peer.go
func (l *PeerList) updatePeer(ps *peerScore, newScore uint64) {
	if ps.score == newScore {
		return
	}

	ps.score = newScore
	l.peerHeap.updatePeer(ps)
}
func (l *PeerList) updatePeer(ps *peerScore, newScore uint64) {
	if ps.score == newScore {
		return
	}

	ps.score = newScore
	l.peerHeap.updatePeer(ps)
}
// updatePeer is called to update the score of the peer given the existing score.
// Note that a Write lock must be held to call this function.