1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79

package httpmetrics

import (
	"strconv"
	"sync"
	"time"

	"github.com/fasthttp/router"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/valyala/fasthttp"
	"github.com/valyala/fasthttp/fasthttpadaptor"

	"{{{ .Package }}}/app/util"
)

var (
	defaultMetricPath  = "/metrics"
	requestHandlerPool sync.Pool
)

func prometheusHandler() fasthttp.RequestHandler {
	return fasthttpadaptor.NewFastHTTPHandler(promhttp.Handler())
}

func (p *Metrics) WrapHandler(r *router.Router, includeMetrics bool) fasthttp.RequestHandler {
	if includeMetrics {
		r.GET(p.MetricsPath, prometheusHandler())
	}
	return func(rc *fasthttp.RequestCtx) {
		if includeMetrics && string(rc.Request.URI().Path()) == defaultMetricPath {
			r.Handler(rc)
			return
		}
		reqBytes := make(chan int)
		frc := acquireRequestFromPool()
		rc.Request.CopyTo(frc)
		go computeApproximateRequestSize(frc, reqBytes)

		start := util.TimeCurrent()
		r.Handler(rc)

		status := strconv.Itoa(rc.Response.StatusCode())
		elapsed := float64(time.Since(start)) / float64(time.Second)
		rspBytes := float64(len(rc.Response.Body()))

		reqDur.WithLabelValues(p.Key, status).Observe(elapsed)
		reqCnt.WithLabelValues(p.Key, status, string(rc.Method())).Inc()
		reqSize.Observe(float64(<-reqBytes))
		rspSize.Observe(rspBytes)
	}
}

func computeApproximateRequestSize(rc *fasthttp.Request, out chan int) {
	s := 0
	if rc.URI() != nil {
		s += len(rc.URI().Path())
		s += len(rc.URI().Host())
	}
	s += len(rc.Header.Method())
	s += len("HTTP/1.1")
	rc.Header.VisitAll(func(key []byte, value []byte) {
		if string(key) != "Host" {
			s += len(key) + len(value)
		}
	})
	if rc.Header.ContentLength() != -1 {
		s += rc.Header.ContentLength()
	}
	out <- s
}

func acquireRequestFromPool() *fasthttp.Request {
	rp := requestHandlerPool.Get()
	if rp == nil {
		return &fasthttp.Request{}
	}
	frc, _ := rp.(*fasthttp.Request)
	return frc
}