RevisionStore.php

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<?php
namespace MediaWiki\Revision;
 
use InvalidArgumentException;
use LogicException;
use MediaWiki\CommentStore\CommentStore;
use MediaWiki\CommentStore\CommentStoreComment;
use MediaWiki\Content\Content;
use MediaWiki\Content\FallbackContent;
use MediaWiki\Content\IContentHandlerFactory;
use MediaWiki\Content\UnknownContentModelException;
use MediaWiki\DAO\WikiAwareEntity;
use MediaWiki\Exception\MWException;
use MediaWiki\HookContainer\HookContainer;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\Page\LegacyArticleIdAccess;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Page\PageIdentityValue;
use MediaWiki\Page\PageReference;
use MediaWiki\Page\PageStore;
use MediaWiki\Permissions\Authority;
use MediaWiki\RecentChanges\RecentChange;
use MediaWiki\RecentChanges\RecentChangeLookup;
use MediaWiki\Storage\BadBlobException;
use MediaWiki\Storage\BlobAccessException;
use MediaWiki\Storage\BlobStore;
use MediaWiki\Storage\NameTableAccessException;
use MediaWiki\Storage\NameTableStore;
use MediaWiki\Storage\RevisionSlotsUpdate;
use MediaWiki\Storage\SqlBlobStore;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleFactory;
use MediaWiki\User\ActorStore;
use MediaWiki\User\UserIdentity;
use MediaWiki\Utils\MWTimestamp;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use RuntimeException;
use StatusValue;
use stdClass;
use Traversable;
use Wikimedia\Assert\Assert;
use Wikimedia\Assert\ParameterAssertionException;
use Wikimedia\Assert\PreconditionException;
use Wikimedia\IPUtils;
use Wikimedia\ObjectCache\BagOStuff;
use Wikimedia\ObjectCache\WANObjectCache;
use Wikimedia\Rdbms\DBAccessObjectUtils;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IDBAccessObject;
use Wikimedia\Rdbms\ILoadBalancer;
use Wikimedia\Rdbms\IReadableDatabase;
use Wikimedia\Rdbms\IResultWrapper;
use Wikimedia\Rdbms\Platform\ISQLPlatform;
use Wikimedia\Rdbms\SelectQueryBuilder;
use Wikimedia\Timestamp\TimestampFormat as TS;
 
class RevisionStore implements RevisionFactory, RevisionLookup, LoggerAwareInterface {
 
    use LegacyArticleIdAccess;
 
    public const ROW_CACHE_KEY = 'revision-row-1.29';
 
    public const ORDER_OLDEST_TO_NEWEST = 'ASC';
    public const ORDER_NEWEST_TO_OLDEST = 'DESC';
 
    // Constants for get(...)Between methods
    public const INCLUDE_OLD = 'include_old';
    public const INCLUDE_NEW = 'include_new';
    public const INCLUDE_BOTH = 'include_both';
    public const INCLUDE_DELETED_REVISIONS = 'include_deleted_revisions';
 
    private $blobStore;
 
    private $wikiId;
 
    private ILoadBalancer $loadBalancer;
    private WANObjectCache $cache;
    private BagOStuff $localCache;
    private CommentStore $commentStore;
    private ActorStore $actorStore;
    private LoggerInterface $logger;
    private NameTableStore $contentModelStore;
    private NameTableStore $slotRoleStore;
    private SlotRoleRegistry $slotRoleRegistry;
    private IContentHandlerFactory $contentHandlerFactory;
    private HookRunner $hookRunner;
    private PageStore $pageStore;
    private TitleFactory $titleFactory;
    private RecentChangeLookup $recentChangeLookup;
 
    public function __construct(
        ILoadBalancer $loadBalancer,
        SqlBlobStore $blobStore,
        WANObjectCache $cache,
        BagOStuff $localCache,
        CommentStore $commentStore,
        NameTableStore $contentModelStore,
        NameTableStore $slotRoleStore,
        SlotRoleRegistry $slotRoleRegistry,
        ActorStore $actorStore,
        IContentHandlerFactory $contentHandlerFactory,
        PageStore $pageStore,
        TitleFactory $titleFactory,
        HookContainer $hookContainer,
        RecentChangeLookup $recentChangeLookup,
        $wikiId = WikiAwareEntity::LOCAL
    ) {
        Assert::parameterType( [ 'string', 'false' ], $wikiId, '$wikiId' );
 
        $this->loadBalancer = $loadBalancer;
        $this->blobStore = $blobStore;
        $this->cache = $cache;
        $this->localCache = $localCache;
        $this->commentStore = $commentStore;
        $this->contentModelStore = $contentModelStore;
        $this->slotRoleStore = $slotRoleStore;
        $this->slotRoleRegistry = $slotRoleRegistry;
        $this->actorStore = $actorStore;
        $this->wikiId = $wikiId;
        $this->logger = new NullLogger();
        $this->contentHandlerFactory = $contentHandlerFactory;
        $this->pageStore = $pageStore;
        $this->titleFactory = $titleFactory;
        $this->hookRunner = new HookRunner( $hookContainer );
        $this->recentChangeLookup = $recentChangeLookup;
    }
 
    public function setLogger( LoggerInterface $logger ): void {
        $this->logger = $logger;
    }
 
    public function isReadOnly() {
        return $this->blobStore->isReadOnly();
    }
 
    public function getWikiId() {
        return $this->wikiId;
    }
 
    private function getDBConnectionRefForQueryFlags( $queryFlags ) {
        if ( ( $queryFlags & IDBAccessObject::READ_LATEST ) == IDBAccessObject::READ_LATEST ) {
            return $this->getPrimaryConnection();
        } else {
            return $this->getReplicaConnection();
        }
    }
 
    private function getReplicaConnection( $groups = [] ) {
        // TODO: Replace with ICP
        return $this->loadBalancer->getConnection( DB_REPLICA, $groups, $this->wikiId );
    }
 
    private function getPrimaryConnection(): IDatabase {
        // TODO: Replace with ICP
        return $this->loadBalancer->getConnection( DB_PRIMARY, [], $this->wikiId );
    }
 
    public function getTitle( $pageId, $revId, $queryFlags = IDBAccessObject::READ_NORMAL ) {
        // TODO: Hard-deprecate this once getPage() returns a PageRecord. T195069
        if ( $this->wikiId !== WikiAwareEntity::LOCAL ) {
            wfDeprecatedMsg( 'Using a Title object to refer to a page on another site.', '1.36' );
        }
 
        $page = $this->getPage( $pageId, $revId, $queryFlags );
        return $this->titleFactory->newFromPageIdentity( $page );
    }
 
    private function getPage( ?int $pageId, ?int $revId, int $queryFlags = IDBAccessObject::READ_NORMAL ) {
        if ( !$pageId && !$revId ) {
            throw new InvalidArgumentException( '$pageId and $revId cannot both be 0 or null' );
        }
 
        // This method recalls itself with READ_LATEST if READ_NORMAL doesn't get us a Title
        // So ignore READ_LATEST_IMMUTABLE flags and handle the fallback logic in this method
        if ( DBAccessObjectUtils::hasFlags( $queryFlags, IDBAccessObject::READ_LATEST_IMMUTABLE ) ) {
            $queryFlags = IDBAccessObject::READ_NORMAL;
        }
 
        // Loading by ID is best
        if ( $pageId !== null && $pageId > 0 ) {
            $page = $this->pageStore->getPageById( $pageId, $queryFlags );
            if ( $page ) {
                return $this->wrapPage( $page );
            }
        }
 
        // rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
        if ( $revId !== null && $revId > 0 ) {
            $pageQuery = $this->pageStore->newSelectQueryBuilder( $queryFlags )
                ->join( 'revision', null, 'page_id=rev_page' )
                ->conds( [ 'rev_id' => $revId ] )
                ->caller( __METHOD__ );
 
            $page = $pageQuery->fetchPageRecord();
            if ( $page ) {
                return $this->wrapPage( $page );
            }
        }
 
        // If we still don't have a title, fallback to primary DB if that wasn't already happening.
        if ( $queryFlags === IDBAccessObject::READ_NORMAL ) {
            $title = $this->getPage( $pageId, $revId, IDBAccessObject::READ_LATEST );
            if ( $title ) {
                $this->logger->info(
                    __METHOD__ . ' fell back to READ_LATEST and got a Title.',
                    [ 'exception' => new RuntimeException() ]
                );
                return $title;
            }
        }
 
        throw new RevisionAccessException(
            'Could not determine title for page ID {page_id} and revision ID {rev_id}',
            [
                'page_id' => $pageId,
                'rev_id' => $revId,
            ]
        );
    }
 
    private function wrapPage( PageIdentity $page ): PageIdentity {
        if ( $this->wikiId === WikiAwareEntity::LOCAL ) {
            // NOTE: since there is still a lot of code that needs a full Title,
            //       and uses Title::castFromPageIdentity() to get one, it's beneficial
            //       to create a Title right away if we can, so we don't have to convert
            //       over and over later on.
            //       When there is less need to convert to Title, this special case can
            //       be removed.
            return $this->titleFactory->newFromPageIdentity( $page );
        } else {
            return $page;
        }
    }
 
    private function failOnNull( $value, $name ) {
        if ( $value === null ) {
            throw new IncompleteRevisionException(
                "$name must not be " . var_export( $value, true ) . "!"
            );
        }
 
        return $value;
    }
 
    private function failOnEmpty( $value, $name ) {
        if ( $value === null || $value === 0 || $value === '' ) {
            throw new IncompleteRevisionException(
                "$name must not be " . var_export( $value, true ) . "!"
            );
        }
 
        return $value;
    }
 
    public function insertRevisionOn( RevisionRecord $rev, IDatabase $dbw ) {
        // TODO: pass in a DBTransactionContext instead of a database connection.
        $this->checkDatabaseDomain( $dbw );
 
        $slotRoles = $rev->getSlotRoles();
 
        // Make sure the main slot is always provided throughout migration
        if ( !in_array( SlotRecord::MAIN, $slotRoles ) ) {
            throw new IncompleteRevisionException(
                'main slot must be provided'
            );
        }
 
        // Checks
        $this->failOnNull( $rev->getSize(), 'size field' );
        $this->failOnEmpty( $rev->getTimestamp(), 'timestamp field' );
        $comment = $this->failOnNull( $rev->getComment( RevisionRecord::RAW ), 'comment' );
        $user = $this->failOnNull( $rev->getUser( RevisionRecord::RAW ), 'user' );
        $this->failOnNull( $user->getId(), 'user field' );
        $this->failOnEmpty( $user->getName(), 'user_text field' );
 
        if ( !$rev->isReadyForInsertion() ) {
            // This is here for future-proofing. At the time this check being added, it
            // was redundant to the individual checks above.
            throw new IncompleteRevisionException( 'Revision is incomplete' );
        }
 
        if ( $slotRoles == [ SlotRecord::MAIN ] ) {
            // T239717: If the main slot is the only slot, make sure the revision's nominal size
            // and hash match the main slot's nominal size and hash.
            $mainSlot = $rev->getSlot( SlotRecord::MAIN, RevisionRecord::RAW );
            Assert::precondition(
                $mainSlot->getSize() === $rev->getSize(),
                'The revisions\'s size must match the main slot\'s size (see T239717)'
            );
        }
 
        $pageId = $this->failOnEmpty( $rev->getPageId( $this->wikiId ), 'rev_page field' ); // check this early
 
        $parentId = $rev->getParentId() ?? $this->getPreviousRevisionId( $dbw, $rev );
 
        Assert::precondition( $pageId > 0, 'revision must have an ID' );
 
        $rev = $dbw->doAtomicSection(
            __METHOD__,
            function ( IDatabase $dbw, $fname ) use (
                $rev,
                $user,
                $comment,
                $pageId,
                $parentId
            ) {
                return $this->insertRevisionInternal(
                    $rev,
                    $dbw,
                    $user,
                    $comment,
                    $rev->getPage(),
                    $pageId,
                    $parentId
                );
            }
        );
 
        Assert::postcondition( $rev->getId( $this->wikiId ) > 0, 'revision must have an ID' );
        Assert::postcondition( $rev->getPageId( $this->wikiId ) > 0, 'revision must have a page ID' );
        Assert::postcondition(
            $rev->getComment( RevisionRecord::RAW ) !== null,
            'revision must have a comment'
        );
        Assert::postcondition(
            $rev->getUser( RevisionRecord::RAW ) !== null,
            'revision must have a user'
        );
 
        // Trigger exception if the main slot is missing.
        // Technically, this could go away after MCR migration: while
        // calling code may require a main slot to exist, RevisionStore
        // really should not know or care about that requirement.
        $rev->getSlot( SlotRecord::MAIN, RevisionRecord::RAW );
 
        foreach ( $slotRoles as $role ) {
            $slot = $rev->getSlot( $role, RevisionRecord::RAW );
            Assert::postcondition(
                $slot->getContent() !== null,
                $role . ' slot must have content'
            );
            Assert::postcondition(
                $slot->hasRevision(),
                $role . ' slot must have a revision associated'
            );
        }
 
        $this->hookRunner->onRevisionRecordInserted( $rev );
 
        return $rev;
    }
 
    public function updateSlotsOn(
        RevisionRecord $revision,
        RevisionSlotsUpdate $revisionSlotsUpdate,
        IDatabase $dbw
    ): array {
        $this->checkDatabaseDomain( $dbw );
 
        // Make sure all modified and removed slots are derived slots
        foreach ( $revisionSlotsUpdate->getModifiedRoles() as $role ) {
            Assert::precondition(
                $this->slotRoleRegistry->getRoleHandler( $role )->isDerived(),
                'Trying to modify a slot that is not derived'
            );
        }
        foreach ( $revisionSlotsUpdate->getRemovedRoles() as $role ) {
            $isDerived = $this->slotRoleRegistry->getRoleHandler( $role )->isDerived();
            Assert::precondition(
                $isDerived,
                'Trying to remove a slot that is not derived'
            );
            throw new LogicException( 'Removing derived slots is not yet implemented. See T277394.' );
        }
 
        $slotRecords = $dbw->doAtomicSection(
            __METHOD__,
            function ( IDatabase $dbw, $fname ) use (
                $revision,
                $revisionSlotsUpdate
            ) {
                return $this->updateSlotsInternal(
                    $revision,
                    $revisionSlotsUpdate,
                    $dbw
                );
            }
        );
 
        foreach ( $slotRecords as $role => $slot ) {
            Assert::postcondition(
                $slot->getContent() !== null,
                $role . ' slot must have content'
            );
            Assert::postcondition(
                $slot->hasRevision(),
                $role . ' slot must have a revision associated'
            );
        }
 
        return $slotRecords;
    }
 
    private function updateSlotsInternal(
        RevisionRecord $revision,
        RevisionSlotsUpdate $revisionSlotsUpdate,
        IDatabase $dbw
    ): array {
        $page = $revision->getPage();
        $revId = $revision->getId( $this->wikiId );
        $blobHints = [
            BlobStore::PAGE_HINT => $page->getId( $this->wikiId ),
            BlobStore::REVISION_HINT => $revId,
            BlobStore::PARENT_HINT => $revision->getParentId( $this->wikiId ),
        ];
 
        $newSlots = [];
        foreach ( $revisionSlotsUpdate->getModifiedRoles() as $role ) {
            $slot = $revisionSlotsUpdate->getModifiedSlot( $role );
            $newSlots[$role] = $this->insertSlotOn( $dbw, $revId, $slot, $page, $blobHints );
        }
 
        return $newSlots;
    }
 
    private function insertRevisionInternal(
        RevisionRecord $rev,
        IDatabase $dbw,
        UserIdentity $user,
        CommentStoreComment $comment,
        PageIdentity $page,
        int $pageId,
        int $parentId
    ): RevisionRecord {
        $slotRoles = $rev->getSlotRoles();
 
        $revisionRow = $this->insertRevisionRowOn(
            $dbw,
            $rev,
            $parentId
        );
 
        $revisionId = $revisionRow['rev_id'];
 
        $blobHints = [
            BlobStore::PAGE_HINT => $pageId,
            BlobStore::REVISION_HINT => $revisionId,
            BlobStore::PARENT_HINT => $parentId,
        ];
 
        $newSlots = [];
        foreach ( $slotRoles as $role ) {
            $slot = $rev->getSlot( $role, RevisionRecord::RAW );
 
            // If the SlotRecord already has a revision ID set, this means it already exists
            // in the database, and should already belong to the latest revision.
            // However, a slot may already have a revision, but no content ID, if the slot
            // is emulated based on the archive table, because we are in SCHEMA_COMPAT_READ_OLD
            // mode, and the respective archive row was not yet migrated to the new schema.
            // In that case, a new slot row (and content row) must be inserted even during
            // undeletion.
            if ( $slot->hasRevision() && $slot->hasContentId() ) {
                // TODO: properly abort transaction if the assertion fails!
                Assert::parameter(
                    $slot->getRevision() === $revisionId,
                    'slot role ' . $slot->getRole(),
                    'Existing slot should belong to revision '
                    . $revisionId . ', but belongs to revision ' . $slot->getRevision() . '!'
                );
 
                // Slot exists, nothing to do, move along.
                // This happens when restoring archived revisions.
 
                $newSlots[$role] = $slot;
            } else {
                $newSlots[$role] = $this->insertSlotOn( $dbw, $revisionId, $slot, $page, $blobHints );
            }
        }
 
        $this->insertIpChangesRow( $dbw, $user, $rev, $revisionId );
 
        $rev = new RevisionStoreRecord(
            $page,
            $user,
            $comment,
            (object)$revisionRow,
            new RevisionSlots( $newSlots ),
            $this->wikiId
        );
 
        return $rev;
    }
 
    private function insertSlotOn(
        IDatabase $dbw,
        $revisionId,
        SlotRecord $protoSlot,
        PageIdentity $page,
        array $blobHints = []
    ) {
        if ( $protoSlot->hasAddress() ) {
            $blobAddress = $protoSlot->getAddress();
        } else {
            $blobAddress = $this->storeContentBlob( $protoSlot, $page, $blobHints );
        }
 
        if ( $protoSlot->hasContentId() ) {
            $contentId = $protoSlot->getContentId();
        } else {
            $contentId = $this->insertContentRowOn( $protoSlot, $dbw, $blobAddress );
        }
 
        $this->insertSlotRowOn( $protoSlot, $dbw, $revisionId, $contentId );
 
        return SlotRecord::newSaved(
            $revisionId,
            $contentId,
            $blobAddress,
            $protoSlot
        );
    }
 
    private function insertIpChangesRow(
        IDatabase $dbw,
        UserIdentity $user,
        RevisionRecord $rev,
        $revisionId
    ) {
        if ( !$user->isRegistered() && IPUtils::isValid( $user->getName() ) ) {
            $dbw->newInsertQueryBuilder()
                ->insertInto( 'ip_changes' )
                ->row( [
                    'ipc_rev_id'        => $revisionId,
                    'ipc_rev_timestamp' => $dbw->timestamp( $rev->getTimestamp() ),
                    'ipc_hex'           => IPUtils::toHex( $user->getName() ),
                ] )
                ->caller( __METHOD__ )->execute();
 
        }
    }
 
    private function insertRevisionRowOn(
        IDatabase $dbw,
        RevisionRecord $rev,
        $parentId
    ) {
        $revisionRow = $this->getBaseRevisionRow( $dbw, $rev, $parentId );
 
        $revisionRow += $this->commentStore->insert(
            $dbw,
            'rev_comment',
            $rev->getComment( RevisionRecord::RAW )
        );
 
        $dbw->newInsertQueryBuilder()
            ->insertInto( 'revision' )
            ->row( $revisionRow )
            ->caller( __METHOD__ )->execute();
 
        if ( !isset( $revisionRow['rev_id'] ) ) {
            // only if auto-increment was used
            $revisionRow['rev_id'] = intval( $dbw->insertId() );
 
            if ( $dbw->getType() === 'mysql' ) {
                // (T202032) MySQL until 8.0 and MariaDB until some version after 10.1.34 don't save the
                // auto-increment value to disk, so on server restart it might reuse IDs from deleted
                // revisions. We can fix that with an insert with an explicit rev_id value, if necessary.
 
                $maxRevId = intval( $dbw->newSelectQueryBuilder()
                    ->select( 'MAX(ar_rev_id)' )
                    ->from( 'archive' )
                    ->caller( __METHOD__ )
                    ->fetchField() );
                $table = 'archive';
                $maxRevId2 = intval( $dbw->newSelectQueryBuilder()
                    ->select( 'MAX(slot_revision_id)' )
                    ->from( 'slots' )
                    ->caller( __METHOD__ )
                    ->fetchField() );
                if ( $maxRevId2 >= $maxRevId ) {
                    $maxRevId = $maxRevId2;
                    $table = 'slots';
                }
 
                if ( $maxRevId >= $revisionRow['rev_id'] ) {
                    $this->logger->debug(
                        '__METHOD__: Inserted revision {revid} but {table} has revisions up to {maxrevid}.'
                            . ' Trying to fix it.',
                        [
                            'revid' => $revisionRow['rev_id'],
                            'table' => $table,
                            'maxrevid' => $maxRevId,
                        ]
                    );
 
                    if ( !$dbw->lock( 'fix-for-T202032', __METHOD__ ) ) {
                        throw new MWException( 'Failed to get database lock for T202032' );
                    }
                    $fname = __METHOD__;
                    $dbw->onTransactionResolution(
                        static function () use ( $dbw, $fname ): void {
                            $dbw->unlock( 'fix-for-T202032', $fname );
                        },
                        __METHOD__
                    );
 
                    $dbw->newDeleteQueryBuilder()
                        ->deleteFrom( 'revision' )
                        ->where( [ 'rev_id' => $revisionRow['rev_id'] ] )
                        ->caller( __METHOD__ )->execute();
 
                    // The locking here is mostly to make MySQL bypass the REPEATABLE-READ transaction
                    // isolation (weird MySQL "feature"). It does seem to block concurrent auto-incrementing
                    // inserts too, though, at least on MariaDB 10.1.29.
                    //
                    // Don't try to lock `revision` in this way, it'll deadlock if there are concurrent
                    // transactions in this code path thanks to the row lock from the original ->insert() above.
                    //
                    // And we have to use raw SQL to bypass the "aggregation used with a locking SELECT" warning
                    // that's for non-MySQL DBs.
                    $row1 = $dbw->query(
                        $dbw->selectSQLText( 'archive', [ 'v' => "MAX(ar_rev_id)" ], '', __METHOD__ ) . ' FOR UPDATE',
                        __METHOD__
                    )->fetchObject();
 
                    $row2 = $dbw->query(
                        $dbw->selectSQLText( 'slots', [ 'v' => "MAX(slot_revision_id)" ], '', __METHOD__ )
                            . ' FOR UPDATE',
                        __METHOD__
                    )->fetchObject();
 
                    $maxRevId = max(
                        $maxRevId,
                        $row1 ? intval( $row1->v ) : 0,
                        $row2 ? intval( $row2->v ) : 0
                    );
 
                    // If we don't have SCHEMA_COMPAT_WRITE_NEW, all except the first of any concurrent
                    // transactions will throw a duplicate key error here. It doesn't seem worth trying
                    // to avoid that.
                    $revisionRow['rev_id'] = $maxRevId + 1;
                    $dbw->newInsertQueryBuilder()
                        ->insertInto( 'revision' )
                        ->row( $revisionRow )
                        ->caller( __METHOD__ )->execute();
                }
            }
        }
 
        return $revisionRow;
    }
 
    private function getBaseRevisionRow(
        IDatabase $dbw,
        RevisionRecord $rev,
        $parentId
    ) {
        // Record the edit in revisions
        $revisionRow = [
            'rev_page'       => $rev->getPageId( $this->wikiId ),
            'rev_parent_id'  => $parentId,
            'rev_actor'      => $this->actorStore->acquireActorId(
                $rev->getUser( RevisionRecord::RAW ),
                $dbw
            ),
            'rev_minor_edit' => $rev->isMinor() ? 1 : 0,
            'rev_timestamp'  => $dbw->timestamp( $rev->getTimestamp() ),
            'rev_deleted'    => $rev->getVisibility(),
            'rev_len'        => $rev->getSize(),
        ];
 
        if ( $rev->getId( $this->wikiId ) !== null ) {
            // Needed to restore revisions with their original ID
            $revisionRow['rev_id'] = $rev->getId( $this->wikiId );
        }
 
        return $revisionRow;
    }
 
    private function storeContentBlob(
        SlotRecord $slot,
        PageIdentity $page,
        array $blobHints = []
    ) {
        $content = $slot->getContent();
        $format = $content->getDefaultFormat();
        $model = $content->getModel();
 
        $this->checkContent( $content, $page, $slot->getRole() );
 
        return $this->blobStore->storeBlob(
            $content->serialize( $format ),
            // These hints "leak" some information from the higher abstraction layer to
            // low level storage to allow for optimization.
            array_merge(
                $blobHints,
                [
                    BlobStore::DESIGNATION_HINT => 'page-content',
                    BlobStore::ROLE_HINT => $slot->getRole(),
                    BlobStore::SHA1_HINT => $slot->getSha1(),
                    BlobStore::MODEL_HINT => $model,
                    BlobStore::FORMAT_HINT => $format,
                ]
            )
        );
    }
 
    private function insertSlotRowOn( SlotRecord $slot, IDatabase $dbw, $revisionId, $contentId ) {
        $dbw->newInsertQueryBuilder()
            ->insertInto( 'slots' )
            ->row( [
                'slot_revision_id' => $revisionId,
                'slot_role_id' => $this->slotRoleStore->acquireId( $slot->getRole() ),
                'slot_content_id' => $contentId,
                // If the slot has a specific origin use that ID, otherwise use the ID of the revision
                // that we just inserted.
                'slot_origin' => $slot->hasOrigin() ? $slot->getOrigin() : $revisionId,
            ] )
            ->caller( __METHOD__ )->execute();
    }
 
    private function insertContentRowOn( SlotRecord $slot, IDatabase $dbw, $blobAddress ) {
        $dbw->newInsertQueryBuilder()
            ->insertInto( 'content' )
            ->row( [
                'content_size' => $slot->getSize(),
                'content_sha1' => $slot->getSha1(),
                'content_model' => $this->contentModelStore->acquireId( $slot->getModel() ),
                'content_address' => $blobAddress,
            ] )
            ->caller( __METHOD__ )->execute();
        return intval( $dbw->insertId() );
    }
 
    private function checkContent( Content $content, PageIdentity $page, string $role ) {
        // Note: may return null for revisions that have not yet been inserted
 
        $model = $content->getModel();
        $format = $content->getDefaultFormat();
        $handler = $content->getContentHandler();
 
        if ( !$handler->isSupportedFormat( $format ) ) {
            throw new MWException(
                "Can't use format $format with content model $model on $page role $role"
            );
        }
 
        if ( !$content->isValid() ) {
            throw new MWException(
                "New content for $page role $role is not valid! Content model is $model"
            );
        }
    }
 
    public function newNullRevision(
        IDatabase $dbw,
        PageIdentity $page,
        CommentStoreComment $comment,
        $minor,
        UserIdentity $user
    ) {
        $this->checkDatabaseDomain( $dbw );
 
        $pageId = $this->getArticleId( $page );
 
        // T51581: Lock the page table row to ensure no other process
        // is adding a revision to the page at the same time.
        // Avoid locking extra tables, compare T191892.
        $pageLatest = $dbw->newSelectQueryBuilder()
            ->select( 'page_latest' )
            ->forUpdate()
            ->from( 'page' )
            ->where( [ 'page_id' => $pageId ] )
            ->caller( __METHOD__ )->fetchField();
 
        if ( !$pageLatest ) {
            $msg = 'T235589: Failed to select table row during dummy revision creation' .
                " Page id '$pageId' does not exist.";
            $this->logger->error(
                $msg,
                [ 'exception' => new RuntimeException( $msg ) ]
            );
 
            return null;
        }
 
        // Fetch the actual revision row from primary DB, without locking all extra tables.
        $oldRevision = $this->loadRevisionFromConds(
            $dbw,
            [ 'rev_id' => intval( $pageLatest ) ],
            IDBAccessObject::READ_LATEST,
            $page
        );
 
        if ( !$oldRevision ) {
            $msg = "Failed to load latest revision ID $pageLatest of page ID $pageId.";
            $this->logger->error(
                $msg,
                [ 'exception' => new RuntimeException( $msg ) ]
            );
            return null;
        }
 
        // Construct the new revision
        $timestamp = MWTimestamp::now( TS::MW );
        $newRevision = MutableRevisionRecord::newFromParentRevision( $oldRevision );
 
        $newRevision->setComment( $comment );
        $newRevision->setUser( $user );
        $newRevision->setTimestamp( $timestamp );
        $newRevision->setMinorEdit( $minor );
 
        return $newRevision;
    }
 
    public function getRcIdIfUnpatrolled( RevisionRecord $rev ) {
        $rc = $this->getRecentChange( $rev );
        if ( $rc && $rc->getAttribute( 'rc_patrolled' ) == RecentChange::PRC_UNPATROLLED ) {
            return $rc->getAttribute( 'rc_id' );
        } else {
            return 0;
        }
    }
 
    public function getRecentChange( RevisionRecord $rev, $flags = 0 ) {
        if ( $this->wikiId !== RevisionRecord::LOCAL ) {
            throw new PreconditionException( 'RecentChangeLookup is only available for the local wiki' );
        }
 
        $rc = $this->recentChangeLookup->getRecentChangeByConds(
            [
                'rc_this_oldid' => $rev->getId( $this->wikiId ),
                // rc_this_oldid does not have to be unique,
                // in particular, it is shared with categorization
                // changes. Prefer the original change because callers
                // often expect a change for patrolling.
                'rc_source' => [ RecentChange::SRC_EDIT, RecentChange::SRC_NEW, RecentChange::SRC_LOG ],
            ],
            __METHOD__,
            ( $flags & IDBAccessObject::READ_LATEST ) == IDBAccessObject::READ_LATEST
        );
 
        // XXX: cache this locally? Glue it to the RevisionRecord?
        return $rc;
    }
 
    private function loadSlotContent(
        SlotRecord $slot,
        ?string $blobData = null,
        ?string $blobFlags = null,
        ?string $blobFormat = null,
        int $queryFlags = 0
    ) {
        if ( $blobData !== null ) {
            $blobAddress = $slot->hasAddress() ? $slot->getAddress() : null;
 
            if ( $blobFlags === null ) {
                // No blob flags, so use the blob verbatim.
                $data = $blobData;
            } else {
                try {
                    $data = $this->blobStore->expandBlob( $blobData, $blobFlags, $blobAddress );
                } catch ( BadBlobException $e ) {
                    throw new BadRevisionException( $e->getMessage(), [], 0, $e );
                }
 
                if ( $data === false ) {
                    throw new RevisionAccessException(
                        'Failed to expand blob data using flags {flags} (key: {cache_key})',
                        [
                            'flags' => $blobFlags,
                            'cache_key' => $blobAddress,
                        ]
                    );
                }
            }
 
        } else {
            $address = $slot->getAddress();
            try {
                $data = $this->blobStore->getBlob( $address, $queryFlags );
            } catch ( BadBlobException $e ) {
                throw new BadRevisionException( $e->getMessage(), [], 0, $e );
            } catch ( BlobAccessException $e ) {
                throw new RevisionAccessException(
                    'Failed to load data blob from {address} for revision {revision}. '
                        . 'If this problem persists, use the findBadBlobs maintenance script '
                        . 'to investigate the issue and mark the bad blobs.',
                    [ 'address' => $e->getMessage(), 'revision' => $slot->getRevision() ],
                    0,
                    $e
                );
            }
        }
 
        $model = $slot->getModel();
 
        // If the content model is not known, don't fail here (T220594, T220793, T228921)
        if ( !$this->contentHandlerFactory->isDefinedModel( $model ) ) {
            $this->logger->warning(
                "Undefined content model '$model', falling back to FallbackContent",
                [
                    'content_address' => $slot->getAddress(),
                    'rev_id' => $slot->getRevision(),
                    'role_name' => $slot->getRole(),
                    'model_name' => $model,
                    'exception' => new RuntimeException()
                ]
            );
 
            return new FallbackContent( $data, $model );
        }
 
        return $this->contentHandlerFactory
            ->getContentHandler( $model )
            ->unserializeContent( $data, $blobFormat );
    }
 
    public function getRevisionById( $id, $flags = 0, ?PageIdentity $page = null ) {
        return $this->newRevisionFromConds( [ 'rev_id' => intval( $id ) ], $flags, $page );
    }
 
    public function getRevisionByTitle( $page, $revId = 0, $flags = 0 ) {
        $conds = $this->getPageConditions( $page );
        if ( !$conds ) {
            return null;
        }
        if ( !( $page instanceof PageIdentity ) ) {
            if ( !( $page instanceof PageReference ) ) {
                wfDeprecated( __METHOD__ . ' with a LinkTarget', '1.45' );
            }
            $page = null;
        }
 
        if ( $revId ) {
            // Use the specified revision ID.
            // Note that we use newRevisionFromConds here because we want to retry
            // and fall back to primary DB if the page is not found on a replica.
            // Since the caller supplied a revision ID, we are pretty sure the revision is
            // supposed to exist, so we should try hard to find it.
            $conds['rev_id'] = $revId;
            return $this->newRevisionFromConds( $conds, $flags, $page );
        } else {
            // Use a join to get the latest revision.
            // Note that we don't use newRevisionFromConds here because we don't want to retry
            // and fall back to primary DB. The assumption is that we only want to force the fallback
            // if we are quite sure the revision exists because the caller supplied a revision ID.
            // If the page isn't found at all on a replica, it probably simply does not exist.
            $db = $this->getDBConnectionRefForQueryFlags( $flags );
            $conds[] = 'rev_id=page_latest';
            return $this->loadRevisionFromConds( $db, $conds, $flags, $page );
        }
    }
 
    public function getRevisionByPageId( $pageId, $revId = 0, $flags = 0 ) {
        $conds = [ 'page_id' => $pageId ];
        if ( $revId ) {
            // Use the specified revision ID.
            // Note that we use newRevisionFromConds here because we want to retry
            // and fall back to primary DB if the page is not found on a replica.
            // Since the caller supplied a revision ID, we are pretty sure the revision is
            // supposed to exist, so we should try hard to find it.
            $conds['rev_id'] = $revId;
            return $this->newRevisionFromConds( $conds, $flags );
        } else {
            // Use a join to get the latest revision.
            // Note that we don't use newRevisionFromConds here because we don't want to retry
            // and fall back to primary DB. The assumption is that we only want to force the fallback
            // if we are quite sure the revision exists because the caller supplied a revision ID.
            // If the page isn't found at all on a replica, it probably simply does not exist.
            $db = $this->getDBConnectionRefForQueryFlags( $flags );
 
            $conds[] = 'rev_id=page_latest';
 
            return $this->loadRevisionFromConds( $db, $conds, $flags );
        }
    }
 
    public function getRevisionByTimestamp(
        $page,
        string $timestamp,
        int $flags = IDBAccessObject::READ_NORMAL
    ): ?RevisionRecord {
        $conds = $this->getPageConditions( $page );
        if ( !$conds ) {
            return null;
        }
        if ( !( $page instanceof PageIdentity ) ) {
            if ( !( $page instanceof PageReference ) ) {
                wfDeprecated( __METHOD__ . ' with a LinkTarget', '1.45' );
            }
            $page = null;
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $flags );
        $conds['rev_timestamp'] = $db->timestamp( $timestamp );
        return $this->newRevisionFromConds( $conds, $flags, $page );
    }
 
    private function loadSlotRecords( $revId, $queryFlags, PageIdentity $page ) {
        // TODO: Find a way to add NS_MODULE from Scribunto here
        if ( $page->getNamespace() !== NS_TEMPLATE ) {
            $res = $this->loadSlotRecordsFromDb( $revId, $queryFlags, $page );
            return $this->constructSlotRecords( $revId, $res, $queryFlags, $page );
        }
 
        // TODO: These caches should not be needed. See T297147#7563670
        $res = $this->localCache->getWithSetCallback(
            $this->localCache->makeKey(
                'revision-slots',
                $page->getWikiId(),
                $page->getId( $page->getWikiId() ),
                $revId
            ),
            $this->localCache::TTL_HOUR,
            function () use ( $revId, $queryFlags, $page ) {
                return $this->cache->getWithSetCallback(
                    $this->cache->makeKey(
                        'revision-slots',
                        $page->getWikiId(),
                        $page->getId( $page->getWikiId() ),
                        $revId
                    ),
                    WANObjectCache::TTL_DAY,
                    function () use ( $revId, $queryFlags, $page ) {
                        $res = $this->loadSlotRecordsFromDb( $revId, $queryFlags, $page );
                        if ( !$res ) {
                            // Avoid caching
                            return false;
                        }
                        return $res;
                    }
                );
            }
        );
        if ( !$res ) {
            $res = [];
        }
 
        return $this->constructSlotRecords( $revId, $res, $queryFlags, $page );
    }
 
    private function loadSlotRecordsFromDb( int $revId, int $queryFlags, PageIdentity $page ): array {
        $revQuery = $this->getSlotsQueryInfo( [ 'content' ] );
 
        $db = $this->getDBConnectionRefForQueryFlags( $queryFlags );
        $res = $db->newSelectQueryBuilder()
            ->queryInfo( $revQuery )
            ->where( [ 'slot_revision_id' => $revId ] )
            ->recency( $queryFlags )
            ->caller( __METHOD__ )->fetchResultSet();
 
        if ( !$res->numRows() && !( $queryFlags & IDBAccessObject::READ_LATEST ) ) {
            // If we found no slots, try looking on the primary database (T212428, T252156)
            $this->logger->info(
                __METHOD__ . ' falling back to READ_LATEST.',
                [
                    'revid' => $revId,
                    'exception' => new RuntimeException(),
                ]
            );
            return $this->loadSlotRecordsFromDb(
                $revId,
                $queryFlags | IDBAccessObject::READ_LATEST,
                $page
            );
        }
        return iterator_to_array( $res );
    }
 
    private function constructSlotRecords(
        $revId,
        $slotRows,
        $queryFlags,
        PageIdentity $page,
        $slotContents = null
    ) {
        $slots = [];
 
        foreach ( $slotRows as $row ) {
            // Resolve role names and model names from in-memory cache, if they were not joined in.
            if ( !isset( $row->role_name ) ) {
                $row->role_name = $this->slotRoleStore->getName( (int)$row->slot_role_id );
            }
 
            if ( !isset( $row->model_name ) ) {
                if ( isset( $row->content_model ) ) {
                    $row->model_name = $this->contentModelStore->getName( (int)$row->content_model );
                } else {
                    // We may get here if $row->model_name is set but null, perhaps because it
                    // came from rev_content_model, which is NULL for the default model.
                    $slotRoleHandler = $this->slotRoleRegistry->getRoleHandler( $row->role_name );
                    $row->model_name = $slotRoleHandler->getDefaultModel( $page );
                }
            }
 
            // We may have a fake blob_data field from getSlotRowsForBatch(), use it!
            if ( isset( $row->blob_data ) ) {
                $slotContents[$row->content_address] = $row->blob_data;
            }
 
            $contentCallback = function ( SlotRecord $slot ) use ( $slotContents, $queryFlags ) {
                $blob = null;
                if ( isset( $slotContents[$slot->getAddress()] ) ) {
                    $blob = $slotContents[$slot->getAddress()];
                    if ( $blob instanceof Content ) {
                        return $blob;
                    }
                }
                return $this->loadSlotContent( $slot, $blob, null, null, $queryFlags );
            };
 
            $slots[$row->role_name] = new SlotRecord( $row, $contentCallback );
        }
 
        if ( !isset( $slots[SlotRecord::MAIN] ) ) {
            $this->logger->error(
                __METHOD__ . ': Main slot of revision not found in database. See T212428.',
                [
                    'revid' => $revId,
                    'queryFlags' => $queryFlags,
                    'exception' => new RuntimeException(),
                ]
            );
 
            throw new RevisionAccessException(
                'Main slot of revision not found in database. See T212428.'
            );
        }
 
        return $slots;
    }
 
    private function newRevisionSlots(
        $revId,
        $slotRows,
        $queryFlags,
        PageIdentity $page
    ) {
        if ( $slotRows ) {
            $slots = new RevisionSlots(
                $this->constructSlotRecords( $revId, $slotRows, $queryFlags, $page )
            );
        } else {
            $slots = new RevisionSlots( function () use( $revId, $queryFlags, $page ) {
                return $this->loadSlotRecords( $revId, $queryFlags, $page );
            } );
        }
 
        return $slots;
    }
 
    public function newRevisionFromArchiveRow(
        $row,
        $queryFlags = 0,
        ?PageIdentity $page = null,
        array $overrides = []
    ) {
        return $this->newRevisionFromArchiveRowAndSlots( $row, null, $queryFlags, $page, $overrides );
    }
 
    public function newRevisionFromRow(
        $row,
        $queryFlags = 0,
        ?PageIdentity $page = null,
        $fromCache = false
    ) {
        return $this->newRevisionFromRowAndSlots( $row, null, $queryFlags, $page, $fromCache );
    }
 
    public function newRevisionFromArchiveRowAndSlots(
        stdClass $row,
        $slots,
        int $queryFlags = 0,
        ?PageIdentity $page = null,
        array $overrides = []
    ) {
        if ( !$page && isset( $overrides['title'] ) ) {
            if ( !( $overrides['title'] instanceof PageIdentity ) ) {
                throw new InvalidArgumentException( 'title field override must contain a PageIdentity object.' );
            }
 
            $page = $overrides['title'];
        }
 
        if ( $page === null ) {
            if ( isset( $row->ar_namespace ) && isset( $row->ar_title ) ) {
                // Represent a non-existing page.
                // NOTE: The page title may be invalid by latest rules (T384628).
                $page = PageIdentityValue::localIdentity( 0, $row->ar_namespace, $row->ar_title );
            } else {
                throw new InvalidArgumentException(
                    'A Title or ar_namespace and ar_title must be given'
                );
            }
        }
 
        foreach ( $overrides as $key => $value ) {
            $field = "ar_$key";
            $row->$field = $value;
        }
 
        try {
            $user = $this->actorStore->newActorFromRowFields(
                $row->ar_user ?? null,
                $row->ar_user_text ?? null,
                $row->ar_actor ?? null
            );
        } catch ( InvalidArgumentException $ex ) {
            $this->logger->warning( 'Could not load user for archive revision {rev_id}', [
                'ar_rev_id' => $row->ar_rev_id,
                'ar_actor' => $row->ar_actor ?? 'null',
                'ar_user_text' => $row->ar_user_text ?? 'null',
                'ar_user' => $row->ar_user ?? 'null',
                'exception' => $ex
            ] );
            $user = $this->actorStore->getUnknownActor();
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $queryFlags );
        // Legacy because $row may have come from self::selectFields()
        $comment = $this->commentStore->getCommentLegacy( $db, 'ar_comment', $row, true );
 
        if ( !( $slots instanceof RevisionSlots ) ) {
            $slots = $this->newRevisionSlots( (int)$row->ar_rev_id, $slots, $queryFlags, $page );
        }
        return new RevisionArchiveRecord( $page, $user, $comment, $row, $slots, $this->wikiId );
    }
 
    public function newRevisionFromRowAndSlots(
        stdClass $row,
        $slots,
        int $queryFlags = 0,
        ?PageIdentity $page = null,
        bool $fromCache = false
    ) {
        if ( !$page ) {
            if ( isset( $row->page_id )
                && isset( $row->page_namespace )
                && isset( $row->page_title )
            ) {
                $page = new PageIdentityValue(
                    (int)$row->page_id,
                    (int)$row->page_namespace,
                    $row->page_title,
                    $this->wikiId
                );
 
                $page = $this->wrapPage( $page );
            } else {
                $pageId = (int)( $row->rev_page ?? 0 );
                $revId = (int)( $row->rev_id ?? 0 );
 
                $page = $this->getPage( $pageId, $revId, $queryFlags );
            }
        } else {
            $page = $this->ensureRevisionRowMatchesPage( $row, $page );
        }
 
        if ( !$page ) {
            // This should already have been caught about, but apparently
            // it not always is, see T286877.
            throw new RevisionAccessException(
                "Failed to determine page associated with revision {$row->rev_id}"
            );
        }
 
        try {
            $user = $this->actorStore->newActorFromRowFields(
                $row->rev_user ?? null,
                $row->rev_user_text ?? null,
                $row->rev_actor ?? null
            );
        } catch ( InvalidArgumentException $ex ) {
            $this->logger->warning( 'Could not load user for revision {rev_id}', [
                'rev_id' => $row->rev_id,
                'rev_actor' => $row->rev_actor ?? 'null',
                'rev_user_text' => $row->rev_user_text ?? 'null',
                'rev_user' => $row->rev_user ?? 'null',
                'exception' => $ex
            ] );
            $user = $this->actorStore->getUnknownActor();
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $queryFlags );
        // Legacy because $row may have come from self::selectFields()
        $comment = $this->commentStore->getCommentLegacy( $db, 'rev_comment', $row, true );
 
        if ( !( $slots instanceof RevisionSlots ) ) {
            $slots = $this->newRevisionSlots( (int)$row->rev_id, $slots, $queryFlags, $page );
        }
 
        // If this is a cached row, instantiate a cache-aware RevisionRecord to avoid stale data.
        if ( $fromCache ) {
            $rev = new RevisionStoreCacheRecord(
                function ( $revId ) use ( $queryFlags ) {
                    $db = $this->getDBConnectionRefForQueryFlags( $queryFlags );
                    $row = $this->fetchRevisionRowFromConds(
                        $db,
                        [ 'rev_id' => intval( $revId ) ]
                    );
                    if ( !$row && !( $queryFlags & IDBAccessObject::READ_LATEST ) ) {
                        // If we found no slots, try looking on the primary database (T259738)
                        $this->logger->info(
                            'RevisionStoreCacheRecord refresh callback falling back to READ_LATEST.',
                            [
                                'revid' => $revId,
                                'exception' => new RuntimeException(),
                            ]
                        );
                        $dbw = $this->getDBConnectionRefForQueryFlags( IDBAccessObject::READ_LATEST );
                        $row = $this->fetchRevisionRowFromConds(
                            $dbw,
                            [ 'rev_id' => intval( $revId ) ]
                        );
                    }
                    if ( !$row ) {
                        return [ null, null ];
                    }
                    return [
                        $row->rev_deleted,
                        $this->actorStore->newActorFromRowFields(
                            $row->rev_user ?? null,
                            $row->rev_user_text ?? null,
                            $row->rev_actor ?? null
                        )
                    ];
                },
                $page, $user, $comment, $row, $slots, $this->wikiId
            );
        } else {
            $rev = new RevisionStoreRecord(
                $page, $user, $comment, $row, $slots, $this->wikiId );
        }
        return $rev;
    }
 
    private function ensureRevisionRowMatchesPage( $row, PageIdentity $page, $context = [] ) {
        $revId = (int)( $row->rev_id ?? 0 );
        $revPageId = (int)( $row->rev_page ?? 0 ); // XXX: also check $row->page_id?
        $expectedPageId = $page->getId( $this->wikiId );
        // Avoid fatal error when the Title's ID changed, T246720
        if ( $revPageId && $expectedPageId && $revPageId !== $expectedPageId ) {
            // NOTE: PageStore::getPageByReference may use the page ID, which we don't want here.
            $pageRec = $this->pageStore->getPageByName(
                $page->getNamespace(),
                $page->getDBkey(),
                IDBAccessObject::READ_LATEST
            );
            $masterPageId = $pageRec->getId( $this->wikiId );
            $masterLatest = $pageRec->getLatest( $this->wikiId );
            if ( $revPageId === $masterPageId ) {
                if ( $page instanceof Title ) {
                    // If we were using a Title object, keep using it, but update the page ID.
                    // This way, we don't unexpectedly mix Titles with immutable value objects.
                    $page->resetArticleID( $masterPageId );
 
                } else {
                    $page = $pageRec;
                }
 
                $this->logger->info(
                    "Encountered stale Title object",
                    [
                        'page_id_stale' => $expectedPageId,
                        'page_id_reloaded' => $masterPageId,
                        'page_latest' => $masterLatest,
                        'rev_id' => $revId,
                        'exception' => new RuntimeException(),
                    ] + $context
                );
            } else {
                $expectedTitle = (string)$page;
                if ( $page instanceof Title ) {
                    // If we started with a Title, keep using a Title.
                    $page = $this->titleFactory->newFromID( $revPageId );
                } else {
                    $page = $pageRec;
                }
 
                // This could happen if a caller to e.g. getRevisionById supplied a Title that is
                // plain wrong. In this case, we should ideally throw an IllegalArgumentException.
                // However, it is more likely that we encountered a race condition during a page
                // move (T268910, T279832) or database corruption (T263340). That situation
                // should not be ignored, but we can allow the request to continue in a reasonable
                // manner without breaking things for the user.
                $this->logger->error(
                    "Encountered mismatching Title object (see T259022, T268910, T279832, T263340)",
                    [
                        'expected_page_id' => $masterPageId,
                        'expected_page_title' => $expectedTitle,
                        'rev_page' => $revPageId,
                        'rev_page_title' => (string)$page,
                        'page_latest' => $masterLatest,
                        'rev_id' => $revId,
                        'exception' => new RuntimeException(),
                    ] + $context
                );
            }
        }
 
        // @phan-suppress-next-line PhanTypeMismatchReturnNullable getPageByName/newFromID should not return null
        return $page;
    }
 
    public function newRevisionsFromBatch(
        $rows,
        array $options = [],
        $queryFlags = 0,
        ?PageIdentity $page = null
    ) {
        $result = new StatusValue();
        $archiveMode = $options['archive'] ?? false;
 
        if ( $archiveMode ) {
            $revIdField = 'ar_rev_id';
        } else {
            $revIdField = 'rev_id';
        }
 
        $rowsByRevId = [];
        $pageIdsToFetchTitles = [];
        $titlesByPageKey = [];
        foreach ( $rows as $row ) {
            if ( isset( $rowsByRevId[$row->$revIdField] ) ) {
                $result->warning(
                    'internalerror_info',
                    "Duplicate rows in newRevisionsFromBatch, $revIdField {$row->$revIdField}"
                );
            }
 
            // Attach a page key to the row, so we can find and reuse Title objects easily.
            $row->_page_key =
                $archiveMode ? $row->ar_namespace . ':' . $row->ar_title : $row->rev_page;
 
            if ( $page ) {
                if ( !$archiveMode && $row->rev_page != $this->getArticleId( $page ) ) {
                    throw new InvalidArgumentException(
                        "Revision {$row->$revIdField} doesn't belong to page "
                            . $this->getArticleId( $page )
                    );
                }
 
                if ( $archiveMode
                    && ( $row->ar_namespace != $page->getNamespace()
                        || $row->ar_title !== $page->getDBkey() )
                ) {
                    throw new InvalidArgumentException(
                        "Revision {$row->$revIdField} doesn't belong to page "
                            . $page
                    );
                }
            } elseif ( !isset( $titlesByPageKey[ $row->_page_key ] ) ) {
                if ( isset( $row->page_namespace ) && isset( $row->page_title )
                    // This should always be true, but just in case we don't have a page_id
                    // set or it doesn't match rev_page, let's fetch the title again.
                    && isset( $row->page_id ) && isset( $row->rev_page )
                    && $row->rev_page === $row->page_id
                ) {
                    $titlesByPageKey[ $row->_page_key ] = Title::newFromRow( $row );
                } elseif ( $archiveMode ) {
                    // Can't look up deleted pages by ID, but we have namespace and title
                    $titlesByPageKey[ $row->_page_key ] =
                        Title::makeTitle( $row->ar_namespace, $row->ar_title );
                } else {
                    $pageIdsToFetchTitles[] = $row->rev_page;
                }
            }
            $rowsByRevId[$row->$revIdField] = $row;
        }
 
        if ( !$rowsByRevId ) {
            $result->setResult( true, [] );
            return $result;
        }
 
        // If the page is not supplied, batch-fetch Title objects.
        if ( $page ) {
            // same logic as for $row->_page_key above
            $pageKey = $archiveMode
                ? $page->getNamespace() . ':' . $page->getDBkey()
                : $this->getArticleId( $page );
 
            $titlesByPageKey[$pageKey] = $page;
        } elseif ( $pageIdsToFetchTitles ) {
            // Note: when we fetch titles by ID, the page key is also the ID.
            // We should never get here if $archiveMode is true.
            Assert::invariant( !$archiveMode, 'Titles are not loaded by ID in archive mode.' );
 
            $pageIdsToFetchTitles = array_unique( $pageIdsToFetchTitles );
            $pageRecords = $this->pageStore
                ->newSelectQueryBuilder()
                ->wherePageIds( $pageIdsToFetchTitles )
                ->caller( __METHOD__ )
                ->fetchPageRecordArray();
            // Cannot array_merge because it re-indexes entries
            $titlesByPageKey = $pageRecords + $titlesByPageKey;
        }
 
        // which method to use for creating RevisionRecords
        $newRevisionRecord = $archiveMode
            ? $this->newRevisionFromArchiveRowAndSlots( ... )
            : $this->newRevisionFromRowAndSlots( ... );
 
        if ( !isset( $options['slots'] ) ) {
            $result->setResult(
                true,
                array_map(
                    static function ( $row )
                    use ( $queryFlags, $titlesByPageKey, $result, $newRevisionRecord, $revIdField ) {
                        try {
                            if ( !isset( $titlesByPageKey[$row->_page_key] ) ) {
                                $result->warning(
                                    'internalerror_info',
                                    "Couldn't find title for rev {$row->$revIdField} "
                                    . "(page key {$row->_page_key})"
                                );
                                return null;
                            }
                            return $newRevisionRecord( $row, null, $queryFlags,
                                $titlesByPageKey[ $row->_page_key ] );
                        } catch ( MWException $e ) {
                            $result->warning( 'internalerror_info', $e->getMessage() );
                            return null;
                        }
                    },
                    $rowsByRevId
                )
            );
            return $result;
        }
 
        $slotRowOptions = [
            'slots' => $options['slots'] ?? true,
            'blobs' => $options['content'] ?? false,
        ];
 
        if ( is_array( $slotRowOptions['slots'] )
            && !in_array( SlotRecord::MAIN, $slotRowOptions['slots'] )
        ) {
            // Make sure the main slot is always loaded, RevisionRecord requires this.
            $slotRowOptions['slots'][] = SlotRecord::MAIN;
        }
 
        $slotRowsStatus = $this->getSlotRowsForBatch( $rowsByRevId, $slotRowOptions, $queryFlags );
 
        $result->merge( $slotRowsStatus );
        $slotRowsByRevId = $slotRowsStatus->getValue();
 
        $result->setResult(
            true,
            array_map(
                function ( $row )
                use ( $slotRowsByRevId, $queryFlags, $titlesByPageKey, $result,
                    $revIdField, $newRevisionRecord
                ) {
                    if ( !isset( $slotRowsByRevId[$row->$revIdField] ) ) {
                        $result->warning(
                            'internalerror_info',
                            "Couldn't find slots for rev {$row->$revIdField}"
                        );
                        return null;
                    }
                    if ( !isset( $titlesByPageKey[$row->_page_key] ) ) {
                        $result->warning(
                            'internalerror_info',
                            "Couldn't find title for rev {$row->$revIdField} "
                                . "(page key {$row->_page_key})"
                        );
                        return null;
                    }
                    try {
                        return $newRevisionRecord(
                            $row,
                            new RevisionSlots(
                                $this->constructSlotRecords(
                                    $row->$revIdField,
                                    $slotRowsByRevId[$row->$revIdField],
                                    $queryFlags,
                                    $titlesByPageKey[$row->_page_key]
                                )
                            ),
                            $queryFlags,
                            $titlesByPageKey[$row->_page_key]
                        );
                    } catch ( MWException | ParameterAssertionException $e ) {
                        $result->warning( 'internalerror_info', $e->getMessage() );
                        return null;
                    }
                },
                $rowsByRevId
            )
        );
        return $result;
    }
 
    private function getSlotRowsForBatch(
        $rowsOrIds,
        array $options = [],
        $queryFlags = 0
    ) {
        $result = new StatusValue();
 
        $revIds = [];
        foreach ( $rowsOrIds as $id ) {
            if ( $id instanceof stdClass ) {
                $id = $id->ar_rev_id ?? $id->rev_id;
            }
            $revIds[] = (int)$id;
        }
 
        // Nothing to do.
        // Note that $rowsOrIds may not be "empty" even if $revIds is, e.g. if it's a ResultWrapper.
        if ( !$revIds ) {
            $result->setResult( true, [] );
            return $result;
        }
 
        // We need to set the `content` flag to join in content meta-data
        $slotQueryInfo = $this->getSlotsQueryInfo( [ 'content' ] );
        $revIdField = $slotQueryInfo['keys']['rev_id'];
        $slotQueryConds = [ $revIdField => $revIds ];
 
        if ( isset( $options['slots'] ) && is_array( $options['slots'] ) ) {
            $slotIds = [];
            foreach ( $options['slots'] as $slot ) {
                try {
                    $slotIds[] = $this->slotRoleStore->getId( $slot );
                } catch ( NameTableAccessException ) {
                    // Do not fail when slot has no id (unused slot)
                    // This also means for this slot are never data in the database
                }
            }
            if ( $slotIds === [] ) {
                // Degenerate case: return no slots for each revision.
                $result->setResult( true, array_fill_keys( $revIds, [] ) );
                return $result;
            }
 
            $roleIdField = $slotQueryInfo['keys']['role_id'];
            $slotQueryConds[$roleIdField] = $slotIds;
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $queryFlags );
        $slotRows = $db->newSelectQueryBuilder()
            ->queryInfo( $slotQueryInfo )
            ->where( $slotQueryConds )
            ->caller( __METHOD__ )
            ->fetchResultSet();
 
        $slotContents = null;
        if ( $options['blobs'] ?? false ) {
            $blobAddresses = [];
            foreach ( $slotRows as $slotRow ) {
                $blobAddresses[] = $slotRow->content_address;
            }
            $slotContentFetchStatus = $this->blobStore
                ->getBlobBatch( $blobAddresses, $queryFlags );
            foreach ( $slotContentFetchStatus->getMessages() as $msg ) {
                $result->warning( $msg );
            }
            $slotContents = $slotContentFetchStatus->getValue();
        }
 
        $slotRowsByRevId = [];
        foreach ( $slotRows as $slotRow ) {
            if ( $slotContents === null ) {
                // nothing to do
            } elseif ( isset( $slotContents[$slotRow->content_address] ) ) {
                $slotRow->blob_data = $slotContents[$slotRow->content_address];
            } else {
                $result->warning(
                    'internalerror_info',
                    "Couldn't find blob data for rev {$slotRow->slot_revision_id}"
                );
                $slotRow->blob_data = null;
            }
 
            // conditional needed for SCHEMA_COMPAT_READ_OLD
            if ( !isset( $slotRow->role_name ) && isset( $slotRow->slot_role_id ) ) {
                $slotRow->role_name = $this->slotRoleStore->getName( (int)$slotRow->slot_role_id );
            }
 
            // conditional needed for SCHEMA_COMPAT_READ_OLD
            if ( !isset( $slotRow->model_name ) && isset( $slotRow->content_model ) ) {
                $slotRow->model_name = $this->contentModelStore->getName( (int)$slotRow->content_model );
            }
 
            $slotRowsByRevId[$slotRow->slot_revision_id][$slotRow->role_name] = $slotRow;
        }
 
        $result->setResult( true, $slotRowsByRevId );
        return $result;
    }
 
    public function getContentBlobsForBatch(
        $rowsOrIds,
        $slots = null,
        $queryFlags = 0
    ) {
        $result = $this->getSlotRowsForBatch(
            $rowsOrIds,
            [ 'slots' => $slots, 'blobs' => true ],
            $queryFlags
        );
 
        if ( $result->isOK() ) {
            // strip out all internal meta data that we don't want to expose
            foreach ( $result->value as $revId => $rowsByRole ) {
                foreach ( $rowsByRole as $role => $slotRow ) {
                    if ( is_array( $slots ) && !in_array( $role, $slots ) ) {
                        // In SCHEMA_COMPAT_READ_OLD mode we may get the main slot even
                        // if we didn't ask for it.
                        unset( $result->value[$revId][$role] );
                        continue;
                    }
 
                    $result->value[$revId][$role] = (object)[
                        'blob_data' => $slotRow->blob_data,
                        'model_name' => $slotRow->model_name,
                    ];
                }
            }
        }
 
        return $result;
    }
 
    private function newRevisionFromConds(
        array $conditions,
        int $flags = IDBAccessObject::READ_NORMAL,
        ?PageIdentity $page = null,
        array $options = []
    ) {
        $db = $this->getDBConnectionRefForQueryFlags( $flags );
        $rev = $this->loadRevisionFromConds( $db, $conditions, $flags, $page, $options );
 
        // Make sure new pending/committed revision are visible later on
        // within web requests to certain avoid bugs like T93866 and T94407.
        if ( !$rev
            && !( $flags & IDBAccessObject::READ_LATEST )
            && $this->loadBalancer->hasStreamingReplicaServers()
            && $this->loadBalancer->hasOrMadeRecentPrimaryChanges()
        ) {
            $flags = IDBAccessObject::READ_LATEST;
            $dbw = $this->getPrimaryConnection();
            $rev = $this->loadRevisionFromConds( $dbw, $conditions, $flags, $page, $options );
        }
 
        return $rev;
    }
 
    private function loadRevisionFromConds(
        IReadableDatabase $db,
        array $conditions,
        int $flags = IDBAccessObject::READ_NORMAL,
        ?PageIdentity $page = null,
        array $options = []
    ) {
        $row = $this->fetchRevisionRowFromConds( $db, $conditions, $flags, $options );
        if ( $row ) {
            return $this->newRevisionFromRow( $row, $flags, $page );
        }
 
        return null;
    }
 
    private function checkDatabaseDomain( IReadableDatabase $db ) {
        $dbDomain = $db->getDomainID();
        $storeDomain = $this->loadBalancer->resolveDomainID( $this->wikiId );
        if ( $dbDomain === $storeDomain ) {
            return;
        }
 
        throw new RuntimeException( "DB connection domain '$dbDomain' does not match '$storeDomain'" );
    }
 
    private function fetchRevisionRowFromConds(
        IReadableDatabase $db,
        array $conditions,
        int $flags = IDBAccessObject::READ_NORMAL,
        array $options = []
    ) {
        $this->checkDatabaseDomain( $db );
 
        $queryBuilder = $this->newSelectQueryBuilder( $db )
            ->joinComment()
            ->joinPage()
            ->joinUser()
            ->where( $conditions )
            ->options( $options );
        if ( ( $flags & IDBAccessObject::READ_LOCKING ) == IDBAccessObject::READ_LOCKING ) {
            $queryBuilder->forUpdate();
        }
        return $queryBuilder->caller( __METHOD__ )->fetchRow();
    }
 
    public function getQueryInfo( $options = [] ) {
        $ret = [
            'tables' => [
                'revision',
                'actor_rev_user' => 'actor',
            ],
            'fields' => [
                'rev_id',
                'rev_page',
                'rev_actor' => 'rev_actor',
                'rev_user' => 'actor_rev_user.actor_user',
                'rev_user_text' => 'actor_rev_user.actor_name',
                'rev_timestamp',
                'rev_minor_edit',
                'rev_deleted',
                'rev_len',
                'rev_parent_id',
            ],
            'joins' => [
                'actor_rev_user' => [ 'JOIN', "actor_rev_user.actor_id = rev_actor" ],
            ]
        ];
 
        $commentQuery = $this->commentStore->getJoin( 'rev_comment' );
        $ret['tables'] = array_merge( $ret['tables'], $commentQuery['tables'] );
        $ret['fields'] = array_merge( $ret['fields'], $commentQuery['fields'] );
        $ret['joins'] = array_merge( $ret['joins'], $commentQuery['joins'] );
 
        if ( in_array( 'page', $options, true ) ) {
            $ret['tables'][] = 'page';
            $ret['fields'] = array_merge( $ret['fields'], [
                'page_namespace',
                'page_title',
                'page_id',
                'page_latest',
                'page_is_redirect',
                'page_len',
            ] );
            $ret['joins']['page'] = [ 'JOIN', [ 'page_id = rev_page' ] ];
        }
 
        if ( in_array( 'user', $options, true ) ) {
            $ret['tables'][] = 'user';
            $ret['fields'][] = 'user_name';
            $ret['joins']['user'] = [
                'LEFT JOIN',
                [ 'actor_rev_user.actor_user != 0', 'user_id = actor_rev_user.actor_user' ]
            ];
        }
 
        if ( in_array( 'text', $options, true ) ) {
            throw new InvalidArgumentException(
                'The `text` option is no longer supported in MediaWiki 1.35 and later.'
            );
        }
 
        return $ret;
    }
 
    public function newSelectQueryBuilder( IReadableDatabase $dbr ): RevisionSelectQueryBuilder {
        return new RevisionSelectQueryBuilder( $dbr );
    }
 
    public function newArchiveSelectQueryBuilder( IReadableDatabase $dbr ): ArchiveSelectQueryBuilder {
        return new ArchiveSelectQueryBuilder( $dbr );
    }
 
    public function getSlotsQueryInfo( $options = [] ) {
        $ret = [
            'tables' => [ 'slots' ],
            'fields' => [
                'slot_revision_id',
                'slot_content_id',
                'slot_origin',
                'slot_role_id',
            ],
            'joins'  => [],
            'keys'  => [
                'rev_id' => 'slot_revision_id',
                'role_id' => 'slot_role_id',
            ],
        ];
 
        if ( in_array( 'role', $options, true ) ) {
            // Use left join to attach role name, so we still find the revision row even
            // if the role name is missing. This triggers a more obvious failure mode.
            $ret['tables'][] = 'slot_roles';
            $ret['joins']['slot_roles'] = [ 'LEFT JOIN', [ 'slot_role_id = role_id' ] ];
            $ret['fields'][] = 'role_name';
        }
 
        if ( in_array( 'content', $options, true ) ) {
            $ret['keys']['model_id'] = 'content_model';
 
            $ret['tables'][] = 'content';
            $ret['fields'] = array_merge( $ret['fields'], [
                'content_size',
                'content_sha1',
                'content_address',
                'content_model',
            ] );
            $ret['joins']['content'] = [ 'JOIN', [ 'slot_content_id = content_id' ] ];
 
            if ( in_array( 'model', $options, true ) ) {
                // Use left join to attach model name, so we still find the revision row even
                // if the model name is missing. This triggers a more obvious failure mode.
                $ret['tables'][] = 'content_models';
                $ret['joins']['content_models'] = [ 'LEFT JOIN', [ 'content_model = model_id' ] ];
                $ret['fields'][] = 'model_name';
            }
 
        }
 
        return $ret;
    }
 
    public function isRevisionRow( $row, string $table = '' ) {
        if ( !( $row instanceof stdClass ) ) {
            return false;
        }
        $queryInfo = $table === 'archive' ? $this->getArchiveQueryInfo() : $this->getQueryInfo();
        foreach ( $queryInfo['fields'] as $alias => $field ) {
            $name = is_numeric( $alias ) ? $field : $alias;
            if ( !property_exists( $row, $name ) ) {
                return false;
            }
        }
        return true;
    }
 
    public function getArchiveQueryInfo() {
        $commentQuery = $this->commentStore->getJoin( 'ar_comment' );
        $ret = [
            'tables' => [
                'archive',
                'archive_actor' => 'actor'
            ] + $commentQuery['tables'],
            'fields' => [
                'ar_id',
                'ar_page_id',
                'ar_namespace',
                'ar_title',
                'ar_rev_id',
                'ar_timestamp',
                'ar_minor_edit',
                'ar_deleted',
                'ar_len',
                'ar_parent_id',
                'ar_actor',
                'ar_user' => 'archive_actor.actor_user',
                'ar_user_text' => 'archive_actor.actor_name',
            ] + $commentQuery['fields'],
            'joins' => [
                'archive_actor' => [ 'JOIN', 'actor_id=ar_actor' ]
            ] + $commentQuery['joins'],
        ];
 
        return $ret;
    }
 
    public function getRevisionSizes( array $revIds ) {
        $dbr = $this->getReplicaConnection();
        $revLens = [];
        if ( !$revIds ) {
            return $revLens; // empty
        }
 
        $res = $dbr->newSelectQueryBuilder()
            ->select( [ 'rev_id', 'rev_len' ] )
            ->from( 'revision' )
            ->where( [ 'rev_id' => $revIds ] )
            ->caller( __METHOD__ )->fetchResultSet();
 
        foreach ( $res as $row ) {
            $revLens[$row->rev_id] = intval( $row->rev_len );
        }
 
        return $revLens;
    }
 
    private function getRelativeRevision( RevisionRecord $rev, $flags, $dir ) {
        $op = $dir === 'next' ? '>' : '<';
        $sort = $dir === 'next' ? 'ASC' : 'DESC';
 
        $revisionIdValue = $rev->getId( $this->wikiId );
 
        if ( !$revisionIdValue || !$rev->getPageId( $this->wikiId ) ) {
            // revision is unsaved or otherwise incomplete
            return null;
        }
 
        if ( $rev instanceof RevisionArchiveRecord ) {
            // revision is deleted, so it's not part of the page history
            return null;
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $flags );
 
        $ts = $rev->getTimestamp() ?? $this->getTimestampFromId( $revisionIdValue, $flags );
        if ( $ts === false ) {
            // XXX Should this be moved into getTimestampFromId?
            $ts = $db->newSelectQueryBuilder()
                ->select( 'ar_timestamp' )
                ->from( 'archive' )
                ->where( [ 'ar_rev_id' => $revisionIdValue ] )
                ->caller( __METHOD__ )->fetchField();
            if ( $ts === false ) {
                // XXX Is this reachable? How can we have a page id but no timestamp?
                return null;
            }
        }
 
        $revId = $db->newSelectQueryBuilder()
            ->select( 'rev_id' )
            ->from( 'revision' )
            ->where( [
                'rev_page' => $rev->getPageId( $this->wikiId ),
                $db->buildComparison( $op, [
                    'rev_timestamp' => $db->timestamp( $ts ),
                    'rev_id' => $revisionIdValue,
                ] ),
            ] )
            ->orderBy( [ 'rev_timestamp', 'rev_id' ], $sort )
            ->ignoreIndex( 'rev_timestamp' ) // Probably needed for T159319
            ->caller( __METHOD__ )
            ->fetchField();
 
        if ( $revId === false ) {
            return null;
        }
 
        return $this->getRevisionById( intval( $revId ), $flags );
    }
 
    public function getPreviousRevision( RevisionRecord $rev, $flags = IDBAccessObject::READ_NORMAL ) {
        return $this->getRelativeRevision( $rev, $flags, 'prev' );
    }
 
    public function getNextRevision( RevisionRecord $rev, $flags = IDBAccessObject::READ_NORMAL ) {
        return $this->getRelativeRevision( $rev, $flags, 'next' );
    }
 
    private function getPreviousRevisionId( IReadableDatabase $db, RevisionRecord $rev ) {
        $this->checkDatabaseDomain( $db );
 
        if ( $rev->getPageId( $this->wikiId ) === null ) {
            return 0;
        }
        # Use page_latest if ID is not given
        if ( !$rev->getId( $this->wikiId ) ) {
            $prevId = $db->newSelectQueryBuilder()
                ->select( 'page_latest' )
                ->from( 'page' )
                ->where( [ 'page_id' => $rev->getPageId( $this->wikiId ) ] )
                ->caller( __METHOD__ )->fetchField();
        } else {
            $prevId = $db->newSelectQueryBuilder()
                ->select( 'rev_id' )
                ->from( 'revision' )
                ->where( [ 'rev_page' => $rev->getPageId( $this->wikiId ) ] )
                ->andWhere( $db->expr( 'rev_id', '<', $rev->getId( $this->wikiId ) ) )
                ->orderBy( 'rev_id DESC' )
                ->caller( __METHOD__ )->fetchField();
        }
        return intval( $prevId );
    }
 
    public function getTimestampFromId( $id, $flags = 0 ) {
        if ( $id instanceof Title ) {
            // Old deprecated calling convention supported for backwards compatibility
            $id = $flags;
            $flags = func_num_args() > 2 ? func_get_arg( 2 ) : 0;
        }
 
        // T270149: Bail out if we know the query will definitely return false. Some callers are
        // passing RevisionRecord::getId() call directly as $id which can possibly return null.
        // Null $id or $id <= 0 will lead to useless query with WHERE clause of 'rev_id IS NULL'
        // or 'rev_id = 0', but 'rev_id' is always greater than zero and cannot be null.
        // @todo typehint $id and remove the null check
        if ( $id === null || $id <= 0 ) {
            return false;
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $flags );
 
        $timestamp =
            $db->newSelectQueryBuilder()
                ->select( 'rev_timestamp' )
                ->from( 'revision' )
                ->where( [ 'rev_id' => $id ] )
                ->caller( __METHOD__ )->fetchField();
 
        return ( $timestamp !== false ) ? MWTimestamp::convert( TS::MW, $timestamp ) : false;
    }
 
    public function countRevisionsByPageId( IReadableDatabase $db, $id ) {
        $this->checkDatabaseDomain( $db );
 
        $row = $db->newSelectQueryBuilder()
            ->select( [ 'revCount' => 'COUNT(*)' ] )
            ->from( 'revision' )
            ->where( [ 'rev_page' => $id ] )
            ->caller( __METHOD__ )->fetchRow();
        if ( $row ) {
            return intval( $row->revCount );
        }
        return 0;
    }
 
    public function countRevisionsByTitle( IReadableDatabase $db, PageIdentity $page ) {
        $id = $this->getArticleId( $page );
        if ( $id ) {
            return $this->countRevisionsByPageId( $db, $id );
        }
        return 0;
    }
 
    public function userWasLastToEdit( IReadableDatabase $db, $pageId, $userId, $since ) {
        $this->checkDatabaseDomain( $db );
 
        if ( !$userId ) {
            return false;
        }
 
        $queryBuilder = $this->newSelectQueryBuilder( $db )
            ->where( [
                'rev_page' => $pageId,
                $db->expr( 'rev_timestamp', '>', $db->timestamp( $since ) )
            ] )
            ->orderBy( 'rev_timestamp', SelectQueryBuilder::SORT_ASC )
            ->limit( 50 );
        $res = $queryBuilder->caller( __METHOD__ )->fetchResultSet();
        foreach ( $res as $row ) {
            if ( $row->rev_user != $userId ) {
                return false;
            }
        }
        return true;
    }
 
    public function getKnownLatestRevision( PageIdentity $page, $revId = 0 ) {
        $db = $this->getReplicaConnection();
        $revIdPassed = $revId;
        $pageId = $this->getArticleId( $page );
        if ( !$pageId ) {
            return false;
        }
 
        if ( !$revId ) {
            if ( $page instanceof Title ) {
                $revId = $page->getLatestRevID();
            } else {
                $pageRecord = $this->pageStore->getPageByReference( $page );
                if ( $pageRecord ) {
                    $revId = $pageRecord->getLatest( $this->getWikiId() );
                }
            }
        }
 
        if ( !$revId ) {
            $this->logger->warning(
                'No latest revision known for page {page} even though it exists with page ID {page_id}', [
                    'page' => $page->__toString(),
                    'page_id' => $pageId,
                    'wiki_id' => $this->getWikiId() ?: 'local',
                ] );
            return false;
        }
 
        // Load the row from cache if possible.  If not possible, populate the cache.
        // As a minor optimization, remember if this was a cache hit or miss.
        // We can sometimes avoid a database query later if this is a cache miss.
        $fromCache = true;
        $row = $this->cache->getWithSetCallback(
            // Page/rev IDs passed in from DB to reflect history merges
            $this->getRevisionRowCacheKey( $db, $pageId, $revId ),
            WANObjectCache::TTL_WEEK,
            function () use ( $db, $revId, &$fromCache ) {
                $row = $this->fetchRevisionRowFromConds( $db, [ 'rev_id' => intval( $revId ) ] );
                if ( $row ) {
                    $fromCache = false;
                }
                return $row; // don't cache negatives
            }
        );
 
        // Reflect revision deletion and user renames.
        if ( $row ) {
            $title = $this->ensureRevisionRowMatchesPage( $row, $page, [
                'from_cache_flag' => $fromCache,
                'page_id_initial' => $pageId,
                'rev_id_used' => $revId,
                'rev_id_requested' => $revIdPassed,
            ] );
 
            return $this->newRevisionFromRow( $row, 0, $title, $fromCache );
        } else {
            return false;
        }
    }
 
    public function getKnownCurrentRevision( PageIdentity $page, $revId = 0 ) {
        return $this->getKnownLatestRevision( $page, $revId );
    }
 
    public function getFirstRevision(
        $page,
        int $flags = IDBAccessObject::READ_NORMAL
    ): ?RevisionRecord {
        $conds = $this->getPageConditions( $page );
        if ( !$conds ) {
            return null;
        }
        if ( !( $page instanceof PageIdentity ) ) {
            if ( !( $page instanceof PageReference ) ) {
                wfDeprecated( __METHOD__ . ' with a LinkTarget', '1.45' );
            }
            $page = null;
        }
 
        return $this->newRevisionFromConds( $conds, $flags, $page,
            [
                'ORDER BY' => [ 'rev_timestamp ASC', 'rev_id ASC' ],
                'IGNORE INDEX' => [ 'revision' => 'rev_timestamp' ], // See T159319
            ]
        );
    }
 
    private function getRevisionRowCacheKey( IReadableDatabase $db, $pageId, $revId ) {
        return $this->cache->makeGlobalKey(
            self::ROW_CACHE_KEY,
            $db->getDomainID(),
            $pageId,
            $revId
        );
    }
 
    private function assertRevisionParameter( $paramName, $pageId, ?RevisionRecord $rev = null ) {
        if ( $rev ) {
            if ( $rev->getId( $this->wikiId ) === null ) {
                throw new InvalidArgumentException( "Unsaved {$paramName} revision passed" );
            }
            if ( $rev->getPageId( $this->wikiId ) !== $pageId ) {
                throw new InvalidArgumentException(
                    "Revision {$rev->getId( $this->wikiId )} doesn't belong to page {$pageId}"
                );
            }
        }
    }
 
    private function getPageConditions( LinkTarget|PageReference $page ): ?array {
        if ( $page instanceof PageIdentity ) {
            return $page->exists() ? [ 'page_id' => $page->getId( $this->wikiId ) ] : null;
        } elseif ( $page instanceof PageReference ) {
            if ( $page->getWikiId() !== $this->wikiId ) {
                throw new InvalidArgumentException( 'Non-matching wiki ID for PageReference' );
            }
            return [
                'page_namespace' => $page->getNamespace(),
                'page_title' => $page->getDBkey(),
            ];
        } else {
            // Only resolve LinkTarget when operating in the context of the local wiki (T248756)
            if ( $this->wikiId !== WikiAwareEntity::LOCAL ) {
                throw new InvalidArgumentException( 'Cannot use non-local LinkTarget' );
            }
            return [
                'page_namespace' => $page->getNamespace(),
                'page_title' => $page->getDBkey(),
            ];
        }
    }
 
    private function getRevisionLimitConditions(
        ISQLPlatform $dbr,
        ?RevisionRecord $old = null,
        ?RevisionRecord $new = null,
        $options = []
    ) {
        $options = (array)$options;
        if ( in_array( self::INCLUDE_OLD, $options ) || in_array( self::INCLUDE_BOTH, $options ) ) {
            $oldCmp = '>=';
        } else {
            $oldCmp = '>';
        }
        if ( in_array( self::INCLUDE_NEW, $options ) || in_array( self::INCLUDE_BOTH, $options ) ) {
            $newCmp = '<=';
        } else {
            $newCmp = '<';
        }
 
        $conds = [];
        if ( $old ) {
            $conds[] = $dbr->buildComparison( $oldCmp, [
                'rev_timestamp' => $dbr->timestamp( $old->getTimestamp() ),
                'rev_id' => $old->getId( $this->wikiId ),
            ] );
        }
        if ( $new ) {
            $conds[] = $dbr->buildComparison( $newCmp, [
                'rev_timestamp' => $dbr->timestamp( $new->getTimestamp() ),
                'rev_id' => $new->getId( $this->wikiId ),
            ] );
        }
        return $conds;
    }
 
    public function getRevisionIdsBetween(
        int $pageId,
        ?RevisionRecord $old = null,
        ?RevisionRecord $new = null,
        ?int $max = null,
        $options = [],
        ?string $order = null,
        int $flags = IDBAccessObject::READ_NORMAL
    ): array {
        $this->assertRevisionParameter( 'old', $pageId, $old );
        $this->assertRevisionParameter( 'new', $pageId, $new );
 
        $options = (array)$options;
        $includeOld = in_array( self::INCLUDE_OLD, $options ) ||
            in_array( self::INCLUDE_BOTH, $options );
        $includeNew = in_array( self::INCLUDE_NEW, $options ) ||
            in_array( self::INCLUDE_BOTH, $options );
 
        // No DB query needed if old and new are the same revision.
        // Can't check for consecutive revisions with 'getParentId' for a similar
        // optimization as edge cases exist when there are revisions between
        // a revision and it's parent. See T185167 for more details.
        if ( $old && $new && $new->getId( $this->wikiId ) === $old->getId( $this->wikiId ) ) {
            return $includeOld || $includeNew ? [ $new->getId( $this->wikiId ) ] : [];
        }
 
        $db = $this->getDBConnectionRefForQueryFlags( $flags );
        $queryBuilder = $db->newSelectQueryBuilder()
            ->select( 'rev_id' )
            ->from( 'revision' )
            ->where( [
                'rev_page' => $pageId,
                $db->bitAnd( 'rev_deleted', RevisionRecord::DELETED_TEXT ) . ' = 0'
            ] )
            ->andWhere( $this->getRevisionLimitConditions( $db, $old, $new, $options ) );
 
        if ( $order !== null ) {
            $queryBuilder->orderBy( [ 'rev_timestamp', 'rev_id' ], $order );
        }
        if ( $max !== null ) {
            // extra to detect truncation
            $queryBuilder->limit( $max + 1 );
        }
 
        $values = $queryBuilder->caller( __METHOD__ )->fetchFieldValues();
        return array_map( 'intval', $values );
    }
 
    public function getAuthorsBetween(
        $pageId,
        ?RevisionRecord $old = null,
        ?RevisionRecord $new = null,
        ?Authority $performer = null,
        $max = null,
        $options = []
    ) {
        $this->assertRevisionParameter( 'old', $pageId, $old );
        $this->assertRevisionParameter( 'new', $pageId, $new );
        $options = (array)$options;
 
        // No DB query needed if old and new are the same revision.
        // Can't check for consecutive revisions with 'getParentId' for a similar
        // optimization as edge cases exist when there are revisions between
        //a revision and it's parent. See T185167 for more details.
        if ( $old && $new && $new->getId( $this->wikiId ) === $old->getId( $this->wikiId ) ) {
            if ( !$options ) {
                return [];
            } elseif ( $performer ) {
                return [ $new->getUser( RevisionRecord::FOR_THIS_USER, $performer ) ];
            } else {
                return [ $new->getUser() ];
            }
        }
 
        $dbr = $this->getReplicaConnection();
        $queryBuilder = $dbr->newSelectQueryBuilder()
            ->select( [
                'rev_actor',
                'rev_user' => 'revision_actor.actor_user',
                'rev_user_text' => 'revision_actor.actor_name',
            ] )
            ->distinct()
            ->from( 'revision' )
            ->join( 'actor', 'revision_actor', 'revision_actor.actor_id = rev_actor' )
            ->where( [
                'rev_page' => $pageId,
                $dbr->bitAnd( 'rev_deleted', RevisionRecord::DELETED_USER ) . " = 0"
            ] )
            ->andWhere( $this->getRevisionLimitConditions( $dbr, $old, $new, $options ) )
            ->caller( __METHOD__ );
        if ( $max !== null ) {
            $queryBuilder->limit( $max + 1 );
        }
 
        return array_map(
            function ( $row ) {
                return $this->actorStore->newActorFromRowFields(
                    $row->rev_user,
                    $row->rev_user_text,
                    $row->rev_actor
                );
            },
            iterator_to_array( $queryBuilder->fetchResultSet() )
        );
    }
 
    public function countAuthorsBetween(
        $pageId,
        ?RevisionRecord $old = null,
        ?RevisionRecord $new = null,
        ?Authority $performer = null,
        $max = null,
        $options = []
    ) {
        // TODO: Implement with a separate query to avoid cost of selecting unneeded fields
        // and creation of UserIdentity stuff.
        return count( $this->getAuthorsBetween( $pageId, $old, $new, $performer, $max, $options ) );
    }
 
    public function countRevisionsBetween(
        $pageId,
        ?RevisionRecord $old = null,
        ?RevisionRecord $new = null,
        $max = null,
        $options = []
    ) {
        $this->assertRevisionParameter( 'old', $pageId, $old );
        $this->assertRevisionParameter( 'new', $pageId, $new );
 
        // No DB query needed if old and new are the same revision.
        // Can't check for consecutive revisions with 'getParentId' for a similar
        // optimization as edge cases exist when there are revisions between
        //a revision and it's parent. See T185167 for more details.
        if ( $old && $new && $new->getId( $this->wikiId ) === $old->getId( $this->wikiId ) ) {
            return 0;
        }
 
        $dbr = $this->getReplicaConnection();
        $where = [ 'rev_page' => $pageId ];
        // If $options is a string, convert it to an array
        $options = (array)$options;
        if ( !in_array( self::INCLUDE_DELETED_REVISIONS, $options ) ) {
            $where[] = $dbr->bitAnd( 'rev_deleted', RevisionRecord::DELETED_TEXT ) . " = 0";
        }
        $conds = array_merge(
            $where,
            $this->getRevisionLimitConditions( $dbr, $old, $new, $options )
        );
        if ( $max !== null ) {
            return $dbr->newSelectQueryBuilder()
                ->select( '1' )
                ->from( 'revision' )
                ->where( $conds )
                ->caller( __METHOD__ )
                ->limit( $max + 1 ) // extra to detect truncation
                ->fetchRowCount();
        } else {
            return (int)$dbr->newSelectQueryBuilder()
                ->select( 'count(*)' )
                ->from( 'revision' )
                ->where( $conds )
                ->caller( __METHOD__ )->fetchField();
        }
    }
 
    public function findIdenticalRevision(
        RevisionRecord $revision,
        int $searchLimit
    ): ?RevisionRecord {
        $revision->assertWiki( $this->wikiId );
        $db = $this->getReplicaConnection();
 
        // Build the target slot role ID => sha1 array from the provided revision
        // (this is seemingly necessary *before* fetching the candidate revisions: T406027)
        $searchedSlotHashes = [];
        $slots = $revision->getSlots()->getPrimarySlots();
        foreach ( $slots as $slot ) {
            $roleId = $this->slotRoleStore->acquireId( $slot->getRole() );
            $searchedSlotHashes[$roleId] = $slot->getSha1();
        }
        ksort( $searchedSlotHashes );
 
        // First fetch the IDs of the most recent revisions for this page, limited by the search limit.
        $candidateRevIds = $db->newSelectQueryBuilder()
            ->select( 'rev_id' )
            ->from( 'revision' )
            ->where( [ 'rev_page' => $revision->getPageId( $this->wikiId ) ] )
            // Include 'rev_id' in the ordering in case there are multiple revs with same timestamp
            ->orderBy( [ 'rev_timestamp', 'rev_id' ], SelectQueryBuilder::SORT_DESC )
            // T354015
            ->useIndex( [ 'revision' => 'rev_page_timestamp' ] )
            ->limit( $searchLimit )
            // skip the most recent edit, we can't revert to it anyway
            ->offset( 1 )
            ->caller( __METHOD__ )
            ->fetchFieldValues();
 
        if ( $candidateRevIds === [] ) {
            return null;
        }
 
        // Then, for only those revisions, fetch their slot role ID => sha1 data.
        $candidateRevisions = $db->newSelectQueryBuilder()
            ->select( [ 'slot_revision_id', 'slot_role_id', 'content_sha1' ] )
            ->from( 'slots' )
            ->join( 'content', null, 'content_id = slot_content_id' )
            ->where( [ 'slot_revision_id' => $candidateRevIds ] )
            ->caller( __METHOD__ )
            ->fetchResultSet();
 
        // Build a map of candidate revisions to their slot role ID => sha1 arrays
        $candidateSlotHashes = [];
        foreach ( $candidateRevisions as $candidate ) {
            $candidateSlotHashes[$candidate->slot_revision_id][$candidate->slot_role_id] = $candidate->content_sha1;
        }
 
        // Find the first revision that has the same slot role ID => sha1 array as the provided revision.
        // We use $candidateRevIds, which are ordered by the revision timestamps, to ensure we return
        // the most recent revision that matches.
        $matchRevId = null;
        foreach ( $candidateRevIds as $revId ) {
            ksort( $candidateSlotHashes[$revId] );
            if ( $candidateSlotHashes[$revId] === $searchedSlotHashes ) {
                $matchRevId = $revId;
                break;
            }
        }
 
        $revisionRow = null;
        if ( $matchRevId !== null ) {
            $revisionRow = $this->newSelectQueryBuilder( $db )
                ->joinComment()
                ->where( [ 'rev_id' => $matchRevId ] )
                ->caller( __METHOD__ )
                ->fetchRow();
        }
 
        return $revisionRow ? $this->newRevisionFromRow( $revisionRow ) : null;
    }
 
    // TODO: move relevant methods from Title here, e.g. isBigDeletion, etc.
}