Move ILoadBalancer to Rdbms namespace

[mediawiki.git] / includes / WatchedItemQueryService.php

<?php

use MediaWiki\Linker\LinkTarget;
use Wikimedia\Assert\Assert;

/**
 * Class performing complex database queries related to WatchedItems.
 *
 * @since 1.28
 *
 * @file
 * @ingroup Watchlist
 *
 * @license GNU GPL v2+
 */
class WatchedItemQueryService {

        const DIR_OLDER = 'older';
        const DIR_NEWER = 'newer';

        const INCLUDE_FLAGS = 'flags';
        const INCLUDE_USER = 'user';
        const INCLUDE_USER_ID = 'userid';
        const INCLUDE_COMMENT = 'comment';
        const INCLUDE_PATROL_INFO = 'patrol';
        const INCLUDE_SIZES = 'sizes';
        const INCLUDE_LOG_INFO = 'loginfo';

        // FILTER_* constants are part of public API (are used in ApiQueryWatchlist and
        // ApiQueryWatchlistRaw classes) and should not be changed.
        // Changing values of those constants will result in a breaking change in the API
        const FILTER_MINOR = 'minor';
        const FILTER_NOT_MINOR = '!minor';
        const FILTER_BOT = 'bot';
        const FILTER_NOT_BOT = '!bot';
        const FILTER_ANON = 'anon';
        const FILTER_NOT_ANON = '!anon';
        const FILTER_PATROLLED = 'patrolled';
        const FILTER_NOT_PATROLLED = '!patrolled';
        const FILTER_UNREAD = 'unread';
        const FILTER_NOT_UNREAD = '!unread';
        const FILTER_CHANGED = 'changed';
        const FILTER_NOT_CHANGED = '!changed';

        const SORT_ASC = 'ASC';
        const SORT_DESC = 'DESC';

        /**
         * @var LoadBalancer
         */
        private $loadBalancer;

        /** @var WatchedItemQueryServiceExtension[]|null */
        private $extensions = null;

        public function __construct( LoadBalancer $loadBalancer ) {
                $this->loadBalancer = $loadBalancer;
        }

        /**
         * @return WatchedItemQueryServiceExtension[]
         */
        private function getExtensions() {
                if ( $this->extensions === null ) {
                        $this->extensions = [];
                        Hooks::run( 'WatchedItemQueryServiceExtensions', [ &$this->extensions, $this ] );
                }
                return $this->extensions;
        }

        /**
         * @return IDatabase
         * @throws MWException
         */
        private function getConnection() {
                return $this->loadBalancer->getConnectionRef( DB_REPLICA, [ 'watchlist' ] );
        }

        /**
         * @param User $user
         * @param array $options Allowed keys:
         *        'includeFields'       => string[] RecentChange fields to be included in the result,
         *                                 self::INCLUDE_* constants should be used
         *        'filters'             => string[] optional filters to narrow down resulted items
         *        'namespaceIds'        => int[] optional namespace IDs to filter by
         *                                 (defaults to all namespaces)
         *        'allRevisions'        => bool return multiple revisions of the same page if true,
         *                                 only the most recent if false (default)
         *        'rcTypes'             => int[] which types of RecentChanges to include
         *                                 (defaults to all types), allowed values: RC_EDIT, RC_NEW,
         *                                 RC_LOG, RC_EXTERNAL, RC_CATEGORIZE
         *        'onlyByUser'          => string only list changes by a specified user
         *        'notByUser'           => string do not incluide changes by a specified user
         *        'dir'                 => string in which direction to enumerate, accepted values:
         *                                 - DIR_OLDER list newest first
         *                                 - DIR_NEWER list oldest first
         *        'start'               => string (format accepted by wfTimestamp) requires 'dir' option,
         *                                 timestamp to start enumerating from
         *        'end'                 => string (format accepted by wfTimestamp) requires 'dir' option,
         *                                 timestamp to end enumerating
         *        'watchlistOwner'      => User user whose watchlist items should be listed if different
         *                                 than the one specified with $user param,
         *                                 requires 'watchlistOwnerToken' option
         *        'watchlistOwnerToken' => string a watchlist token used to access another user's
         *                                 watchlist, used with 'watchlistOwnerToken' option
         *        'limit'               => int maximum numbers of items to return
         *        'usedInGenerator'     => bool include only RecentChange id field required by the
         *                                 generator ('rc_cur_id' or 'rc_this_oldid') if true, or all
         *                                 id fields ('rc_cur_id', 'rc_this_oldid', 'rc_last_oldid')
         *                                 if false (default)
         * @param array|null &$startFrom Continuation value: [ string $rcTimestamp, int $rcId ]
         * @return array of pairs ( WatchedItem $watchedItem, string[] $recentChangeInfo ),
         *         where $recentChangeInfo contains the following keys:
         *         - 'rc_id',
         *         - 'rc_namespace',
         *         - 'rc_title',
         *         - 'rc_timestamp',
         *         - 'rc_type',
         *         - 'rc_deleted',
         *         Additional keys could be added by specifying the 'includeFields' option
         */
        public function getWatchedItemsWithRecentChangeInfo(
                User $user, array $options = [], &$startFrom = null
        ) {
                $options += [
                        'includeFields' => [],
                        'namespaceIds' => [],
                        'filters' => [],
                        'allRevisions' => false,
                        'usedInGenerator' => false
                ];

                Assert::parameter(
                        !isset( $options['rcTypes'] )
                                || !array_diff( $options['rcTypes'], [ RC_EDIT, RC_NEW, RC_LOG, RC_EXTERNAL, RC_CATEGORIZE ] ),
                        '$options[\'rcTypes\']',
                        'must be an array containing only: RC_EDIT, RC_NEW, RC_LOG, RC_EXTERNAL and/or RC_CATEGORIZE'
                );
                Assert::parameter(
                        !isset( $options['dir'] ) || in_array( $options['dir'], [ self::DIR_OLDER, self::DIR_NEWER ] ),
                        '$options[\'dir\']',
                        'must be DIR_OLDER or DIR_NEWER'
                );
                Assert::parameter(
                        !isset( $options['start'] ) && !isset( $options['end'] ) && $startFrom === null
                                || isset( $options['dir'] ),
                        '$options[\'dir\']',
                        'must be provided when providing the "start" or "end" options or the $startFrom parameter'
                );
                Assert::parameter(
                        !isset( $options['startFrom'] ),
                        '$options[\'startFrom\']',
                        'must not be provided, use $startFrom instead'
                );
                Assert::parameter(
                        !isset( $startFrom ) || ( is_array( $startFrom ) && count( $startFrom ) === 2 ),
                        '$startFrom',
                        'must be a two-element array'
                );
                if ( array_key_exists( 'watchlistOwner', $options ) ) {
                        Assert::parameterType(
                                User::class,
                                $options['watchlistOwner'],
                                '$options[\'watchlistOwner\']'
                        );
                        Assert::parameter(
                                isset( $options['watchlistOwnerToken'] ),
                                '$options[\'watchlistOwnerToken\']',
                                'must be provided when providing watchlistOwner option'
                        );
                }

                $tables = [ 'recentchanges', 'watchlist' ];
                if ( !$options['allRevisions'] ) {
                        $tables[] = 'page';
                }

                $db = $this->getConnection();

                $fields = $this->getWatchedItemsWithRCInfoQueryFields( $options );
                $conds = $this->getWatchedItemsWithRCInfoQueryConds( $db, $user, $options );
                $dbOptions = $this->getWatchedItemsWithRCInfoQueryDbOptions( $options );
                $joinConds = $this->getWatchedItemsWithRCInfoQueryJoinConds( $options );

                if ( $startFrom !== null ) {
                        $conds[] = $this->getStartFromConds( $db, $options, $startFrom );
                }

                foreach ( $this->getExtensions() as $extension ) {
                        $extension->modifyWatchedItemsWithRCInfoQuery(
                                $user, $options, $db,
                                $tables,
                                $fields,
                                $conds,
                                $dbOptions,
                                $joinConds
                        );
                }

                $res = $db->select(
                        $tables,
                        $fields,
                        $conds,
                        __METHOD__,
                        $dbOptions,
                        $joinConds
                );

                $limit = isset( $dbOptions['LIMIT'] ) ? $dbOptions['LIMIT'] : INF;
                $items = [];
                $startFrom = null;
                foreach ( $res as $row ) {
                        if ( --$limit <= 0 ) {
                                $startFrom = [ $row->rc_timestamp, $row->rc_id ];
                                break;
                        }

                        $items[] = [
                                new WatchedItem(
                                        $user,
                                        new TitleValue( (int)$row->rc_namespace, $row->rc_title ),
                                        $row->wl_notificationtimestamp
                                ),
                                $this->getRecentChangeFieldsFromRow( $row )
                        ];
                }

                foreach ( $this->getExtensions() as $extension ) {
                        $extension->modifyWatchedItemsWithRCInfo( $user, $options, $db, $items, $res, $startFrom );
                }

                return $items;
        }

        /**
         * For simple listing of user's watchlist items, see WatchedItemStore::getWatchedItemsForUser
         *
         * @param User $user
         * @param array $options Allowed keys:
         *        'sort'         => string optional sorting by namespace ID and title
         *                          one of the self::SORT_* constants
         *        'namespaceIds' => int[] optional namespace IDs to filter by (defaults to all namespaces)
         *        'limit'        => int maximum number of items to return
         *        'filter'       => string optional filter, one of the self::FILTER_* contants
         *        'from'         => LinkTarget requires 'sort' key, only return items starting from
         *                          those related to the link target
         *        'until'        => LinkTarget requires 'sort' key, only return items until
         *                          those related to the link target
         *        'startFrom'    => LinkTarget requires 'sort' key, only return items starting from
         *                          those related to the link target, allows to skip some link targets
         *                          specified using the form option
         * @return WatchedItem[]
         */
        public function getWatchedItemsForUser( User $user, array $options = [] ) {
                if ( $user->isAnon() ) {
                        // TODO: should this just return an empty array or rather complain loud at this point
                        // as e.g. ApiBase::getWatchlistUser does?
                        return [];
                }

                $options += [ 'namespaceIds' => [] ];

                Assert::parameter(
                        !isset( $options['sort'] ) || in_array( $options['sort'], [ self::SORT_ASC, self::SORT_DESC ] ),
                        '$options[\'sort\']',
                        'must be SORT_ASC or SORT_DESC'
                );
                Assert::parameter(
                        !isset( $options['filter'] ) || in_array(
                                $options['filter'], [ self::FILTER_CHANGED, self::FILTER_NOT_CHANGED ]
                        ),
                        '$options[\'filter\']',
                        'must be FILTER_CHANGED or FILTER_NOT_CHANGED'
                );
                Assert::parameter(
                        !isset( $options['from'] ) && !isset( $options['until'] ) && !isset( $options['startFrom'] )
                        || isset( $options['sort'] ),
                        '$options[\'sort\']',
                        'must be provided if any of "from", "until", "startFrom" options is provided'
                );

                $db = $this->getConnection();

                $conds = $this->getWatchedItemsForUserQueryConds( $db, $user, $options );
                $dbOptions = $this->getWatchedItemsForUserQueryDbOptions( $options );

                $res = $db->select(
                        'watchlist',
                        [ 'wl_namespace', 'wl_title', 'wl_notificationtimestamp' ],
                        $conds,
                        __METHOD__,
                        $dbOptions
                );

                $watchedItems = [];
                foreach ( $res as $row ) {
                        // todo these could all be cached at some point?
                        $watchedItems[] = new WatchedItem(
                                $user,
                                new TitleValue( (int)$row->wl_namespace, $row->wl_title ),
                                $row->wl_notificationtimestamp
                        );
                }

                return $watchedItems;
        }

        private function getRecentChangeFieldsFromRow( stdClass $row ) {
                // This can be simplified to single array_filter call filtering by key value,
                // once we stop supporting PHP 5.5
                $allFields = get_object_vars( $row );
                $rcKeys = array_filter(
                        array_keys( $allFields ),
                        function( $key ) {
                                return substr( $key, 0, 3 ) === 'rc_';
                        }
                );
                return array_intersect_key( $allFields, array_flip( $rcKeys ) );
        }

        private function getWatchedItemsWithRCInfoQueryFields( array $options ) {
                $fields = [
                        'rc_id',
                        'rc_namespace',
                        'rc_title',
                        'rc_timestamp',
                        'rc_type',
                        'rc_deleted',
                        'wl_notificationtimestamp'
                ];

                $rcIdFields = [
                        'rc_cur_id',
                        'rc_this_oldid',
                        'rc_last_oldid',
                ];
                if ( $options['usedInGenerator'] ) {
                        if ( $options['allRevisions'] ) {
                                $rcIdFields = [ 'rc_this_oldid' ];
                        } else {
                                $rcIdFields = [ 'rc_cur_id' ];
                        }
                }
                $fields = array_merge( $fields, $rcIdFields );

                if ( in_array( self::INCLUDE_FLAGS, $options['includeFields'] ) ) {
                        $fields = array_merge( $fields, [ 'rc_type', 'rc_minor', 'rc_bot' ] );
                }
                if ( in_array( self::INCLUDE_USER, $options['includeFields'] ) ) {
                        $fields[] = 'rc_user_text';
                }
                if ( in_array( self::INCLUDE_USER_ID, $options['includeFields'] ) ) {
                        $fields[] = 'rc_user';
                }
                if ( in_array( self::INCLUDE_COMMENT, $options['includeFields'] ) ) {
                        $fields[] = 'rc_comment';
                }
                if ( in_array( self::INCLUDE_PATROL_INFO, $options['includeFields'] ) ) {
                        $fields = array_merge( $fields, [ 'rc_patrolled', 'rc_log_type' ] );
                }
                if ( in_array( self::INCLUDE_SIZES, $options['includeFields'] ) ) {
                        $fields = array_merge( $fields, [ 'rc_old_len', 'rc_new_len' ] );
                }
                if ( in_array( self::INCLUDE_LOG_INFO, $options['includeFields'] ) ) {
                        $fields = array_merge( $fields, [ 'rc_logid', 'rc_log_type', 'rc_log_action', 'rc_params' ] );
                }

                return $fields;
        }

        private function getWatchedItemsWithRCInfoQueryConds(
                IDatabase $db,
                User $user,
                array $options
        ) {
                $watchlistOwnerId = $this->getWatchlistOwnerId( $user, $options );
                $conds = [ 'wl_user' => $watchlistOwnerId ];

                if ( !$options['allRevisions'] ) {
                        $conds[] = $db->makeList(
                                [ 'rc_this_oldid=page_latest', 'rc_type=' . RC_LOG ],
                                LIST_OR
                        );
                }

                if ( $options['namespaceIds'] ) {
                        $conds['wl_namespace'] = array_map( 'intval', $options['namespaceIds'] );
                }

                if ( array_key_exists( 'rcTypes', $options ) ) {
                        $conds['rc_type'] = array_map( 'intval',  $options['rcTypes'] );
                }

                $conds = array_merge(
                        $conds,
                        $this->getWatchedItemsWithRCInfoQueryFilterConds( $user, $options )
                );

                $conds = array_merge( $conds, $this->getStartEndConds( $db, $options ) );

                if ( !isset( $options['start'] ) && !isset( $options['end'] ) ) {
                        if ( $db->getType() === 'mysql' ) {
                                // This is an index optimization for mysql
                                $conds[] = "rc_timestamp > ''";
                        }
                }

                $conds = array_merge( $conds, $this->getUserRelatedConds( $db, $user, $options ) );

                $deletedPageLogCond = $this->getExtraDeletedPageLogEntryRelatedCond( $db, $user );
                if ( $deletedPageLogCond ) {
                        $conds[] = $deletedPageLogCond;
                }

                return $conds;
        }

        private function getWatchlistOwnerId( User $user, array $options ) {
                if ( array_key_exists( 'watchlistOwner', $options ) ) {
                        /** @var User $watchlistOwner */
                        $watchlistOwner = $options['watchlistOwner'];
                        $ownersToken = $watchlistOwner->getOption( 'watchlisttoken' );
                        $token = $options['watchlistOwnerToken'];
                        if ( $ownersToken == '' || !hash_equals( $ownersToken, $token ) ) {
                                throw ApiUsageException::newWithMessage( null, 'apierror-bad-watchlist-token', 'bad_wltoken' );
                        }
                        return $watchlistOwner->getId();
                }
                return $user->getId();
        }

        private function getWatchedItemsWithRCInfoQueryFilterConds( User $user, array $options ) {
                $conds = [];

                if ( in_array( self::FILTER_MINOR, $options['filters'] ) ) {
                        $conds[] = 'rc_minor != 0';
                } elseif ( in_array( self::FILTER_NOT_MINOR, $options['filters'] ) ) {
                        $conds[] = 'rc_minor = 0';
                }

                if ( in_array( self::FILTER_BOT, $options['filters'] ) ) {
                        $conds[] = 'rc_bot != 0';
                } elseif ( in_array( self::FILTER_NOT_BOT, $options['filters'] ) ) {
                        $conds[] = 'rc_bot = 0';
                }

                if ( in_array( self::FILTER_ANON, $options['filters'] ) ) {
                        $conds[] = 'rc_user = 0';
                } elseif ( in_array( self::FILTER_NOT_ANON, $options['filters'] ) ) {
                        $conds[] = 'rc_user != 0';
                }

                if ( $user->useRCPatrol() || $user->useNPPatrol() ) {
                        // TODO: not sure if this should simply ignore patrolled filters if user does not have the patrol
                        // right, or maybe rather fail loud at this point, same as e.g. ApiQueryWatchlist does?
                        if ( in_array( self::FILTER_PATROLLED, $options['filters'] ) ) {
                                $conds[] = 'rc_patrolled != 0';
                        } elseif ( in_array( self::FILTER_NOT_PATROLLED, $options['filters'] ) ) {
                                $conds[] = 'rc_patrolled = 0';
                        }
                }

                if ( in_array( self::FILTER_UNREAD, $options['filters'] ) ) {
                        $conds[] = 'rc_timestamp >= wl_notificationtimestamp';
                } elseif ( in_array( self::FILTER_NOT_UNREAD, $options['filters'] ) ) {
                        // TODO: should this be changed to use Database::makeList?
                        $conds[] = 'wl_notificationtimestamp IS NULL OR rc_timestamp < wl_notificationtimestamp';
                }

                return $conds;
        }

        private function getStartEndConds( IDatabase $db, array $options ) {
                if ( !isset( $options['start'] ) && !isset( $options['end'] ) ) {
                        return [];
                }

                $conds = [];

                if ( isset( $options['start'] ) ) {
                        $after = $options['dir'] === self::DIR_OLDER ? '<=' : '>=';
                        $conds[] = 'rc_timestamp ' . $after . ' ' .
                                $db->addQuotes( $db->timestamp( $options['start'] ) );
                }
                if ( isset( $options['end'] ) ) {
                        $before = $options['dir'] === self::DIR_OLDER ? '>=' : '<=';
                        $conds[] = 'rc_timestamp ' . $before . ' ' .
                                $db->addQuotes( $db->timestamp( $options['end'] ) );
                }

                return $conds;
        }

        private function getUserRelatedConds( IDatabase $db, User $user, array $options ) {
                if ( !array_key_exists( 'onlyByUser', $options ) && !array_key_exists( 'notByUser', $options ) ) {
                        return [];
                }

                $conds = [];

                if ( array_key_exists( 'onlyByUser', $options ) ) {
                        $conds['rc_user_text'] = $options['onlyByUser'];
                } elseif ( array_key_exists( 'notByUser', $options ) ) {
                        $conds[] = 'rc_user_text != ' . $db->addQuotes( $options['notByUser'] );
                }

                // Avoid brute force searches (bug 17342)
                $bitmask = 0;
                if ( !$user->isAllowed( 'deletedhistory' ) ) {
                        $bitmask = Revision::DELETED_USER;
                } elseif ( !$user->isAllowedAny( 'suppressrevision', 'viewsuppressed' ) ) {
                        $bitmask = Revision::DELETED_USER | Revision::DELETED_RESTRICTED;
                }
                if ( $bitmask ) {
                        $conds[] = $db->bitAnd( 'rc_deleted', $bitmask ) . " != $bitmask";
                }

                return $conds;
        }

        private function getExtraDeletedPageLogEntryRelatedCond( IDatabase $db, User $user ) {
                // LogPage::DELETED_ACTION hides the affected page, too. So hide those
                // entirely from the watchlist, or someone could guess the title.
                $bitmask = 0;
                if ( !$user->isAllowed( 'deletedhistory' ) ) {
                        $bitmask = LogPage::DELETED_ACTION;
                } elseif ( !$user->isAllowedAny( 'suppressrevision', 'viewsuppressed' ) ) {
                        $bitmask = LogPage::DELETED_ACTION | LogPage::DELETED_RESTRICTED;
                }
                if ( $bitmask ) {
                        return $db->makeList( [
                                'rc_type != ' . RC_LOG,
                                $db->bitAnd( 'rc_deleted', $bitmask ) . " != $bitmask",
                        ], LIST_OR );
                }
                return '';
        }

        private function getStartFromConds( IDatabase $db, array $options, array $startFrom ) {
                $op = $options['dir'] === self::DIR_OLDER ? '<' : '>';
                list( $rcTimestamp, $rcId ) = $startFrom;
                $rcTimestamp = $db->addQuotes( $db->timestamp( $rcTimestamp ) );
                $rcId = (int)$rcId;
                return $db->makeList(
                        [
                                "rc_timestamp $op $rcTimestamp",
                                $db->makeList(
                                        [
                                                "rc_timestamp = $rcTimestamp",
                                                "rc_id $op= $rcId"
                                        ],
                                        LIST_AND
                                )
                        ],
                        LIST_OR
                );
        }

        private function getWatchedItemsForUserQueryConds( IDatabase $db, User $user, array $options ) {
                $conds = [ 'wl_user' => $user->getId() ];
                if ( $options['namespaceIds'] ) {
                        $conds['wl_namespace'] = array_map( 'intval', $options['namespaceIds'] );
                }
                if ( isset( $options['filter'] ) ) {
                        $filter = $options['filter'];
                        if ( $filter ===  self::FILTER_CHANGED ) {
                                $conds[] = 'wl_notificationtimestamp IS NOT NULL';
                        } else {
                                $conds[] = 'wl_notificationtimestamp IS NULL';
                        }
                }

                if ( isset( $options['from'] ) ) {
                        $op = $options['sort'] === self::SORT_ASC ? '>' : '<';
                        $conds[] = $this->getFromUntilTargetConds( $db, $options['from'], $op );
                }
                if ( isset( $options['until'] ) ) {
                        $op = $options['sort'] === self::SORT_ASC ? '<' : '>';
                        $conds[] = $this->getFromUntilTargetConds( $db, $options['until'], $op );
                }
                if ( isset( $options['startFrom'] ) ) {
                        $op = $options['sort'] === self::SORT_ASC ? '>' : '<';
                        $conds[] = $this->getFromUntilTargetConds( $db, $options['startFrom'], $op );
                }

                return $conds;
        }

        /**
         * Creates a query condition part for getting only items before or after the given link target
         * (while ordering using $sort mode)
         *
         * @param IDatabase $db
         * @param LinkTarget $target
         * @param string $op comparison operator to use in the conditions
         * @return string
         */
        private function getFromUntilTargetConds( IDatabase $db, LinkTarget $target, $op ) {
                return $db->makeList(
                        [
                                "wl_namespace $op " . $target->getNamespace(),
                                $db->makeList(
                                        [
                                                'wl_namespace = ' . $target->getNamespace(),
                                                "wl_title $op= " . $db->addQuotes( $target->getDBkey() )
                                        ],
                                        LIST_AND
                                )
                        ],
                        LIST_OR
                );
        }

        private function getWatchedItemsWithRCInfoQueryDbOptions( array $options ) {
                $dbOptions = [];

                if ( array_key_exists( 'dir', $options ) ) {
                        $sort = $options['dir'] === self::DIR_OLDER ? ' DESC' : '';
                        $dbOptions['ORDER BY'] = [ 'rc_timestamp' . $sort, 'rc_id' . $sort ];
                }

                if ( array_key_exists( 'limit', $options ) ) {
                        $dbOptions['LIMIT'] = (int)$options['limit'] + 1;
                }

                return $dbOptions;
        }

        private function getWatchedItemsForUserQueryDbOptions( array $options ) {
                $dbOptions = [];
                if ( array_key_exists( 'sort', $options ) ) {
                        $dbOptions['ORDER BY'] = [
                                "wl_namespace {$options['sort']}",
                                "wl_title {$options['sort']}"
                        ];
                        if ( count( $options['namespaceIds'] ) === 1 ) {
                                $dbOptions['ORDER BY'] = "wl_title {$options['sort']}";
                        }
                }
                if ( array_key_exists( 'limit', $options ) ) {
                        $dbOptions['LIMIT'] = (int)$options['limit'];
                }
                return $dbOptions;
        }

        private function getWatchedItemsWithRCInfoQueryJoinConds( array $options ) {
                $joinConds = [
                        'watchlist' => [ 'INNER JOIN',
                                [
                                        'wl_namespace=rc_namespace',
                                        'wl_title=rc_title'
                                ]
                        ]
                ];
                if ( !$options['allRevisions'] ) {
                        $joinConds['page'] = [ 'LEFT JOIN', 'rc_cur_id=page_id' ];
                }
                return $joinConds;
        }

}