func (c *SubChannel) Isolated() bool {
	c.RLock()
	defer c.RUnlock()
	return c.topChannel.Peers() != c.peers
}
func (c *SubChannel) Isolated() bool {
	c.RLock()
	defer c.RUnlock()
	return c.topChannel.Peers() != c.peers
}
// Isolated returns whether this subchannel is an isolated subchannel.