| 1 | package bakeoff |
| 2 | |
| 3 | import ( |
| 4 | "crypto/tls" |
| 5 | "io" |
| 6 | "net/http" |
| 7 | "net/http/httptrace" |
| 8 | "sort" |
| 9 | "time" |
| 10 | ) |
| 11 | |
| 12 | // Stats summarises a set of samples in milliseconds. |
| 13 | type Stats struct { |
| 14 | N int |
| 15 | P50, P95, P99, Min, Max float64 |
| 16 | } |
| 17 | |
| 18 | func summarise(ms []float64) Stats { |
| 19 | sort.Float64s(ms) |
| 20 | pick := func(p float64) float64 { return ms[int(p*float64(len(ms)-1)+0.5)] } |
| 21 | return Stats{N: len(ms), P50: pick(0.5), P95: pick(0.95), P99: pick(0.99), Min: ms[0], Max: ms[len(ms)-1]} |
| 22 | } |
| 23 | |
| 24 | // timeToFirstByte makes one GET on a fresh connection (DNS, TCP and TLS |
| 25 | // included, as a new visitor would pay them) and returns the milliseconds |
| 26 | // until the first response byte. |
| 27 | func (s *Session) timeToFirstByte(path string) (float64, error) { |
| 28 | tr := &http.Transport{DisableKeepAlives: true, TLSClientConfig: &tls.Config{}} |
| 29 | defer tr.CloseIdleConnections() |
| 30 | c := &http.Client{Transport: tr, Jar: s.Client.Jar, CheckRedirect: s.Client.CheckRedirect, Timeout: s.Client.Timeout} |
| 31 | var first time.Time |
| 32 | req, _ := http.NewRequest("GET", s.Base.String()+path, nil) |
| 33 | req = req.WithContext(httptrace.WithClientTrace(req.Context(), &httptrace.ClientTrace{ |
| 34 | GotFirstResponseByte: func() { first = time.Now() }, |
| 35 | })) |
| 36 | start := time.Now() |
| 37 | res, err := c.Do(req) |
| 38 | if err != nil { |
| 39 | return 0, err |
| 40 | } |
| 41 | io.Copy(io.Discard, res.Body) |
| 42 | res.Body.Close() |
| 43 | return float64(first.Sub(start).Microseconds()) / 1000, nil |
| 44 | } |
| 45 | |
| 46 | // MeasureTTFB discards warmup requests, then times n. |
| 47 | func MeasureTTFB(s *Session, path string, warmup, n int) (Stats, error) { |
| 48 | for i := 0; i < warmup; i++ { |
| 49 | if _, err := s.timeToFirstByte(path); err != nil { |
| 50 | return Stats{}, err |
| 51 | } |
| 52 | } |
| 53 | ms := make([]float64, 0, n) |
| 54 | for i := 0; i < n; i++ { |
| 55 | v, err := s.timeToFirstByte(path) |
| 56 | if err != nil { |
| 57 | return Stats{}, err |
| 58 | } |
| 59 | ms = append(ms, v) |
| 60 | } |
| 61 | return summarise(ms), nil |
| 62 | } |
| 63 | |
amadan