From e37bee9bf2520fcdaae79113185c105068bfa552 Mon Sep 17 00:00:00 2001
From: Dave Rawks <dave@pandora.com>
Date: Mon, 14 Aug 2017 11:20:47 -0700
Subject: [PATCH 1/3] Resolves #88 - histograms use wrong units

---
 exporter.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporter.go b/exporter.go
index 3ebdf44..6f6e20e 100644
--- a/exporter.go
+++ b/exporter.go
@@ -327,7 +327,7 @@ func (b *Exporter) Listen(e <-chan Events) {
 						mapping,
 					)
 					if err == nil {
-						histogram.Observe(event.Value())
+						histogram.Observe(event.Value() / 1000) // prometheus presumes seconds, statsd millisecond
 						eventStats.WithLabelValues("timer").Inc()
 					} else {
 						log.Errorf(regErrF, metricName, err)

From b2082eda2b101f3a02f78c254c94a76bbed513ee Mon Sep 17 00:00:00 2001
From: Dave Rawks <dave@pandora.com>
Date: Mon, 14 Aug 2017 15:20:45 -0700
Subject: [PATCH 2/3] Added test for histogram unit conversion

---
 exporter_test.go | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/exporter_test.go b/exporter_test.go
index cbfb910..d37f0ba 100644
--- a/exporter_test.go
+++ b/exporter_test.go
@@ -15,6 +15,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/prometheus/client_golang/prometheus"
 	"net"
 	"testing"
 	"time"
@@ -74,6 +75,44 @@ func TestInvalidUtf8InDatadogTagValue(t *testing.T) {
 	}
 }
 
+type MockHistogram struct {
+	prometheus.Metric
+	prometheus.Collector
+	value float64
+}
+
+func (h *MockHistogram) Observe(n float64) {
+	h.value = n
+
+}
+
+func TestHistogramUnits(t *testing.T) {
+	events := make(chan Events, 1)
+	c := Events{
+		&TimerEvent{
+			metricName: "foo",
+			value:      300,
+		},
+	}
+	events <- c
+	ex := NewExporter(&metricMapper{}, true)
+	ex.mapper.Defaults.TimerType = timerTypeHistogram
+
+	// Close channel to signify we are done with the listener after a short period.
+	go func() {
+		time.Sleep(time.Millisecond * 100)
+		close(events)
+	}()
+	mock := &MockHistogram{}
+	ex.Histograms.Elements[7787632782521330630] = mock
+	ex.Listen(events)
+	if mock.value == 300 {
+		t.Fatalf("Histogram observations not scaled into Seconds")
+	} else if mock.value != .300 {
+		t.Fatalf("Received unexpected value for histogram observation %f != .300", mock.value)
+	}
+}
+
 type statsDPacketHandler interface {
 	handlePacket(packet []byte, e chan<- Events)
 }

From 06444ed5c0411bc64e473e81533a2da5bc0df87c Mon Sep 17 00:00:00 2001
From: Dave Rawks <dave@pandora.com>
Date: Tue, 15 Aug 2017 08:51:13 -0700
Subject: [PATCH 3/3] Minor fix-ups per PR discussion

  * Removed extraneous newline
  * Reformatted/ordered imports
  * Used hash function to derive index of `Elements` instead of
    hardcoding hash result
---
 exporter_test.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/exporter_test.go b/exporter_test.go
index d37f0ba..3d81f99 100644
--- a/exporter_test.go
+++ b/exporter_test.go
@@ -15,10 +15,11 @@ package main
 
 import (
 	"fmt"
-	"github.com/prometheus/client_golang/prometheus"
 	"net"
 	"testing"
 	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 // TestNegativeCounter validates when we send a negative
@@ -83,14 +84,14 @@ type MockHistogram struct {
 
 func (h *MockHistogram) Observe(n float64) {
 	h.value = n
-
 }
 
 func TestHistogramUnits(t *testing.T) {
 	events := make(chan Events, 1)
+	name := "foo"
 	c := Events{
 		&TimerEvent{
-			metricName: "foo",
+			metricName: name,
 			value:      300,
 		},
 	}
@@ -104,7 +105,8 @@ func TestHistogramUnits(t *testing.T) {
 		close(events)
 	}()
 	mock := &MockHistogram{}
-	ex.Histograms.Elements[7787632782521330630] = mock
+	key := hashNameAndLabels(name+"_timer", nil)
+	ex.Histograms.Elements[key] = mock
 	ex.Listen(events)
 	if mock.value == 300 {
 		t.Fatalf("Histogram observations not scaled into Seconds")