From e44d3abc775efbef6a53e6a540b0bd818297658e Mon Sep 17 00:00:00 2001
From: Gyu-Ho Lee <gyuhox@gmail.com>
Date: Tue, 10 Jan 2017 18:15:53 -0800
Subject: [PATCH] pkg/report: support 99.9-percentile, change column name

---
 pkg/report/report.go      | 22 +++++++++++++++-------
 pkg/report/report_test.go | 33 +++++++++++++++++++++++++++++++++
 pkg/report/timeseries.go  |  2 +-
 3 files changed, 49 insertions(+), 8 deletions(-)
 create mode 100644 pkg/report/report_test.go

diff --git a/pkg/report/report.go b/pkg/report/report.go
index ea4d17695..bf8b47730 100644
--- a/pkg/report/report.go
+++ b/pkg/report/report.go
@@ -99,7 +99,7 @@ func (r *report) String() (s string) {
 		s += fmt.Sprintf("  Stddev:\t%s.\n", r.sec2str(r.stddev))
 		s += fmt.Sprintf("  Requests/sec:\t"+r.precision+"\n", r.rps)
 		s += r.histogram()
-		s += r.latencies()
+		s += r.sprintLatencies()
 		if r.sps != nil {
 			s += fmt.Sprintf("%v\n", r.sps.getTimeSeries())
 		}
@@ -156,17 +156,25 @@ func (r *report) processResults() {
 	}
 }
 
-func (r *report) latencies() string {
-	pctls := []int{10, 25, 50, 75, 90, 95, 99}
-	data := make([]float64, len(pctls))
+var pctls = []float64{10, 25, 50, 75, 90, 95, 99, 99.9}
+
+// percentiles returns percentile distribution of float64 slice.
+func percentiles(nums []float64) (data []float64) {
+	data = make([]float64, len(pctls))
 	j := 0
-	for i := 0; i < len(r.lats) && j < len(pctls); i++ {
-		current := i * 100 / len(r.lats)
+	n := len(nums)
+	for i := 0; i < n && j < len(pctls); i++ {
+		current := float64(i) * 100.0 / float64(n)
 		if current >= pctls[j] {
-			data[j] = r.lats[i]
+			data[j] = nums[i]
 			j++
 		}
 	}
+	return
+}
+
+func (r *report) sprintLatencies() string {
+	data := percentiles(r.lats)
 	s := fmt.Sprintf("\nLatency distribution:\n")
 	for i := 0; i < len(pctls); i++ {
 		if data[i] > 0 {
diff --git a/pkg/report/report_test.go b/pkg/report/report_test.go
new file mode 100644
index 000000000..a77c1a68d
--- /dev/null
+++ b/pkg/report/report_test.go
@@ -0,0 +1,33 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package report
+
+import "testing"
+
+func TestPercentiles(t *testing.T) {
+	nums := make([]float64, 100)
+	nums[99] = 1 // 99-percentile (1 out of 100)
+	data := percentiles(nums)
+	if data[len(pctls)-2] != 1 {
+		t.Fatalf("99-percentile expected 1, got %f", data[len(pctls)-2])
+	}
+
+	nums = make([]float64, 1000)
+	nums[999] = 1 // 99.9-percentile (1 out of 1000)
+	data = percentiles(nums)
+	if data[len(pctls)-1] != 1 {
+		t.Fatalf("99.9-percentile expected 1, got %f", data[len(pctls)-1])
+	}
+}
diff --git a/pkg/report/timeseries.go b/pkg/report/timeseries.go
index 0cabb2339..76c194911 100644
--- a/pkg/report/timeseries.go
+++ b/pkg/report/timeseries.go
@@ -111,7 +111,7 @@ func (sp *secondPoints) getTimeSeries() TimeSeries {
 func (ts TimeSeries) String() string {
 	buf := new(bytes.Buffer)
 	wr := csv.NewWriter(buf)
-	if err := wr.Write([]string{"unix_ts", "avg_latency", "throughput"}); err != nil {
+	if err := wr.Write([]string{"UNIX-TS", "AVG-LATENCY-MS", "AVG-THROUGHPUT"}); err != nil {
 		log.Fatal(err)
 	}
 	rows := [][]string{}