forked from golang/tools
/
prometheus.go
129 lines (117 loc) · 3.59 KB
/
prometheus.go
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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package prometheus
import (
"bytes"
"context"
"fmt"
"net/http"
"sort"
"sync"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/event/core"
"golang.org/x/tools/internal/event/export/metric"
"golang.org/x/tools/internal/event/label"
)
func New() *Exporter {
return &Exporter{}
}
type Exporter struct {
mu sync.Mutex
metrics []metric.Data
}
func (e *Exporter) ProcessEvent(ctx context.Context, ev core.Event, ln label.Map) context.Context {
if !event.IsMetric(ev) {
return ctx
}
e.mu.Lock()
defer e.mu.Unlock()
metrics := metric.Entries.Get(ln).([]metric.Data)
for _, data := range metrics {
name := data.Handle()
// We keep the metrics in name sorted order so the page is stable and easy
// to read. We do this with an insertion sort rather than sorting the list
// each time
index := sort.Search(len(e.metrics), func(i int) bool {
return e.metrics[i].Handle() >= name
})
if index >= len(e.metrics) || e.metrics[index].Handle() != name {
// we have a new metric, so we need to make a space for it
old := e.metrics
e.metrics = make([]metric.Data, len(old)+1)
copy(e.metrics, old[:index])
copy(e.metrics[index+1:], old[index:])
}
e.metrics[index] = data
}
return ctx
}
func (e *Exporter) header(w http.ResponseWriter, name, description string, isGauge, isHistogram bool) {
kind := "counter"
if isGauge {
kind = "gauge"
}
if isHistogram {
kind = "histogram"
}
fmt.Fprintf(w, "# HELP %s %s\n", name, description)
fmt.Fprintf(w, "# TYPE %s %s\n", name, kind)
}
func (e *Exporter) row(w http.ResponseWriter, name string, group []label.Label, extra string, value interface{}) {
fmt.Fprint(w, name)
buf := &bytes.Buffer{}
fmt.Fprint(buf, group)
if extra != "" {
if buf.Len() > 0 {
fmt.Fprint(buf, ",")
}
fmt.Fprint(buf, extra)
}
if buf.Len() > 0 {
fmt.Fprint(w, "{")
buf.WriteTo(w)
fmt.Fprint(w, "}")
}
fmt.Fprintf(w, " %v\n", value)
}
func (e *Exporter) Serve(w http.ResponseWriter, r *http.Request) {
e.mu.Lock()
defer e.mu.Unlock()
for _, data := range e.metrics {
switch data := data.(type) {
case *metric.Int64Data:
e.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
for i, group := range data.Groups() {
e.row(w, data.Info.Name, group, "", data.Rows[i])
}
case *metric.Float64Data:
e.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
for i, group := range data.Groups() {
e.row(w, data.Info.Name, group, "", data.Rows[i])
}
case *metric.HistogramInt64Data:
e.header(w, data.Info.Name, data.Info.Description, false, true)
for i, group := range data.Groups() {
row := data.Rows[i]
for j, b := range data.Info.Buckets {
e.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
}
e.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
e.row(w, data.Info.Name+"_count", group, "", row.Count)
e.row(w, data.Info.Name+"_sum", group, "", row.Sum)
}
case *metric.HistogramFloat64Data:
e.header(w, data.Info.Name, data.Info.Description, false, true)
for i, group := range data.Groups() {
row := data.Rows[i]
for j, b := range data.Info.Buckets {
e.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
}
e.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
e.row(w, data.Info.Name+"_count", group, "", row.Count)
e.row(w, data.Info.Name+"_sum", group, "", row.Sum)
}
}
}
}