         return self::countByPageId( $db, $id );
2021                 }
2022                 return 0;
2023         }
2024
2025         /**
2026          * Check if no edits were made by other users since
2027          * the time a user started editing the page. Limit to
2028          * 50 revisions for the sake of performance.
2029          *
2030          * @since 1.20
2031          * @deprecated since 1.24
2032          *
2033          * @param IDatabase|int $db The Database to perform the check on. May be given as a
2034          *        Database object or a database identifier usable with wfGetDB.
2035          * @param int $pageId The ID of the page in question
2036          * @param int $userId The ID of the user in question
2037          * @param string $since Look at edits since this time
2038          *
2039          * @return bool True if the given user was the only one to edit since the given timestamp
2040          */
2041         public static function userWasLastToEdit( $db, $pageId, $userId, $since ) {
2042                 if ( !$userId ) {
2043                         return false;
2044                 }
2045
2046                 if ( is_int( $db ) ) {
2047                         $db = wfGetDB( $db );
2048                 }
2049
2050                 $res = $db->select( 'revision',
2051                         'rev_user',
2052                         [
2053                                 'rev_page' => $pageId,
2054                                 'rev_timestamp > ' . $db->addQuotes( $db->timestamp( $since ) )
2055                         ],
2056                         __METHOD__,
2057                         [ 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 50 ] );
2058                 foreach ( $res as $row ) {
2059                         if ( $row->rev_user != $userId ) {
2060                                 return false;
2061                         }
2062                 }
2063                 return true;
2064         }
2065
2066         /**
2067          * Load a revision based on a known page ID and current revision ID from the DB
2068          *
2069          * This method allows for the use of caching, though accessing anything that normally
2070          * requires permission checks (aside from the text) will trigger a small DB lookup.
2071          * The title will also be lazy loaded, though setTitle() can be used to preload it.
2072          *
2073          * @param IDatabase $db
2074          * @param int $pageId Page ID
2075          * @param int $revId Known current revision of this page
2076          * @return Revision|bool Returns false if missing
2077          * @since 1.28
2078          */
2079         public static function newKnownCurrent( IDatabase $db, $pageId, $revId ) {
2080                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
2081                 return $cache->getWithSetCallback(
2082                         // Page/rev IDs passed in from DB to reflect history merges
2083                         $cache->makeGlobalKey( 'revision', $db->getDomainID(), $pageId, $revId ),
2084                         $cache::TTL_WEEK,
2085                         function ( $curValue, &$ttl, array &$setOpts ) use ( $db, $pageId, $revId ) {
2086                                 $setOpts += Database::getCacheSetOptions( $db );
2087
2088                                 $rev = Revision::loadFromPageId( $db, $pageId, $revId );
2089                                 // Reflect revision deletion and user renames
2090                                 if ( $rev ) {
2091                                         $rev->mTitle = null; // mutable; lazy-load
2092                                         $rev->mRefreshMutableFields = true;
2093                                 }
2094
2095                                 return $rev ?: false; // don't cache negatives
2096                         }
2097                 );
2098         }
2099
2100         /**
2101          * For cached revisions, make sure the user name and rev_deleted is up-to-date
2102          */
2103         private function loadMutableFields() {
2104                 if ( !$this->mRefreshMutableFields ) {
2105                         return; // not needed
2106                 }
2107
2108                 $this->mRefreshMutableFields = false;
2109                 $dbr = wfGetLB( $this->mWiki )->getConnectionRef( DB_REPLICA, [], $this->mWiki );
2110                 $row = $dbr->selectRow(
2111                         [ 'revision', 'user' ],
2112                         [ 'rev_deleted', 'user_name' ],
2113                         [ 'rev_id' => $this->mId, 'user_id = rev_user' ],
2114                         __METHOD__
2115                 );
2116                 if ( $row ) { // update values
2117                         $this->mDeleted = (int)$row->rev_deleted;
2118                         $this->mUserText = $row->user_name;
2119                 }
2120         }
2121 }