There are something wrongs when no sendQueue message

[yuancpfive]

func (r *Rudp) sendMessage(tmp *packageBuffer) {
	m := r.sendQueue.head
	for m != nil {
		tmp.packMessage(m)
		m = m.next
	}

        // ***  this is not correct when some situation
	if r.sendQueue.head != nil {
		if r.sendHistory.tail == nil {
			r.sendHistory = r.sendQueue
		} else {
			r.sendHistory.tail.next = r.sendQueue.head
			r.sendHistory.tail = r.sendQueue.tail
		}
		r.sendQueue.head = nil
		r.sendQueue.tail = nil
	}
}

if sendQueue is empty , and the program will never send sendHistory's message
or sendHistory's message will be sent when sendQueue contain message.