Proper logging

[henry40408]

closes #96

• I reverse the logic about content length. We should unset it only when response body is compressed.
• Since response body was polled by hyper, it's too early for us to show log message in original implementation. I implement a "loggable body" to track whether we should print log message.
• I have considered trace in tower-http, but I will have to
  • add tower-http as dependency, which might increase binary size
  • encapsulate my own response to keep log information from request like how I do now
  • comply with tower-http trace signature and lifetime

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Send request with curl

$ curl http://localhost:5000/Cargo.toml
127.0.0.1 - - [24/Sep/2022 16:14:55 +0800] "GET /Cargo.toml HTTP/1.1" 200 1535 "-" "curl/7.68.0" "-"

Enable compression and send request with curl

$ curl --compressed http://localhost:5000/Cargo.toml
127.0.0.1 - - [24/Sep/2022 16:15:29 +0800] "GET /Cargo.toml HTTP/1.1" 200 859 "-" "curl/7.68.0" "-"

Send request with HTTPie

$ http http://localhost:5000/Cargo.toml
127.0.0.1 - - [24/Sep/2022 16:16:00 +0800] "GET /Cargo.toml HTTP/1.1" 200 739 "-" "HTTPie/1.0.3" "-"

Performance is not compromised

$ wrk http://localhost:5000/Cargo.toml
Running 10s test @ http://localhost:5000/Cargo.toml
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.29ms    1.27ms  23.19ms   92.44%
    Req/Sec     4.58k   715.61     5.63k    67.50%
  91141 requests in 10.00s, 156.54MB read
Requests/sec:   9111.59
Transfer/sec:     15.65MB

Partial content log

$ curl -r 10-20 http://localhost:5000/Cargo.toml
127.0.0.1 - - [24/Sep/2022 16:48:41 +0800] "GET /Cargo.toml HTTP/1.1" 206 11 "-" "curl/7.68.0" "-"