includes/Storage/RevisionStore.php

   1 <?php
   2 /**
   3  * Service for looking up page revisions.
   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  * Attribution notice: when this file was created, much of its content was taken
  21  * from the Revision.php file as present in release 1.30. Refer to the history
  22  * of that file for original authorship.
  23  *
  24  * @file
  25  */
  26
  27 namespace MediaWiki\Storage;
  28
  29 use CommentStore;
  30 use CommentStoreComment;
  31 use Content;
  32 use ContentHandler;
  33 use DBAccessObjectUtils;
  34 use Hooks;
  35 use IDBAccessObject;
  36 use InvalidArgumentException;
  37 use IP;
  38 use LogicException;
  39 use MediaWiki\Linker\LinkTarget;
  40 use MediaWiki\User\UserIdentity;
  41 use MediaWiki\User\UserIdentityValue;
  42 use Message;
  43 use MWException;
  44 use MWUnknownContentModelException;
  45 use RecentChange;
  46 use stdClass;
  47 use Title;
  48 use User;
  49 use WANObjectCache;
  50 use Wikimedia\Assert\Assert;
  51 use Wikimedia\Rdbms\Database;
  52 use Wikimedia\Rdbms\DBConnRef;
  53 use Wikimedia\Rdbms\IDatabase;
  54 use Wikimedia\Rdbms\LoadBalancer;
  55
  56 /**
  57  * Service for looking up page revisions.
  58  *
  59  * @since 1.31
  60  *
  61  * @note This was written to act as a drop-in replacement for the corresponding
  62  *       static methods in Revision.
  63  */
  64 class RevisionStore implements IDBAccessObject, RevisionFactory, RevisionLookup {
  65
  66         /**
  67          * @var SqlBlobStore
  68          */
  69         private $blobStore;
  70
  71         /**
  72          * @var bool|string
  73          */
  74         private $wikiId;
  75
  76         /**
  77          * @var boolean
  78          */
  79         private $contentHandlerUseDB = true;
  80
  81         /**
  82          * @var LoadBalancer
  83          */
  84         private $loadBalancer;
  85
  86         /**
  87          * @var WANObjectCache
  88          */
  89         private $cache;
  90
  91         /**
  92          * @todo $blobStore should be allowed to be any BlobStore!
  93          *
  94          * @param LoadBalancer $loadBalancer
  95          * @param SqlBlobStore $blobStore
  96          * @param WANObjectCache $cache
  97          * @param bool|string $wikiId
  98          */
  99         public function __construct(
 100                 LoadBalancer $loadBalancer,
 101                 SqlBlobStore $blobStore,
 102                 WANObjectCache $cache,
 103                 $wikiId = false
 104         ) {
 105                 Assert::parameterType( 'string|boolean', $wikiId, '$wikiId' );
 106
 107                 $this->loadBalancer = $loadBalancer;
 108                 $this->blobStore = $blobStore;
 109                 $this->cache = $cache;
 110                 $this->wikiId = $wikiId;
 111         }
 112
 113         /**
 114          * @return bool
 115          */
 116         public function getContentHandlerUseDB() {
 117                 return $this->contentHandlerUseDB;
 118         }
 119
 120         /**
 121          * @param bool $contentHandlerUseDB
 122          */
 123         public function setContentHandlerUseDB( $contentHandlerUseDB ) {
 124                 $this->contentHandlerUseDB = $contentHandlerUseDB;
 125         }
 126
 127         /**
 128          * @return LoadBalancer
 129          */
 130         private function getDBLoadBalancer() {
 131                 return $this->loadBalancer;
 132         }
 133
 134         /**
 135          * @param int $mode DB_MASTER or DB_REPLICA
 136          *
 137          * @return IDatabase
 138          */
 139         private function getDBConnection( $mode ) {
 140                 $lb = $this->getDBLoadBalancer();
 141                 return $lb->getConnection( $mode, [], $this->wikiId );
 142         }
 143
 144         /**
 145          * @param IDatabase $connection
 146          */
 147         private function releaseDBConnection( IDatabase $connection ) {
 148                 $lb = $this->getDBLoadBalancer();
 149                 $lb->reuseConnection( $connection );
 150         }
 151
 152         /**
 153          * @param int $mode DB_MASTER or DB_REPLICA
 154          *
 155          * @return DBConnRef
 156          */
 157         private function getDBConnectionRef( $mode ) {
 158                 $lb = $this->getDBLoadBalancer();
 159                 return $lb->getConnectionRef( $mode, [], $this->wikiId );
 160         }
 161
 162         /**
 163          * Determines the page Title based on the available information.
 164          *
 165          * MCR migration note: this corresponds to Revision::getTitle
 166          *
 167          * @note this method should be private, external use should be avoided!
 168          *
 169          * @param int|null $pageId
 170          * @param int|null $revId
 171          * @param int $queryFlags
 172          *
 173          * @return Title
 174          * @throws RevisionAccessException
 175          */
 176         public function getTitle( $pageId, $revId, $queryFlags = 0 ) {
 177                 if ( !$pageId && !$revId ) {
 178                         throw new InvalidArgumentException( '$pageId and $revId cannot both be 0 or null' );
 179                 }
 180
 181                 list( $dbMode, $dbOptions, , ) = DBAccessObjectUtils::getDBOptions( $queryFlags );
 182                 $titleFlags = $dbMode == DB_MASTER ? Title::GAID_FOR_UPDATE : 0;
 183                 $title = null;
 184
 185                 // Loading by ID is best, but Title::newFromID does not support that for foreign IDs.
 186                 if ( $pageId !== null && $pageId > 0 && $this->wikiId === false ) {
 187                         // TODO: better foreign title handling (introduce TitleFactory)
 188                         $title = Title::newFromID( $pageId, $titleFlags );
 189                 }
 190
 191                 // rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
 192                 if ( !$title && $revId !== null && $revId > 0 ) {
 193                         $dbr = $this->getDbConnectionRef( $dbMode );
 194                         // @todo: Title::getSelectFields(), or Title::getQueryInfo(), or something like that
 195                         $row = $dbr->selectRow(
 196                                 [ 'revision', 'page' ],
 197                                 [
 198                                         'page_namespace',
 199                                         'page_title',
 200                                         'page_id',
 201                                         'page_latest',
 202                                         'page_is_redirect',
 203                                         'page_len',
 204                                 ],
 205                                 [ 'rev_id' => $revId ],
 206                                 __METHOD__,
 207                                 $dbOptions,
 208                                 [ 'page' => [ 'JOIN', 'page_id=rev_page' ] ]
 209                         );
 210                         if ( $row ) {
 211                                 // TODO: better foreign title handling (introduce TitleFactory)
 212                                 $title = Title::newFromRow( $row );
 213                         }
 214                 }
 215
 216                 if ( !$title ) {
 217                         throw new RevisionAccessException(
 218                                 "Could not determine title for page ID $pageId and revision ID $revId"
 219                         );
 220                 }
 221
 222                 return $title;
 223         }
 224
 225         /**
 226          * @param mixed $value
 227          * @param string $name
 228          *
 229          * @throw IncompleteRevisionException if $value is null
 230          * @return mixed $value, if $value is not null
 231          */
 232         private function failOnNull( $value, $name ) {
 233                 if ( $value === null ) {
 234                         throw new IncompleteRevisionException(
 235                                 "$name must not be " . var_export( $value, true ) . "!"
 236                         );
 237                 }
 238
 239                 return $value;
 240         }
 241
 242         /**
 243          * @param mixed $value
 244          * @param string $name
 245          *
 246          * @throw IncompleteRevisionException if $value is empty
 247          * @return mixed $value, if $value is not null
 248          */
 249         private function failOnEmpty( $value, $name ) {
 250                 if ( $value === null || $value === 0 || $value === '' ) {
 251                         throw new IncompleteRevisionException(
 252                                 "$name must not be " . var_export( $value, true ) . "!"
 253                         );
 254                 }
 255
 256                 return $value;
 257         }
 258
 259         /**
 260          * Insert a new revision into the database, returning the new revision ID
 261          * number on success and dies horribly on failure.
 262          *
 263          * MCR migration note: this replaces Revision::insertOn
 264          *
 265          * @param RevisionRecord $rev
 266          * @param IDatabase $dbw (master connection)
 267          *
 268          * @throws InvalidArgumentException
 269          * @return RevisionRecord the new revision record.
 270          */
 271         public function insertRevisionOn( RevisionRecord $rev, IDatabase $dbw ) {
 272                 // TODO: pass in a DBTransactionContext instead of a database connection.
 273                 $this->checkDatabaseWikiId( $dbw );
 274
 275                 if ( !$rev->getSlotRoles() ) {
 276                         throw new InvalidArgumentException( 'At least one slot needs to be defined!' );
 277                 }
 278
 279                 if ( $rev->getSlotRoles() !== [ 'main' ] ) {
 280                         throw new InvalidArgumentException( 'Only the main slot is supported for now!' );
 281                 }
 282
 283                 // TODO: we shouldn't need an actual Title here.
 284                 $title = Title::newFromLinkTarget( $rev->getPageAsLinkTarget() );
 285                 $pageId = $this->failOnEmpty( $rev->getPageId(), 'rev_page field' ); // check this early
 286
 287                 $parentId = $rev->getParentId() === null
 288                         ? $this->getPreviousRevisionId( $dbw, $rev )
 289                         : $rev->getParentId();
 290
 291                 // Record the text (or external storage URL) to the blob store
 292                 $slot = $rev->getSlot( 'main', RevisionRecord::RAW );
 293
 294                 $size = $this->failOnNull( $rev->getSize(), 'size field' );
 295                 $sha1 = $this->failOnEmpty( $rev->getSha1(), 'sha1 field' );
 296
 297                 if ( !$slot->hasAddress() ) {
 298                         $content = $slot->getContent();
 299                         $format = $content->getDefaultFormat();
 300                         $model = $content->getModel();
 301
 302                         $this->checkContentModel( $content, $title );
 303
 304                         $data = $content->serialize( $format );
 305
 306                         // Hints allow the blob store to optimize by "leaking" application level information to it.
 307                         // TODO: with the new MCR storage schema, we rev_id have this before storing the blobs.
 308                         // When we have it, add rev_id as a hint. Can be used with rev_parent_id for
 309                         // differential storage or compression of subsequent revisions.
 310                         $blobHints = [
 311                                 BlobStore::DESIGNATION_HINT => 'page-content', // BlobStore may be used for other things too.
 312                                 BlobStore::PAGE_HINT => $pageId,
 313                                 BlobStore::ROLE_HINT => $slot->getRole(),
 314                                 BlobStore::PARENT_HINT => $parentId,
 315                                 BlobStore::SHA1_HINT => $slot->getSha1(),
 316                                 BlobStore::MODEL_HINT => $model,
 317                                 BlobStore::FORMAT_HINT => $format,
 318                         ];
 319
 320                         $blobAddress = $this->blobStore->storeBlob( $data, $blobHints );
 321                 } else {
 322                         $blobAddress = $slot->getAddress();
 323                         $model = $slot->getModel();
 324                         $format = $slot->getFormat();
 325                 }
 326
 327                 $textId = $this->blobStore->getTextIdFromAddress( $blobAddress );
 328
 329                 if ( !$textId ) {
 330                         throw new LogicException(
 331                                 'Blob address not supported in 1.29 database schema: ' . $blobAddress
 332                         );
 333                 }
 334
 335                 // getTextIdFromAddress() is free to insert something into the text table, so $textId
 336                 // may be a new value, not anything already contained in $blobAddress.
 337                 $blobAddress = 'tt:' . $textId;
 338
 339                 $comment = $this->failOnNull( $rev->getComment( RevisionRecord::RAW ), 'comment' );
 340                 $user = $this->failOnNull( $rev->getUser( RevisionRecord::RAW ), 'user' );
 341                 $timestamp = $this->failOnEmpty( $rev->getTimestamp(), 'timestamp field' );
 342
 343                 # Record the edit in revisions
 344                 $row = [
 345                         'rev_page'       => $pageId,
 346                         'rev_parent_id'  => $parentId,
 347                         'rev_text_id'    => $textId,
 348                         'rev_minor_edit' => $rev->isMinor() ? 1 : 0,
 349                         'rev_user'       => $this->failOnNull( $user->getId(), 'user field' ),
 350                         'rev_user_text'  => $this->failOnEmpty( $user->getName(), 'user_text field' ),
 351                         'rev_timestamp'  => $dbw->timestamp( $timestamp ),
 352                         'rev_deleted'    => $rev->getVisibility(),
 353                         'rev_len'        => $size,
 354                         'rev_sha1'       => $sha1,
 355                 ];
 356
 357                 if ( $rev->getId() !== null ) {
 358                         // Needed to restore revisions with their original ID
 359                         $row['rev_id'] = $rev->getId();
 360                 }
 361
 362                 list( $commentFields, $commentCallback ) =
 363                         CommentStore::newKey( 'rev_comment' )->insertWithTempTable( $dbw, $comment );
 364                 $row += $commentFields;
 365
 366                 if ( $this->contentHandlerUseDB ) {
 367                         // MCR migration note: rev_content_model and rev_content_format will go away
 368
 369                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
 370                         $defaultFormat = ContentHandler::getForModelID( $defaultModel )->getDefaultFormat();
 371
 372                         $row['rev_content_model'] = ( $model === $defaultModel ) ? null : $model;
 373                         $row['rev_content_format'] = ( $format === $defaultFormat ) ? null : $format;
 374                 }
 375
 376                 $dbw->insert( 'revision', $row, __METHOD__ );
 377
 378                 if ( !isset( $row['rev_id'] ) ) {
 379                         // only if auto-increment was used
 380                         $row['rev_id'] = intval( $dbw->insertId() );
 381                 }
 382                 $commentCallback( $row['rev_id'] );
 383
 384                 // Insert IP revision into ip_changes for use when querying for a range.
 385                 if ( $row['rev_user'] === 0 && IP::isValid( $row['rev_user_text'] ) ) {
 386                         $ipcRow = [
 387                                 'ipc_rev_id'        => $row['rev_id'],
 388                                 'ipc_rev_timestamp' => $row['rev_timestamp'],
 389                                 'ipc_hex'           => IP::toHex( $row['rev_user_text'] ),
 390                         ];
 391                         $dbw->insert( 'ip_changes', $ipcRow, __METHOD__ );
 392                 }
 393
 394                 $newSlot = SlotRecord::newSaved( $row['rev_id'], $blobAddress, $slot );
 395                 $slots = new RevisionSlots( [ 'main' => $newSlot ] );
 396
 397                 $user = new UserIdentityValue( intval( $row['rev_user'] ), $row['rev_user_text'] );
 398
 399                 $rev = new RevisionStoreRecord(
 400                         $title,
 401                         $user,
 402                         $comment,
 403                         (object)$row,
 404                         $slots,
 405                         $this->wikiId
 406                 );
 407
 408                 $newSlot = $rev->getSlot( 'main', RevisionRecord::RAW );
 409
 410                 // sanity checks
 411                 Assert::postcondition( $rev->getId() > 0, 'revision must have an ID' );
 412                 Assert::postcondition( $rev->getPageId() > 0, 'revision must have a page ID' );
 413                 Assert::postcondition(
 414                         $rev->getComment( RevisionRecord::RAW ) !== null,
 415                         'revision must have a comment'
 416                 );
 417                 Assert::postcondition(
 418                         $rev->getUser( RevisionRecord::RAW ) !== null,
 419                         'revision must have a user'
 420                 );
 421
 422                 Assert::postcondition( $newSlot !== null, 'revision must have a main slot' );
 423                 Assert::postcondition(
 424                         $newSlot->getAddress() !== null,
 425                         'main slot must have an addess'
 426                 );
 427
 428                 Hooks::run( 'RevisionRecordInserted', [ $rev ] );
 429
 430                 return $rev;
 431         }
 432
 433         /**
 434          * MCR migration note: this corresponds to Revision::checkContentModel
 435          *
 436          * @param Content $content
 437          * @param Title $title
 438          *
 439          * @throws MWException
 440          * @throws MWUnknownContentModelException
 441          */
 442         private function checkContentModel( Content $content, Title $title ) {
 443                 // Note: may return null for revisions that have not yet been inserted
 444
 445                 $model = $content->getModel();
 446                 $format = $content->getDefaultFormat();
 447                 $handler = $content->getContentHandler();
 448
 449                 $name = "$title";
 450
 451                 if ( !$handler->isSupportedFormat( $format ) ) {
 452                         throw new MWException( "Can't use format $format with content model $model on $name" );
 453                 }
 454
 455                 if ( !$this->contentHandlerUseDB ) {
 456                         // if $wgContentHandlerUseDB is not set,
 457                         // all revisions must use the default content model and format.
 458
 459                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
 460                         $defaultHandler = ContentHandler::getForModelID( $defaultModel );
 461                         $defaultFormat = $defaultHandler->getDefaultFormat();
 462
 463                         if ( $model != $defaultModel ) {
 464                                 throw new MWException( "Can't save non-default content model with "
 465                                         . "\$wgContentHandlerUseDB disabled: model is $model, "
 466                                         . "default for $name is $defaultModel"
 467                                 );
 468                         }
 469
 470                         if ( $format != $defaultFormat ) {
 471                                 throw new MWException( "Can't use non-default content format with "
 472                                         . "\$wgContentHandlerUseDB disabled: format is $format, "
 473                                         . "default for $name is $defaultFormat"
 474                                 );
 475                         }
 476                 }
 477
 478                 if ( !$content->isValid() ) {
 479                         throw new MWException(
 480                                 "New content for $name is not valid! Content model is $model"
 481                         );
 482                 }
 483         }
 484
 485         /**
 486          * Create a new null-revision for insertion into a page's
 487          * history. This will not re-save the text, but simply refer
 488          * to the text from the previous version.
 489          *
 490          * Such revisions can for instance identify page rename
 491          * operations and other such meta-modifications.
 492          *
 493          * MCR migration note: this replaces Revision::newNullRevision
 494          *
 495          * @todo Introduce newFromParentRevision(). newNullRevision can then be based on that
 496          * (or go away).
 497          *
 498          * @param IDatabase $dbw
 499          * @param Title $title Title of the page to read from
 500          * @param CommentStoreComment $comment RevisionRecord's summary
 501          * @param bool $minor Whether the revision should be considered as minor
 502          * @param User $user The user to attribute the revision to
 503          * @return RevisionRecord|null RevisionRecord or null on error
 504          */
 505         public function newNullRevision(
 506                 IDatabase $dbw,
 507                 Title $title,
 508                 CommentStoreComment $comment,
 509                 $minor,
 510                 User $user
 511         ) {
 512                 $this->checkDatabaseWikiId( $dbw );
 513
 514                 $fields = [ 'page_latest', 'page_namespace', 'page_title',
 515                         'rev_id', 'rev_text_id', 'rev_len', 'rev_sha1' ];
 516
 517                 if ( $this->contentHandlerUseDB ) {
 518                         $fields[] = 'rev_content_model';
 519                         $fields[] = 'rev_content_format';
 520                 }
 521
 522                 $current = $dbw->selectRow(
 523                         [ 'page', 'revision' ],
 524                         $fields,
 525                         [
 526                                 'page_id' => $title->getArticleID(),
 527                                 'page_latest=rev_id',
 528                         ],
 529                         __METHOD__,
 530                         [ 'FOR UPDATE' ] // T51581
 531                 );
 532
 533                 if ( $current ) {
 534                         $fields = [
 535                                 'page'       => $title->getArticleID(),
 536                                 'user_text'  => $user->getName(),
 537                                 'user'       => $user->getId(),
 538                                 'comment'    => $comment,
 539                                 'minor_edit' => $minor,
 540                                 'text_id'    => $current->rev_text_id,
 541                                 'parent_id'  => $current->page_latest,
 542                                 'len'        => $current->rev_len,
 543                                 'sha1'       => $current->rev_sha1
 544                         ];
 545
 546                         if ( $this->contentHandlerUseDB ) {
 547                                 $fields['content_model'] = $current->rev_content_model;
 548                                 $fields['content_format'] = $current->rev_content_format;
 549                         }
 550
 551                         $fields['title'] = Title::makeTitle( $current->page_namespace, $current->page_title );
 552
 553                         $mainSlot = $this->emulateMainSlot_1_29( $fields, 0, $title );
 554                         $revision = new MutableRevisionRecord( $title, $this->wikiId );
 555                         $this->initializeMutableRevisionFromArray( $revision, $fields );
 556                         $revision->setSlot( $mainSlot );
 557                 } else {
 558                         $revision = null;
 559                 }
 560
 561                 return $revision;
 562         }
 563
 564         /**
 565          * MCR migration note: this replaces Revision::isUnpatrolled
 566          *
 567          * @todo This is overly specific, so move or kill this method.
 568          *
 569          * @param RevisionRecord $rev
 570          *
 571          * @return int Rcid of the unpatrolled row, zero if there isn't one
 572          */
 573         public function getRcIdIfUnpatrolled( RevisionRecord $rev ) {
 574                 $rc = $this->getRecentChange( $rev );
 575                 if ( $rc && $rc->getAttribute( 'rc_patrolled' ) == 0 ) {
 576                         return $rc->getAttribute( 'rc_id' );
 577                 } else {
 578                         return 0;
 579                 }
 580         }
 581
 582         /**
 583          * Get the RC object belonging to the current revision, if there's one
 584          *
 585          * MCR migration note: this replaces Revision::getRecentChange
 586          *
 587          * @todo move this somewhere else?
 588          *
 589          * @param RevisionRecord $rev
 590          * @param int $flags (optional) $flags include:
 591          *      IDBAccessObject::READ_LATEST: Select the data from the master
 592          *
 593          * @return null|RecentChange
 594          */
 595         public function getRecentChange( RevisionRecord $rev, $flags = 0 ) {
 596                 $dbr = $this->getDBConnection( DB_REPLICA );
 597
 598                 list( $dbType, ) = DBAccessObjectUtils::getDBOptions( $flags );
 599
 600                 $userIdentity = $rev->getUser( RevisionRecord::RAW );
 601
 602                 if ( !$userIdentity ) {
 603                         // If the revision has no user identity, chances are it never went
 604                         // into the database, and doesn't have an RC entry.
 605                         return null;
 606                 }
 607
 608                 // TODO: Select by rc_this_oldid alone - but as of Nov 2017, there is no index on that!
 609                 $rc = RecentChange::newFromConds(
 610                         [
 611                                 'rc_user_text' => $userIdentity->getName(),
 612                                 'rc_timestamp' => $dbr->timestamp( $rev->getTimestamp() ),
 613                                 'rc_this_oldid' => $rev->getId()
 614                         ],
 615                         __METHOD__,
 616                         $dbType
 617                 );
 618
 619                 $this->releaseDBConnection( $dbr );
 620
 621                 // XXX: cache this locally? Glue it to the RevisionRecord?
 622                 return $rc;
 623         }
 624
 625         /**
 626          * Maps fields of the archive row to corresponding revision rows.
 627          *
 628          * @param object $archiveRow
 629          *
 630          * @return object a revision row object, corresponding to $archiveRow.
 631          */
 632         private static function mapArchiveFields( $archiveRow ) {
 633                 $fieldMap = [
 634                         // keep with ar prefix:
 635                         'ar_id'        => 'ar_id',
 636
 637                         // not the same suffix:
 638                         'ar_page_id'        => 'rev_page',
 639                         'ar_rev_id'         => 'rev_id',
 640
 641                         // same suffix:
 642                         'ar_text_id'        => 'rev_text_id',
 643                         'ar_timestamp'      => 'rev_timestamp',
 644                         'ar_user_text'      => 'rev_user_text',
 645                         'ar_user'           => 'rev_user',
 646                         'ar_minor_edit'     => 'rev_minor_edit',
 647                         'ar_deleted'        => 'rev_deleted',
 648                         'ar_len'            => 'rev_len',
 649                         'ar_parent_id'      => 'rev_parent_id',
 650                         'ar_sha1'           => 'rev_sha1',
 651                         'ar_comment'        => 'rev_comment',
 652                         'ar_comment_cid'    => 'rev_comment_cid',
 653                         'ar_comment_id'     => 'rev_comment_id',
 654                         'ar_comment_text'   => 'rev_comment_text',
 655                         'ar_comment_data'   => 'rev_comment_data',
 656                         'ar_comment_old'    => 'rev_comment_old',
 657                         'ar_content_format' => 'rev_content_format',
 658                         'ar_content_model'  => 'rev_content_model',
 659                 ];
 660
 661                 if ( empty( $archiveRow->ar_text_id ) ) {
 662                         $fieldMap['ar_text'] = 'old_text';
 663                         $fieldMap['ar_flags'] = 'old_flags';
 664                 }
 665
 666                 $revRow = new stdClass();
 667                 foreach ( $fieldMap as $arKey => $revKey ) {
 668                         if ( property_exists( $archiveRow, $arKey ) ) {
 669                                 $revRow->$revKey = $archiveRow->$arKey;
 670                         }
 671                 }
 672
 673                 return $revRow;
 674         }
 675
 676         /**
 677          * Constructs a RevisionRecord for the revisions main slot, based on the MW1.29 schema.
 678          *
 679          * @param object|array $row Either a database row or an array
 680          * @param int $queryFlags for callbacks
 681          * @param Title $title
 682          *
 683          * @return SlotRecord The main slot, extracted from the MW 1.29 style row.
 684          * @throws MWException
 685          */
 686         private function emulateMainSlot_1_29( $row, $queryFlags, Title $title ) {
 687                 $mainSlotRow = new stdClass();
 688                 $mainSlotRow->role_name = 'main';
 689
 690                 $content = null;
 691                 $blobData = null;
 692                 $blobFlags = '';
 693
 694                 if ( is_object( $row ) ) {
 695                         // archive row
 696                         if ( !isset( $row->rev_id ) && isset( $row->ar_user ) ) {
 697                                 $row = $this->mapArchiveFields( $row );
 698                         }
 699
 700                         if ( isset( $row->rev_text_id ) && $row->rev_text_id > 0 ) {
 701                                 $mainSlotRow->cont_address = 'tt:' . $row->rev_text_id;
 702                         } elseif ( isset( $row->ar_id ) ) {
 703                                 $mainSlotRow->cont_address = 'ar:' . $row->ar_id;
 704                         }
 705
 706                         if ( isset( $row->old_text ) ) {
 707                                 // this happens when the text-table gets joined directly, in the pre-1.30 schema
 708                                 $blobData = isset( $row->old_text ) ? strval( $row->old_text ) : null;
 709                                 $blobFlags = isset( $row->old_flags ) ? strval( $row->old_flags ) : '';
 710                         }
 711
 712                         $mainSlotRow->slot_revision = intval( $row->rev_id );
 713
 714                         $mainSlotRow->cont_size = isset( $row->rev_len ) ? intval( $row->rev_len ) : null;
 715                         $mainSlotRow->cont_sha1 = isset( $row->rev_sha1 ) ? strval( $row->rev_sha1 ) : null;
 716                         $mainSlotRow->model_name = isset( $row->rev_content_model )
 717                                 ? strval( $row->rev_content_model )
 718                                 : null;
 719                         // XXX: in the future, we'll probably always use the default format, and drop content_format
 720                         $mainSlotRow->format_name = isset( $row->rev_content_format )
 721                                 ? strval( $row->rev_content_format )
 722                                 : null;
 723                 } elseif ( is_array( $row ) ) {
 724                         $mainSlotRow->slot_revision = isset( $row['id'] ) ? intval( $row['id'] ) : null;
 725
 726                         $mainSlotRow->cont_address = isset( $row['text_id'] )
 727                                 ? 'tt:' . intval( $row['text_id'] )
 728                                 : null;
 729                         $mainSlotRow->cont_size = isset( $row['len'] ) ? intval( $row['len'] ) : null;
 730                         $mainSlotRow->cont_sha1 = isset( $row['sha1'] ) ? strval( $row['sha1'] ) : null;
 731
 732                         $mainSlotRow->model_name = isset( $row['content_model'] )
 733                                 ? strval( $row['content_model'] ) : null;  // XXX: must be a string!
 734                         // XXX: in the future, we'll probably always use the default format, and drop content_format
 735                         $mainSlotRow->format_name = isset( $row['content_format'] )
 736                                 ? strval( $row['content_format'] ) : null;
 737                         $blobData = isset( $row['text'] ) ? rtrim( strval( $row['text'] ) ) : null;
 738                         $blobFlags = isset( $row['flags'] ) ? trim( strval( $row['flags'] ) ) : '';
 739
 740                         // if we have a Content object, override mText and mContentModel
 741                         if ( !empty( $row['content'] ) ) {
 742                                 if ( !( $row['content'] instanceof Content ) ) {
 743                                         throw new MWException( 'content field must contain a Content object.' );
 744                                 }
 745
 746                                 /** @var Content $content */
 747                                 $content = $row['content'];
 748                                 $handler = $content->getContentHandler();
 749
 750                                 $mainSlotRow->model_name = $content->getModel();
 751
 752                                 // XXX: in the future, we'll probably always use the default format.
 753                                 if ( $mainSlotRow->format_name === null ) {
 754                                         $mainSlotRow->format_name = $handler->getDefaultFormat();
 755                                 }
 756                         }
 757                 } else {
 758                         throw new MWException( 'Revision constructor passed invalid row format.' );
 759                 }
 760
 761                 // With the old schema, the content changes with every revision.
 762                 // ...except for null-revisions. Would be nice if we could detect them.
 763                 $mainSlotRow->slot_inherited = 0;
 764
 765                 if ( $mainSlotRow->model_name === null ) {
 766                         $mainSlotRow->model_name = function ( SlotRecord $slot ) use ( $title ) {
 767                                 // TODO: MCR: consider slot role in getDefaultModelFor()! Use LinkTarget!
 768                                 // TODO: MCR: deprecate $title->getModel().
 769                                 return ContentHandler::getDefaultModelFor( $title );
 770                         };
 771                 }
 772
 773                 if ( !$content ) {
 774                         $content = function ( SlotRecord $slot )
 775                                 use ( $blobData, $blobFlags, $queryFlags, $mainSlotRow )
 776                         {
 777                                 return $this->loadSlotContent(
 778                                         $slot,
 779                                         $blobData,
 780                                         $blobFlags,
 781                                         $mainSlotRow->format_name,
 782                                         $queryFlags
 783                                 );
 784                         };
 785                 }
 786
 787                 return new SlotRecord( $mainSlotRow, $content );
 788         }
 789
 790         /**
 791          * Loads a Content object based on a slot row.
 792          *
 793          * This method does not call $slot->getContent(), and may be used as a callback
 794          * called by $slot->getContent().
 795          *
 796          * MCR migration note: this roughly corresponds to Revision::getContentInternal
 797          *
 798          * @param SlotRecord $slot The SlotRecord to load content for
 799          * @param string|null $blobData The content blob, in the form indicated by $blobFlags
 800          * @param string $blobFlags Flags indicating how $blobData needs to be processed
 801          * @param string|null $blobFormat MIME type indicating how $dataBlob is encoded
 802          * @param int $queryFlags
 803          *
 804          * @throw RevisionAccessException
 805          * @return Content
 806          */
 807         private function loadSlotContent(
 808                 SlotRecord $slot,
 809                 $blobData = null,
 810                 $blobFlags = '',
 811                 $blobFormat = null,
 812                 $queryFlags = 0
 813         ) {
 814                 if ( $blobData !== null ) {
 815                         Assert::parameterType( 'string', $blobData, '$blobData' );
 816                         Assert::parameterType( 'string', $blobFlags, '$blobFlags' );
 817
 818                         $cacheKey = $slot->hasAddress() ? $slot->getAddress() : null;
 819
 820                         $data = $this->blobStore->expandBlob( $blobData, $blobFlags, $cacheKey );
 821
 822                         if ( $data === false ) {
 823                                 throw new RevisionAccessException(
 824                                         "Failed to expand blob data using flags $blobFlags (key: $cacheKey)"
 825                                 );
 826                         }
 827                 } else {
 828                         $address = $slot->getAddress();
 829                         try {
 830                                 $data = $this->blobStore->getBlob( $address, $queryFlags );
 831                         } catch ( BlobAccessException $e ) {
 832                                 throw new RevisionAccessException(
 833                                         "Failed to load data blob from $address: " . $e->getMessage(), 0, $e
 834                                 );
 835                         }
 836                 }
 837
 838                 // Unserialize content
 839                 $handler = ContentHandler::getForModelID( $slot->getModel() );
 840
 841                 $content = $handler->unserializeContent( $data, $blobFormat );
 842                 return $content;
 843         }
 844
 845         /**
 846          * Load a page revision from a given revision ID number.
 847          * Returns null if no such revision can be found.
 848          *
 849          * MCR migration note: this replaces Revision::newFromId
 850          *
 851          * $flags include:
 852          *      IDBAccessObject::READ_LATEST: Select the data from the master
 853          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 854          *
 855          * @param int $id
 856          * @param int $flags (optional)
 857          * @return RevisionRecord|null
 858          */
 859         public function getRevisionById( $id, $flags = 0 ) {
 860                 return $this->newRevisionFromConds( [ 'rev_id' => intval( $id ) ], $flags );
 861         }
 862
 863         /**
 864          * Load either the current, or a specified, revision
 865          * that's attached to a given link target. If not attached
 866          * to that link target, will return null.
 867          *
 868          * MCR migration note: this replaces Revision::newFromTitle
 869          *
 870          * $flags include:
 871          *      IDBAccessObject::READ_LATEST: Select the data from the master
 872          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 873          *
 874          * @param LinkTarget $linkTarget
 875          * @param int $revId (optional)
 876          * @param int $flags Bitfield (optional)
 877          * @return RevisionRecord|null
 878          */
 879         public function getRevisionByTitle( LinkTarget $linkTarget, $revId = 0, $flags = 0 ) {
 880                 $conds = [
 881                         'page_namespace' => $linkTarget->getNamespace(),
 882                         'page_title' => $linkTarget->getDBkey()
 883                 ];
 884                 if ( $revId ) {
 885                         // Use the specified revision ID.
 886                         // Note that we use newRevisionFromConds here because we want to retry
 887                         // and fall back to master if the page is not found on a replica.
 888                         // Since the caller supplied a revision ID, we are pretty sure the revision is
 889                         // supposed to exist, so we should try hard to find it.
 890                         $conds['rev_id'] = $revId;
 891                         return $this->newRevisionFromConds( $conds, $flags );
 892                 } else {
 893                         // Use a join to get the latest revision.
 894                         // Note that we don't use newRevisionFromConds here because we don't want to retry
 895                         // and fall back to master. The assumption is that we only want to force the fallback
 896                         // if we are quite sure the revision exists because the caller supplied a revision ID.
 897                         // If the page isn't found at all on a replica, it probably simply does not exist.
 898                         $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 899
 900                         $conds[] = 'rev_id=page_latest';
 901                         $rev = $this->loadRevisionFromConds( $db, $conds, $flags );
 902
 903                         $this->releaseDBConnection( $db );
 904                         return $rev;
 905                 }
 906         }
 907
 908         /**
 909          * Load either the current, or a specified, revision
 910          * that's attached to a given page ID.
 911          * Returns null if no such revision can be found.
 912          *
 913          * MCR migration note: this replaces Revision::newFromPageId
 914          *
 915          * $flags include:
 916          *      IDBAccessObject::READ_LATEST: Select the data from the master (since 1.20)
 917          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 918          *
 919          * @param int $pageId
 920          * @param int $revId (optional)
 921          * @param int $flags Bitfield (optional)
 922          * @return RevisionRecord|null
 923          */
 924         public function getRevisionByPageId( $pageId, $revId = 0, $flags = 0 ) {
 925                 $conds = [ 'page_id' => $pageId ];
 926                 if ( $revId ) {
 927                         // Use the specified revision ID.
 928                         // Note that we use newRevisionFromConds here because we want to retry
 929                         // and fall back to master if the page is not found on a replica.
 930                         // Since the caller supplied a revision ID, we are pretty sure the revision is
 931                         // supposed to exist, so we should try hard to find it.
 932                         $conds['rev_id'] = $revId;
 933                         return $this->newRevisionFromConds( $conds, $flags );
 934                 } else {
 935                         // Use a join to get the latest revision.
 936                         // Note that we don't use newRevisionFromConds here because we don't want to retry
 937                         // and fall back to master. The assumption is that we only want to force the fallback
 938                         // if we are quite sure the revision exists because the caller supplied a revision ID.
 939                         // If the page isn't found at all on a replica, it probably simply does not exist.
 940                         $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 941
 942                         $conds[] = 'rev_id=page_latest';
 943                         $rev = $this->loadRevisionFromConds( $db, $conds, $flags );
 944
 945                         $this->releaseDBConnection( $db );
 946                         return $rev;
 947                 }
 948         }
 949
 950         /**
 951          * Load the revision for the given title with the given timestamp.
 952          * WARNING: Timestamps may in some circumstances not be unique,
 953          * so this isn't the best key to use.
 954          *
 955          * MCR migration note: this replaces Revision::loadFromTimestamp
 956          *
 957          * @param Title $title
 958          * @param string $timestamp
 959          * @return RevisionRecord|null
 960          */
 961         public function getRevisionByTimestamp( $title, $timestamp ) {
 962                 return $this->newRevisionFromConds(
 963                         [
 964                                 'rev_timestamp' => $timestamp,
 965                                 'page_namespace' => $title->getNamespace(),
 966                                 'page_title' => $title->getDBkey()
 967                         ],
 968                         0,
 969                         $title
 970                 );
 971         }
 972
 973         /**
 974          * Make a fake revision object from an archive table row. This is queried
 975          * for permissions or even inserted (as in Special:Undelete)
 976          *
 977          * MCR migration note: this replaces Revision::newFromArchiveRow
 978          *
 979          * @param object $row
 980          * @param int $queryFlags
 981          * @param Title|null $title
 982          * @param array $overrides associative array with fields of $row to override. This may be
 983          *   used e.g. to force the parent revision ID or page ID. Keys in the array are fields
 984          *   names from the archive table without the 'ar_' prefix, i.e. use 'parent_id' to
 985          *   override ar_parent_id.
 986          *
 987          * @return RevisionRecord
 988          * @throws MWException
 989          */
 990         public function newRevisionFromArchiveRow(
 991                 $row,
 992                 $queryFlags = 0,
 993                 Title $title = null,
 994                 array $overrides = []
 995         ) {
 996                 Assert::parameterType( 'object', $row, '$row' );
 997
 998                 // check second argument, since Revision::newFromArchiveRow had $overrides in that spot.
 999                 Assert::parameterType( 'integer', $queryFlags, '$queryFlags' );
1000
1001                 if ( !$title && isset( $overrides['title'] ) ) {
1002                         if ( !( $overrides['title'] instanceof Title ) ) {
1003                                 throw new MWException( 'title field override must contain a Title object.' );
1004                         }
1005
1006                         $title = $overrides['title'];
1007                 }
1008
1009                 if ( !isset( $title ) ) {
1010                         if ( isset( $row->ar_namespace ) && isset( $row->ar_title ) ) {
1011                                 $title = Title::makeTitle( $row->ar_namespace, $row->ar_title );
1012                         } else {
1013                                 throw new InvalidArgumentException(
1014                                         'A Title or ar_namespace and ar_title must be given'
1015                                 );
1016                         }
1017                 }
1018
1019                 foreach ( $overrides as $key => $value ) {
1020                         $field = "ar_$key";
1021                         $row->$field = $value;
1022                 }
1023
1024                 $user = $this->getUserIdentityFromRowObject( $row, 'ar_' );
1025
1026                 $comment = CommentStore::newKey( 'ar_comment' )
1027                         // Legacy because $row may have come from self::selectFields()
1028                         ->getCommentLegacy( $this->getDBConnection( DB_REPLICA ), $row, true );
1029
1030                 $mainSlot = $this->emulateMainSlot_1_29( $row, $queryFlags, $title );
1031                 $slots = new RevisionSlots( [ 'main' => $mainSlot ] );
1032
1033                 return new RevisionArchiveRecord( $title, $user, $comment, $row, $slots, $this->wikiId );
1034         }
1035
1036         /**
1037          * @param object $row
1038          * @param string $prefix Field prefix, such as 'rev_' or 'ar_'.
1039          *
1040          * @return UserIdentityValue
1041          */
1042         private function getUserIdentityFromRowObject( $row, $prefix = 'rev_' ) {
1043                 $idField = "{$prefix}user";
1044                 $nameField = "{$prefix}user_text";
1045
1046                 $userId = intval( $row->$idField );
1047
1048                 if ( isset( $row->user_name ) ) {
1049                         $userName = $row->user_name;
1050                 } elseif ( isset( $row->$nameField ) ) {
1051                         $userName = $row->$nameField;
1052                 } else {
1053                         $userName = User::whoIs( $userId );
1054                 }
1055
1056                 if ( $userName === false ) {
1057                         wfWarn( __METHOD__ . ': Cannot determine user name for user ID ' . $userId );
1058                         $userName = '';
1059                 }
1060
1061                 return new UserIdentityValue( $userId, $userName );
1062         }
1063
1064         /**
1065          * @see RevisionFactory::newRevisionFromRow_1_29
1066          *
1067          * MCR migration note: this replaces Revision::newFromRow
1068          *
1069          * @param object $row
1070          * @param int $queryFlags
1071          * @param Title|null $title
1072          *
1073          * @return RevisionRecord
1074          * @throws MWException
1075          * @throws RevisionAccessException
1076          */
1077         private function newRevisionFromRow_1_29( $row, $queryFlags = 0, Title $title = null ) {
1078                 Assert::parameterType( 'object', $row, '$row' );
1079
1080                 if ( !$title ) {
1081                         $pageId = isset( $row->rev_page ) ? $row->rev_page : 0; // XXX: also check page_id?
1082                         $revId = isset( $row->rev_id ) ? $row->rev_id : 0;
1083
1084                         $title = $this->getTitle( $pageId, $revId, $queryFlags );
1085                 }
1086
1087                 if ( !isset( $row->page_latest ) ) {
1088                         $row->page_latest = $title->getLatestRevID();
1089                         if ( $row->page_latest === 0 && $title->exists() ) {
1090                                 wfWarn( 'Encountered title object in limbo: ID ' . $title->getArticleID() );
1091                         }
1092                 }
1093
1094                 $user = $this->getUserIdentityFromRowObject( $row );
1095
1096                 $comment = CommentStore::newKey( 'rev_comment' )
1097                         // Legacy because $row may have come from self::selectFields()
1098                         ->getCommentLegacy( $this->getDBConnection( DB_REPLICA ), $row, true );
1099
1100                 $mainSlot = $this->emulateMainSlot_1_29( $row, $queryFlags, $title );
1101                 $slots = new RevisionSlots( [ 'main' => $mainSlot ] );
1102
1103                 return new RevisionStoreRecord( $title, $user, $comment, $row, $slots, $this->wikiId );
1104         }
1105
1106         /**
1107          * @see RevisionFactory::newRevisionFromRow
1108          *
1109          * MCR migration note: this replaces Revision::newFromRow
1110          *
1111          * @param object $row
1112          * @param int $queryFlags
1113          * @param Title|null $title
1114          *
1115          * @return RevisionRecord
1116          */
1117         public function newRevisionFromRow( $row, $queryFlags = 0, Title $title = null ) {
1118                 return $this->newRevisionFromRow_1_29( $row, $queryFlags, $title );
1119         }
1120
1121         /**
1122          * Constructs a new MutableRevisionRecord based on the given associative array following
1123          * the MW1.29 convention for the Revision constructor.
1124          *
1125          * MCR migration note: this replaces Revision::newFromRow
1126          *
1127          * @param array $fields
1128          * @param int $queryFlags
1129          * @param Title|null $title
1130          *
1131          * @return MutableRevisionRecord
1132          * @throws MWException
1133          * @throws RevisionAccessException
1134          */
1135         public function newMutableRevisionFromArray(
1136                 array $fields,
1137                 $queryFlags = 0,
1138                 Title $title = null
1139         ) {
1140                 if ( !$title && isset( $fields['title'] ) ) {
1141                         if ( !( $fields['title'] instanceof Title ) ) {
1142                                 throw new MWException( 'title field must contain a Title object.' );
1143                         }
1144
1145                         $title = $fields['title'];
1146                 }
1147
1148                 if ( !$title ) {
1149                         $pageId = isset( $fields['page'] ) ? $fields['page'] : 0;
1150                         $revId = isset( $fields['id'] ) ? $fields['id'] : 0;
1151
1152                         $title = $this->getTitle( $pageId, $revId, $queryFlags );
1153                 }
1154
1155                 if ( !isset( $fields['page'] ) ) {
1156                         $fields['page'] = $title->getArticleID( $queryFlags );
1157                 }
1158
1159                 // if we have a content object, use it to set the model and type
1160                 if ( !empty( $fields['content'] ) ) {
1161                         if ( !( $fields['content'] instanceof Content ) ) {
1162                                 throw new MWException( 'content field must contain a Content object.' );
1163                         }
1164
1165                         if ( !empty( $fields['text_id'] ) ) {
1166                                 throw new MWException(
1167                                         "Text already stored in external store (id {$fields['text_id']}), " .
1168                                         "can't serialize content object"
1169                                 );
1170                         }
1171                 }
1172
1173                 // Replaces old lazy loading logic in Revision::getUserText.
1174                 if ( !isset( $fields['user_text'] ) && isset( $fields['user'] ) ) {
1175                         if ( $fields['user'] instanceof UserIdentity ) {
1176                                 /** @var User $user */
1177                                 $user = $fields['user'];
1178                                 $fields['user_text'] = $user->getName();
1179                                 $fields['user'] = $user->getId();
1180                         } else {
1181                                 // TODO: wrap this in a callback to make it lazy again.
1182                                 $name = $fields['user'] === 0 ? false : User::whoIs( $fields['user'] );
1183
1184                                 if ( $name === false ) {
1185                                         throw new MWException(
1186                                                 'user_text not given, and unknown user ID ' . $fields['user']
1187                                         );
1188                                 }
1189
1190                                 $fields['user_text'] = $name;
1191                         }
1192                 }
1193
1194                 if (
1195                         isset( $fields['comment'] )
1196                         && !( $fields['comment'] instanceof CommentStoreComment )
1197                 ) {
1198                         $commentData = isset( $fields['comment_data'] ) ? $fields['comment_data'] : null;
1199
1200                         if ( $fields['comment'] instanceof Message ) {
1201                                 $fields['comment'] = CommentStoreComment::newUnsavedComment(
1202                                         $fields['comment'],
1203                                         $commentData
1204                                 );
1205                         } else {
1206                                 $commentText = trim( strval( $fields['comment'] ) );
1207                                 $fields['comment'] = CommentStoreComment::newUnsavedComment(
1208                                         $commentText,
1209                                         $commentData
1210                                 );
1211                         }
1212                 }
1213
1214                 $mainSlot = $this->emulateMainSlot_1_29( $fields, $queryFlags, $title );
1215
1216                 $revision = new MutableRevisionRecord( $title, $this->wikiId );
1217                 $this->initializeMutableRevisionFromArray( $revision, $fields );
1218                 $revision->setSlot( $mainSlot );
1219
1220                 return $revision;
1221         }
1222
1223         /**
1224          * @param MutableRevisionRecord $record
1225          * @param array $fields
1226          */
1227         private function initializeMutableRevisionFromArray(
1228                 MutableRevisionRecord $record,
1229                 array $fields
1230         ) {
1231                 /** @var UserIdentity $user */
1232                 $user = null;
1233
1234                 if ( isset( $fields['user'] ) && ( $fields['user'] instanceof UserIdentity ) ) {
1235                         $user = $fields['user'];
1236                 } elseif ( isset( $fields['user'] ) && isset( $fields['user_text'] ) ) {
1237                         $user = new UserIdentityValue( intval( $fields['user'] ), $fields['user_text'] );
1238                 } elseif ( isset( $fields['user'] ) ) {
1239                         $user = User::newFromId( intval( $fields['user'] ) );
1240                 } elseif ( isset( $fields['user_text'] ) ) {
1241                         $user = User::newFromName( $fields['user_text'] );
1242
1243                         // User::newFromName will return false for IP addresses (and invalid names)
1244                         if ( $user == false ) {
1245                                 $user = new UserIdentityValue( 0, $fields['user_text'] );
1246                         }
1247                 }
1248
1249                 if ( $user ) {
1250                         $record->setUser( $user );
1251                 }
1252
1253                 $timestamp = isset( $fields['timestamp'] )
1254                         ? strval( $fields['timestamp'] )
1255                         : wfTimestampNow(); // TODO: use a callback, so we can override it for testing.
1256
1257                 $record->setTimestamp( $timestamp );
1258
1259                 if ( isset( $fields['page'] ) ) {
1260                         $record->setPageId( intval( $fields['page'] ) );
1261                 }
1262
1263                 if ( isset( $fields['id'] ) ) {
1264                         $record->setId( intval( $fields['id'] ) );
1265                 }
1266                 if ( isset( $fields['parent_id'] ) ) {
1267                         $record->setParentId( intval( $fields['parent_id'] ) );
1268                 }
1269
1270                 if ( isset( $fields['sha1'] ) ) {
1271                         $record->setSha1( $fields['sha1'] );
1272                 }
1273                 if ( isset( $fields['size'] ) ) {
1274                         $record->setSize( intval( $fields['size'] ) );
1275                 }
1276
1277                 if ( isset( $fields['minor_edit'] ) ) {
1278                         $record->setMinorEdit( intval( $fields['minor_edit'] ) !== 0 );
1279                 }
1280                 if ( isset( $fields['deleted'] ) ) {
1281                         $record->setVisibility( intval( $fields['deleted'] ) );
1282                 }
1283
1284                 if ( isset( $fields['comment'] ) ) {
1285                         Assert::parameterType(
1286                                 CommentStoreComment::class,
1287                                 $fields['comment'],
1288                                 '$row[\'comment\']'
1289                         );
1290                         $record->setComment( $fields['comment'] );
1291                 }
1292         }
1293
1294         /**
1295          * Load a page revision from a given revision ID number.
1296          * Returns null if no such revision can be found.
1297          *
1298          * MCR migration note: this corresponds to Revision::loadFromId
1299          *
1300          * @note direct use is deprecated!
1301          * @todo remove when unused! there seem to be no callers of Revision::loadFromId
1302          *
1303          * @param IDatabase $db
1304          * @param int $id
1305          *
1306          * @return RevisionRecord|null
1307          */
1308         public function loadRevisionFromId( IDatabase $db, $id ) {
1309                 return $this->loadRevisionFromConds( $db, [ 'rev_id' => intval( $id ) ] );
1310         }
1311
1312         /**
1313          * Load either the current, or a specified, revision
1314          * that's attached to a given page. If not attached
1315          * to that page, will return null.
1316          *
1317          * MCR migration note: this replaces Revision::loadFromPageId
1318          *
1319          * @note direct use is deprecated!
1320          * @todo remove when unused!
1321          *
1322          * @param IDatabase $db
1323          * @param int $pageid
1324          * @param int $id
1325          * @return RevisionRecord|null
1326          */
1327         public function loadRevisionFromPageId( IDatabase $db, $pageid, $id = 0 ) {
1328                 $conds = [ 'rev_page' => intval( $pageid ), 'page_id' => intval( $pageid ) ];
1329                 if ( $id ) {
1330                         $conds['rev_id'] = intval( $id );
1331                 } else {
1332                         $conds[] = 'rev_id=page_latest';
1333                 }
1334                 return $this->loadRevisionFromConds( $db, $conds );
1335         }
1336
1337         /**
1338          * Load either the current, or a specified, revision
1339          * that's attached to a given page. If not attached
1340          * to that page, will return null.
1341          *
1342          * MCR migration note: this replaces Revision::loadFromTitle
1343          *
1344          * @note direct use is deprecated!
1345          * @todo remove when unused!
1346          *
1347          * @param IDatabase $db
1348          * @param Title $title
1349          * @param int $id
1350          *
1351          * @return RevisionRecord|null
1352          */
1353         public function loadRevisionFromTitle( IDatabase $db, $title, $id = 0 ) {
1354                 if ( $id ) {
1355                         $matchId = intval( $id );
1356                 } else {
1357                         $matchId = 'page_latest';
1358                 }
1359
1360                 return $this->loadRevisionFromConds(
1361                         $db,
1362                         [
1363                                 "rev_id=$matchId",
1364                                 'page_namespace' => $title->getNamespace(),
1365                                 'page_title' => $title->getDBkey()
1366                         ],
1367                         0,
1368                         $title
1369                 );
1370         }
1371
1372         /**
1373          * Load the revision for the given title with the given timestamp.
1374          * WARNING: Timestamps may in some circumstances not be unique,
1375          * so this isn't the best key to use.
1376          *
1377          * MCR migration note: this replaces Revision::loadFromTimestamp
1378          *
1379          * @note direct use is deprecated! Use getRevisionFromTimestamp instead!
1380          * @todo remove when unused!
1381          *
1382          * @param IDatabase $db
1383          * @param Title $title
1384          * @param string $timestamp
1385          * @return RevisionRecord|null
1386          */
1387         public function loadRevisionFromTimestamp( IDatabase $db, $title, $timestamp ) {
1388                 return $this->loadRevisionFromConds( $db,
1389                         [
1390                                 'rev_timestamp' => $db->timestamp( $timestamp ),
1391                                 'page_namespace' => $title->getNamespace(),
1392                                 'page_title' => $title->getDBkey()
1393                         ],
1394                         0,
1395                         $title
1396                 );
1397         }
1398
1399         /**
1400          * Given a set of conditions, fetch a revision
1401          *
1402          * This method should be used if we are pretty sure the revision exists.
1403          * Unless $flags has READ_LATEST set, this method will first try to find the revision
1404          * on a replica before hitting the master database.
1405          *
1406          * MCR migration note: this corresponds to Revision::newFromConds
1407          *
1408          * @param array $conditions
1409          * @param int $flags (optional)
1410          * @param Title $title
1411          *
1412          * @return RevisionRecord|null
1413          */
1414         private function newRevisionFromConds( $conditions, $flags = 0, Title $title = null ) {
1415                 $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
1416                 $rev = $this->loadRevisionFromConds( $db, $conditions, $flags, $title );
1417                 $this->releaseDBConnection( $db );
1418
1419                 $lb = $this->getDBLoadBalancer();
1420
1421                 // Make sure new pending/committed revision are visibile later on
1422                 // within web requests to certain avoid bugs like T93866 and T94407.
1423                 if ( !$rev
1424                         && !( $flags & self::READ_LATEST )
1425                         && $lb->getServerCount() > 1
1426                         && $lb->hasOrMadeRecentMasterChanges()
1427                 ) {
1428                         $flags = self::READ_LATEST;
1429                         $db = $this->getDBConnection( DB_MASTER );
1430                         $rev = $this->loadRevisionFromConds( $db, $conditions, $flags, $title );
1431                         $this->releaseDBConnection( $db );
1432                 }
1433
1434                 return $rev;
1435         }
1436
1437         /**
1438          * Given a set of conditions, fetch a revision from
1439          * the given database connection.
1440          *
1441          * MCR migration note: this corresponds to Revision::loadFromConds
1442          *
1443          * @param IDatabase $db
1444          * @param array $conditions
1445          * @param int $flags (optional)
1446          * @param Title $title
1447          *
1448          * @return RevisionRecord|null
1449          */
1450         private function loadRevisionFromConds(
1451                 IDatabase $db,
1452                 $conditions,
1453                 $flags = 0,
1454                 Title $title = null
1455         ) {
1456                 $row = $this->fetchRevisionRowFromConds( $db, $conditions, $flags );
1457                 if ( $row ) {
1458                         $rev = $this->newRevisionFromRow( $row, $flags, $title );
1459
1460                         return $rev;
1461                 }
1462
1463                 return null;
1464         }
1465
1466         /**
1467          * Throws an exception if the given database connection does not belong to the wiki this
1468          * RevisionStore is bound to.
1469          *
1470          * @param IDatabase $db
1471          * @throws MWException
1472          */
1473         private function checkDatabaseWikiId( IDatabase $db ) {
1474                 $storeWiki = $this->wikiId;
1475                 $dbWiki = $db->getDomainID();
1476
1477                 if ( $dbWiki === $storeWiki ) {
1478                         return;
1479                 }
1480
1481                 // XXX: we really want the default database ID...
1482                 $storeWiki = $storeWiki ?: wfWikiID();
1483                 $dbWiki = $dbWiki ?: wfWikiID();
1484
1485                 if ( $dbWiki === $storeWiki ) {
1486                         return;
1487                 }
1488
1489                 // HACK: counteract encoding imposed by DatabaseDomain
1490                 $storeWiki = str_replace( '?h', '-', $storeWiki );
1491                 $dbWiki = str_replace( '?h', '-', $dbWiki );
1492
1493                 if ( $dbWiki === $storeWiki ) {
1494                         return;
1495                 }
1496
1497                 throw new MWException( "RevisionStore for $storeWiki "
1498                         . "cannot be used with a DB connection for $dbWiki" );
1499         }
1500
1501         /**
1502          * Given a set of conditions, return a row with the
1503          * fields necessary to build RevisionRecord objects.
1504          *
1505          * MCR migration note: this corresponds to Revision::fetchFromConds
1506          *
1507          * @param IDatabase $db
1508          * @param array $conditions
1509          * @param int $flags (optional)
1510          *
1511          * @return object|false data row as a raw object
1512          */
1513         private function fetchRevisionRowFromConds( IDatabase $db, $conditions, $flags = 0 ) {
1514                 $this->checkDatabaseWikiId( $db );
1515
1516                 $revQuery = self::getQueryInfo( [ 'page', 'user' ] );
1517                 $options = [];
1518                 if ( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING ) {
1519                         $options[] = 'FOR UPDATE';
1520                 }
1521                 return $db->selectRow(
1522                         $revQuery['tables'],
1523                         $revQuery['fields'],
1524                         $conditions,
1525                         __METHOD__,
1526                         $options,
1527                         $revQuery['joins']
1528                 );
1529         }
1530
1531         /**
1532          * Return the tables, fields, and join conditions to be selected to create
1533          * a new revision object.
1534          *
1535          * MCR migration note: this replaces Revision::getQueryInfo
1536          *
1537          * @since 1.31
1538          *
1539          * @param array $options Any combination of the following strings
1540          *  - 'page': Join with the page table, and select fields to identify the page
1541          *  - 'user': Join with the user table, and select the user name
1542          *  - 'text': Join with the text table, and select fields to load page text
1543          *
1544          * @return array With three keys:
1545          *  - tables: (string[]) to include in the `$table` to `IDatabase->select()`
1546          *  - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
1547          *  - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
1548          */
1549         public function getQueryInfo( $options = [] ) {
1550                 $ret = [
1551                         'tables' => [],
1552                         'fields' => [],
1553                         'joins'  => [],
1554                 ];
1555
1556                 $ret['tables'][] = 'revision';
1557                 $ret['fields'] = array_merge( $ret['fields'], [
1558                         'rev_id',
1559                         'rev_page',
1560                         'rev_text_id',
1561                         'rev_timestamp',
1562                         'rev_user_text',
1563                         'rev_user',
1564                         'rev_minor_edit',
1565                         'rev_deleted',
1566                         'rev_len',
1567                         'rev_parent_id',
1568                         'rev_sha1',
1569                 ] );
1570
1571                 $commentQuery = CommentStore::newKey( 'rev_comment' )->getJoin();
1572                 $ret['tables'] = array_merge( $ret['tables'], $commentQuery['tables'] );
1573                 $ret['fields'] = array_merge( $ret['fields'], $commentQuery['fields'] );
1574                 $ret['joins'] = array_merge( $ret['joins'], $commentQuery['joins'] );
1575
1576                 if ( $this->contentHandlerUseDB ) {
1577                         $ret['fields'][] = 'rev_content_format';
1578                         $ret['fields'][] = 'rev_content_model';
1579                 }
1580
1581                 if ( in_array( 'page', $options, true ) ) {
1582                         $ret['tables'][] = 'page';
1583                         $ret['fields'] = array_merge( $ret['fields'], [
1584                                 'page_namespace',
1585                                 'page_title',
1586                                 'page_id',
1587                                 'page_latest',
1588                                 'page_is_redirect',
1589                                 'page_len',
1590                         ] );
1591                         $ret['joins']['page'] = [ 'INNER JOIN', [ 'page_id = rev_page' ] ];
1592                 }
1593
1594                 if ( in_array( 'user', $options, true ) ) {
1595                         $ret['tables'][] = 'user';
1596                         $ret['fields'] = array_merge( $ret['fields'], [
1597                                 'user_name',
1598                         ] );
1599                         $ret['joins']['user'] = [ 'LEFT JOIN', [ 'rev_user != 0', 'user_id = rev_user' ] ];
1600                 }
1601
1602                 if ( in_array( 'text', $options, true ) ) {
1603                         $ret['tables'][] = 'text';
1604                         $ret['fields'] = array_merge( $ret['fields'], [
1605                                 'old_text',
1606                                 'old_flags'
1607                         ] );
1608                         $ret['joins']['text'] = [ 'INNER JOIN', [ 'rev_text_id=old_id' ] ];
1609                 }
1610
1611                 return $ret;
1612         }
1613
1614         /**
1615          * Return the tables, fields, and join conditions to be selected to create
1616          * a new archived revision object.
1617          *
1618          * MCR migration note: this replaces Revision::getArchiveQueryInfo
1619          *
1620          * @since 1.31
1621          *
1622          * @return array With three keys:
1623          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
1624          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
1625          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
1626          */
1627         public function getArchiveQueryInfo() {
1628                 $commentQuery = CommentStore::newKey( 'ar_comment' )->getJoin();
1629                 $ret = [
1630                         'tables' => [ 'archive' ] + $commentQuery['tables'],
1631                         'fields' => [
1632                                         'ar_id',
1633                                         'ar_page_id',
1634                                         'ar_namespace',
1635                                         'ar_title',
1636                                         'ar_rev_id',
1637                                         'ar_text',
1638                                         'ar_text_id',
1639                                         'ar_timestamp',
1640                                         'ar_user_text',
1641                                         'ar_user',
1642                                         'ar_minor_edit',
1643                                         'ar_deleted',
1644                                         'ar_len',
1645                                         'ar_parent_id',
1646                                         'ar_sha1',
1647                                 ] + $commentQuery['fields'],
1648                         'joins' => $commentQuery['joins'],
1649                 ];
1650
1651                 if ( $this->contentHandlerUseDB ) {
1652                         $ret['fields'][] = 'ar_content_format';
1653                         $ret['fields'][] = 'ar_content_model';
1654                 }
1655
1656                 return $ret;
1657         }
1658
1659         /**
1660          * Do a batched query for the sizes of a set of revisions.
1661          *
1662          * MCR migration note: this replaces Revision::getParentLengths
1663          *
1664          * @param int[] $revIds
1665          * @return int[] associative array mapping revision IDs from $revIds to the nominal size
1666          *         of the corresponding revision.
1667          */
1668         public function getRevisionSizes( array $revIds ) {
1669                 return $this->listRevisionSizes( $this->getDBConnection( DB_REPLICA ), $revIds );
1670         }
1671
1672         /**
1673          * Do a batched query for the sizes of a set of revisions.
1674          *
1675          * MCR migration note: this replaces Revision::getParentLengths
1676          *
1677          * @deprecated use RevisionStore::getRevisionSizes instead.
1678          *
1679          * @param IDatabase $db
1680          * @param int[] $revIds
1681          * @return int[] associative array mapping revision IDs from $revIds to the nominal size
1682          *         of the corresponding revision.
1683          */
1684         public function listRevisionSizes( IDatabase $db, array $revIds ) {
1685                 $this->checkDatabaseWikiId( $db );
1686
1687                 $revLens = [];
1688                 if ( !$revIds ) {
1689                         return $revLens; // empty
1690                 }
1691
1692                 $res = $db->select(
1693                         'revision',
1694                         [ 'rev_id', 'rev_len' ],
1695                         [ 'rev_id' => $revIds ],
1696                         __METHOD__
1697                 );
1698
1699                 foreach ( $res as $row ) {
1700                         $revLens[$row->rev_id] = intval( $row->rev_len );
1701                 }
1702
1703                 return $revLens;
1704         }
1705
1706         /**
1707          * Get previous revision for this title
1708          *
1709          * MCR migration note: this replaces Revision::getPrevious
1710          *
1711          * @param RevisionRecord $rev
1712          * @param Title $title if known (optional)
1713          *
1714          * @return RevisionRecord|null
1715          */
1716         public function getPreviousRevision( RevisionRecord $rev, Title $title = null ) {
1717                 if ( $title === null ) {
1718                         $title = $this->getTitle( $rev->getPageId(), $rev->getId() );
1719                 }
1720                 $prev = $title->getPreviousRevisionID( $rev->getId() );
1721                 if ( $prev ) {
1722                         return $this->getRevisionByTitle( $title, $prev );
1723                 }
1724                 return null;
1725         }
1726
1727         /**
1728          * Get next revision for this title
1729          *
1730          * MCR migration note: this replaces Revision::getNext
1731          *
1732          * @param RevisionRecord $rev
1733          * @param Title $title if known (optional)
1734          *
1735          * @return RevisionRecord|null
1736          */
1737         public function getNextRevision( RevisionRecord $rev, Title $title = null ) {
1738                 if ( $title === null ) {
1739                         $title = $this->getTitle( $rev->getPageId(), $rev->getId() );
1740                 }
1741                 $next = $title->getNextRevisionID( $rev->getId() );
1742                 if ( $next ) {
1743                         return $this->getRevisionByTitle( $title, $next );
1744                 }
1745                 return null;
1746         }
1747
1748         /**
1749          * Get previous revision Id for this page_id
1750          * This is used to populate rev_parent_id on save
1751          *
1752          * MCR migration note: this corresponds to Revision::getPreviousRevisionId
1753          *
1754          * @param IDatabase $db
1755          * @param RevisionRecord $rev
1756          *
1757          * @return int
1758          */
1759         private function getPreviousRevisionId( IDatabase $db, RevisionRecord $rev ) {
1760                 $this->checkDatabaseWikiId( $db );
1761
1762                 if ( $rev->getPageId() === null ) {
1763                         return 0;
1764                 }
1765                 # Use page_latest if ID is not given
1766                 if ( !$rev->getId() ) {
1767                         $prevId = $db->selectField(
1768                                 'page', 'page_latest',
1769                                 [ 'page_id' => $rev->getPageId() ],
1770                                 __METHOD__
1771                         );
1772                 } else {
1773                         $prevId = $db->selectField(
1774                                 'revision', 'rev_id',
1775                                 [ 'rev_page' => $rev->getPageId(), 'rev_id < ' . $rev->getId() ],
1776                                 __METHOD__,
1777                                 [ 'ORDER BY' => 'rev_id DESC' ]
1778                         );
1779                 }
1780                 return intval( $prevId );
1781         }
1782
1783         /**
1784          * Get rev_timestamp from rev_id, without loading the rest of the row
1785          *
1786          * MCR migration note: this replaces Revision::getTimestampFromId
1787          *
1788          * @param Title $title
1789          * @param int $id
1790          * @param int $flags
1791          * @return string|bool False if not found
1792          */
1793         public function getTimestampFromId( $title, $id, $flags = 0 ) {
1794                 $db = $this->getDBConnection(
1795                         ( $flags & IDBAccessObject::READ_LATEST ) ? DB_MASTER : DB_REPLICA
1796                 );
1797
1798                 $conds = [ 'rev_id' => $id ];
1799                 $conds['rev_page'] = $title->getArticleID();
1800                 $timestamp = $db->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1801
1802                 $this->releaseDBConnection( $db );
1803                 return ( $timestamp !== false ) ? wfTimestamp( TS_MW, $timestamp ) : false;
1804         }
1805
1806         /**
1807          * Get count of revisions per page...not very efficient
1808          *
1809          * MCR migration note: this replaces Revision::countByPageId
1810          *
1811          * @param IDatabase $db
1812          * @param int $id Page id
1813          * @return int
1814          */
1815         public function countRevisionsByPageId( IDatabase $db, $id ) {
1816                 $this->checkDatabaseWikiId( $db );
1817
1818                 $row = $db->selectRow( 'revision',
1819                         [ 'revCount' => 'COUNT(*)' ],
1820                         [ 'rev_page' => $id ],
1821                         __METHOD__
1822                 );
1823                 if ( $row ) {
1824                         return intval( $row->revCount );
1825                 }
1826                 return 0;
1827         }
1828
1829         /**
1830          * Get count of revisions per page...not very efficient
1831          *
1832          * MCR migration note: this replaces Revision::countByTitle
1833          *
1834          * @param IDatabase $db
1835          * @param Title $title
1836          * @return int
1837          */
1838         public function countRevisionsByTitle( IDatabase $db, $title ) {
1839                 $id = $title->getArticleID();
1840                 if ( $id ) {
1841                         return $this->countRevisionsByPageId( $db, $id );
1842                 }
1843                 return 0;
1844         }
1845
1846         /**
1847          * Check if no edits were made by other users since
1848          * the time a user started editing the page. Limit to
1849          * 50 revisions for the sake of performance.
1850          *
1851          * MCR migration note: this replaces Revision::userWasLastToEdit
1852          *
1853          * @deprecated since 1.31; Can possibly be removed, since the self-conflict suppression
1854          *       logic in EditPage that uses this seems conceptually dubious. Revision::userWasLastToEdit
1855          *       has been deprecated since 1.24.
1856          *
1857          * @param IDatabase $db The Database to perform the check on.
1858          * @param int $pageId The ID of the page in question
1859          * @param int $userId The ID of the user in question
1860          * @param string $since Look at edits since this time
1861          *
1862          * @return bool True if the given user was the only one to edit since the given timestamp
1863          */
1864         public function userWasLastToEdit( IDatabase $db, $pageId, $userId, $since ) {
1865                 $this->checkDatabaseWikiId( $db );
1866
1867                 if ( !$userId ) {
1868                         return false;
1869                 }
1870
1871                 $res = $db->select(
1872                         'revision',
1873                         'rev_user',
1874                         [
1875                                 'rev_page' => $pageId,
1876                                 'rev_timestamp > ' . $db->addQuotes( $db->timestamp( $since ) )
1877                         ],
1878                         __METHOD__,
1879                         [ 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 50 ]
1880                 );
1881                 foreach ( $res as $row ) {
1882                         if ( $row->rev_user != $userId ) {
1883                                 return false;
1884                         }
1885                 }
1886                 return true;
1887         }
1888
1889         /**
1890          * Load a revision based on a known page ID and current revision ID from the DB
1891          *
1892          * This method allows for the use of caching, though accessing anything that normally
1893          * requires permission checks (aside from the text) will trigger a small DB lookup.
1894          *
1895          * MCR migration note: this replaces Revision::newKnownCurrent
1896          *
1897          * @param Title $title the associated page title
1898          * @param int $revId current revision of this page. Defaults to $title->getLatestRevID().
1899          *
1900          * @return RevisionRecord|bool Returns false if missing
1901          */
1902         public function getKnownCurrentRevision( Title $title, $revId ) {
1903                 $db = $this->getDBConnectionRef( DB_REPLICA );
1904
1905                 $pageId = $title->getArticleID();
1906
1907                 if ( !$pageId ) {
1908                         return false;
1909                 }
1910
1911                 if ( !$revId ) {
1912                         $revId = $title->getLatestRevID();
1913                 }
1914
1915                 if ( !$revId ) {
1916                         wfWarn(
1917                                 'No latest revision known for page ' . $title->getPrefixedDBkey()
1918                                 . ' even though it exists with page ID ' . $pageId
1919                         );
1920                         return false;
1921                 }
1922
1923                 $row = $this->cache->getWithSetCallback(
1924                         // Page/rev IDs passed in from DB to reflect history merges
1925                         $this->cache->makeGlobalKey( 'revision-row-1.29', $db->getDomainID(), $pageId, $revId ),
1926                         WANObjectCache::TTL_WEEK,
1927                         function ( $curValue, &$ttl, array &$setOpts ) use ( $db, $pageId, $revId ) {
1928                                 $setOpts += Database::getCacheSetOptions( $db );
1929
1930                                 $conds = [
1931                                         'rev_page' => intval( $pageId ),
1932                                         'page_id' => intval( $pageId ),
1933                                         'rev_id' => intval( $revId ),
1934                                 ];
1935
1936                                 $row = $this->fetchRevisionRowFromConds( $db, $conds );
1937                                 return $row ?: false; // don't cache negatives
1938                         }
1939                 );
1940
1941                 // Reflect revision deletion and user renames
1942                 if ( $row ) {
1943                         return $this->newRevisionFromRow( $row, 0, $title );
1944                 } else {
1945                         return false;
1946                 }
1947         }
1948
1949         // TODO: move relevant methods from Title here, e.g. getFirstRevision, isBigDeletion, etc.
1950
1951 }