A80: Export TCP Telemetry from gRPC

[AananthV]

No description provided.

[markdroth]

This looks good! My comments are mostly minor cosmetic things, but there are two small substantive comments.

Please let me know if you have any questions. Thanks!

[ejona86]

So you understand why I'm looking at this so much more closely now vs before: Earlier this was "some metrics y'all wanted for yourselves". And I knew why you'd want them, and why they'd be useful to others, but there wasn't an idea we'd move quickly to implement this cross-language for wide availability. With the idea these are going to be on by default, that means these are seen as being more important/widely used metrics. They are now intended for the masses. Thus I started reviewing them as such.

Since I'm going to be unavailable next week: I'd said the comments I need to say. Once the threads are actually resolved (not just marked resolved), it seems it would be good to go.

[ejona86]

I had thought grpc.tcp.connections_created would be paired with a closed counter, as that's what we've done in the past instead of UpDown counters. But I can live with this.

Thank you!