Log network latency breakdow somehow.

[fulmicoton]

Problem

Today we do not really understand how long is spent in the different phase of a data request.

Ideally we would like a breakdown of

did we need to establish a connection how long did connection establishment (if there was one) how long does TLS handshake took time elapsed between sending the request and receiving the first byte. (TTFB) Once we have this information, we need to try and see if we can lower the latency (connection pool misconfigured, TCP::NO_DELAY).

Notes

Getting that logging will be a bit tricky. Rusoto let's us plug in any client, http::Client is the one that we us (and it is the default).

http::Client currently does not log all of this information, but maybe we could contribute this upstream, or wrap http::Client and wrap the result Stream to log the first byte.