metrics: pull library and introduce ResettingTimer and InfluxDB reporter (#15910)

* go-metrics: fork library and introduce ResettingTimer and InfluxDB reporter.

* vendor: change nonsense/go-metrics to ethersphere/go-metrics

* go-metrics: add tests. move ResettingTimer logic from reporter to type.

* all, metrics: pull in metrics package in go-ethereum

* metrics/test: make sure metrics are enabled for tests

* metrics: apply gosimple rules

* metrics/exp, internal/debug: init expvar endpoint when starting pprof server

* internal/debug: tiny comment formatting fix

3 files changed, 276 insertions, 0 deletions

diff --git a/metrics/influxdb/LICENSE b/metrics/influxdb/LICENSE
new file mode 100644
index 000000000..e5bf20cdb
--- /dev/null
+++ b/metrics/influxdb/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2015 Vincent Rischmann
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/metrics/influxdb/README.md b/metrics/influxdb/README.md
new file mode 100644
index 000000000..b76b1a3f9
--- /dev/null
+++ b/metrics/influxdb/README.md
@@ -0,0 +1,30 @@
+go-metrics-influxdb
+===================
+
+This is a reporter for the [go-metrics](https://github.com/rcrowley/go-metrics) library which will post the metrics to [InfluxDB](https://influxdb.com/).
+
+Note
+----
+
+This is only compatible with InfluxDB 0.9+.
+
+Usage
+-----
+
+```go
+import "github.com/vrischmann/go-metrics-influxdb"
+
+go influxdb.InfluxDB(
+    metrics.DefaultRegistry, // metrics registry
+    time.Second * 10,        // interval
+    "http://localhost:8086", // the InfluxDB url
+    "mydb",                  // your InfluxDB database
+    "myuser",                // your InfluxDB user
+    "mypassword",            // your InfluxDB password
+)
+```
+
+License
+-------
+
+go-metrics-influxdb is licensed under the MIT license. See the LICENSE file for details.
diff --git a/metrics/influxdb/influxdb.go b/metrics/influxdb/influxdb.go
new file mode 100644
index 000000000..d5cb4da66
--- /dev/null
+++ b/metrics/influxdb/influxdb.go
@@ -0,0 +1,227 @@
+package influxdb
+
+import (
+	"fmt"
+	"log"
+	uurl "net/url"
+	"time"
+
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/influxdata/influxdb/client"
+)
+
+type reporter struct {
+	reg      metrics.Registry
+	interval time.Duration
+
+	url       uurl.URL
+	database  string
+	username  string
+	password  string
+	namespace string
+	tags      map[string]string
+
+	client *client.Client
+
+	cache map[string]int64
+}
+
+// InfluxDB starts a InfluxDB reporter which will post the from the given metrics.Registry at each d interval.
+func InfluxDB(r metrics.Registry, d time.Duration, url, database, username, password, namespace string) {
+	InfluxDBWithTags(r, d, url, database, username, password, namespace, nil)
+}
+
+// InfluxDBWithTags starts a InfluxDB reporter which will post the from the given metrics.Registry at each d interval with the specified tags
+func InfluxDBWithTags(r metrics.Registry, d time.Duration, url, database, username, password, namespace string, tags map[string]string) {
+	u, err := uurl.Parse(url)
+	if err != nil {
+		log.Printf("unable to parse InfluxDB url %s. err=%v", url, err)
+		return
+	}
+
+	rep := &reporter{
+		reg:       r,
+		interval:  d,
+		url:       *u,
+		database:  database,
+		username:  username,
+		password:  password,
+		namespace: namespace,
+		tags:      tags,
+		cache:     make(map[string]int64),
+	}
+	if err := rep.makeClient(); err != nil {
+		log.Printf("unable to make InfluxDB client. err=%v", err)
+		return
+	}
+
+	rep.run()
+}
+
+func (r *reporter) makeClient() (err error) {
+	r.client, err = client.NewClient(client.Config{
+		URL:      r.url,
+		Username: r.username,
+		Password: r.password,
+	})
+
+	return
+}
+
+func (r *reporter) run() {
+	intervalTicker := time.Tick(r.interval)
+	pingTicker := time.Tick(time.Second * 5)
+
+	for {
+		select {
+		case <-intervalTicker:
+			if err := r.send(); err != nil {
+				log.Printf("unable to send to InfluxDB. err=%v", err)
+			}
+		case <-pingTicker:
+			_, _, err := r.client.Ping()
+			if err != nil {
+				log.Printf("got error while sending a ping to InfluxDB, trying to recreate client. err=%v", err)
+
+				if err = r.makeClient(); err != nil {
+					log.Printf("unable to make InfluxDB client. err=%v", err)
+				}
+			}
+		}
+	}
+}
+
+func (r *reporter) send() error {
+	var pts []client.Point
+
+	r.reg.Each(func(name string, i interface{}) {
+		now := time.Now()
+		namespace := r.namespace
+
+		switch metric := i.(type) {
+		case metrics.Counter:
+			v := metric.Count()
+			l := r.cache[name]
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.count", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"value": v - l,
+				},
+				Time: now,
+			})
+			r.cache[name] = v
+		case metrics.Gauge:
+			ms := metric.Snapshot()
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.gauge", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"value": ms.Value(),
+				},
+				Time: now,
+			})
+		case metrics.GaugeFloat64:
+			ms := metric.Snapshot()
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.gauge", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"value": ms.Value(),
+				},
+				Time: now,
+			})
+		case metrics.Histogram:
+			ms := metric.Snapshot()
+			ps := ms.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999, 0.9999})
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.histogram", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"count":    ms.Count(),
+					"max":      ms.Max(),
+					"mean":     ms.Mean(),
+					"min":      ms.Min(),
+					"stddev":   ms.StdDev(),
+					"variance": ms.Variance(),
+					"p50":      ps[0],
+					"p75":      ps[1],
+					"p95":      ps[2],
+					"p99":      ps[3],
+					"p999":     ps[4],
+					"p9999":    ps[5],
+				},
+				Time: now,
+			})
+		case metrics.Meter:
+			ms := metric.Snapshot()
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.meter", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"count": ms.Count(),
+					"m1":    ms.Rate1(),
+					"m5":    ms.Rate5(),
+					"m15":   ms.Rate15(),
+					"mean":  ms.RateMean(),
+				},
+				Time: now,
+			})
+		case metrics.Timer:
+			ms := metric.Snapshot()
+			ps := ms.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999, 0.9999})
+			pts = append(pts, client.Point{
+				Measurement: fmt.Sprintf("%s%s.timer", namespace, name),
+				Tags:        r.tags,
+				Fields: map[string]interface{}{
+					"count":    ms.Count(),
+					"max":      ms.Max(),
+					"mean":     ms.Mean(),
+					"min":      ms.Min(),
+					"stddev":   ms.StdDev(),
+					"variance": ms.Variance(),
+					"p50":      ps[0],
+					"p75":      ps[1],
+					"p95":      ps[2],
+					"p99":      ps[3],
+					"p999":     ps[4],
+					"p9999":    ps[5],
+					"m1":       ms.Rate1(),
+					"m5":       ms.Rate5(),
+					"m15":      ms.Rate15(),
+					"meanrate": ms.RateMean(),
+				},
+				Time: now,
+			})
+		case metrics.ResettingTimer:
+			t := metric.Snapshot()
+
+			if len(t.Values()) > 0 {
+				ps := t.Percentiles([]float64{50, 95, 99})
+				val := t.Values()
+				pts = append(pts, client.Point{
+					Measurement: fmt.Sprintf("%s%s.span", namespace, name),
+					Tags:        r.tags,
+					Fields: map[string]interface{}{
+						"count": len(val),
+						"max":   val[len(val)-1],
+						"mean":  t.Mean(),
+						"min":   val[0],
+						"p50":   ps[0],
+						"p95":   ps[1],
+						"p99":   ps[2],
+					},
+					Time: now,
+				})
+			}
+		}
+	})
+
+	bps := client.BatchPoints{
+		Points:   pts,
+		Database: r.database,
+	}
+
+	_, err := r.client.Write(bps)
+	return err
+}