分享一个乐观锁的代码，大家提点意见，优化优化

代码可以放在基类Model中

    protected $cas_version = 'new_version';

    public function cas() {

        if(!$this->exists) {
            return;
        }

        if(!in_array($this->cas_version, array_keys($this->original))) {
            throw new \Exception('查询结果不包含version字段');
        }

        // 获取已经修改的字段
        $dirty = $this->getDirty();
        $query = $this->newModelQuery()->where($this->getKeyName(), $this->getKey())->where($this->cas_version, $this->getOriginal($this->cas_version));
        $dirty = array_merge($dirty, [$this->cas_version => $this->getOriginal($this->cas_version) + 1]);
        $row = $query->update($dirty);
        if ($row > 0) {
            $this->syncChanges();
            $this->syncOriginal();
        }

        return $row;
    }