Is there a way to check for dropped messages that don't have headers?
In particular, I am sending some joy/Joy messages over a WLAN and am hinting ros::TransportHints().unreliable() in the subscriber (the publisher is a joy/joy_node).
I've occasionally seen a delay of > 0.5 s, where the in the received messages based on timing within the subscriber's callback, and I'd like to see if that might have to do with dropped UDP packets. I was thinking that I would just look at the header.seq field in each received message, looking for and increment greater than 1, and then realized that joy/Joy messages have no header.
Am I SOL or is there some way to determine whether messages are being dropped?
I also wonder about out-of-order messages which I think are theoretically possible with UDP and was hoping to also watch out for those in a similar manner. Maybe a Header could be added to joy/Joy in a future release?
