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 = null;
 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                                 // Check against selects that might have not included old_flags
 710                                 if ( !property_exists( $row, 'old_flags' ) ) {
 711                                         throw new InvalidArgumentException( 'old_flags was not set in $row' );
 712                                 }
 713                                 $blobFlags = ( $row->old_flags === null ) ? '' : $row->old_flags;
 714                         }
 715
 716                         $mainSlotRow->slot_revision = intval( $row->rev_id );
 717
 718                         $mainSlotRow->cont_size = isset( $row->rev_len ) ? intval( $row->rev_len ) : null;
 719                         $mainSlotRow->cont_sha1 = isset( $row->rev_sha1 ) ? strval( $row->rev_sha1 ) : null;
 720                         $mainSlotRow->model_name = isset( $row->rev_content_model )
 721                                 ? strval( $row->rev_content_model )
 722                                 : null;
 723                         // XXX: in the future, we'll probably always use the default format, and drop content_format
 724                         $mainSlotRow->format_name = isset( $row->rev_content_format )
 725                                 ? strval( $row->rev_content_format )
 726                                 : null;
 727                 } elseif ( is_array( $row ) ) {
 728                         $mainSlotRow->slot_revision = isset( $row['id'] ) ? intval( $row['id'] ) : null;
 729
 730                         $mainSlotRow->cont_address = isset( $row['text_id'] )
 731                                 ? 'tt:' . intval( $row['text_id'] )
 732                                 : null;
 733                         $mainSlotRow->cont_size = isset( $row['len'] ) ? intval( $row['len'] ) : null;
 734                         $mainSlotRow->cont_sha1 = isset( $row['sha1'] ) ? strval( $row['sha1'] ) : null;
 735
 736                         $mainSlotRow->model_name = isset( $row['content_model'] )
 737                                 ? strval( $row['content_model'] ) : null;  // XXX: must be a string!
 738                         // XXX: in the future, we'll probably always use the default format, and drop content_format
 739                         $mainSlotRow->format_name = isset( $row['content_format'] )
 740                                 ? strval( $row['content_format'] ) : null;
 741                         $blobData = isset( $row['text'] ) ? rtrim( strval( $row['text'] ) ) : null;
 742                         // XXX: If the flags field is not set then $blobFlags should be null so that no
 743                         // decoding will happen. An empty string will result in default decodings.
 744                         $blobFlags = isset( $row['flags'] ) ? trim( strval( $row['flags'] ) ) : null;
 745
 746                         // if we have a Content object, override mText and mContentModel
 747                         if ( !empty( $row['content'] ) ) {
 748                                 if ( !( $row['content'] instanceof Content ) ) {
 749                                         throw new MWException( 'content field must contain a Content object.' );
 750                                 }
 751
 752                                 /** @var Content $content */
 753                                 $content = $row['content'];
 754                                 $handler = $content->getContentHandler();
 755
 756                                 $mainSlotRow->model_name = $content->getModel();
 757
 758                                 // XXX: in the future, we'll probably always use the default format.
 759                                 if ( $mainSlotRow->format_name === null ) {
 760                                         $mainSlotRow->format_name = $handler->getDefaultFormat();
 761                                 }
 762                         }
 763                 } else {
 764                         throw new MWException( 'Revision constructor passed invalid row format.' );
 765                 }
 766
 767                 // With the old schema, the content changes with every revision.
 768                 // ...except for null-revisions. Would be nice if we could detect them.
 769                 $mainSlotRow->slot_inherited = 0;
 770
 771                 if ( $mainSlotRow->model_name === null ) {
 772                         $mainSlotRow->model_name = function ( SlotRecord $slot ) use ( $title ) {
 773                                 // TODO: MCR: consider slot role in getDefaultModelFor()! Use LinkTarget!
 774                                 // TODO: MCR: deprecate $title->getModel().
 775                                 return ContentHandler::getDefaultModelFor( $title );
 776                         };
 777                 }
 778
 779                 if ( !$content ) {
 780                         $content = function ( SlotRecord $slot )
 781                                 use ( $blobData, $blobFlags, $queryFlags, $mainSlotRow )
 782                         {
 783                                 return $this->loadSlotContent(
 784                                         $slot,
 785                                         $blobData,
 786                                         $blobFlags,
 787                                         $mainSlotRow->format_name,
 788                                         $queryFlags
 789                                 );
 790                         };
 791                 }
 792
 793                 return new SlotRecord( $mainSlotRow, $content );
 794         }
 795
 796         /**
 797          * Loads a Content object based on a slot row.
 798          *
 799          * This method does not call $slot->getContent(), and may be used as a callback
 800          * called by $slot->getContent().
 801          *
 802          * MCR migration note: this roughly corresponds to Revision::getContentInternal
 803          *
 804          * @param SlotRecord $slot The SlotRecord to load content for
 805          * @param string|null $blobData The content blob, in the form indicated by $blobFlags
 806          * @param string|null $blobFlags Flags indicating how $blobData needs to be processed.
 807          *  null if no processing should happen.
 808          * @param string|null $blobFormat MIME type indicating how $dataBlob is encoded
 809          * @param int $queryFlags
 810          *
 811          * @throw RevisionAccessException
 812          * @return Content
 813          */
 814         private function loadSlotContent(
 815                 SlotRecord $slot,
 816                 $blobData = null,
 817                 $blobFlags = null,
 818                 $blobFormat = null,
 819                 $queryFlags = 0
 820         ) {
 821                 if ( $blobData !== null ) {
 822                         Assert::parameterType( 'string', $blobData, '$blobData' );
 823                         Assert::parameterType( 'string|null', $blobFlags, '$blobFlags' );
 824
 825                         $cacheKey = $slot->hasAddress() ? $slot->getAddress() : null;
 826
 827                         if ( $blobFlags === null ) {
 828                                 $data = $blobData;
 829                         } else {
 830                                 $data = $this->blobStore->expandBlob( $blobData, $blobFlags, $cacheKey );
 831                                 if ( $data === false ) {
 832                                         throw new RevisionAccessException(
 833                                                 "Failed to expand blob data using flags $blobFlags (key: $cacheKey)"
 834                                         );
 835                                 }
 836                         }
 837
 838                 } else {
 839                         $address = $slot->getAddress();
 840                         try {
 841                                 $data = $this->blobStore->getBlob( $address, $queryFlags );
 842                         } catch ( BlobAccessException $e ) {
 843                                 throw new RevisionAccessException(
 844                                         "Failed to load data blob from $address: " . $e->getMessage(), 0, $e
 845                                 );
 846                         }
 847                 }
 848
 849                 // Unserialize content
 850                 $handler = ContentHandler::getForModelID( $slot->getModel() );
 851
 852                 $content = $handler->unserializeContent( $data, $blobFormat );
 853                 return $content;
 854         }
 855
 856         /**
 857          * Load a page revision from a given revision ID number.
 858          * Returns null if no such revision can be found.
 859          *
 860          * MCR migration note: this replaces Revision::newFromId
 861          *
 862          * $flags include:
 863          *      IDBAccessObject::READ_LATEST: Select the data from the master
 864          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 865          *
 866          * @param int $id
 867          * @param int $flags (optional)
 868          * @return RevisionRecord|null
 869          */
 870         public function getRevisionById( $id, $flags = 0 ) {
 871                 return $this->newRevisionFromConds( [ 'rev_id' => intval( $id ) ], $flags );
 872         }
 873
 874         /**
 875          * Load either the current, or a specified, revision
 876          * that's attached to a given link target. If not attached
 877          * to that link target, will return null.
 878          *
 879          * MCR migration note: this replaces Revision::newFromTitle
 880          *
 881          * $flags include:
 882          *      IDBAccessObject::READ_LATEST: Select the data from the master
 883          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 884          *
 885          * @param LinkTarget $linkTarget
 886          * @param int $revId (optional)
 887          * @param int $flags Bitfield (optional)
 888          * @return RevisionRecord|null
 889          */
 890         public function getRevisionByTitle( LinkTarget $linkTarget, $revId = 0, $flags = 0 ) {
 891                 $conds = [
 892                         'page_namespace' => $linkTarget->getNamespace(),
 893                         'page_title' => $linkTarget->getDBkey()
 894                 ];
 895                 if ( $revId ) {
 896                         // Use the specified revision ID.
 897                         // Note that we use newRevisionFromConds here because we want to retry
 898                         // and fall back to master if the page is not found on a replica.
 899                         // Since the caller supplied a revision ID, we are pretty sure the revision is
 900                         // supposed to exist, so we should try hard to find it.
 901                         $conds['rev_id'] = $revId;
 902                         return $this->newRevisionFromConds( $conds, $flags );
 903                 } else {
 904                         // Use a join to get the latest revision.
 905                         // Note that we don't use newRevisionFromConds here because we don't want to retry
 906                         // and fall back to master. The assumption is that we only want to force the fallback
 907                         // if we are quite sure the revision exists because the caller supplied a revision ID.
 908                         // If the page isn't found at all on a replica, it probably simply does not exist.
 909                         $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 910
 911                         $conds[] = 'rev_id=page_latest';
 912                         $rev = $this->loadRevisionFromConds( $db, $conds, $flags );
 913
 914                         $this->releaseDBConnection( $db );
 915                         return $rev;
 916                 }
 917         }
 918
 919         /**
 920          * Load either the current, or a specified, revision
 921          * that's attached to a given page ID.
 922          * Returns null if no such revision can be found.
 923          *
 924          * MCR migration note: this replaces Revision::newFromPageId
 925          *
 926          * $flags include:
 927          *      IDBAccessObject::READ_LATEST: Select the data from the master (since 1.20)
 928          *      IDBAccessObject::READ_LOCKING : Select & lock the data from the master
 929          *
 930          * @param int $pageId
 931          * @param int $revId (optional)
 932          * @param int $flags Bitfield (optional)
 933          * @return RevisionRecord|null
 934          */
 935         public function getRevisionByPageId( $pageId, $revId = 0, $flags = 0 ) {
 936                 $conds = [ 'page_id' => $pageId ];
 937                 if ( $revId ) {
 938                         // Use the specified revision ID.
 939                         // Note that we use newRevisionFromConds here because we want to retry
 940                         // and fall back to master if the page is not found on a replica.
 941                         // Since the caller supplied a revision ID, we are pretty sure the revision is
 942                         // supposed to exist, so we should try hard to find it.
 943                         $conds['rev_id'] = $revId;
 944                         return $this->newRevisionFromConds( $conds, $flags );
 945                 } else {
 946                         // Use a join to get the latest revision.
 947                         // Note that we don't use newRevisionFromConds here because we don't want to retry
 948                         // and fall back to master. The assumption is that we only want to force the fallback
 949                         // if we are quite sure the revision exists because the caller supplied a revision ID.
 950                         // If the page isn't found at all on a replica, it probably simply does not exist.
 951                         $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
 952
 953                         $conds[] = 'rev_id=page_latest';
 954                         $rev = $this->loadRevisionFromConds( $db, $conds, $flags );
 955
 956                         $this->releaseDBConnection( $db );
 957                         return $rev;
 958                 }
 959         }
 960
 961         /**
 962          * Load the revision for the given title with the given timestamp.
 963          * WARNING: Timestamps may in some circumstances not be unique,
 964          * so this isn't the best key to use.
 965          *
 966          * MCR migration note: this replaces Revision::loadFromTimestamp
 967          *
 968          * @param Title $title
 969          * @param string $timestamp
 970          * @return RevisionRecord|null
 971          */
 972         public function getRevisionByTimestamp( $title, $timestamp ) {
 973                 return $this->newRevisionFromConds(
 974                         [
 975                                 'rev_timestamp' => $timestamp,
 976                                 'page_namespace' => $title->getNamespace(),
 977                                 'page_title' => $title->getDBkey()
 978                         ],
 979                         0,
 980                         $title
 981                 );
 982         }
 983
 984         /**
 985          * Make a fake revision object from an archive table row. This is queried
 986          * for permissions or even inserted (as in Special:Undelete)
 987          *
 988          * MCR migration note: this replaces Revision::newFromArchiveRow
 989          *
 990          * @param object $row
 991          * @param int $queryFlags
 992          * @param Title|null $title
 993          * @param array $overrides associative array with fields of $row to override. This may be
 994          *   used e.g. to force the parent revision ID or page ID. Keys in the array are fields
 995          *   names from the archive table without the 'ar_' prefix, i.e. use 'parent_id' to
 996          *   override ar_parent_id.
 997          *
 998          * @return RevisionRecord
 999          * @throws MWException
1000          */
1001         public function newRevisionFromArchiveRow(
1002                 $row,
1003                 $queryFlags = 0,
1004                 Title $title = null,
1005                 array $overrides = []
1006         ) {
1007                 Assert::parameterType( 'object', $row, '$row' );
1008
1009                 // check second argument, since Revision::newFromArchiveRow had $overrides in that spot.
1010                 Assert::parameterType( 'integer', $queryFlags, '$queryFlags' );
1011
1012                 if ( !$title && isset( $overrides['title'] ) ) {
1013                         if ( !( $overrides['title'] instanceof Title ) ) {
1014                                 throw new MWException( 'title field override must contain a Title object.' );
1015                         }
1016
1017                         $title = $overrides['title'];
1018                 }
1019
1020                 if ( !isset( $title ) ) {
1021                         if ( isset( $row->ar_namespace ) && isset( $row->ar_title ) ) {
1022                                 $title = Title::makeTitle( $row->ar_namespace, $row->ar_title );
1023                         } else {
1024                                 throw new InvalidArgumentException(
1025                                         'A Title or ar_namespace and ar_title must be given'
1026                                 );
1027                         }
1028                 }
1029
1030                 foreach ( $overrides as $key => $value ) {
1031                         $field = "ar_$key";
1032                         $row->$field = $value;
1033                 }
1034
1035                 $user = $this->getUserIdentityFromRowObject( $row, 'ar_' );
1036
1037                 $comment = CommentStore::newKey( 'ar_comment' )
1038                         // Legacy because $row may have come from self::selectFields()
1039                         ->getCommentLegacy( $this->getDBConnection( DB_REPLICA ), $row, true );
1040
1041                 $mainSlot = $this->emulateMainSlot_1_29( $row, $queryFlags, $title );
1042                 $slots = new RevisionSlots( [ 'main' => $mainSlot ] );
1043
1044                 return new RevisionArchiveRecord( $title, $user, $comment, $row, $slots, $this->wikiId );
1045         }
1046
1047         /**
1048          * @param object $row
1049          * @param string $prefix Field prefix, such as 'rev_' or 'ar_'.
1050          *
1051          * @return UserIdentityValue
1052          */
1053         private function getUserIdentityFromRowObject( $row, $prefix = 'rev_' ) {
1054                 $idField = "{$prefix}user";
1055                 $nameField = "{$prefix}user_text";
1056
1057                 $userId = intval( $row->$idField );
1058
1059                 if ( isset( $row->user_name ) ) {
1060                         $userName = $row->user_name;
1061                 } elseif ( isset( $row->$nameField ) ) {
1062                         $userName = $row->$nameField;
1063                 } else {
1064                         $userName = User::whoIs( $userId );
1065                 }
1066
1067                 if ( $userName === false ) {
1068                         wfWarn( __METHOD__ . ': Cannot determine user name for user ID ' . $userId );
1069                         $userName = '';
1070                 }
1071
1072                 return new UserIdentityValue( $userId, $userName );
1073         }
1074
1075         /**
1076          * @see RevisionFactory::newRevisionFromRow_1_29
1077          *
1078          * MCR migration note: this replaces Revision::newFromRow
1079          *
1080          * @param object $row
1081          * @param int $queryFlags
1082          * @param Title|null $title
1083          *
1084          * @return RevisionRecord
1085          * @throws MWException
1086          * @throws RevisionAccessException
1087          */
1088         private function newRevisionFromRow_1_29( $row, $queryFlags = 0, Title $title = null ) {
1089                 Assert::parameterType( 'object', $row, '$row' );
1090
1091                 if ( !$title ) {
1092                         $pageId = isset( $row->rev_page ) ? $row->rev_page : 0; // XXX: also check page_id?
1093                         $revId = isset( $row->rev_id ) ? $row->rev_id : 0;
1094
1095                         $title = $this->getTitle( $pageId, $revId, $queryFlags );
1096                 }
1097
1098                 if ( !isset( $row->page_latest ) ) {
1099                         $row->page_latest = $title->getLatestRevID();
1100                         if ( $row->page_latest === 0 && $title->exists() ) {
1101                                 wfWarn( 'Encountered title object in limbo: ID ' . $title->getArticleID() );
1102                         }
1103                 }
1104
1105                 $user = $this->getUserIdentityFromRowObject( $row );
1106
1107                 $comment = CommentStore::newKey( 'rev_comment' )
1108                         // Legacy because $row may have come from self::selectFields()
1109                         ->getCommentLegacy( $this->getDBConnection( DB_REPLICA ), $row, true );
1110
1111                 $mainSlot = $this->emulateMainSlot_1_29( $row, $queryFlags, $title );
1112                 $slots = new RevisionSlots( [ 'main' => $mainSlot ] );
1113
1114                 return new RevisionStoreRecord( $title, $user, $comment, $row, $slots, $this->wikiId );
1115         }
1116
1117         /**
1118          * @see RevisionFactory::newRevisionFromRow
1119          *
1120          * MCR migration note: this replaces Revision::newFromRow
1121          *
1122          * @param object $row
1123          * @param int $queryFlags
1124          * @param Title|null $title
1125          *
1126          * @return RevisionRecord
1127          */
1128         public function newRevisionFromRow( $row, $queryFlags = 0, Title $title = null ) {
1129                 return $this->newRevisionFromRow_1_29( $row, $queryFlags, $title );
1130         }
1131
1132         /**
1133          * Constructs a new MutableRevisionRecord based on the given associative array following
1134          * the MW1.29 convention for the Revision constructor.
1135          *
1136          * MCR migration note: this replaces Revision::newFromRow
1137          *
1138          * @param array $fields
1139          * @param int $queryFlags
1140          * @param Title|null $title
1141          *
1142          * @return MutableRevisionRecord
1143          * @throws MWException
1144          * @throws RevisionAccessException
1145          */
1146         public function newMutableRevisionFromArray(
1147                 array $fields,
1148                 $queryFlags = 0,
1149                 Title $title = null
1150         ) {
1151                 if ( !$title && isset( $fields['title'] ) ) {
1152                         if ( !( $fields['title'] instanceof Title ) ) {
1153                                 throw new MWException( 'title field must contain a Title object.' );
1154                         }
1155
1156                         $title = $fields['title'];
1157                 }
1158
1159                 if ( !$title ) {
1160                         $pageId = isset( $fields['page'] ) ? $fields['page'] : 0;
1161                         $revId = isset( $fields['id'] ) ? $fields['id'] : 0;
1162
1163                         $title = $this->getTitle( $pageId, $revId, $queryFlags );
1164                 }
1165
1166                 if ( !isset( $fields['page'] ) ) {
1167                         $fields['page'] = $title->getArticleID( $queryFlags );
1168                 }
1169
1170                 // if we have a content object, use it to set the model and type
1171                 if ( !empty( $fields['content'] ) ) {
1172                         if ( !( $fields['content'] instanceof Content ) ) {
1173                                 throw new MWException( 'content field must contain a Content object.' );
1174                         }
1175
1176                         if ( !empty( $fields['text_id'] ) ) {
1177                                 throw new MWException(
1178                                         "Text already stored in external store (id {$fields['text_id']}), " .
1179                                         "can't serialize content object"
1180                                 );
1181                         }
1182                 }
1183
1184                 // Replaces old lazy loading logic in Revision::getUserText.
1185                 if ( !isset( $fields['user_text'] ) && isset( $fields['user'] ) ) {
1186                         if ( $fields['user'] instanceof UserIdentity ) {
1187                                 /** @var User $user */
1188                                 $user = $fields['user'];
1189                                 $fields['user_text'] = $user->getName();
1190                                 $fields['user'] = $user->getId();
1191                         } else {
1192                                 // TODO: wrap this in a callback to make it lazy again.
1193                                 $name = $fields['user'] === 0 ? false : User::whoIs( $fields['user'] );
1194
1195                                 if ( $name === false ) {
1196                                         throw new MWException(
1197                                                 'user_text not given, and unknown user ID ' . $fields['user']
1198                                         );
1199                                 }
1200
1201                                 $fields['user_text'] = $name;
1202                         }
1203                 }
1204
1205                 if (
1206                         isset( $fields['comment'] )
1207                         && !( $fields['comment'] instanceof CommentStoreComment )
1208                 ) {
1209                         $commentData = isset( $fields['comment_data'] ) ? $fields['comment_data'] : null;
1210
1211                         if ( $fields['comment'] instanceof Message ) {
1212                                 $fields['comment'] = CommentStoreComment::newUnsavedComment(
1213                                         $fields['comment'],
1214                                         $commentData
1215                                 );
1216                         } else {
1217                                 $commentText = trim( strval( $fields['comment'] ) );
1218                                 $fields['comment'] = CommentStoreComment::newUnsavedComment(
1219                                         $commentText,
1220                                         $commentData
1221                                 );
1222                         }
1223                 }
1224
1225                 $mainSlot = $this->emulateMainSlot_1_29( $fields, $queryFlags, $title );
1226
1227                 $revision = new MutableRevisionRecord( $title, $this->wikiId );
1228                 $this->initializeMutableRevisionFromArray( $revision, $fields );
1229                 $revision->setSlot( $mainSlot );
1230
1231                 return $revision;
1232         }
1233
1234         /**
1235          * @param MutableRevisionRecord $record
1236          * @param array $fields
1237          */
1238         private function initializeMutableRevisionFromArray(
1239                 MutableRevisionRecord $record,
1240                 array $fields
1241         ) {
1242                 /** @var UserIdentity $user */
1243                 $user = null;
1244
1245                 if ( isset( $fields['user'] ) && ( $fields['user'] instanceof UserIdentity ) ) {
1246                         $user = $fields['user'];
1247                 } elseif ( isset( $fields['user'] ) && isset( $fields['user_text'] ) ) {
1248                         $user = new UserIdentityValue( intval( $fields['user'] ), $fields['user_text'] );
1249                 } elseif ( isset( $fields['user'] ) ) {
1250                         $user = User::newFromId( intval( $fields['user'] ) );
1251                 } elseif ( isset( $fields['user_text'] ) ) {
1252                         $user = User::newFromName( $fields['user_text'] );
1253
1254                         // User::newFromName will return false for IP addresses (and invalid names)
1255                         if ( $user == false ) {
1256                                 $user = new UserIdentityValue( 0, $fields['user_text'] );
1257                         }
1258                 }
1259
1260                 if ( $user ) {
1261                         $record->setUser( $user );
1262                 }
1263
1264                 $timestamp = isset( $fields['timestamp'] )
1265                         ? strval( $fields['timestamp'] )
1266                         : wfTimestampNow(); // TODO: use a callback, so we can override it for testing.
1267
1268                 $record->setTimestamp( $timestamp );
1269
1270                 if ( isset( $fields['page'] ) ) {
1271                         $record->setPageId( intval( $fields['page'] ) );
1272                 }
1273
1274                 if ( isset( $fields['id'] ) ) {
1275                         $record->setId( intval( $fields['id'] ) );
1276                 }
1277                 if ( isset( $fields['parent_id'] ) ) {
1278                         $record->setParentId( intval( $fields['parent_id'] ) );
1279                 }
1280
1281                 if ( isset( $fields['sha1'] ) ) {
1282                         $record->setSha1( $fields['sha1'] );
1283                 }
1284                 if ( isset( $fields['size'] ) ) {
1285                         $record->setSize( intval( $fields['size'] ) );
1286                 }
1287
1288                 if ( isset( $fields['minor_edit'] ) ) {
1289                         $record->setMinorEdit( intval( $fields['minor_edit'] ) !== 0 );
1290                 }
1291                 if ( isset( $fields['deleted'] ) ) {
1292                         $record->setVisibility( intval( $fields['deleted'] ) );
1293                 }
1294
1295                 if ( isset( $fields['comment'] ) ) {
1296                         Assert::parameterType(
1297                                 CommentStoreComment::class,
1298                                 $fields['comment'],
1299                                 '$row[\'comment\']'
1300                         );
1301                         $record->setComment( $fields['comment'] );
1302                 }
1303         }
1304
1305         /**
1306          * Load a page revision from a given revision ID number.
1307          * Returns null if no such revision can be found.
1308          *
1309          * MCR migration note: this corresponds to Revision::loadFromId
1310          *
1311          * @note direct use is deprecated!
1312          * @todo remove when unused! there seem to be no callers of Revision::loadFromId
1313          *
1314          * @param IDatabase $db
1315          * @param int $id
1316          *
1317          * @return RevisionRecord|null
1318          */
1319         public function loadRevisionFromId( IDatabase $db, $id ) {
1320                 return $this->loadRevisionFromConds( $db, [ 'rev_id' => intval( $id ) ] );
1321         }
1322
1323         /**
1324          * Load either the current, or a specified, revision
1325          * that's attached to a given page. If not attached
1326          * to that page, will return null.
1327          *
1328          * MCR migration note: this replaces Revision::loadFromPageId
1329          *
1330          * @note direct use is deprecated!
1331          * @todo remove when unused!
1332          *
1333          * @param IDatabase $db
1334          * @param int $pageid
1335          * @param int $id
1336          * @return RevisionRecord|null
1337          */
1338         public function loadRevisionFromPageId( IDatabase $db, $pageid, $id = 0 ) {
1339                 $conds = [ 'rev_page' => intval( $pageid ), 'page_id' => intval( $pageid ) ];
1340                 if ( $id ) {
1341                         $conds['rev_id'] = intval( $id );
1342                 } else {
1343                         $conds[] = 'rev_id=page_latest';
1344                 }
1345                 return $this->loadRevisionFromConds( $db, $conds );
1346         }
1347
1348         /**
1349          * Load either the current, or a specified, revision
1350          * that's attached to a given page. If not attached
1351          * to that page, will return null.
1352          *
1353          * MCR migration note: this replaces Revision::loadFromTitle
1354          *
1355          * @note direct use is deprecated!
1356          * @todo remove when unused!
1357          *
1358          * @param IDatabase $db
1359          * @param Title $title
1360          * @param int $id
1361          *
1362          * @return RevisionRecord|null
1363          */
1364         public function loadRevisionFromTitle( IDatabase $db, $title, $id = 0 ) {
1365                 if ( $id ) {
1366                         $matchId = intval( $id );
1367                 } else {
1368                         $matchId = 'page_latest';
1369                 }
1370
1371                 return $this->loadRevisionFromConds(
1372                         $db,
1373                         [
1374                                 "rev_id=$matchId",
1375                                 'page_namespace' => $title->getNamespace(),
1376                                 'page_title' => $title->getDBkey()
1377                         ],
1378                         0,
1379                         $title
1380                 );
1381         }
1382
1383         /**
1384          * Load the revision for the given title with the given timestamp.
1385          * WARNING: Timestamps may in some circumstances not be unique,
1386          * so this isn't the best key to use.
1387          *
1388          * MCR migration note: this replaces Revision::loadFromTimestamp
1389          *
1390          * @note direct use is deprecated! Use getRevisionFromTimestamp instead!
1391          * @todo remove when unused!
1392          *
1393          * @param IDatabase $db
1394          * @param Title $title
1395          * @param string $timestamp
1396          * @return RevisionRecord|null
1397          */
1398         public function loadRevisionFromTimestamp( IDatabase $db, $title, $timestamp ) {
1399                 return $this->loadRevisionFromConds( $db,
1400                         [
1401                                 'rev_timestamp' => $db->timestamp( $timestamp ),
1402                                 'page_namespace' => $title->getNamespace(),
1403                                 'page_title' => $title->getDBkey()
1404                         ],
1405                         0,
1406                         $title
1407                 );
1408         }
1409
1410         /**
1411          * Given a set of conditions, fetch a revision
1412          *
1413          * This method should be used if we are pretty sure the revision exists.
1414          * Unless $flags has READ_LATEST set, this method will first try to find the revision
1415          * on a replica before hitting the master database.
1416          *
1417          * MCR migration note: this corresponds to Revision::newFromConds
1418          *
1419          * @param array $conditions
1420          * @param int $flags (optional)
1421          * @param Title $title
1422          *
1423          * @return RevisionRecord|null
1424          */
1425         private function newRevisionFromConds( $conditions, $flags = 0, Title $title = null ) {
1426                 $db = $this->getDBConnection( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_REPLICA );
1427                 $rev = $this->loadRevisionFromConds( $db, $conditions, $flags, $title );
1428                 $this->releaseDBConnection( $db );
1429
1430                 $lb = $this->getDBLoadBalancer();
1431
1432                 // Make sure new pending/committed revision are visibile later on
1433                 // within web requests to certain avoid bugs like T93866 and T94407.
1434                 if ( !$rev
1435                         && !( $flags & self::READ_LATEST )
1436                         && $lb->getServerCount() > 1
1437                         && $lb->hasOrMadeRecentMasterChanges()
1438                 ) {
1439                         $flags = self::READ_LATEST;
1440                         $db = $this->getDBConnection( DB_MASTER );
1441                         $rev = $this->loadRevisionFromConds( $db, $conditions, $flags, $title );
1442                         $this->releaseDBConnection( $db );
1443                 }
1444
1445                 return $rev;
1446         }
1447
1448         /**
1449          * Given a set of conditions, fetch a revision from
1450          * the given database connection.
1451          *
1452          * MCR migration note: this corresponds to Revision::loadFromConds
1453          *
1454          * @param IDatabase $db
1455          * @param array $conditions
1456          * @param int $flags (optional)
1457          * @param Title $title
1458          *
1459          * @return RevisionRecord|null
1460          */
1461         private function loadRevisionFromConds(
1462                 IDatabase $db,
1463                 $conditions,
1464                 $flags = 0,
1465                 Title $title = null
1466         ) {
1467                 $row = $this->fetchRevisionRowFromConds( $db, $conditions, $flags );
1468                 if ( $row ) {
1469                         $rev = $this->newRevisionFromRow( $row, $flags, $title );
1470
1471                         return $rev;
1472                 }
1473
1474                 return null;
1475         }
1476
1477         /**
1478          * Throws an exception if the given database connection does not belong to the wiki this
1479          * RevisionStore is bound to.
1480          *
1481          * @param IDatabase $db
1482          * @throws MWException
1483          */
1484         private function checkDatabaseWikiId( IDatabase $db ) {
1485                 $storeWiki = $this->wikiId;
1486                 $dbWiki = $db->getDomainID();
1487
1488                 if ( $dbWiki === $storeWiki ) {
1489                         return;
1490                 }
1491
1492                 // XXX: we really want the default database ID...
1493                 $storeWiki = $storeWiki ?: wfWikiID();
1494                 $dbWiki = $dbWiki ?: wfWikiID();
1495
1496                 if ( $dbWiki === $storeWiki ) {
1497                         return;
1498                 }
1499
1500                 // HACK: counteract encoding imposed by DatabaseDomain
1501                 $storeWiki = str_replace( '?h', '-', $storeWiki );
1502                 $dbWiki = str_replace( '?h', '-', $dbWiki );
1503
1504                 if ( $dbWiki === $storeWiki ) {
1505                         return;
1506                 }
1507
1508                 throw new MWException( "RevisionStore for $storeWiki "
1509                         . "cannot be used with a DB connection for $dbWiki" );
1510         }
1511
1512         /**
1513          * Given a set of conditions, return a row with the
1514          * fields necessary to build RevisionRecord objects.
1515          *
1516          * MCR migration note: this corresponds to Revision::fetchFromConds
1517          *
1518          * @param IDatabase $db
1519          * @param array $conditions
1520          * @param int $flags (optional)
1521          *
1522          * @return object|false data row as a raw object
1523          */
1524         private function fetchRevisionRowFromConds( IDatabase $db, $conditions, $flags = 0 ) {
1525                 $this->checkDatabaseWikiId( $db );
1526
1527                 $revQuery = self::getQueryInfo( [ 'page', 'user' ] );
1528                 $options = [];
1529                 if ( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING ) {
1530                         $options[] = 'FOR UPDATE';
1531                 }
1532                 return $db->selectRow(
1533                         $revQuery['tables'],
1534                         $revQuery['fields'],
1535                         $conditions,
1536                         __METHOD__,
1537                         $options,
1538                         $revQuery['joins']
1539                 );
1540         }
1541
1542         /**
1543          * Return the tables, fields, and join conditions to be selected to create
1544          * a new revision object.
1545          *
1546          * MCR migration note: this replaces Revision::getQueryInfo
1547          *
1548          * @since 1.31
1549          *
1550          * @param array $options Any combination of the following strings
1551          *  - 'page': Join with the page table, and select fields to identify the page
1552          *  - 'user': Join with the user table, and select the user name
1553          *  - 'text': Join with the text table, and select fields to load page text
1554          *
1555          * @return array With three keys:
1556          *  - tables: (string[]) to include in the `$table` to `IDatabase->select()`
1557          *  - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
1558          *  - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
1559          */
1560         public function getQueryInfo( $options = [] ) {
1561                 $ret = [
1562                         'tables' => [],
1563                         'fields' => [],
1564                         'joins'  => [],
1565                 ];
1566
1567                 $ret['tables'][] = 'revision';
1568                 $ret['fields'] = array_merge( $ret['fields'], [
1569                         'rev_id',
1570                         'rev_page',
1571                         'rev_text_id',
1572                         'rev_timestamp',
1573                         'rev_user_text',
1574                         'rev_user',
1575                         'rev_minor_edit',
1576                         'rev_deleted',
1577                         'rev_len',
1578                         'rev_parent_id',
1579                         'rev_sha1',
1580                 ] );
1581
1582                 $commentQuery = CommentStore::newKey( 'rev_comment' )->getJoin();
1583                 $ret['tables'] = array_merge( $ret['tables'], $commentQuery['tables'] );
1584                 $ret['fields'] = array_merge( $ret['fields'], $commentQuery['fields'] );
1585                 $ret['joins'] = array_merge( $ret['joins'], $commentQuery['joins'] );
1586
1587                 if ( $this->contentHandlerUseDB ) {
1588                         $ret['fields'][] = 'rev_content_format';
1589                         $ret['fields'][] = 'rev_content_model';
1590                 }
1591
1592                 if ( in_array( 'page', $options, true ) ) {
1593                         $ret['tables'][] = 'page';
1594                         $ret['fields'] = array_merge( $ret['fields'], [
1595                                 'page_namespace',
1596                                 'page_title',
1597                                 'page_id',
1598                                 'page_latest',
1599                                 'page_is_redirect',
1600                                 'page_len',
1601                         ] );
1602                         $ret['joins']['page'] = [ 'INNER JOIN', [ 'page_id = rev_page' ] ];
1603                 }
1604
1605                 if ( in_array( 'user', $options, true ) ) {
1606                         $ret['tables'][] = 'user';
1607                         $ret['fields'] = array_merge( $ret['fields'], [
1608                                 'user_name',
1609                         ] );
1610                         $ret['joins']['user'] = [ 'LEFT JOIN', [ 'rev_user != 0', 'user_id = rev_user' ] ];
1611                 }
1612
1613                 if ( in_array( 'text', $options, true ) ) {
1614                         $ret['tables'][] = 'text';
1615                         $ret['fields'] = array_merge( $ret['fields'], [
1616                                 'old_text',
1617                                 'old_flags'
1618                         ] );
1619                         $ret['joins']['text'] = [ 'INNER JOIN', [ 'rev_text_id=old_id' ] ];
1620                 }
1621
1622                 return $ret;
1623         }
1624
1625         /**
1626          * Return the tables, fields, and join conditions to be selected to create
1627          * a new archived revision object.
1628          *
1629          * MCR migration note: this replaces Revision::getArchiveQueryInfo
1630          *
1631          * @since 1.31
1632          *
1633          * @return array With three keys:
1634          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
1635          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
1636          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
1637          */
1638         public function getArchiveQueryInfo() {
1639                 $commentQuery = CommentStore::newKey( 'ar_comment' )->getJoin();
1640                 $ret = [
1641                         'tables' => [ 'archive' ] + $commentQuery['tables'],
1642                         'fields' => [
1643                                         'ar_id',
1644                                         'ar_page_id',
1645                                         'ar_namespace',
1646                                         'ar_title',
1647                                         'ar_rev_id',
1648                                         'ar_text',
1649                                         'ar_text_id',
1650                                         'ar_timestamp',
1651                                         'ar_user_text',
1652                                         'ar_user',
1653                                         'ar_minor_edit',
1654                                         'ar_deleted',
1655                                         'ar_len',
1656                                         'ar_parent_id',
1657                                         'ar_sha1',
1658                                 ] + $commentQuery['fields'],
1659                         'joins' => $commentQuery['joins'],
1660                 ];
1661
1662                 if ( $this->contentHandlerUseDB ) {
1663                         $ret['fields'][] = 'ar_content_format';
1664                         $ret['fields'][] = 'ar_content_model';
1665                 }
1666
1667                 return $ret;
1668         }
1669
1670         /**
1671          * Do a batched query for the sizes of a set of revisions.
1672          *
1673          * MCR migration note: this replaces Revision::getParentLengths
1674          *
1675          * @param int[] $revIds
1676          * @return int[] associative array mapping revision IDs from $revIds to the nominal size
1677          *         of the corresponding revision.
1678          */
1679         public function getRevisionSizes( array $revIds ) {
1680                 return $this->listRevisionSizes( $this->getDBConnection( DB_REPLICA ), $revIds );
1681         }
1682
1683         /**
1684          * Do a batched query for the sizes of a set of revisions.
1685          *
1686          * MCR migration note: this replaces Revision::getParentLengths
1687          *
1688          * @deprecated use RevisionStore::getRevisionSizes instead.
1689          *
1690          * @param IDatabase $db
1691          * @param int[] $revIds
1692          * @return int[] associative array mapping revision IDs from $revIds to the nominal size
1693          *         of the corresponding revision.
1694          */
1695         public function listRevisionSizes( IDatabase $db, array $revIds ) {
1696                 $this->checkDatabaseWikiId( $db );
1697
1698                 $revLens = [];
1699                 if ( !$revIds ) {
1700                         return $revLens; // empty
1701                 }
1702
1703                 $res = $db->select(
1704                         'revision',
1705                         [ 'rev_id', 'rev_len' ],
1706                         [ 'rev_id' => $revIds ],
1707                         __METHOD__
1708                 );
1709
1710                 foreach ( $res as $row ) {
1711                         $revLens[$row->rev_id] = intval( $row->rev_len );
1712                 }
1713
1714                 return $revLens;
1715         }
1716
1717         /**
1718          * Get previous revision for this title
1719          *
1720          * MCR migration note: this replaces Revision::getPrevious
1721          *
1722          * @param RevisionRecord $rev
1723          * @param Title $title if known (optional)
1724          *
1725          * @return RevisionRecord|null
1726          */
1727         public function getPreviousRevision( RevisionRecord $rev, Title $title = null ) {
1728                 if ( $title === null ) {
1729                         $title = $this->getTitle( $rev->getPageId(), $rev->getId() );
1730                 }
1731                 $prev = $title->getPreviousRevisionID( $rev->getId() );
1732                 if ( $prev ) {
1733                         return $this->getRevisionByTitle( $title, $prev );
1734                 }
1735                 return null;
1736         }
1737
1738         /**
1739          * Get next revision for this title
1740          *
1741          * MCR migration note: this replaces Revision::getNext
1742          *
1743          * @param RevisionRecord $rev
1744          * @param Title $title if known (optional)
1745          *
1746          * @return RevisionRecord|null
1747          */
1748         public function getNextRevision( RevisionRecord $rev, Title $title = null ) {
1749                 if ( $title === null ) {
1750                         $title = $this->getTitle( $rev->getPageId(), $rev->getId() );
1751                 }
1752                 $next = $title->getNextRevisionID( $rev->getId() );
1753                 if ( $next ) {
1754                         return $this->getRevisionByTitle( $title, $next );
1755                 }
1756                 return null;
1757         }
1758
1759         /**
1760          * Get previous revision Id for this page_id
1761          * This is used to populate rev_parent_id on save
1762          *
1763          * MCR migration note: this corresponds to Revision::getPreviousRevisionId
1764          *
1765          * @param IDatabase $db
1766          * @param RevisionRecord $rev
1767          *
1768          * @return int
1769          */
1770         private function getPreviousRevisionId( IDatabase $db, RevisionRecord $rev ) {
1771                 $this->checkDatabaseWikiId( $db );
1772
1773                 if ( $rev->getPageId() === null ) {
1774                         return 0;
1775                 }
1776                 # Use page_latest if ID is not given
1777                 if ( !$rev->getId() ) {
1778                         $prevId = $db->selectField(
1779                                 'page', 'page_latest',
1780                                 [ 'page_id' => $rev->getPageId() ],
1781                                 __METHOD__
1782                         );
1783                 } else {
1784                         $prevId = $db->selectField(
1785                                 'revision', 'rev_id',
1786                                 [ 'rev_page' => $rev->getPageId(), 'rev_id < ' . $rev->getId() ],
1787                                 __METHOD__,
1788                                 [ 'ORDER BY' => 'rev_id DESC' ]
1789                         );
1790                 }
1791                 return intval( $prevId );
1792         }
1793
1794         /**
1795          * Get rev_timestamp from rev_id, without loading the rest of the row
1796          *
1797          * MCR migration note: this replaces Revision::getTimestampFromId
1798          *
1799          * @param Title $title
1800          * @param int $id
1801          * @param int $flags
1802          * @return string|bool False if not found
1803          */
1804         public function getTimestampFromId( $title, $id, $flags = 0 ) {
1805                 $db = $this->getDBConnection(
1806                         ( $flags & IDBAccessObject::READ_LATEST ) ? DB_MASTER : DB_REPLICA
1807                 );
1808
1809                 $conds = [ 'rev_id' => $id ];
1810                 $conds['rev_page'] = $title->getArticleID();
1811                 $timestamp = $db->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1812
1813                 $this->releaseDBConnection( $db );
1814                 return ( $timestamp !== false ) ? wfTimestamp( TS_MW, $timestamp ) : false;
1815         }
1816
1817         /**
1818          * Get count of revisions per page...not very efficient
1819          *
1820          * MCR migration note: this replaces Revision::countByPageId
1821          *
1822          * @param IDatabase $db
1823          * @param int $id Page id
1824          * @return int
1825          */
1826         public function countRevisionsByPageId( IDatabase $db, $id ) {
1827                 $this->checkDatabaseWikiId( $db );
1828
1829                 $row = $db->selectRow( 'revision',
1830                         [ 'revCount' => 'COUNT(*)' ],
1831                         [ 'rev_page' => $id ],
1832                         __METHOD__
1833                 );
1834                 if ( $row ) {
1835                         return intval( $row->revCount );
1836                 }
1837                 return 0;
1838         }
1839
1840         /**
1841          * Get count of revisions per page...not very efficient
1842          *
1843          * MCR migration note: this replaces Revision::countByTitle
1844          *
1845          * @param IDatabase $db
1846          * @param Title $title
1847          * @return int
1848          */
1849         public function countRevisionsByTitle( IDatabase $db, $title ) {
1850                 $id = $title->getArticleID();
1851                 if ( $id ) {
1852                         return $this->countRevisionsByPageId( $db, $id );
1853                 }
1854                 return 0;
1855         }
1856
1857         /**
1858          * Check if no edits were made by other users since
1859          * the time a user started editing the page. Limit to
1860          * 50 revisions for the sake of performance.
1861          *
1862          * MCR migration note: this replaces Revision::userWasLastToEdit
1863          *
1864          * @deprecated since 1.31; Can possibly be removed, since the self-conflict suppression
1865          *       logic in EditPage that uses this seems conceptually dubious. Revision::userWasLastToEdit
1866          *       has been deprecated since 1.24.
1867          *
1868          * @param IDatabase $db The Database to perform the check on.
1869          * @param int $pageId The ID of the page in question
1870          * @param int $userId The ID of the user in question
1871          * @param string $since Look at edits since this time
1872          *
1873          * @return bool True if the given user was the only one to edit since the given timestamp
1874          */
1875         public function userWasLastToEdit( IDatabase $db, $pageId, $userId, $since ) {
1876                 $this->checkDatabaseWikiId( $db );
1877
1878                 if ( !$userId ) {
1879                         return false;
1880                 }
1881
1882                 $res = $db->select(
1883                         'revision',
1884                         'rev_user',
1885                         [
1886                                 'rev_page' => $pageId,
1887                                 'rev_timestamp > ' . $db->addQuotes( $db->timestamp( $since ) )
1888                         ],
1889                         __METHOD__,
1890                         [ 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 50 ]
1891                 );
1892                 foreach ( $res as $row ) {
1893                         if ( $row->rev_user != $userId ) {
1894                                 return false;
1895                         }
1896                 }
1897                 return true;
1898         }
1899
1900         /**
1901          * Load a revision based on a known page ID and current revision ID from the DB
1902          *
1903          * This method allows for the use of caching, though accessing anything that normally
1904          * requires permission checks (aside from the text) will trigger a small DB lookup.
1905          *
1906          * MCR migration note: this replaces Revision::newKnownCurrent
1907          *
1908          * @param Title $title the associated page title
1909          * @param int $revId current revision of this page. Defaults to $title->getLatestRevID().
1910          *
1911          * @return RevisionRecord|bool Returns false if missing
1912          */
1913         public function getKnownCurrentRevision( Title $title, $revId ) {
1914                 $db = $this->getDBConnectionRef( DB_REPLICA );
1915
1916                 $pageId = $title->getArticleID();
1917
1918                 if ( !$pageId ) {
1919                         return false;
1920                 }
1921
1922                 if ( !$revId ) {
1923                         $revId = $title->getLatestRevID();
1924                 }
1925
1926                 if ( !$revId ) {
1927                         wfWarn(
1928                                 'No latest revision known for page ' . $title->getPrefixedDBkey()
1929                                 . ' even though it exists with page ID ' . $pageId
1930                         );
1931                         return false;
1932                 }
1933
1934                 $row = $this->cache->getWithSetCallback(
1935                         // Page/rev IDs passed in from DB to reflect history merges
1936                         $this->cache->makeGlobalKey( 'revision-row-1.29', $db->getDomainID(), $pageId, $revId ),
1937                         WANObjectCache::TTL_WEEK,
1938                         function ( $curValue, &$ttl, array &$setOpts ) use ( $db, $pageId, $revId ) {
1939                                 $setOpts += Database::getCacheSetOptions( $db );
1940
1941                                 $conds = [
1942                                         'rev_page' => intval( $pageId ),
1943                                         'page_id' => intval( $pageId ),
1944                                         'rev_id' => intval( $revId ),
1945                                 ];
1946
1947                                 $row = $this->fetchRevisionRowFromConds( $db, $conds );
1948                                 return $row ?: false; // don't cache negatives
1949                         }
1950                 );
1951
1952                 // Reflect revision deletion and user renames
1953                 if ( $row ) {
1954                         return $this->newRevisionFromRow( $row, 0, $title );
1955                 } else {
1956                         return false;
1957                 }
1958         }
1959
1960         // TODO: move relevant methods from Title here, e.g. getFirstRevision, isBigDeletion, etc.
1961
1962 }