etcdserver/util.go
func numConnectedSince(transport rafthttp.Transporter, since time.Time, self types.ID, members []*membership.Member) int {
	connectedNum := 0
	for _, m := range members {
		if m.ID == self || isConnectedSince(transport, since, m.ID) {
			connectedNum++
		}
	}
	return connectedNum
}
func numConnectedSince(transport rafthttp.Transporter, since time.Time, self types.ID, members []*membership.Member) int {
	connectedNum := 0
	for _, m := range members {
		if m.ID == self || isConnectedSince(transport, since, m.ID) {
			connectedNum++
		}
	}
	return connectedNum
}
// numConnectedSince counts how many members are connected to the local member
// since the given time.