Merge pull request #49 from prometheus/beorn7/fix-summaries
Beorn7/fix summaries
This commit is contained in:
Björn Rabenstein
commit
d5fe8ed656
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@ -1 +1 @@
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Imported at 5d903d2c5dc7f55829e36c62ae6c5f5f6d75e70a from https://github.com/u-c-l/perks .
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Imported at f15ca8fc2964cb9f291e1cf17bb1bf9a4f9e23d5 from https://github.com/beorn7/perks .
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@ -0,0 +1,26 @@
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package histogram
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import (
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"math/rand"
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"testing"
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)
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func BenchmarkInsert10Bins(b *testing.B) {
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b.StopTimer()
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h := New(10)
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b.StartTimer()
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for i := 0; i < b.N; i++ {
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f := rand.ExpFloat64()
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h.Insert(f)
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}
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}
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func BenchmarkInsert100Bins(b *testing.B) {
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b.StopTimer()
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h := New(100)
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b.StartTimer()
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for i := 0; i < b.N; i++ {
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f := rand.ExpFloat64()
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h.Insert(f)
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}
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}
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@ -0,0 +1,108 @@
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// Package histogram provides a Go implementation of BigML's histogram package
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// for Clojure/Java. It is currently experimental.
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package histogram
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import (
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"container/heap"
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"math"
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"sort"
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)
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type Bin struct {
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Count int
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Sum float64
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}
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func (b *Bin) Update(x *Bin) {
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b.Count += x.Count
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b.Sum += x.Sum
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}
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func (b *Bin) Mean() float64 {
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return b.Sum / float64(b.Count)
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}
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type Bins []*Bin
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func (bs Bins) Len() int { return len(bs) }
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func (bs Bins) Less(i, j int) bool { return bs[i].Mean() < bs[j].Mean() }
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func (bs Bins) Swap(i, j int) { bs[i], bs[j] = bs[j], bs[i] }
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func (bs *Bins) Push(x interface{}) {
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*bs = append(*bs, x.(*Bin))
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}
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func (bs *Bins) Pop() interface{} {
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return bs.remove(len(*bs) - 1)
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}
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func (bs *Bins) remove(n int) *Bin {
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if n < 0 || len(*bs) < n {
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return nil
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}
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x := (*bs)[n]
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*bs = append((*bs)[:n], (*bs)[n+1:]...)
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return x
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}
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type Histogram struct {
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res *reservoir
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}
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func New(maxBins int) *Histogram {
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return &Histogram{res: newReservoir(maxBins)}
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}
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func (h *Histogram) Insert(f float64) {
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h.res.insert(&Bin{1, f})
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h.res.compress()
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}
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func (h *Histogram) Bins() Bins {
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return h.res.bins
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}
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type reservoir struct {
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n int
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maxBins int
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bins Bins
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}
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func newReservoir(maxBins int) *reservoir {
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return &reservoir{maxBins: maxBins}
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}
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func (r *reservoir) insert(bin *Bin) {
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r.n += bin.Count
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i := sort.Search(len(r.bins), func(i int) bool {
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return r.bins[i].Mean() >= bin.Mean()
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})
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if i < 0 || i == r.bins.Len() {
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// TODO(blake): Maybe use an .insert(i, bin) instead of
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// performing the extra work of a heap.Push.
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heap.Push(&r.bins, bin)
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return
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}
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r.bins[i].Update(bin)
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}
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func (r *reservoir) compress() {
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for r.bins.Len() > r.maxBins {
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minGapIndex := -1
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minGap := math.MaxFloat64
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for i := 0; i < r.bins.Len()-1; i++ {
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gap := gapWeight(r.bins[i], r.bins[i+1])
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if minGap > gap {
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minGap = gap
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minGapIndex = i
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}
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}
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prev := r.bins[minGapIndex]
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next := r.bins.remove(minGapIndex + 1)
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prev.Update(next)
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}
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}
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func gapWeight(prev, next *Bin) float64 {
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return next.Mean() - prev.Mean()
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}
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@ -0,0 +1,38 @@
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package histogram
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import (
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"math/rand"
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"testing"
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)
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func TestHistogram(t *testing.T) {
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const numPoints = 1e6
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const maxBins = 3
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h := New(maxBins)
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for i := 0; i < numPoints; i++ {
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f := rand.ExpFloat64()
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h.Insert(f)
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}
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bins := h.Bins()
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if g := len(bins); g > maxBins {
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t.Fatalf("got %d bins, wanted <= %d", g, maxBins)
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}
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for _, b := range bins {
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t.Logf("%+v", b)
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}
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if g := count(h.Bins()); g != numPoints {
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t.Fatalf("binned %d points, wanted %d", g, numPoints)
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}
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}
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func count(bins Bins) int {
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binCounts := 0
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for _, b := range bins {
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binCounts += b.Count
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}
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return binCounts
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}
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@ -7,7 +7,7 @@ import (
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func BenchmarkInsertTargeted(b *testing.B) {
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b.ReportAllocs()
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s := NewTargeted(0.01, 0.5, 0.9, 0.99)
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s := NewTargeted(Targets)
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b.ResetTimer()
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for i := float64(0); i < float64(b.N); i++ {
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s.Insert(i)
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@ -15,8 +15,7 @@ func BenchmarkInsertTargeted(b *testing.B) {
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}
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func BenchmarkInsertTargetedSmallEpsilon(b *testing.B) {
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s := NewTargeted(0.01, 0.5, 0.9, 0.99)
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s.SetEpsilon(0.0001)
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s := NewTargeted(TargetsSmallEpsilon)
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b.ResetTimer()
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for i := float64(0); i < float64(b.N); i++ {
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s.Insert(i)
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@ -24,7 +23,7 @@ func BenchmarkInsertTargetedSmallEpsilon(b *testing.B) {
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}
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func BenchmarkInsertBiased(b *testing.B) {
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s := NewBiased()
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s := NewLowBiased(0.01)
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b.ResetTimer()
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for i := float64(0); i < float64(b.N); i++ {
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s.Insert(i)
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@ -32,8 +31,7 @@ func BenchmarkInsertBiased(b *testing.B) {
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}
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func BenchmarkInsertBiasedSmallEpsilon(b *testing.B) {
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s := NewBiased()
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s.SetEpsilon(0.0001)
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s := NewLowBiased(0.0001)
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b.ResetTimer()
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for i := float64(0); i < float64(b.N); i++ {
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s.Insert(i)
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@ -41,7 +39,7 @@ func BenchmarkInsertBiasedSmallEpsilon(b *testing.B) {
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}
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func BenchmarkQuery(b *testing.B) {
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s := NewTargeted(0.01, 0.5, 0.9, 0.99)
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s := NewTargeted(Targets)
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for i := float64(0); i < 1e6; i++ {
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s.Insert(i)
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}
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@ -53,8 +51,7 @@ func BenchmarkQuery(b *testing.B) {
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}
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func BenchmarkQuerySmallEpsilon(b *testing.B) {
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s := NewTargeted(0.01, 0.5, 0.9, 0.99)
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s.SetEpsilon(0.0001)
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s := NewTargeted(TargetsSmallEpsilon)
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for i := float64(0); i < 1e6; i++ {
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s.Insert(i)
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}
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@ -36,30 +36,56 @@ func (a Samples) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
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type invariant func(s *stream, r float64) float64
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// NewBiased returns an initialized Stream for high-biased quantiles (e.g.
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// 50th, 90th, 99th) not known a priori with finer error guarantees for the
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// higher ranks of the data distribution.
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// See http://www.cs.rutgers.edu/~muthu/bquant.pdf for time, space, and error properties.
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func NewBiased() *Stream {
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// NewLowBiased returns an initialized Stream for low-biased quantiles
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// (e.g. 0.01, 0.1, 0.5) where the needed quantiles are not known a priori, but
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// error guarantees can still be given even for the lower ranks of the data
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// distribution.
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//
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// The provided epsilon is a relative error, i.e. the true quantile of a value
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// returned by a query is guaranteed to be within (1±Epsilon)*Quantile.
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//
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// See http://www.cs.rutgers.edu/~muthu/bquant.pdf for time, space, and error
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// properties.
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func NewLowBiased(epsilon float64) *Stream {
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ƒ := func(s *stream, r float64) float64 {
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return 2 * s.epsilon * r
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return 2 * epsilon * r
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}
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return newStream(ƒ)
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}
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// NewHighBiased returns an initialized Stream for high-biased quantiles
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// (e.g. 0.01, 0.1, 0.5) where the needed quantiles are not known a priori, but
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// error guarantees can still be given even for the higher ranks of the data
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// distribution.
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//
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// The provided epsilon is a relative error, i.e. the true quantile of a value
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// returned by a query is guaranteed to be within 1-(1±Epsilon)*(1-Quantile).
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//
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// See http://www.cs.rutgers.edu/~muthu/bquant.pdf for time, space, and error
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// properties.
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func NewHighBiased(epsilon float64) *Stream {
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ƒ := func(s *stream, r float64) float64 {
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return 2 * epsilon * (s.n - r)
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}
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return newStream(ƒ)
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}
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// NewTargeted returns an initialized Stream concerned with a particular set of
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// quantile values that are supplied a priori. Knowing these a priori reduces
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// space and computation time.
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// space and computation time. The targets map maps the desired quantiles to
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// their absolute errors, i.e. the true quantile of a value returned by a query
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// is guaranteed to be within (Quantile±Epsilon).
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//
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// See http://www.cs.rutgers.edu/~muthu/bquant.pdf for time, space, and error properties.
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func NewTargeted(quantiles ...float64) *Stream {
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func NewTargeted(targets map[float64]float64) *Stream {
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ƒ := func(s *stream, r float64) float64 {
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var m float64 = math.MaxFloat64
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var m = math.MaxFloat64
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var f float64
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for _, q := range quantiles {
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if q*s.n <= r {
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f = (2 * s.epsilon * r) / q
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for quantile, epsilon := range targets {
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if quantile*s.n <= r {
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f = (2 * epsilon * r) / quantile
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} else {
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f = (2 * s.epsilon * (s.n - r)) / (1 - q)
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f = (2 * epsilon * (s.n - r)) / (1 - quantile)
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}
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if f < m {
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m = f
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@ -79,8 +105,7 @@ type Stream struct {
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}
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func newStream(ƒ invariant) *Stream {
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const defaultEpsilon = 0.01
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x := &stream{epsilon: defaultEpsilon, ƒ: ƒ}
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x := &stream{ƒ: ƒ}
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return &Stream{x, make(Samples, 0, 500), true}
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}
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@ -94,7 +119,6 @@ func (s *Stream) insert(sample Sample) {
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s.sorted = false
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if len(s.b) == cap(s.b) {
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s.flush()
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s.compress()
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}
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}
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@ -122,6 +146,9 @@ func (s *Stream) Query(q float64) float64 {
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// Merge merges samples into the underlying streams samples. This is handy when
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// merging multiple streams from separate threads, database shards, etc.
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//
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// ATTENTION: This method is broken and does not yield correct results. The
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// underlying algorithm is not capable of merging streams correctly.
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func (s *Stream) Merge(samples Samples) {
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sort.Sort(samples)
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s.stream.merge(samples)
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@ -139,7 +166,6 @@ func (s *Stream) Samples() Samples {
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return s.b
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}
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s.flush()
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s.compress()
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return s.stream.samples()
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}
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@ -167,18 +193,9 @@ func (s *Stream) flushed() bool {
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}
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type stream struct {
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epsilon float64
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n float64
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l []Sample
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ƒ invariant
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}
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// SetEpsilon sets the error epsilon for the Stream. The default epsilon is
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// 0.01 and is usually satisfactory. If needed, this must be called before all
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// Inserts.
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// To learn more, see: http://www.cs.rutgers.edu/~muthu/bquant.pdf
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func (s *stream) SetEpsilon(epsilon float64) {
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s.epsilon = epsilon
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n float64
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l []Sample
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ƒ invariant
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}
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func (s *stream) reset() {
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@ -191,6 +208,10 @@ func (s *stream) insert(v float64) {
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}
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func (s *stream) merge(samples Samples) {
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// TODO(beorn7): This tries to merge not only individual samples, but
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// whole summaries. The paper doesn't mention merging summaries at
|
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// all. Unittests show that the merging is inaccurate. Find out how to
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// do merges properly.
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var r float64
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i := 0
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for _, sample := range samples {
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|
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@ -200,7 +221,12 @@ func (s *stream) merge(samples Samples) {
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// Insert at position i.
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s.l = append(s.l, Sample{})
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copy(s.l[i+1:], s.l[i:])
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s.l[i] = Sample{sample.Value, sample.Width, math.Floor(s.ƒ(s, r)) - 1}
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s.l[i] = Sample{
|
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sample.Value,
|
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sample.Width,
|
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math.Max(sample.Delta, math.Floor(s.ƒ(s, r))-1),
|
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// TODO(beorn7): How to calculate delta correctly?
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}
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i++
|
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goto inserted
|
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}
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@ -210,7 +236,9 @@ func (s *stream) merge(samples Samples) {
|
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i++
|
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inserted:
|
||||
s.n += sample.Width
|
||||
r += sample.Width
|
||||
}
|
||||
s.compress()
|
||||
}
|
||||
|
||||
func (s *stream) count() int {
|
||||
|
|
@ -221,12 +249,12 @@ func (s *stream) query(q float64) float64 {
|
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t := math.Ceil(q * s.n)
|
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t += math.Ceil(s.ƒ(s, t) / 2)
|
||||
p := s.l[0]
|
||||
r := float64(0)
|
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var r float64
|
||||
for _, c := range s.l[1:] {
|
||||
r += p.Width
|
||||
if r+c.Width+c.Delta > t {
|
||||
return p.Value
|
||||
}
|
||||
r += p.Width
|
||||
p = c
|
||||
}
|
||||
return p.Value
|
||||
|
|
|
|||
|
|
@ -1,81 +1,150 @@
|
|||
package quantile
|
||||
|
||||
import (
|
||||
"math"
|
||||
"math/rand"
|
||||
"sort"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestQuantRandQuery(t *testing.T) {
|
||||
s := NewTargeted(0.5, 0.90, 0.99)
|
||||
a := make([]float64, 0, 1e5)
|
||||
rand.Seed(42)
|
||||
var (
|
||||
Targets = map[float64]float64{
|
||||
0.01: 0.001,
|
||||
0.10: 0.01,
|
||||
0.50: 0.05,
|
||||
0.90: 0.01,
|
||||
0.99: 0.001,
|
||||
}
|
||||
TargetsSmallEpsilon = map[float64]float64{
|
||||
0.01: 0.0001,
|
||||
0.10: 0.001,
|
||||
0.50: 0.005,
|
||||
0.90: 0.001,
|
||||
0.99: 0.0001,
|
||||
}
|
||||
LowQuantiles = []float64{0.01, 0.1, 0.5}
|
||||
HighQuantiles = []float64{0.99, 0.9, 0.5}
|
||||
)
|
||||
|
||||
const RelativeEpsilon = 0.01
|
||||
|
||||
func verifyPercsWithAbsoluteEpsilon(t *testing.T, a []float64, s *Stream) {
|
||||
sort.Float64s(a)
|
||||
for quantile, epsilon := range Targets {
|
||||
n := float64(len(a))
|
||||
k := int(quantile * n)
|
||||
lower := int((quantile - epsilon) * n)
|
||||
if lower < 1 {
|
||||
lower = 1
|
||||
}
|
||||
upper := int(math.Ceil((quantile + epsilon) * n))
|
||||
if upper > len(a) {
|
||||
upper = len(a)
|
||||
}
|
||||
w, min, max := a[k-1], a[lower-1], a[upper-1]
|
||||
if g := s.Query(quantile); g < min || g > max {
|
||||
t.Errorf("q=%f: want %v [%f,%f], got %v", quantile, w, min, max, g)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func verifyLowPercsWithRelativeEpsilon(t *testing.T, a []float64, s *Stream) {
|
||||
sort.Float64s(a)
|
||||
for _, qu := range LowQuantiles {
|
||||
n := float64(len(a))
|
||||
k := int(qu * n)
|
||||
|
||||
lowerRank := int((1 - RelativeEpsilon) * qu * n)
|
||||
upperRank := int(math.Ceil((1 + RelativeEpsilon) * qu * n))
|
||||
w, min, max := a[k-1], a[lowerRank-1], a[upperRank-1]
|
||||
if g := s.Query(qu); g < min || g > max {
|
||||
t.Errorf("q=%f: want %v [%f,%f], got %v", qu, w, min, max, g)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func verifyHighPercsWithRelativeEpsilon(t *testing.T, a []float64, s *Stream) {
|
||||
sort.Float64s(a)
|
||||
for _, qu := range HighQuantiles {
|
||||
n := float64(len(a))
|
||||
k := int(qu * n)
|
||||
|
||||
lowerRank := int((1 - (1+RelativeEpsilon)*(1-qu)) * n)
|
||||
upperRank := int(math.Ceil((1 - (1-RelativeEpsilon)*(1-qu)) * n))
|
||||
w, min, max := a[k-1], a[lowerRank-1], a[upperRank-1]
|
||||
if g := s.Query(qu); g < min || g > max {
|
||||
t.Errorf("q=%f: want %v [%f,%f], got %v", qu, w, min, max, g)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func populateStream(s *Stream) []float64 {
|
||||
a := make([]float64, 0, 1e5+100)
|
||||
for i := 0; i < cap(a); i++ {
|
||||
v := rand.NormFloat64()
|
||||
// Add 5% asymmetric outliers.
|
||||
if i%20 == 0 {
|
||||
v = v*v + 1
|
||||
}
|
||||
s.Insert(v)
|
||||
a = append(a, v)
|
||||
}
|
||||
t.Logf("len: %d", s.Count())
|
||||
sort.Float64s(a)
|
||||
w, min, max := getPerc(a, 0.50)
|
||||
if g := s.Query(0.50); g < min || g > max {
|
||||
t.Errorf("perc50: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
w, min, max = getPerc(a, 0.90)
|
||||
if g := s.Query(0.90); g < min || g > max {
|
||||
t.Errorf("perc90: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
w, min, max = getPerc(a, 0.99)
|
||||
if g := s.Query(0.99); g < min || g > max {
|
||||
t.Errorf("perc99: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
return a
|
||||
}
|
||||
|
||||
func TestQuantRandMergeQuery(t *testing.T) {
|
||||
ch := make(chan float64)
|
||||
done := make(chan *Stream)
|
||||
for i := 0; i < 2; i++ {
|
||||
go func() {
|
||||
s := NewTargeted(0.5, 0.90, 0.99)
|
||||
for v := range ch {
|
||||
s.Insert(v)
|
||||
}
|
||||
done <- s
|
||||
}()
|
||||
}
|
||||
|
||||
func TestTargetedQuery(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
a := make([]float64, 0, 1e6)
|
||||
for i := 0; i < cap(a); i++ {
|
||||
v := rand.NormFloat64()
|
||||
a = append(a, v)
|
||||
ch <- v
|
||||
}
|
||||
close(ch)
|
||||
s := NewTargeted(Targets)
|
||||
a := populateStream(s)
|
||||
verifyPercsWithAbsoluteEpsilon(t, a, s)
|
||||
}
|
||||
|
||||
s := <-done
|
||||
o := <-done
|
||||
s.Merge(o.Samples())
|
||||
func TestLowBiasedQuery(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
s := NewLowBiased(RelativeEpsilon)
|
||||
a := populateStream(s)
|
||||
verifyLowPercsWithRelativeEpsilon(t, a, s)
|
||||
}
|
||||
|
||||
t.Logf("len: %d", s.Count())
|
||||
sort.Float64s(a)
|
||||
w, min, max := getPerc(a, 0.50)
|
||||
if g := s.Query(0.50); g < min || g > max {
|
||||
t.Errorf("perc50: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
w, min, max = getPerc(a, 0.90)
|
||||
if g := s.Query(0.90); g < min || g > max {
|
||||
t.Errorf("perc90: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
w, min, max = getPerc(a, 0.99)
|
||||
if g := s.Query(0.99); g < min || g > max {
|
||||
t.Errorf("perc99: want %v [%f,%f], got %v", w, min, max, g)
|
||||
}
|
||||
func TestHighBiasedQuery(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
s := NewHighBiased(RelativeEpsilon)
|
||||
a := populateStream(s)
|
||||
verifyHighPercsWithRelativeEpsilon(t, a, s)
|
||||
}
|
||||
|
||||
func TestTargetedMerge(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
s1 := NewTargeted(Targets)
|
||||
s2 := NewTargeted(Targets)
|
||||
a := populateStream(s1)
|
||||
a = append(a, populateStream(s2)...)
|
||||
s1.Merge(s2.Samples())
|
||||
verifyPercsWithAbsoluteEpsilon(t, a, s1)
|
||||
}
|
||||
|
||||
func TestLowBiasedMerge(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
s1 := NewLowBiased(RelativeEpsilon)
|
||||
s2 := NewLowBiased(RelativeEpsilon)
|
||||
a := populateStream(s1)
|
||||
a = append(a, populateStream(s2)...)
|
||||
s1.Merge(s2.Samples())
|
||||
verifyLowPercsWithRelativeEpsilon(t, a, s2)
|
||||
}
|
||||
|
||||
func TestHighBiasedMerge(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
s1 := NewHighBiased(RelativeEpsilon)
|
||||
s2 := NewHighBiased(RelativeEpsilon)
|
||||
a := populateStream(s1)
|
||||
a = append(a, populateStream(s2)...)
|
||||
s1.Merge(s2.Samples())
|
||||
verifyHighPercsWithRelativeEpsilon(t, a, s2)
|
||||
}
|
||||
|
||||
func TestUncompressed(t *testing.T) {
|
||||
tests := []float64{0.50, 0.90, 0.95, 0.99}
|
||||
q := NewTargeted(tests...)
|
||||
q := NewTargeted(Targets)
|
||||
for i := 100; i > 0; i-- {
|
||||
q.Insert(float64(i))
|
||||
}
|
||||
|
|
@ -83,16 +152,16 @@ func TestUncompressed(t *testing.T) {
|
|||
t.Errorf("want count 100, got %d", g)
|
||||
}
|
||||
// Before compression, Query should have 100% accuracy.
|
||||
for _, v := range tests {
|
||||
w := v * 100
|
||||
if g := q.Query(v); g != w {
|
||||
for quantile := range Targets {
|
||||
w := quantile * 100
|
||||
if g := q.Query(quantile); g != w {
|
||||
t.Errorf("want %f, got %f", w, g)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func TestUncompressedSamples(t *testing.T) {
|
||||
q := NewTargeted(0.99)
|
||||
q := NewTargeted(map[float64]float64{0.99: 0.001})
|
||||
for i := 1; i <= 100; i++ {
|
||||
q.Insert(float64(i))
|
||||
}
|
||||
|
|
@ -102,7 +171,7 @@ func TestUncompressedSamples(t *testing.T) {
|
|||
}
|
||||
|
||||
func TestUncompressedOne(t *testing.T) {
|
||||
q := NewTargeted(0.90)
|
||||
q := NewTargeted(map[float64]float64{0.99: 0.01})
|
||||
q.Insert(3.14)
|
||||
if g := q.Query(0.90); g != 3.14 {
|
||||
t.Error("want PI, got", g)
|
||||
|
|
@ -110,20 +179,7 @@ func TestUncompressedOne(t *testing.T) {
|
|||
}
|
||||
|
||||
func TestDefaults(t *testing.T) {
|
||||
if g := NewTargeted(0.99).Query(0.99); g != 0 {
|
||||
if g := NewTargeted(map[float64]float64{0.99: 0.001}).Query(0.99); g != 0 {
|
||||
t.Errorf("want 0, got %f", g)
|
||||
}
|
||||
}
|
||||
|
||||
func getPerc(x []float64, p float64) (want, min, max float64) {
|
||||
k := int(float64(len(x)) * p)
|
||||
lower := int(float64(len(x)) * (p - 0.04))
|
||||
if lower < 0 {
|
||||
lower = 0
|
||||
}
|
||||
upper := int(float64(len(x))*(p+0.04)) + 1
|
||||
if upper >= len(x) {
|
||||
upper = len(x) - 1
|
||||
}
|
||||
return x[k], x[lower], x[upper]
|
||||
}
|
||||
|
|
|
|||
|
|
@ -0,0 +1,90 @@
|
|||
package topk
|
||||
|
||||
import (
|
||||
"sort"
|
||||
)
|
||||
|
||||
// http://www.cs.ucsb.edu/research/tech_reports/reports/2005-23.pdf
|
||||
|
||||
type Element struct {
|
||||
Value string
|
||||
Count int
|
||||
}
|
||||
|
||||
type Samples []*Element
|
||||
|
||||
func (sm Samples) Len() int {
|
||||
return len(sm)
|
||||
}
|
||||
|
||||
func (sm Samples) Less(i, j int) bool {
|
||||
return sm[i].Count < sm[j].Count
|
||||
}
|
||||
|
||||
func (sm Samples) Swap(i, j int) {
|
||||
sm[i], sm[j] = sm[j], sm[i]
|
||||
}
|
||||
|
||||
type Stream struct {
|
||||
k int
|
||||
mon map[string]*Element
|
||||
|
||||
// the minimum Element
|
||||
min *Element
|
||||
}
|
||||
|
||||
func New(k int) *Stream {
|
||||
s := new(Stream)
|
||||
s.k = k
|
||||
s.mon = make(map[string]*Element)
|
||||
s.min = &Element{}
|
||||
|
||||
// Track k+1 so that less frequenet items contended for that spot,
|
||||
// resulting in k being more accurate.
|
||||
return s
|
||||
}
|
||||
|
||||
func (s *Stream) Insert(x string) {
|
||||
s.insert(&Element{x, 1})
|
||||
}
|
||||
|
||||
func (s *Stream) Merge(sm Samples) {
|
||||
for _, e := range sm {
|
||||
s.insert(e)
|
||||
}
|
||||
}
|
||||
|
||||
func (s *Stream) insert(in *Element) {
|
||||
e := s.mon[in.Value]
|
||||
if e != nil {
|
||||
e.Count++
|
||||
} else {
|
||||
if len(s.mon) < s.k+1 {
|
||||
e = &Element{in.Value, in.Count}
|
||||
s.mon[in.Value] = e
|
||||
} else {
|
||||
e = s.min
|
||||
delete(s.mon, e.Value)
|
||||
e.Value = in.Value
|
||||
e.Count += in.Count
|
||||
s.min = e
|
||||
}
|
||||
}
|
||||
if e.Count < s.min.Count {
|
||||
s.min = e
|
||||
}
|
||||
}
|
||||
|
||||
func (s *Stream) Query() Samples {
|
||||
var sm Samples
|
||||
for _, e := range s.mon {
|
||||
sm = append(sm, e)
|
||||
}
|
||||
sort.Sort(sort.Reverse(sm))
|
||||
|
||||
if len(sm) < s.k {
|
||||
return sm
|
||||
}
|
||||
|
||||
return sm[:s.k]
|
||||
}
|
||||
|
|
@ -0,0 +1,57 @@
|
|||
package topk
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"math/rand"
|
||||
"sort"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestTopK(t *testing.T) {
|
||||
stream := New(10)
|
||||
ss := []*Stream{New(10), New(10), New(10)}
|
||||
m := make(map[string]int)
|
||||
for _, s := range ss {
|
||||
for i := 0; i < 1e6; i++ {
|
||||
v := fmt.Sprintf("%x", int8(rand.ExpFloat64()))
|
||||
s.Insert(v)
|
||||
m[v]++
|
||||
}
|
||||
stream.Merge(s.Query())
|
||||
}
|
||||
|
||||
var sm Samples
|
||||
for x, s := range m {
|
||||
sm = append(sm, &Element{x, s})
|
||||
}
|
||||
sort.Sort(sort.Reverse(sm))
|
||||
|
||||
g := stream.Query()
|
||||
if len(g) != 10 {
|
||||
t.Fatalf("got %d, want 10", len(g))
|
||||
}
|
||||
for i, e := range g {
|
||||
if sm[i].Value != e.Value {
|
||||
t.Errorf("at %d: want %q, got %q", i, sm[i].Value, e.Value)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func TestQuery(t *testing.T) {
|
||||
queryTests := []struct {
|
||||
value string
|
||||
expected int
|
||||
}{
|
||||
{"a", 1},
|
||||
{"b", 2},
|
||||
{"c", 2},
|
||||
}
|
||||
|
||||
stream := New(2)
|
||||
for _, tt := range queryTests {
|
||||
stream.Insert(tt.value)
|
||||
if n := len(stream.Query()); n != tt.expected {
|
||||
t.Errorf("want %d, got %d", tt.expected, n)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -362,11 +362,11 @@ func ExampleSummary() {
|
|||
// sample_sum: 29969.50000000001
|
||||
// quantile: <
|
||||
// quantile: 0.5
|
||||
// value: 30.2
|
||||
// value: 31.1
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.9
|
||||
// value: 41.4
|
||||
// value: 41.3
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.99
|
||||
|
|
@ -419,11 +419,11 @@ func ExampleSummaryVec() {
|
|||
// sample_sum: 31956.100000000017
|
||||
// quantile: <
|
||||
// quantile: 0.5
|
||||
// value: 32
|
||||
// value: 32.4
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.9
|
||||
// value: 41.5
|
||||
// value: 41.4
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.99
|
||||
|
|
@ -439,11 +439,11 @@ func ExampleSummaryVec() {
|
|||
// sample_sum: 29969.50000000001
|
||||
// quantile: <
|
||||
// quantile: 0.5
|
||||
// value: 30.2
|
||||
// value: 31.1
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.9
|
||||
// value: 41.4
|
||||
// value: 41.3
|
||||
// >
|
||||
// quantile: <
|
||||
// quantile: 0.99
|
||||
|
|
|
|||
|
|
@ -43,6 +43,7 @@ func TestGoCollector(t *testing.T) {
|
|||
}
|
||||
|
||||
if diff := int(pb.GetGauge().GetValue()) - old; diff != 1 {
|
||||
// TODO: This is flaky in highly concurrent situations.
|
||||
t.Errorf("want 1 new goroutine, got %d", diff)
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -46,7 +46,7 @@ type Summary interface {
|
|||
|
||||
// DefObjectives are the default Summary quantile values.
|
||||
var (
|
||||
DefObjectives = []float64{0.5, 0.9, 0.99}
|
||||
DefObjectives = map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001}
|
||||
)
|
||||
|
||||
// Default values for SummaryOpts.
|
||||
|
|
@ -56,11 +56,9 @@ const (
|
|||
DefMaxAge time.Duration = 10 * time.Minute
|
||||
// DefAgeBuckets is the default number of buckets used to calculate the
|
||||
// age of observations.
|
||||
DefAgeBuckets = 10
|
||||
DefAgeBuckets = 5
|
||||
// DefBufCap is the standard buffer size for collecting Summary observations.
|
||||
DefBufCap = 500
|
||||
// DefEpsilon is the default error epsilon for the quantile rank estimates.
|
||||
DefEpsilon = 0.001
|
||||
)
|
||||
|
||||
// SummaryOpts bundles the options for creating a Summary metric. It is
|
||||
|
|
@ -101,9 +99,9 @@ type SummaryOpts struct {
|
|||
// metric name).
|
||||
ConstLabels Labels
|
||||
|
||||
// Objectives defines the quantile rank estimates. The default value is
|
||||
// DefObjectives.
|
||||
Objectives []float64
|
||||
// Objectives defines the quantile rank estimates with their respective
|
||||
// absolute error. The default value is DefObjectives.
|
||||
Objectives map[float64]float64
|
||||
|
||||
// MaxAge defines the duration for which an observation stays relevant
|
||||
// for the summary. Must be positive. The default value is DefMaxAge.
|
||||
|
|
@ -127,6 +125,21 @@ type SummaryOpts struct {
|
|||
Epsilon float64
|
||||
}
|
||||
|
||||
// TODO: Great fuck-up with the sliding-window decay algorithm... The Merge
|
||||
// method of perk/quantile is actually not working as advertised - and it might
|
||||
// be unfixable, as the underlying algorithm is apparently not capable of
|
||||
// merging summaries in the first place. To avoid using Merge, we are currently
|
||||
// adding observations to _each_ age bucket, i.e. the effort to add a sample is
|
||||
// essentially multiplied by the number of age buckets. When rotating age
|
||||
// buckets, we empty the previous head stream. On scrape time, we simply take
|
||||
// the quantiles from the head stream (no merging required). Result: More effort
|
||||
// on observation time, less effort on scrape time, which is exactly the
|
||||
// opposite of what we try to accomplish, but at least the results are correct.
|
||||
//
|
||||
// The quite elegant previous contraption to merge the age buckets efficiently
|
||||
// on scrape time (see code up commit 6b9530d72ea715f0ba612c0120e6e09fbf1d49d0)
|
||||
// can't be used anymore.
|
||||
|
||||
// NewSummary creates a new Summary based on the provided SummaryOpts.
|
||||
func NewSummary(opts SummaryOpts) Summary {
|
||||
return newSummary(
|
||||
|
|
@ -164,18 +177,11 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
|
|||
opts.BufCap = DefBufCap
|
||||
}
|
||||
|
||||
if opts.Epsilon < 0 {
|
||||
panic(fmt.Errorf("illegal value for Epsilon=%f", opts.Epsilon))
|
||||
}
|
||||
if opts.Epsilon == 0. {
|
||||
opts.Epsilon = DefEpsilon
|
||||
}
|
||||
|
||||
s := &summary{
|
||||
desc: desc,
|
||||
|
||||
objectives: opts.Objectives,
|
||||
epsilon: opts.Epsilon,
|
||||
objectives: opts.Objectives,
|
||||
sortedObjectives: make([]float64, 0, len(opts.Objectives)),
|
||||
|
||||
labelPairs: makeLabelPairs(desc, labelValues),
|
||||
|
||||
|
|
@ -183,8 +189,6 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
|
|||
coldBuf: make([]float64, 0, opts.BufCap),
|
||||
streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets),
|
||||
}
|
||||
s.mergedTailStreams = s.newStream()
|
||||
s.mergedAllStreams = s.newStream()
|
||||
s.headStreamExpTime = time.Now().Add(s.streamDuration)
|
||||
s.hotBufExpTime = s.headStreamExpTime
|
||||
|
||||
|
|
@ -193,6 +197,11 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
|
|||
}
|
||||
s.headStream = s.streams[0]
|
||||
|
||||
for qu := range s.objectives {
|
||||
s.sortedObjectives = append(s.sortedObjectives, qu)
|
||||
}
|
||||
sort.Float64s(s.sortedObjectives)
|
||||
|
||||
s.Init(s) // Init self-collection.
|
||||
return s
|
||||
}
|
||||
|
|
@ -206,8 +215,8 @@ type summary struct {
|
|||
|
||||
desc *Desc
|
||||
|
||||
objectives []float64
|
||||
epsilon float64
|
||||
objectives map[float64]float64
|
||||
sortedObjectives []float64
|
||||
|
||||
labelPairs []*dto.LabelPair
|
||||
|
||||
|
|
@ -218,10 +227,9 @@ type summary struct {
|
|||
|
||||
streams []*quantile.Stream
|
||||
streamDuration time.Duration
|
||||
headStream *quantile.Stream
|
||||
headStreamIdx int
|
||||
headStreamExpTime, hotBufExpTime time.Time
|
||||
|
||||
headStream, mergedTailStreams, mergedAllStreams *quantile.Stream
|
||||
}
|
||||
|
||||
func (s *summary) Desc() *Desc {
|
||||
|
|
@ -255,18 +263,15 @@ func (s *summary) Write(out *dto.Metric) error {
|
|||
s.bufMtx.Unlock()
|
||||
|
||||
s.flushColdBuf()
|
||||
s.mergedAllStreams.Merge(s.mergedTailStreams.Samples())
|
||||
s.mergedAllStreams.Merge(s.headStream.Samples())
|
||||
sum.SampleCount = proto.Uint64(s.cnt)
|
||||
sum.SampleSum = proto.Float64(s.sum)
|
||||
|
||||
for _, rank := range s.objectives {
|
||||
for _, rank := range s.sortedObjectives {
|
||||
qs = append(qs, &dto.Quantile{
|
||||
Quantile: proto.Float64(rank),
|
||||
Value: proto.Float64(s.mergedAllStreams.Query(rank)),
|
||||
Value: proto.Float64(s.headStream.Query(rank)),
|
||||
})
|
||||
}
|
||||
s.mergedAllStreams.Reset()
|
||||
|
||||
s.mtx.Unlock()
|
||||
|
||||
|
|
@ -281,9 +286,7 @@ func (s *summary) Write(out *dto.Metric) error {
|
|||
}
|
||||
|
||||
func (s *summary) newStream() *quantile.Stream {
|
||||
stream := quantile.NewTargeted(s.objectives...)
|
||||
stream.SetEpsilon(s.epsilon)
|
||||
return stream
|
||||
return quantile.NewTargeted(s.objectives)
|
||||
}
|
||||
|
||||
// asyncFlush needs bufMtx locked.
|
||||
|
|
@ -302,32 +305,23 @@ func (s *summary) asyncFlush(now time.Time) {
|
|||
|
||||
// rotateStreams needs mtx AND bufMtx locked.
|
||||
func (s *summary) maybeRotateStreams() {
|
||||
if s.hotBufExpTime.Equal(s.headStreamExpTime) {
|
||||
// Fast return to avoid re-merging s.mergedTailStreams.
|
||||
return
|
||||
}
|
||||
for !s.hotBufExpTime.Equal(s.headStreamExpTime) {
|
||||
s.headStream.Reset()
|
||||
s.headStreamIdx++
|
||||
if s.headStreamIdx >= len(s.streams) {
|
||||
s.headStreamIdx = 0
|
||||
}
|
||||
s.headStream = s.streams[s.headStreamIdx]
|
||||
s.headStream.Reset()
|
||||
s.headStreamExpTime = s.headStreamExpTime.Add(s.streamDuration)
|
||||
}
|
||||
s.mergedTailStreams.Reset()
|
||||
for _, stream := range s.streams {
|
||||
if stream != s.headStream {
|
||||
s.mergedTailStreams.Merge(stream.Samples())
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
// flushColdBuf needs mtx locked.
|
||||
func (s *summary) flushColdBuf() {
|
||||
for _, v := range s.coldBuf {
|
||||
s.headStream.Insert(v)
|
||||
for _, stream := range s.streams {
|
||||
stream.Insert(v)
|
||||
}
|
||||
s.cnt++
|
||||
s.sum += v
|
||||
}
|
||||
|
|
@ -337,6 +331,9 @@ func (s *summary) flushColdBuf() {
|
|||
|
||||
// swapBufs needs mtx AND bufMtx locked, coldBuf must be empty.
|
||||
func (s *summary) swapBufs(now time.Time) {
|
||||
if len(s.coldBuf) != 0 {
|
||||
panic("coldBuf is not empty")
|
||||
}
|
||||
s.hotBuf, s.coldBuf = s.coldBuf, s.hotBuf
|
||||
// hotBuf is now empty and gets new expiration set.
|
||||
for now.After(s.hotBufExpTime) {
|
||||
|
|
|
|||
|
|
@ -123,19 +123,17 @@ func TestSummaryConcurrency(t *testing.T) {
|
|||
rand.Seed(42)
|
||||
|
||||
it := func(n uint32) bool {
|
||||
mutations := int(n%10000 + 1)
|
||||
concLevel := int(n%15 + 1)
|
||||
mutations := int(n%1e4 + 1e4)
|
||||
concLevel := int(n%5 + 1)
|
||||
total := mutations * concLevel
|
||||
ε := 0.001
|
||||
|
||||
var start, end sync.WaitGroup
|
||||
start.Add(1)
|
||||
end.Add(concLevel)
|
||||
|
||||
sum := NewSummary(SummaryOpts{
|
||||
Name: "test_summary",
|
||||
Help: "helpless",
|
||||
Epsilon: ε,
|
||||
Name: "test_summary",
|
||||
Help: "helpless",
|
||||
})
|
||||
|
||||
allVars := make([]float64, total)
|
||||
|
|
@ -170,14 +168,21 @@ func TestSummaryConcurrency(t *testing.T) {
|
|||
t.Errorf("got sample sum %f, want %f", got, want)
|
||||
}
|
||||
|
||||
for i, wantQ := range DefObjectives {
|
||||
objectives := make([]float64, 0, len(DefObjectives))
|
||||
for qu := range DefObjectives {
|
||||
objectives = append(objectives, qu)
|
||||
}
|
||||
sort.Float64s(objectives)
|
||||
|
||||
for i, wantQ := range objectives {
|
||||
ε := DefObjectives[wantQ]
|
||||
gotQ := *m.Summary.Quantile[i].Quantile
|
||||
gotV := *m.Summary.Quantile[i].Value
|
||||
min, max := getBounds(allVars, wantQ, ε)
|
||||
if gotQ != wantQ {
|
||||
t.Errorf("got quantile %f, want %f", gotQ, wantQ)
|
||||
}
|
||||
if (gotV < min || gotV > max) && len(allVars) > 500 { // Avoid statistical outliers.
|
||||
if gotV < min || gotV > max {
|
||||
t.Errorf("got %f for quantile %f, want [%f,%f]", gotV, gotQ, min, max)
|
||||
}
|
||||
}
|
||||
|
|
@ -192,11 +197,17 @@ func TestSummaryConcurrency(t *testing.T) {
|
|||
func TestSummaryVecConcurrency(t *testing.T) {
|
||||
rand.Seed(42)
|
||||
|
||||
objectives := make([]float64, 0, len(DefObjectives))
|
||||
for qu := range DefObjectives {
|
||||
|
||||
objectives = append(objectives, qu)
|
||||
}
|
||||
sort.Float64s(objectives)
|
||||
|
||||
it := func(n uint32) bool {
|
||||
mutations := int(n%10000 + 1)
|
||||
concLevel := int(n%15 + 1)
|
||||
ε := 0.001
|
||||
vecLength := int(n%5 + 1)
|
||||
mutations := int(n%1e4 + 1e4)
|
||||
concLevel := int(n%7 + 1)
|
||||
vecLength := int(n%3 + 1)
|
||||
|
||||
var start, end sync.WaitGroup
|
||||
start.Add(1)
|
||||
|
|
@ -204,9 +215,8 @@ func TestSummaryVecConcurrency(t *testing.T) {
|
|||
|
||||
sum := NewSummaryVec(
|
||||
SummaryOpts{
|
||||
Name: "test_summary",
|
||||
Help: "helpless",
|
||||
Epsilon: ε,
|
||||
Name: "test_summary",
|
||||
Help: "helpless",
|
||||
},
|
||||
[]string{"label"},
|
||||
)
|
||||
|
|
@ -249,16 +259,16 @@ func TestSummaryVecConcurrency(t *testing.T) {
|
|||
if got, want := *m.Summary.SampleSum, sampleSums[i]; math.Abs((got-want)/want) > 0.001 {
|
||||
t.Errorf("got sample sum %f for label %c, want %f", got, 'A'+i, want)
|
||||
}
|
||||
for j, wantQ := range DefObjectives {
|
||||
for j, wantQ := range objectives {
|
||||
ε := DefObjectives[wantQ]
|
||||
gotQ := *m.Summary.Quantile[j].Quantile
|
||||
gotV := *m.Summary.Quantile[j].Value
|
||||
min, max := getBounds(allVars[i], wantQ, ε)
|
||||
if gotQ != wantQ {
|
||||
t.Errorf("got quantile %f for label %c, want %f", gotQ, 'A'+i, wantQ)
|
||||
}
|
||||
if (gotV < min || gotV > max) && len(allVars[i]) > 500 { // Avoid statistical outliers.
|
||||
if gotV < min || gotV > max {
|
||||
t.Errorf("got %f for quantile %f for label %c, want [%f,%f]", gotV, gotQ, 'A'+i, min, max)
|
||||
t.Log(len(allVars[i]))
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -270,20 +280,18 @@ func TestSummaryVecConcurrency(t *testing.T) {
|
|||
}
|
||||
}
|
||||
|
||||
// TODO(beorn): This test fails on Travis, likely because it depends on
|
||||
// timing. Fix that and then Remove the leading X from the function name.
|
||||
func XTestSummaryDecay(t *testing.T) {
|
||||
func TestSummaryDecay(t *testing.T) {
|
||||
sum := NewSummary(SummaryOpts{
|
||||
Name: "test_summary",
|
||||
Help: "helpless",
|
||||
Epsilon: 0.001,
|
||||
MaxAge: 10 * time.Millisecond,
|
||||
Objectives: []float64{0.1},
|
||||
MaxAge: 100 * time.Millisecond,
|
||||
Objectives: map[float64]float64{0.1: 0.001},
|
||||
AgeBuckets: 10,
|
||||
})
|
||||
|
||||
m := &dto.Metric{}
|
||||
i := 0
|
||||
tick := time.NewTicker(100 * time.Microsecond)
|
||||
tick := time.NewTicker(time.Millisecond)
|
||||
for _ = range tick.C {
|
||||
i++
|
||||
sum.Observe(float64(i))
|
||||
|
|
@ -302,15 +310,19 @@ func XTestSummaryDecay(t *testing.T) {
|
|||
}
|
||||
|
||||
func getBounds(vars []float64, q, ε float64) (min, max float64) {
|
||||
lower := int((q - 4*ε) * float64(len(vars)))
|
||||
upper := int((q+4*ε)*float64(len(vars))) + 1
|
||||
// TODO: This currently tolerates an error of up to 2*ε. The error must
|
||||
// be at most ε, but for some reason, it's sometimes slightly
|
||||
// higher. That's a bug.
|
||||
n := float64(len(vars))
|
||||
lower := int((q - 2*ε) * n)
|
||||
upper := int(math.Ceil((q + 2*ε) * n))
|
||||
min = vars[0]
|
||||
if lower > 0 {
|
||||
min = vars[lower]
|
||||
if lower > 1 {
|
||||
min = vars[lower-1]
|
||||
}
|
||||
max = vars[len(vars)-1]
|
||||
if upper < len(vars)-1 {
|
||||
max = vars[upper]
|
||||
if upper < len(vars) {
|
||||
max = vars[upper-1]
|
||||
}
|
||||
return
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue