From 7e3f7461ef5f81202ae533c860822abd6e9eb883 Mon Sep 17 00:00:00 2001
From: Matthew Pound <mwp@signalfx.com>
Date: Fri, 22 May 2020 14:16:31 -0700
Subject: [PATCH] add ability to expose go-metrics as sfxclient.Collector

---
 go-metrics/exporter.go      | 91 +++++++++++++++++++++++++++++++++++++
 go-metrics/exporter_test.go | 24 ++++++++++
 go.mod                      |  1 +
 go.sum                      |  2 +
 4 files changed, 118 insertions(+)
 create mode 100644 go-metrics/exporter.go
 create mode 100644 go-metrics/exporter_test.go

diff --git a/go-metrics/exporter.go b/go-metrics/exporter.go
new file mode 100644
index 0000000..3957d16
--- /dev/null
+++ b/go-metrics/exporter.go
@@ -0,0 +1,91 @@
+package go_metrics
+
+import (
+	"github.com/rcrowley/go-metrics"
+	"github.com/signalfx/golib/v3/datapoint"
+	"github.com/signalfx/golib/v3/sfxclient"
+)
+
+var defaultQuantiles = []float64{.25, .5, .9, .99}
+
+// Exporter wraps the go-metrics registry as an sfxclient.Collector
+type Exporter struct {
+	r        metrics.Registry
+	lastSize int
+	dims     map[string]string
+}
+
+func (e *Exporter) metricToDatapoints(dps []*datapoint.Datapoint, name string, i interface{}) []*datapoint.Datapoint {
+	switch metric := i.(type) {
+	case metrics.Counter:
+		dps = append(dps, sfxclient.Counter(name, e.dims, metric.Count()))
+
+	case metrics.Gauge:
+		dps = append(dps, sfxclient.Gauge(name, e.dims, metric.Value()))
+
+	case metrics.GaugeFloat64:
+		dps = append(dps, sfxclient.GaugeF(name, e.dims, metric.Value()))
+
+	case metrics.Histogram:
+		h := metric.Snapshot()
+		dps = e.harvestHistoTypeThing(dps, name, h)
+
+	case metrics.Meter:
+		m := metric.Snapshot()
+		dps = append(dps,
+			sfxclient.Counter(name+".count", e.dims, m.Count()),
+			sfxclient.GaugeF(name+".1m", e.dims, m.Rate1()),
+			sfxclient.GaugeF(name+".5m", e.dims, m.Rate5()),
+			sfxclient.GaugeF(name+".15m", e.dims, m.Rate15()),
+			sfxclient.GaugeF(name+".meanRate", e.dims, m.RateMean()),
+		)
+
+	case metrics.Timer:
+		t := metric.Snapshot()
+		dps = e.harvestHistoTypeThing(dps, name, t)
+	}
+	return dps
+}
+
+type histoTypeThing interface {
+	Count() int64
+	Max() int64
+	Mean() float64
+	Min() int64
+	Percentile(float64) float64
+	Percentiles([]float64) []float64
+	StdDev() float64
+	Sum() int64
+	Variance() float64
+}
+
+func (e *Exporter) harvestHistoTypeThing(dps []*datapoint.Datapoint, name string, h histoTypeThing) []*datapoint.Datapoint {
+	ps := h.Percentiles(defaultQuantiles)
+	dps = append(dps,
+		sfxclient.Counter(name+".count", e.dims, h.Count()),
+		sfxclient.Gauge(name+".min", e.dims, h.Min()),
+		sfxclient.Gauge(name+".max", e.dims, h.Max()),
+		sfxclient.GaugeF(name+".mean", e.dims, h.Mean()),
+		sfxclient.GaugeF(name+".stdDev", e.dims, h.StdDev()),
+		sfxclient.GaugeF(name+".p25", e.dims, ps[0]),
+		sfxclient.GaugeF(name+".median", e.dims, ps[1]),
+		sfxclient.GaugeF(name+".p90", e.dims, ps[2]),
+		sfxclient.GaugeF(name+".p99", e.dims, ps[3]),
+	)
+	return dps
+}
+
+// Datapoints implements sfxclient.Collector
+func (e *Exporter) Datapoints() []*datapoint.Datapoint {
+	dps := make([]*datapoint.Datapoint, 0, e.lastSize)
+	e.r.Each(func(name string, i interface{}) {
+		dps = e.metricToDatapoints(dps, name, i)
+	})
+	e.lastSize = len(dps)
+	return dps
+}
+
+// New returns a new &Exporter
+func New(r metrics.Registry, dims map[string]string) *Exporter {
+	return &Exporter{r: r, dims: dims}
+}
diff --git a/go-metrics/exporter_test.go b/go-metrics/exporter_test.go
new file mode 100644
index 0000000..dbae877
--- /dev/null
+++ b/go-metrics/exporter_test.go
@@ -0,0 +1,24 @@
+package go_metrics
+
+import (
+	"testing"
+
+	"github.com/rcrowley/go-metrics"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func Test(t *testing.T) {
+	Convey("test the go-metrics exporter", t, func() {
+		r := metrics.NewRegistry()
+		e := New(r, map[string]string{"foo": "bar"})
+		r.Register("timer", metrics.NewTimer())
+		r.Register("histo", metrics.NewHistogram(metrics.NewUniformSample(10)))
+		r.Register("gague", metrics.NewGauge())
+		r.Register("f64", metrics.NewGaugeFloat64())
+		r.Register("meter", metrics.NewMeter())
+		r.Register("counter", metrics.NewCounter())
+
+		dps := e.Datapoints()
+		So(len(dps), ShouldEqual, 26)
+	})
+}
diff --git a/go.mod b/go.mod
index 8c0ec21..6e38688 100644
--- a/go.mod
+++ b/go.mod
@@ -20,6 +20,7 @@ require (
 	github.com/juju/testing v0.0.0-20191001232224-ce9dec17d28b // indirect
 	github.com/mailru/easyjson v0.0.0-20190626092158-b2ccc519800e
 	github.com/opentracing/opentracing-go v1.1.0
+	github.com/rcrowley/go-metrics v0.0.0-20200313005456-10cdbea86bc0
 	github.com/samuel/go-zookeeper v0.0.0-20190810000440-0ceca61e4d75
 	github.com/shirou/gopsutil v2.18.10+incompatible
 	github.com/shirou/w32 v0.0.0-20160930032740-bb4de0191aa4 // indirect
diff --git a/go.sum b/go.sum
index 5776dc2..2fe045a 100644
--- a/go.sum
+++ b/go.sum
@@ -71,6 +71,8 @@ github.com/pavius/impi v0.0.0-20180302134524-c1cbdcb8df2b h1:yS0+/i6mwRZCdssUd+M
 github.com/pavius/impi v0.0.0-20180302134524-c1cbdcb8df2b/go.mod h1:x/hU0bfdWIhuOT1SKwiJg++yvkk6EuOtJk8WtDZqgr8=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rcrowley/go-metrics v0.0.0-20200313005456-10cdbea86bc0 h1:MkV+77GLUNo5oJ0jf870itWm3D0Sjh7+Za9gazKc5LQ=
+github.com/rcrowley/go-metrics v0.0.0-20200313005456-10cdbea86bc0/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/samuel/go-zookeeper v0.0.0-20190810000440-0ceca61e4d75 h1:cA+Ubq9qEVIQhIWvP2kNuSZ2CmnfBJFSRq+kO1pu2cc=
 github.com/samuel/go-zookeeper v0.0.0-20190810000440-0ceca61e4d75/go.mod h1:gi+0XIa01GRL2eRQVjQkKGqKF3SF9vZR/HnPullcV2E=