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// Copyright 2017 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 trace
import (
"bytes"
"io/ioutil"
"math"
"testing"
"time"
)
// aeq returns true if x and y are equal up to 8 digits (1 part in 100
// million).
func aeq(x, y float64) bool {
if x < 0 && y < 0 {
x, y = -x, -y
}
const digits = 8
factor := 1 - math.Pow(10, -digits+1)
return x*factor <= y && y*factor <= x
}
func TestMMU(t *testing.T) {
t.Parallel()
// MU
// 1.0 ***** ***** *****
// 0.5 * * * *
// 0.0 ***** *****
// 0 1 2 3 4 5
util := [][]MutatorUtil{{
{0e9, 1},
{1e9, 0},
{2e9, 1},
{3e9, 0},
{4e9, 1},
{5e9, 0},
}}
mmuCurve := NewMMUCurve(util)
for _, test := range []struct {
window time.Duration
want float64
worst []float64
}{
{0, 0, []float64{}},
{time.Millisecond, 0, []float64{0, 0}},
{time.Second, 0, []float64{0, 0}},
{2 * time.Second, 0.5, []float64{0.5, 0.5}},
{3 * time.Second, 1 / 3.0, []float64{1 / 3.0}},
{4 * time.Second, 0.5, []float64{0.5}},
{5 * time.Second, 3 / 5.0, []float64{3 / 5.0}},
{6 * time.Second, 3 / 5.0, []float64{3 / 5.0}},
} {
if got := mmuCurve.MMU(test.window); !aeq(test.want, got) {
t.Errorf("for %s window, want mu = %f, got %f", test.window, test.want, got)
}
worst := mmuCurve.Examples(test.window, 2)
// Which exact windows are returned is unspecified
// (and depends on the exact banding), so we just
// check that we got the right number with the right
// utilizations.
if len(worst) != len(test.worst) {
t.Errorf("for %s window, want worst %v, got %v", test.window, test.worst, worst)
} else {
for i := range worst {
if worst[i].MutatorUtil != test.worst[i] {
t.Errorf("for %s window, want worst %v, got %v", test.window, test.worst, worst)
break
}
}
}
}
}
func TestMMUTrace(t *testing.T) {
// Can't be t.Parallel() because it modifies the
// testingOneBand package variable.
data, err := ioutil.ReadFile("testdata/stress_1_10_good")
if err != nil {
t.Fatalf("failed to read input file: %v", err)
}
_, events, err := parse(bytes.NewReader(data), "")
if err != nil {
t.Fatalf("failed to parse trace: %s", err)
}
mu := MutatorUtilization(events.Events, UtilSTW|UtilBackground|UtilAssist)
mmuCurve := NewMMUCurve(mu)
// Test the optimized implementation against the "obviously
// correct" implementation.
for window := time.Nanosecond; window < 10*time.Second; window *= 10 {
want := mmuSlow(mu[0], window)
got := mmuCurve.MMU(window)
if !aeq(want, got) {
t.Errorf("want %f, got %f mutator utilization in window %s", want, got, window)
}
}
// Test MUD with band optimization against MUD without band
// optimization. We don't have a simple testing implementation
// of MUDs (the simplest implementation is still quite
// complex), but this is still a pretty good test.
defer func(old int) { bandsPerSeries = old }(bandsPerSeries)
bandsPerSeries = 1
mmuCurve2 := NewMMUCurve(mu)
quantiles := []float64{0, 1 - .999, 1 - .99}
for window := time.Microsecond; window < time.Second; window *= 10 {
mud1 := mmuCurve.MUD(window, quantiles)
mud2 := mmuCurve2.MUD(window, quantiles)
for i := range mud1 {
if !aeq(mud1[i], mud2[i]) {
t.Errorf("for quantiles %v at window %v, want %v, got %v", quantiles, window, mud2, mud1)
break
}
}
}
}
func BenchmarkMMU(b *testing.B) {
data, err := ioutil.ReadFile("testdata/stress_1_10_good")
if err != nil {
b.Fatalf("failed to read input file: %v", err)
}
_, events, err := parse(bytes.NewReader(data), "")
if err != nil {
b.Fatalf("failed to parse trace: %s", err)
}
mu := MutatorUtilization(events.Events, UtilSTW|UtilBackground|UtilAssist|UtilSweep)
b.ResetTimer()
for i := 0; i < b.N; i++ {
mmuCurve := NewMMUCurve(mu)
xMin, xMax := time.Microsecond, time.Second
logMin, logMax := math.Log(float64(xMin)), math.Log(float64(xMax))
const samples = 100
for i := 0; i < samples; i++ {
window := time.Duration(math.Exp(float64(i)/(samples-1)*(logMax-logMin) + logMin))
mmuCurve.MMU(window)
}
}
}
func mmuSlow(util []MutatorUtil, window time.Duration) (mmu float64) {
if max := time.Duration(util[len(util)-1].Time - util[0].Time); window > max {
window = max
}
mmu = 1.0
// muInWindow returns the mean mutator utilization between
// util[0].Time and end.
muInWindow := func(util []MutatorUtil, end int64) float64 {
total := 0.0
var prevU MutatorUtil
for _, u := range util {
if u.Time > end {
total += prevU.Util * float64(end-prevU.Time)
break
}
total += prevU.Util * float64(u.Time-prevU.Time)
prevU = u
}
return total / float64(end-util[0].Time)
}
update := func() {
for i, u := range util {
if u.Time+int64(window) > util[len(util)-1].Time {
break
}
mmu = math.Min(mmu, muInWindow(util[i:], u.Time+int64(window)))
}
}
// Consider all left-aligned windows.
update()
// Reverse the trace. Slightly subtle because each MutatorUtil
// is a *change*.
rutil := make([]MutatorUtil, len(util))
if util[len(util)-1].Util != 0 {
panic("irreversible trace")
}
for i, u := range util {
util1 := 0.0
if i != 0 {
util1 = util[i-1].Util
}
rutil[len(rutil)-i-1] = MutatorUtil{Time: -u.Time, Util: util1}
}
util = rutil
// Consider all right-aligned windows.
update()
return
}
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