HTTP/3: Figure out ConnectionId, RequestId, TraceId

[JamesNK]

Various IDs are assigned to connections and requests. These are output in logging.

The current design on ConnectionContext wasn't designed with HTTP/3 in mind which has a multiplexed transport context plus per-stream contexts.

Want to give users informative IDs in log messages without allocating a string ID per-stream.

[BrennanConroy]

Triage: We're fine allocating, as long as it's lazy.

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[JamesNK]

Today in HTTP/3:

• ConnectionId = Stream ConnectionId. Allocates a new string per request by combining QUIC connection ID with stream number. $"{_connection.ConnectionId}:{StreamId}". e.g. "0HMAGF2FLQPAO:4"
• RequestId = Stream ConnectionId again.
• TraceId = Stream ConnectionId again.

When we log about events on a request stream the logs all contain an argument with the Stream ID number. e.g.

Connection id "0HMAGF2FLQPAO:3" sending GO_AWAY frame for stream ID 3 with length 1.

Because the stream number is always logged, I think we should change ConnectionId to be the actual QUIC connection ID (so, no longer be concatenated with the StreamId). That makes it consistent with HTTP/2 and it will no longer be allocated per request.

In HTTP/3, RequestId and TraceId will continue to be a concat of both data, e.g. "0HMAGF2FLQPAO:4".

Question: should the value be updated to be consistent with HTTP/2? i.e. change $"{_connection.ConnectionId}:{StreamId}" to StringUtilities.ConcatAsHexSuffix(ConnectionId, ':', (uint)StreamId)?

[JamesNK]

Thoughts @Tratcher @halter73 @wtgodbe?

[JamesNK]

Discussed with HTTP/3 team. Will follow proposed changes. Will make consistent with HTTP/2.