public function initSlave($point)
    {
        $this->db->{'local.oplog.$main'}->find(

        /**
         * @param \MongoTimestamp $cursor
         */
            function ($cursor) {
                $this->cursor = $cursor;
                $cursor->state = 1;
                $cursor->lastOpId = null;

                foreach ($cursor->items as $k => &$item) {
                    if (\PHPDaemon\Core\Daemon::$config->logevents->value) {
                        \PHPDaemon\Core\Daemon::log(get_class($this) . ': caught oplog-record with ts = (' . \PHPDaemon\Core\Debug::dump($item['ts']) . ')');
                    }

                    $cursor->lastOpId = $item['ts'];

                    if ($item['op'] === 'i') {
                        $this->cacheObject($item['o']);
                    } elseif ($item['op'] === 'd') {
                        $this->deleteObject($item['o']);
                    } elseif ($item['op'] === 'u') {
                        if (
                            isset($item['b'])
                            && ($item['b'] === false)
                        ) {
                            $item['o']['_id'] = $item['o2']['_id'];
                            $this->cacheObject($item['o']);
                        } else {
                            $cursor->appInstance->{$item['ns']}->findOne(

                            /**
                             * @param \MongoTimestamp $item
                             */
                                function ($item) {
                                    $this->cacheObject($item);
                                },
                                ['where' => ['_id' => $item['o2']['_id']]]
                            );
                        }
                    }

                    unset($cursor->items[$k]);
                }
            }, [
                'tailable' => true,
                'sort' => ['$natural' => 1],
                'snapshot' => 1,
                'where' => [
                    'ts' => [
                        '$gt' => $point
                    ],
                    '$exists' => [
                        '_key' => true
                    ]
                ],
                'parse_oplog' => true,
            ]
        );
    }