code: func (c *Ctrie) rdcssRoot(old *iNode, expected *mainNode, nv *iNode) bool {
  	desc := &iNode{
  		rdcss: &rdcssDescriptor{
  			old:      old,
  			expected: expected,
  			nv:       nv,
  		},
  	}
  	if c.casRoot(old, desc) {
  		c.rdcssComplete(false)
  		return atomic.LoadInt32(&desc.rdcss.committed) == 1
  	}
  	return false
  }
docs: // rdcssRoot performs a RDCSS on the Ctrie root. This is used to create a
  // snapshot of the Ctrie by copying the root I-node and setting it to a new
  // generation.