Function isJSControlMessage

js.go:2125–2137

isJSControlMessage will return true if this is an empty control status message and indicate what type of control message it is, say jsCtrlHB or jsCtrlFC

(msg *Msg)

// isJSControlMessage will return true if this is an empty control status message
// and indicate what type of control message it is, say jsCtrlHB or jsCtrlFC
func isJSControlMessage(msg *Msg) (bool, int) {
	if len(msg.Data) > 0 || msg.Header.Get(statusHdr) != controlMsg {
		return false, 0
	}
	val := msg.Header.Get(descrHdr)
	if strings.HasPrefix(val, "Idle") {
		return true, jsCtrlHB
	}
	if strings.HasPrefix(val, "Flow") {
		return true, jsCtrlFC
	}
	return true, 0
}

// Keeps track of the incoming message's reply subject so that the consumer's
// state (deliver sequence, etc..) can be checked against heartbeats.