Adding qlog support for lost packets and bytes through ex_data

[estcarisimo]

No description provided.

[antoniovicente]

Should we consider only including the deltas for now?

I guess both provide value, no objection to including both.

[estcarisimo]

Yeah, deltas provide much more value right now. At the risk of overpopulating the QLOG i am inclined towards adding both now

[LPardue]

Consider representing these as a structure defined in quiche rather than two independent fields e.g.

struct CfLostPackets {
  total: u64,
  delta: Option<u64>,
}

(activitity for the reader, to apply the needed serde decorations)
More formally defining our custom event object model will help maintenance in the longer run.

[antoniovicente]

I think the idea behind your suggestion is that we could do something like:

struct TotalAndDelta {
  total: u64,
  delta: u64,
}

ex_data.insert(
  "cf_lost_packets".to_string(),
  serde_json::json!(TotalAndDelta {total, delta}),
);

[LPardue]

I'd take it a bit further and do something like I proposed in #2355. That way, you'd use CustomCfQlogField to wrap any/all of these fields, with the value being generic but needing to implement a Serialize trait