UserGroupManager.php

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<?php
namespace MediaWiki\User;
 
use InvalidArgumentException;
use MediaWiki\Config\ServiceOptions;
use MediaWiki\Deferred\DeferredUpdates;
use MediaWiki\HookContainer\HookContainer;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\JobQueue\JobQueueGroup;
use MediaWiki\Logging\ManualLogEntry;
use MediaWiki\MainConfigNames;
use MediaWiki\Permissions\Authority;
use MediaWiki\User\TempUser\TempUserConfig;
use MediaWiki\WikiMap\WikiMap;
use Wikimedia\Assert\Assert;
use Wikimedia\Rdbms\IConnectionProvider;
use Wikimedia\Rdbms\IDBAccessObject;
use Wikimedia\Rdbms\IReadableDatabase;
use Wikimedia\Rdbms\ReadOnlyMode;
use Wikimedia\Rdbms\SelectQueryBuilder;
use Wikimedia\Timestamp\TimestampFormat as TS;
 
class UserGroupManager {
 
    public const CONSTRUCTOR_OPTIONS = [
        MainConfigNames::AddGroups,
        MainConfigNames::Autopromote,
        MainConfigNames::AutopromoteOnce,
        MainConfigNames::AutopromoteOnceLogInRC,
        MainConfigNames::AutopromoteOnceRCExcludedGroups,
        MainConfigNames::ImplicitGroups,
        MainConfigNames::GroupInheritsPermissions,
        MainConfigNames::GroupPermissions,
        MainConfigNames::GroupsAddToSelf,
        MainConfigNames::GroupsRemoveFromSelf,
        MainConfigNames::RevokePermissions,
        MainConfigNames::RemoveGroups,
        MainConfigNames::PrivilegedGroups,
    ];
 
    public const VALID_OPS = UserRequirementsConditionChecker::VALID_OPS;
 
    private HookRunner $hookRunner;
 
    private const CACHE_IMPLICIT = 'implicit';
 
    private const CACHE_EFFECTIVE = 'effective';
 
    private const CACHE_MEMBERSHIP = 'membership';
 
    private const CACHE_FORMER = 'former';
 
    private const CACHE_PRIVILEGED = 'privileged';
 
    private $userGroupCache = [];
 
    private array $queryFlagsUsedForCaching = [];
 
    public function __construct(
        private readonly ServiceOptions $options,
        private readonly ReadOnlyMode $readOnlyMode,
        private readonly IConnectionProvider $connectionProvider,
        private readonly HookContainer $hookContainer,
        private readonly JobQueueGroup $jobQueueGroup,
        private readonly TempUserConfig $tempUserConfig,
        private readonly UserRequirementsConditionCheckerFactory $userRequirementsConditionCheckerFactory,
        private readonly array $clearCacheCallbacks = [],
        private readonly string|false $wikiId = UserIdentity::LOCAL
    ) {
        $options->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS );
        $this->hookRunner = new HookRunner( $hookContainer );
    }
 
    public function listAllGroups(): array {
        return array_values(
            array_diff(
                array_keys( array_merge(
                    $this->options->get( MainConfigNames::GroupPermissions ),
                    $this->options->get( MainConfigNames::RevokePermissions ),
                    $this->options->get( MainConfigNames::GroupInheritsPermissions ),
                ) ),
                $this->listAllImplicitGroups()
            )
        );
    }
 
    public function listAllImplicitGroups(): array {
        return $this->options->get( MainConfigNames::ImplicitGroups );
    }
 
    public function newGroupMembershipFromRow( \stdClass $row ): UserGroupMembership {
        return new UserGroupMembership(
            (int)$row->ug_user,
            $row->ug_group,
            $row->ug_expiry === null ? null : wfTimestamp(
                TS::MW,
                $row->ug_expiry
            )
        );
    }
 
    public function loadGroupMembershipsFromArray(
        UserIdentity $user,
        array $userGroups,
        int $queryFlags = IDBAccessObject::READ_NORMAL
    ) {
        $user->assertWiki( $this->wikiId );
        $membershipGroups = [];
        reset( $userGroups );
        foreach ( $userGroups as $row ) {
            $ugm = $this->newGroupMembershipFromRow( $row );
            $membershipGroups[ $ugm->getGroup() ] = $ugm;
        }
        $this->setCache(
            $this->getCacheKey( $user ),
            self::CACHE_MEMBERSHIP,
            $membershipGroups,
            $queryFlags
        );
    }
 
    public function getUserImplicitGroups(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL,
        bool $recache = false
    ): array {
        $user->assertWiki( $this->wikiId );
        $userKey = $this->getCacheKey( $user );
        if ( $recache ||
            !isset( $this->userGroupCache[$userKey][self::CACHE_IMPLICIT] ) ||
            !$this->canUseCachedValues( $user, self::CACHE_IMPLICIT, $queryFlags )
        ) {
            $groups = [ '*' ];
            if ( $this->tempUserConfig->isTempName( $user->getName() ) ) {
                $groups[] = 'temp';
            } elseif ( $user->isRegistered() ) {
                $groups[] = 'user';
                $groups = array_unique( array_merge(
                    $groups,
                    $this->getUserAutopromoteGroups( $user )
                ) );
            }
            $this->setCache( $userKey, self::CACHE_IMPLICIT, $groups, $queryFlags );
            if ( $recache ) {
                // Assure data consistency with rights/groups,
                // as getUserEffectiveGroups() depends on this function
                $this->clearUserCacheForKind( $user, self::CACHE_EFFECTIVE );
            }
        }
        return $this->userGroupCache[$userKey][self::CACHE_IMPLICIT];
    }
 
    public function getUserEffectiveGroups(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL,
        bool $recache = false
    ): array {
        $user->assertWiki( $this->wikiId );
        $userKey = $this->getCacheKey( $user );
        // Ignore cache if the $recache flag is set, cached values can not be used
        // or the cache value is missing
        if (
            $recache ||
            !isset( $this->userGroupCache[$userKey][self::CACHE_EFFECTIVE] ) ||
            !$this->canUseCachedValues( $user, self::CACHE_EFFECTIVE, $queryFlags )
        ) {
            $groups = array_unique( array_merge(
                // explicit groups
                $this->getUserGroups( $user, $queryFlags ),
                // implicit groups
                $this->getUserImplicitGroups( $user, $queryFlags, $recache )
            ) );
            // TODO: Deprecate passing out user object in the hook by introducing
            // an alternative hook
            if ( $this->hookContainer->isRegistered( 'UserEffectiveGroups' ) ) {
                $userObj = User::newFromIdentity( $user );
                $userObj->load();
                // Hook for additional groups
                $this->hookRunner->onUserEffectiveGroups( $userObj, $groups );
            }
            // Force re-indexing of groups when a hook has unset one of them
            $effectiveGroups = array_values( array_unique( $groups ) );
            $this->setCache( $userKey, self::CACHE_EFFECTIVE, $effectiveGroups, $queryFlags );
        }
        return $this->userGroupCache[$userKey][self::CACHE_EFFECTIVE];
    }
 
    public function getUserFormerGroups(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL
    ): array {
        $user->assertWiki( $this->wikiId );
        $userKey = $this->getCacheKey( $user );
 
        if (
            isset( $this->userGroupCache[$userKey][self::CACHE_FORMER] ) &&
            $this->canUseCachedValues( $user, self::CACHE_FORMER, $queryFlags )
        ) {
            return $this->userGroupCache[$userKey][self::CACHE_FORMER];
        }
 
        if ( !$user->isRegistered() ) {
            // Anon users don't have groups stored in the database
            return [];
        }
 
        $formerGroups = $this->getDBConnectionRefForQueryFlags( $queryFlags )->newSelectQueryBuilder()
            ->select( 'ufg_group' )
            ->from( 'user_former_groups' )
            ->where( [ 'ufg_user' => $user->getId( $this->wikiId ) ] )
            ->caller( __METHOD__ )
            ->fetchFieldValues();
        $this->setCache( $userKey, self::CACHE_FORMER, $formerGroups, $queryFlags );
 
        return $this->userGroupCache[$userKey][self::CACHE_FORMER];
    }
 
    public function getUserAutopromoteGroups( UserIdentity $user ): array {
        $user->assertWiki( $this->wikiId );
        $promote = [];
        // TODO: remove the need for the full user object
        $userObj = User::newFromIdentity( $user );
        if ( $userObj->isTemp() ) {
            return [];
        }
 
        $checker = $this->userRequirementsConditionCheckerFactory->getUserRequirementsConditionChecker(
            $this, $this->wikiId
        );
        foreach ( $this->options->get( MainConfigNames::Autopromote ) as $group => $cond ) {
            if ( $checker->recursivelyCheckCondition( $cond, $userObj ) ) {
                $promote[] = $group;
            }
        }
 
        $this->hookRunner->onGetAutoPromoteGroups( $userObj, $promote );
        return $promote;
    }
 
    public function getUserAutopromoteOnceGroups(
        UserIdentity $user,
        string $event
    ): array {
        $user->assertWiki( $this->wikiId );
        $autopromoteOnce = $this->options->get( MainConfigNames::AutopromoteOnce );
        $promote = [];
 
        if ( isset( $autopromoteOnce[$event] ) && count( $autopromoteOnce[$event] ) ) {
            // TODO: remove the need for the full user object
            $userObj = User::newFromIdentity( $user );
            if ( $userObj->isTemp() ) {
                return [];
            }
            $currentGroups = $this->getUserGroups( $user );
            $formerGroups = $this->getUserFormerGroups( $user );
            $checker = $this->userRequirementsConditionCheckerFactory->getUserRequirementsConditionChecker(
                $this, $this->wikiId
            );
            foreach ( $autopromoteOnce[$event] as $group => $cond ) {
                // Do not check if the user's already a member
                if ( in_array( $group, $currentGroups ) ) {
                    continue;
                }
                // Do not autopromote if the user has belonged to the group
                if ( in_array( $group, $formerGroups ) ) {
                    continue;
                }
                // Finally - check the conditions
                if ( $checker->recursivelyCheckCondition( $cond, $userObj ) ) {
                    $promote[] = $group;
                }
            }
        }
 
        return $promote;
    }
 
    public function getUserPrivilegedGroups(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL,
        bool $recache = false
    ): array {
        $userKey = $this->getCacheKey( $user );
 
        if (
            !$recache &&
            isset( $this->userGroupCache[$userKey][self::CACHE_PRIVILEGED] ) &&
            $this->canUseCachedValues( $user, self::CACHE_PRIVILEGED, $queryFlags )
        ) {
            return $this->userGroupCache[$userKey][self::CACHE_PRIVILEGED];
        }
 
        if ( !$user->isRegistered() ) {
            return [];
        }
 
        $groups = array_intersect(
            $this->getUserEffectiveGroups( $user, $queryFlags, $recache ),
            $this->options->get( MainConfigNames::PrivilegedGroups )
        );
 
        $this->hookRunner->onUserPrivilegedGroups( $user, $groups );
 
        $this->setCache(
            $this->getCacheKey( $user ),
            self::CACHE_PRIVILEGED,
            array_values( array_unique( $groups ) ),
            $queryFlags
        );
 
        return $this->userGroupCache[$userKey][self::CACHE_PRIVILEGED];
    }
 
    public function addUserToAutopromoteOnceGroups(
        UserIdentity $user,
        string $event
    ): array {
        $user->assertWiki( $this->wikiId );
        Assert::precondition(
            !$this->wikiId || WikiMap::isCurrentWikiDbDomain( $this->wikiId ),
            __METHOD__ . " is not supported for foreign wikis: {$this->wikiId} used"
        );
 
        if (
            $this->readOnlyMode->isReadOnly( $this->wikiId ) ||
            !$user->isRegistered() ||
            $this->tempUserConfig->isTempName( $user->getName() )
        ) {
            return [];
        }
 
        $toPromote = $this->getUserAutopromoteOnceGroups( $user, $event );
        if ( $toPromote === [] ) {
            return [];
        }
 
        $userObj = User::newFromIdentity( $user );
        if ( !$userObj->checkAndSetTouched() ) {
            // @codeCoverageIgnoreStart
            // raced out (bug T48834)
            return [];
            // @codeCoverageIgnoreEnd
        }
 
        // previous groups
        $oldGroups = $this->getUserGroups( $user );
        $oldUGMs = $this->getUserGroupMemberships( $user );
        $this->addUserToMultipleGroups( $user, $toPromote );
        // all groups
        $newGroups = array_merge( $oldGroups, $toPromote );
        $newUGMs = $this->getUserGroupMemberships( $user );
 
        // update groups in external authentication database
        // TODO: deprecate passing full User object to hook
        $this->hookRunner->onUserGroupsChanged(
            $userObj,
            $toPromote,
            [],
            false,
            false,
            $oldUGMs,
            $newUGMs
        );
 
        $logEntry = new ManualLogEntry( 'rights', 'autopromote' );
        $logEntry->setPerformer( $user );
        $logEntry->setTarget( $userObj->getUserPage() );
        $logEntry->setParameters( [
            '4::oldgroups' => $oldGroups,
            '5::newgroups' => $newGroups,
        ] );
        $logid = $logEntry->insert();
 
        // Allow excluding autopromotions into select groups from RecentChanges (T377829).
        $groupsToShowInRC = array_diff(
            $toPromote,
            $this->options->get( MainConfigNames::AutopromoteOnceRCExcludedGroups )
        );
 
        if ( $this->options->get( MainConfigNames::AutopromoteOnceLogInRC ) && count( $groupsToShowInRC ) ) {
            $logEntry->publish( $logid );
        }
 
        return $toPromote;
    }
 
    public function getUserGroups(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL
    ): array {
        return array_keys( $this->getUserGroupMemberships( $user, $queryFlags ) );
    }
 
    public function getUserGroupMemberships(
        UserIdentity $user,
        int $queryFlags = IDBAccessObject::READ_NORMAL
    ): array {
        $user->assertWiki( $this->wikiId );
        $userKey = $this->getCacheKey( $user );
 
        if (
            $this->canUseCachedValues( $user, self::CACHE_MEMBERSHIP, $queryFlags ) &&
            isset( $this->userGroupCache[$userKey][self::CACHE_MEMBERSHIP] )
        ) {
            return $this->userGroupCache[$userKey][self::CACHE_MEMBERSHIP];
        }
 
        if ( !$user->isRegistered() ) {
            // Anon users don't have groups stored in the database
            return [];
        }
 
        $queryBuilder = $this->newQueryBuilder( $this->getDBConnectionRefForQueryFlags( $queryFlags ) );
        $res = $queryBuilder
            ->where( [ 'ug_user' => $user->getId( $this->wikiId ) ] )
            ->caller( __METHOD__ )
            ->fetchResultSet();
 
        $ugms = [];
        foreach ( $res as $row ) {
            $ugm = $this->newGroupMembershipFromRow( $row );
            if ( !$ugm->isExpired() ) {
                $ugms[$ugm->getGroup()] = $ugm;
            }
        }
        ksort( $ugms );
 
        $this->setCache( $userKey, self::CACHE_MEMBERSHIP, $ugms, $queryFlags );
 
        return $ugms;
    }
 
    public function addUserToGroup(
        UserIdentity $user,
        string $group,
        ?string $expiry = null,
        bool $allowUpdate = false
    ): bool {
        $user->assertWiki( $this->wikiId );
        if ( $this->readOnlyMode->isReadOnly( $this->wikiId ) ) {
            return false;
        }
 
        $isTemp = $this->tempUserConfig->isTempName( $user->getName() );
        if ( !$user->isRegistered() ) {
            throw new InvalidArgumentException(
                'UserGroupManager::addUserToGroup() needs a positive user ID. ' .
                'Perhaps addUserToGroup() was called before the user was added to the database.'
            );
        }
        if ( $isTemp ) {
            throw new InvalidArgumentException(
                'UserGroupManager::addUserToGroup() cannot be called on a temporary user.'
            );
        }
 
        if ( $expiry ) {
            $expiry = wfTimestamp( TS::MW, $expiry );
        }
 
        // TODO: Deprecate passing out user object in the hook by introducing
        // an alternative hook
        if ( $this->hookContainer->isRegistered( 'UserAddGroup' ) ) {
            $userObj = User::newFromIdentity( $user );
            $userObj->load();
            if ( !$this->hookRunner->onUserAddGroup( $userObj, $group, $expiry ) ) {
                return false;
            }
        }
 
        $oldUgms = $this->getUserGroupMemberships( $user, IDBAccessObject::READ_LATEST );
        $dbw = $this->connectionProvider->getPrimaryDatabase( $this->wikiId );
 
        $dbw->startAtomic( __METHOD__ );
        $dbw->newInsertQueryBuilder()
            ->insertInto( 'user_groups' )
            ->ignore()
            ->row( [
                'ug_user' => $user->getId( $this->wikiId ),
                'ug_group' => $group,
                'ug_expiry' => $expiry ? $dbw->timestamp( $expiry ) : null,
            ] )
            ->caller( __METHOD__ )->execute();
 
        $affected = $dbw->affectedRows();
        if ( !$affected ) {
            // A conflicting row already exists; it should be overridden if it is either expired
            // or if $allowUpdate is true and the current row is different than the loaded row.
            $conds = [
                'ug_user' => $user->getId( $this->wikiId ),
                'ug_group' => $group
            ];
            if ( $allowUpdate ) {
                // Update the current row if its expiry does not match that of the loaded row
                $conds[] = $expiry
                    ? $dbw->expr( 'ug_expiry', '=', null )
                        ->or( 'ug_expiry', '!=', $dbw->timestamp( $expiry ) )
                    : $dbw->expr( 'ug_expiry', '!=', null );
            } else {
                // Update the current row if it is expired
                $conds[] = $dbw->expr( 'ug_expiry', '<', $dbw->timestamp() );
            }
            $dbw->newUpdateQueryBuilder()
                ->update( 'user_groups' )
                ->set( [ 'ug_expiry' => $expiry ? $dbw->timestamp( $expiry ) : null ] )
                ->where( $conds )
                ->caller( __METHOD__ )->execute();
            $affected = $dbw->affectedRows();
        }
        $dbw->endAtomic( __METHOD__ );
 
        // Purge old, expired memberships from the DB
        DeferredUpdates::addCallableUpdate( function ( $fname ) {
            $dbr = $this->connectionProvider->getReplicaDatabase( $this->wikiId );
            $hasExpiredRow = (bool)$dbr->newSelectQueryBuilder()
                ->select( '1' )
                ->from( 'user_groups' )
                ->where( [ $dbr->expr( 'ug_expiry', '<', $dbr->timestamp() ) ] )
                ->caller( $fname )
                ->fetchField();
            if ( $hasExpiredRow ) {
                $this->jobQueueGroup->push( new UserGroupExpiryJob( [] ) );
            }
        } );
 
        if ( $affected > 0 ) {
            $oldUgms[$group] = new UserGroupMembership( $user->getId( $this->wikiId ), $group, $expiry );
            if ( !$oldUgms[$group]->isExpired() ) {
                $this->setCache(
                    $this->getCacheKey( $user ),
                    self::CACHE_MEMBERSHIP,
                    $oldUgms,
                    IDBAccessObject::READ_LATEST
                );
                $this->clearUserCacheForKind( $user, self::CACHE_EFFECTIVE );
            }
            foreach ( $this->clearCacheCallbacks as $callback ) {
                $callback( $user );
            }
            return true;
        }
        return false;
    }
 
    public function addUserToMultipleGroups(
        UserIdentity $user,
        array $groups,
        ?string $expiry = null,
        bool $allowUpdate = false
    ) {
        foreach ( $groups as $group ) {
            $this->addUserToGroup( $user, $group, $expiry, $allowUpdate );
        }
    }
 
    public function removeUserFromGroup( UserIdentity $user, string $group ): bool {
        $user->assertWiki( $this->wikiId );
        // TODO: Deprecate passing out user object in the hook by introducing
        // an alternative hook
        if ( $this->hookContainer->isRegistered( 'UserRemoveGroup' ) ) {
            $userObj = User::newFromIdentity( $user );
            $userObj->load();
            if ( !$this->hookRunner->onUserRemoveGroup( $userObj, $group ) ) {
                return false;
            }
        }
 
        if ( $this->readOnlyMode->isReadOnly( $this->wikiId ) ) {
            return false;
        }
 
        if ( !$user->isRegistered() ) {
            throw new InvalidArgumentException(
                'UserGroupManager::removeUserFromGroup() needs a positive user ID. ' .
                'Perhaps removeUserFromGroup() was called before the user was added to the database.'
            );
        }
 
        $oldUgms = $this->getUserGroupMemberships( $user, IDBAccessObject::READ_LATEST );
        $oldFormerGroups = $this->getUserFormerGroups( $user, IDBAccessObject::READ_LATEST );
        $dbw = $this->connectionProvider->getPrimaryDatabase( $this->wikiId );
        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'user_groups' )
            ->where( [ 'ug_user' => $user->getId( $this->wikiId ), 'ug_group' => $group ] )
            ->caller( __METHOD__ )->execute();
 
        if ( !$dbw->affectedRows() ) {
            return false;
        }
        // Remember that the user was in this group
        $dbw->newInsertQueryBuilder()
            ->insertInto( 'user_former_groups' )
            ->ignore()
            ->row( [ 'ufg_user' => $user->getId( $this->wikiId ), 'ufg_group' => $group ] )
            ->caller( __METHOD__ )->execute();
 
        unset( $oldUgms[$group] );
        $userKey = $this->getCacheKey( $user );
        $this->setCache( $userKey, self::CACHE_MEMBERSHIP, $oldUgms, IDBAccessObject::READ_LATEST );
        $oldFormerGroups[] = $group;
        $this->setCache( $userKey, self::CACHE_FORMER, $oldFormerGroups, IDBAccessObject::READ_LATEST );
        $this->clearUserCacheForKind( $user, self::CACHE_EFFECTIVE );
        foreach ( $this->clearCacheCallbacks as $callback ) {
            $callback( $user );
        }
        return true;
    }
 
    public function newQueryBuilder( IReadableDatabase $db ): SelectQueryBuilder {
        return $db->newSelectQueryBuilder()
            ->select( [
                'ug_user',
                'ug_group',
                'ug_expiry',
            ] )
            ->from( 'user_groups' );
    }
 
    public function purgeExpired() {
        if ( $this->readOnlyMode->isReadOnly( $this->wikiId ) ) {
            return false;
        }
 
        $ticket = $this->connectionProvider->getEmptyTransactionTicket( __METHOD__ );
        $dbw = $this->connectionProvider->getPrimaryDatabase( $this->wikiId );
 
        // per-wiki
        $lockKey = "{$dbw->getDomainID()}:UserGroupManager:purge";
        $scopedLock = $dbw->getScopedLockAndFlush( $lockKey, __METHOD__, 0 );
        if ( !$scopedLock ) {
            // @codeCoverageIgnoreStart
            // already running
            return false;
            // @codeCoverageIgnoreEnd
        }
 
        $now = time();
        $purgedRows = 0;
        do {
            $dbw->startAtomic( __METHOD__ );
            $res = $this->newQueryBuilder( $dbw )
                ->where( [ $dbw->expr( 'ug_expiry', '<', $dbw->timestamp( $now ) ) ] )
                ->forUpdate()
                ->limit( 100 )
                ->caller( __METHOD__ )
                ->fetchResultSet();
 
            if ( $res->numRows() > 0 ) {
                // array of users/groups to insert to user_former_groups
                $insertData = [];
                // array for deleting the rows that are to be moved around
                $deleteCond = [];
                foreach ( $res as $row ) {
                    $insertData[] = [ 'ufg_user' => $row->ug_user, 'ufg_group' => $row->ug_group ];
                    $deleteCond[] = $dbw
                        ->expr( 'ug_user', '=', $row->ug_user )
                        ->and( 'ug_group', '=', $row->ug_group );
                }
                // Delete the rows we're about to move
                $dbw->newDeleteQueryBuilder()
                    ->deleteFrom( 'user_groups' )
                    ->where( $dbw->orExpr( $deleteCond ) )
                    ->caller( __METHOD__ )->execute();
                // Push the groups to user_former_groups
                $dbw->newInsertQueryBuilder()
                    ->insertInto( 'user_former_groups' )
                    ->ignore()
                    ->rows( $insertData )
                    ->caller( __METHOD__ )->execute();
                // Count how many rows were purged
                $purgedRows += $res->numRows();
            }
 
            $dbw->endAtomic( __METHOD__ );
 
            $this->connectionProvider->commitAndWaitForReplication( __METHOD__, $ticket );
        } while ( $res->numRows() > 0 );
        return $purgedRows;
    }
 
    private function expandChangeableGroupConfig( array $config, string $group ): array {
        if ( empty( $config[$group] ) ) {
            return [];
        }
 
        if ( $config[$group] === true ) {
            // You get everything
            return $this->listAllGroups();
        }
 
        if ( is_array( $config[$group] ) ) {
            return $config[$group];
        }
 
        return [];
    }
 
    public function getGroupsChangeableByGroup( string $group ): array {
        return [
            'add' => $this->expandChangeableGroupConfig(
                $this->options->get( MainConfigNames::AddGroups ), $group
            ),
            'remove' => $this->expandChangeableGroupConfig(
                $this->options->get( MainConfigNames::RemoveGroups ), $group
            ),
            'add-self' => $this->expandChangeableGroupConfig(
                $this->options->get( MainConfigNames::GroupsAddToSelf ), $group
            ),
            'remove-self' => $this->expandChangeableGroupConfig(
                $this->options->get( MainConfigNames::GroupsRemoveFromSelf ), $group
            ),
        ];
    }
 
    public function getGroupsChangeableBy( Authority $authority ): array {
        if ( $authority->isAllowed( 'userrights' ) ) {
            // This group gives the right to modify everything (reverse-
            // compatibility with old "userrights lets you change
            // everything")
            $all = array_values( $this->listAllGroups() );
            return [
                'add' => $all,
                'remove' => $all,
                'add-self' => [],
                'remove-self' => []
            ];
        }
 
        // Okay, it's not so simple; we will have to go through the arrays
        $actorGroups = $this->getUserEffectiveGroups( $authority->getUser() );
        $changeableGroups = [];
        foreach ( $actorGroups as $actorGroup ) {
            $changeableGroups[] = $this->getGroupsChangeableByGroup( $actorGroup );
        }
        $groups = array_merge_recursive( [
            'add' => [],
            'remove' => [],
            'add-self' => [],
            'remove-self' => []
        ], ...$changeableGroups );
        return array_map( array_values( ... ), array_map( array_unique( ... ), $groups ) );
    }
 
    public function clearCache( UserIdentity $user ) {
        $user->assertWiki( $this->wikiId );
        $userKey = $this->getCacheKey( $user );
        unset( $this->userGroupCache[$userKey] );
        unset( $this->queryFlagsUsedForCaching[$userKey] );
    }
 
    private function setCache(
        string $userKey,
        string $cacheKind,
        array $groupValue,
        int $queryFlags
    ) {
        $this->userGroupCache[$userKey][$cacheKind] = $groupValue;
        $this->queryFlagsUsedForCaching[$userKey][$cacheKind] = $queryFlags;
    }
 
    private function clearUserCacheForKind( UserIdentity $user, string $cacheKind ) {
        $userKey = $this->getCacheKey( $user );
        unset( $this->userGroupCache[$userKey][$cacheKind] );
        unset( $this->queryFlagsUsedForCaching[$userKey][$cacheKind] );
    }
 
    private function getDBConnectionRefForQueryFlags( int $recency ): IReadableDatabase {
        if ( ( IDBAccessObject::READ_LATEST & $recency ) === IDBAccessObject::READ_LATEST ) {
            return $this->connectionProvider->getPrimaryDatabase( $this->wikiId );
        }
        return $this->connectionProvider->getReplicaDatabase( $this->wikiId );
    }
 
    private function getCacheKey( UserIdentity $user ): string {
        return $user->isRegistered() ? "u:{$user->getId( $this->wikiId )}" : "anon:{$user->getName()}";
    }
 
    private function canUseCachedValues(
        UserIdentity $user,
        string $cacheKind,
        int $queryFlags
    ): bool {
        if ( !$user->isRegistered() ) {
            // Anon users don't have groups stored in the database,
            // so $queryFlags are ignored.
            return true;
        }
        if ( $queryFlags >= IDBAccessObject::READ_LOCKING ) {
            return false;
        }
        $userKey = $this->getCacheKey( $user );
        $queryFlagsUsed = $this->queryFlagsUsedForCaching[$userKey][$cacheKind] ?? IDBAccessObject::READ_NONE;
        return $queryFlagsUsed >= $queryFlags;
    }
}