code: func (q *queue) ShouldThrottleBlocks() bool {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  
  	return q.resultSlots(q.blockPendPool, q.blockDonePool) <= 0
  }
docs: // ShouldThrottleBlocks checks if the download should be throttled (active block (body)
  // fetches exceed block cache).