关于session 的 redis 实现问题，目前参考了ci和laravel 的实现，有些疑问？

    /**
     * {@inheritdoc}
     * @return bool
     */
    #[\ReturnTypeWillChange]
    public function write($session_id, $session_data)
    {
        $this->client->setex($session_id, $this->ttl, $session_data);

        return true;
    }Copy

    /**
     * Acquires an emulated lock.
     *
     * @param string $sessionID Session ID
     */
    protected function lockSession(string $sessionID): bool
    {
        // PHP 7 reuses the SessionHandler object on regeneration,
        // so we need to check here if the lock key is for the
        // correct session ID.
        if ($this->lockKey === $this->keyPrefix . $sessionID . ':lock') {
            return $this->redis->expire($this->lockKey, 300);
        }

        $lockKey = $this->keyPrefix . $sessionID . ':lock';
        $attempt = 0;

        do {
            if (($ttl = $this->redis->ttl($lockKey)) > 0) {
                sleep(1);

                continue;
            }

            if (! $this->redis->setex($lockKey, 300, (string) time())) {
                $this->logger->error('Session: Error while trying to obtain lock for ' . $this->keyPrefix . $sessionID);

                return false;
            }

            $this->lockKey = $lockKey;
            break;
        } while (++$attempt < 30);

        if ($attempt === 30) {
            log_message('error', 'Session: Unable to obtain lock for ' . $this->keyPrefix . $sessionID . ' after 30 attempts, aborting.');

            return false;
        }

        if ($ttl === -1) {
            log_message('debug', 'Session: Lock for ' . $this->keyPrefix . $sessionID . ' had no TTL, overriding.');
        }

        $this->lock = true;

        return true;
    }Copy