resc := make(chan *ProgResponse, 1)
	if err := c.writeToChild(req, resc); err != nil {
		return nil, err
	}
	select {
	case res := <-resc:
		if res.Err != "" {
			return nil, errors.New(res.Err)
		}
		return res, nil
	case <-ctx.Done():
		return nil, ctx.Err()
	}
}

func (c *ProgCache) writeToChild(req *ProgRequest, resc chan<- *ProgResponse) (err error) {
	c.mu.Lock()