plugeth/vendor/github.com/rcrowley/go-metrics/sample.go
Péter Szilágyi 289b30715d Godeps, vendor: convert dependency management to trash (#3198)
This commit converts the dependency management from Godeps to the vendor
folder, also switching the tool from godep to trash. Since the upstream tool
lacks a few features proposed via a few PRs, until those PRs are merged in
(if), use github.com/karalabe/trash.

You can update dependencies via trash --update.

All dependencies have been updated to their latest version.

Parts of the build system are reworked to drop old notions of Godeps and
invocation of the go vet command so that it doesn't run against the vendor
folder, as that will just blow up during vetting.

The conversion drops OpenCL (and hence GPU mining support) from ethash and our
codebase. The short reasoning is that there's noone to maintain and having
opencl libs in our deps messes up builds as go install ./... tries to build
them, failing with unsatisfied link errors for the C OpenCL deps.

golang.org/x/net/context is not vendored in. We expect it to be fetched by the
user (i.e. using go get). To keep ci.go builds reproducible the package is
"vendored" in build/_vendor.
2016-10-28 19:05:01 +02:00

610 lines
15 KiB
Go

package metrics
import (
"math"
"math/rand"
"sort"
"sync"
"time"
)
const rescaleThreshold = time.Hour
// Samples maintain a statistically-significant selection of values from
// a stream.
type Sample interface {
Clear()
Count() int64
Max() int64
Mean() float64
Min() int64
Percentile(float64) float64
Percentiles([]float64) []float64
Size() int
Snapshot() Sample
StdDev() float64
Sum() int64
Update(int64)
Values() []int64
Variance() float64
}
// ExpDecaySample is an exponentially-decaying sample using a forward-decaying
// priority reservoir. See Cormode et al's "Forward Decay: A Practical Time
// Decay Model for Streaming Systems".
//
// <http://www.research.att.com/people/Cormode_Graham/library/publications/CormodeShkapenyukSrivastavaXu09.pdf>
type ExpDecaySample struct {
alpha float64
count int64
mutex sync.Mutex
reservoirSize int
t0, t1 time.Time
values *expDecaySampleHeap
}
// NewExpDecaySample constructs a new exponentially-decaying sample with the
// given reservoir size and alpha.
func NewExpDecaySample(reservoirSize int, alpha float64) Sample {
if UseNilMetrics {
return NilSample{}
}
s := &ExpDecaySample{
alpha: alpha,
reservoirSize: reservoirSize,
t0: time.Now(),
values: newExpDecaySampleHeap(reservoirSize),
}
s.t1 = s.t0.Add(rescaleThreshold)
return s
}
// Clear clears all samples.
func (s *ExpDecaySample) Clear() {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count = 0
s.t0 = time.Now()
s.t1 = s.t0.Add(rescaleThreshold)
s.values.Clear()
}
// Count returns the number of samples recorded, which may exceed the
// reservoir size.
func (s *ExpDecaySample) Count() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return s.count
}
// Max returns the maximum value in the sample, which may not be the maximum
// value ever to be part of the sample.
func (s *ExpDecaySample) Max() int64 {
return SampleMax(s.Values())
}
// Mean returns the mean of the values in the sample.
func (s *ExpDecaySample) Mean() float64 {
return SampleMean(s.Values())
}
// Min returns the minimum value in the sample, which may not be the minimum
// value ever to be part of the sample.
func (s *ExpDecaySample) Min() int64 {
return SampleMin(s.Values())
}
// Percentile returns an arbitrary percentile of values in the sample.
func (s *ExpDecaySample) Percentile(p float64) float64 {
return SamplePercentile(s.Values(), p)
}
// Percentiles returns a slice of arbitrary percentiles of values in the
// sample.
func (s *ExpDecaySample) Percentiles(ps []float64) []float64 {
return SamplePercentiles(s.Values(), ps)
}
// Size returns the size of the sample, which is at most the reservoir size.
func (s *ExpDecaySample) Size() int {
s.mutex.Lock()
defer s.mutex.Unlock()
return s.values.Size()
}
// Snapshot returns a read-only copy of the sample.
func (s *ExpDecaySample) Snapshot() Sample {
s.mutex.Lock()
defer s.mutex.Unlock()
vals := s.values.Values()
values := make([]int64, len(vals))
for i, v := range vals {
values[i] = v.v
}
return &SampleSnapshot{
count: s.count,
values: values,
}
}
// StdDev returns the standard deviation of the values in the sample.
func (s *ExpDecaySample) StdDev() float64 {
return SampleStdDev(s.Values())
}
// Sum returns the sum of the values in the sample.
func (s *ExpDecaySample) Sum() int64 {
return SampleSum(s.Values())
}
// Update samples a new value.
func (s *ExpDecaySample) Update(v int64) {
s.update(time.Now(), v)
}
// Values returns a copy of the values in the sample.
func (s *ExpDecaySample) Values() []int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
vals := s.values.Values()
values := make([]int64, len(vals))
for i, v := range vals {
values[i] = v.v
}
return values
}
// Variance returns the variance of the values in the sample.
func (s *ExpDecaySample) Variance() float64 {
return SampleVariance(s.Values())
}
// update samples a new value at a particular timestamp. This is a method all
// its own to facilitate testing.
func (s *ExpDecaySample) update(t time.Time, v int64) {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count++
if s.values.Size() == s.reservoirSize {
s.values.Pop()
}
s.values.Push(expDecaySample{
k: math.Exp(t.Sub(s.t0).Seconds()*s.alpha) / rand.Float64(),
v: v,
})
if t.After(s.t1) {
values := s.values.Values()
t0 := s.t0
s.values.Clear()
s.t0 = t
s.t1 = s.t0.Add(rescaleThreshold)
for _, v := range values {
v.k = v.k * math.Exp(-s.alpha*s.t0.Sub(t0).Seconds())
s.values.Push(v)
}
}
}
// NilSample is a no-op Sample.
type NilSample struct{}
// Clear is a no-op.
func (NilSample) Clear() {}
// Count is a no-op.
func (NilSample) Count() int64 { return 0 }
// Max is a no-op.
func (NilSample) Max() int64 { return 0 }
// Mean is a no-op.
func (NilSample) Mean() float64 { return 0.0 }
// Min is a no-op.
func (NilSample) Min() int64 { return 0 }
// Percentile is a no-op.
func (NilSample) Percentile(p float64) float64 { return 0.0 }
// Percentiles is a no-op.
func (NilSample) Percentiles(ps []float64) []float64 {
return make([]float64, len(ps))
}
// Size is a no-op.
func (NilSample) Size() int { return 0 }
// Sample is a no-op.
func (NilSample) Snapshot() Sample { return NilSample{} }
// StdDev is a no-op.
func (NilSample) StdDev() float64 { return 0.0 }
// Sum is a no-op.
func (NilSample) Sum() int64 { return 0 }
// Update is a no-op.
func (NilSample) Update(v int64) {}
// Values is a no-op.
func (NilSample) Values() []int64 { return []int64{} }
// Variance is a no-op.
func (NilSample) Variance() float64 { return 0.0 }
// SampleMax returns the maximum value of the slice of int64.
func SampleMax(values []int64) int64 {
if 0 == len(values) {
return 0
}
var max int64 = math.MinInt64
for _, v := range values {
if max < v {
max = v
}
}
return max
}
// SampleMean returns the mean value of the slice of int64.
func SampleMean(values []int64) float64 {
if 0 == len(values) {
return 0.0
}
return float64(SampleSum(values)) / float64(len(values))
}
// SampleMin returns the minimum value of the slice of int64.
func SampleMin(values []int64) int64 {
if 0 == len(values) {
return 0
}
var min int64 = math.MaxInt64
for _, v := range values {
if min > v {
min = v
}
}
return min
}
// SamplePercentiles returns an arbitrary percentile of the slice of int64.
func SamplePercentile(values int64Slice, p float64) float64 {
return SamplePercentiles(values, []float64{p})[0]
}
// SamplePercentiles returns a slice of arbitrary percentiles of the slice of
// int64.
func SamplePercentiles(values int64Slice, ps []float64) []float64 {
scores := make([]float64, len(ps))
size := len(values)
if size > 0 {
sort.Sort(values)
for i, p := range ps {
pos := p * float64(size+1)
if pos < 1.0 {
scores[i] = float64(values[0])
} else if pos >= float64(size) {
scores[i] = float64(values[size-1])
} else {
lower := float64(values[int(pos)-1])
upper := float64(values[int(pos)])
scores[i] = lower + (pos-math.Floor(pos))*(upper-lower)
}
}
}
return scores
}
// SampleSnapshot is a read-only copy of another Sample.
type SampleSnapshot struct {
count int64
values []int64
}
// Clear panics.
func (*SampleSnapshot) Clear() {
panic("Clear called on a SampleSnapshot")
}
// Count returns the count of inputs at the time the snapshot was taken.
func (s *SampleSnapshot) Count() int64 { return s.count }
// Max returns the maximal value at the time the snapshot was taken.
func (s *SampleSnapshot) Max() int64 { return SampleMax(s.values) }
// Mean returns the mean value at the time the snapshot was taken.
func (s *SampleSnapshot) Mean() float64 { return SampleMean(s.values) }
// Min returns the minimal value at the time the snapshot was taken.
func (s *SampleSnapshot) Min() int64 { return SampleMin(s.values) }
// Percentile returns an arbitrary percentile of values at the time the
// snapshot was taken.
func (s *SampleSnapshot) Percentile(p float64) float64 {
return SamplePercentile(s.values, p)
}
// Percentiles returns a slice of arbitrary percentiles of values at the time
// the snapshot was taken.
func (s *SampleSnapshot) Percentiles(ps []float64) []float64 {
return SamplePercentiles(s.values, ps)
}
// Size returns the size of the sample at the time the snapshot was taken.
func (s *SampleSnapshot) Size() int { return len(s.values) }
// Snapshot returns the snapshot.
func (s *SampleSnapshot) Snapshot() Sample { return s }
// StdDev returns the standard deviation of values at the time the snapshot was
// taken.
func (s *SampleSnapshot) StdDev() float64 { return SampleStdDev(s.values) }
// Sum returns the sum of values at the time the snapshot was taken.
func (s *SampleSnapshot) Sum() int64 { return SampleSum(s.values) }
// Update panics.
func (*SampleSnapshot) Update(int64) {
panic("Update called on a SampleSnapshot")
}
// Values returns a copy of the values in the sample.
func (s *SampleSnapshot) Values() []int64 {
values := make([]int64, len(s.values))
copy(values, s.values)
return values
}
// Variance returns the variance of values at the time the snapshot was taken.
func (s *SampleSnapshot) Variance() float64 { return SampleVariance(s.values) }
// SampleStdDev returns the standard deviation of the slice of int64.
func SampleStdDev(values []int64) float64 {
return math.Sqrt(SampleVariance(values))
}
// SampleSum returns the sum of the slice of int64.
func SampleSum(values []int64) int64 {
var sum int64
for _, v := range values {
sum += v
}
return sum
}
// SampleVariance returns the variance of the slice of int64.
func SampleVariance(values []int64) float64 {
if 0 == len(values) {
return 0.0
}
m := SampleMean(values)
var sum float64
for _, v := range values {
d := float64(v) - m
sum += d * d
}
return sum / float64(len(values))
}
// A uniform sample using Vitter's Algorithm R.
//
// <http://www.cs.umd.edu/~samir/498/vitter.pdf>
type UniformSample struct {
count int64
mutex sync.Mutex
reservoirSize int
values []int64
}
// NewUniformSample constructs a new uniform sample with the given reservoir
// size.
func NewUniformSample(reservoirSize int) Sample {
if UseNilMetrics {
return NilSample{}
}
return &UniformSample{
reservoirSize: reservoirSize,
values: make([]int64, 0, reservoirSize),
}
}
// Clear clears all samples.
func (s *UniformSample) Clear() {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count = 0
s.values = make([]int64, 0, s.reservoirSize)
}
// Count returns the number of samples recorded, which may exceed the
// reservoir size.
func (s *UniformSample) Count() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return s.count
}
// Max returns the maximum value in the sample, which may not be the maximum
// value ever to be part of the sample.
func (s *UniformSample) Max() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleMax(s.values)
}
// Mean returns the mean of the values in the sample.
func (s *UniformSample) Mean() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleMean(s.values)
}
// Min returns the minimum value in the sample, which may not be the minimum
// value ever to be part of the sample.
func (s *UniformSample) Min() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleMin(s.values)
}
// Percentile returns an arbitrary percentile of values in the sample.
func (s *UniformSample) Percentile(p float64) float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SamplePercentile(s.values, p)
}
// Percentiles returns a slice of arbitrary percentiles of values in the
// sample.
func (s *UniformSample) Percentiles(ps []float64) []float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SamplePercentiles(s.values, ps)
}
// Size returns the size of the sample, which is at most the reservoir size.
func (s *UniformSample) Size() int {
s.mutex.Lock()
defer s.mutex.Unlock()
return len(s.values)
}
// Snapshot returns a read-only copy of the sample.
func (s *UniformSample) Snapshot() Sample {
s.mutex.Lock()
defer s.mutex.Unlock()
values := make([]int64, len(s.values))
copy(values, s.values)
return &SampleSnapshot{
count: s.count,
values: values,
}
}
// StdDev returns the standard deviation of the values in the sample.
func (s *UniformSample) StdDev() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleStdDev(s.values)
}
// Sum returns the sum of the values in the sample.
func (s *UniformSample) Sum() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleSum(s.values)
}
// Update samples a new value.
func (s *UniformSample) Update(v int64) {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count++
if len(s.values) < s.reservoirSize {
s.values = append(s.values, v)
} else {
r := rand.Int63n(s.count)
if r < int64(len(s.values)) {
s.values[int(r)] = v
}
}
}
// Values returns a copy of the values in the sample.
func (s *UniformSample) Values() []int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
values := make([]int64, len(s.values))
copy(values, s.values)
return values
}
// Variance returns the variance of the values in the sample.
func (s *UniformSample) Variance() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return SampleVariance(s.values)
}
// expDecaySample represents an individual sample in a heap.
type expDecaySample struct {
k float64
v int64
}
func newExpDecaySampleHeap(reservoirSize int) *expDecaySampleHeap {
return &expDecaySampleHeap{make([]expDecaySample, 0, reservoirSize)}
}
// expDecaySampleHeap is a min-heap of expDecaySamples.
// The internal implementation is copied from the standard library's container/heap
type expDecaySampleHeap struct {
s []expDecaySample
}
func (h *expDecaySampleHeap) Clear() {
h.s = h.s[:0]
}
func (h *expDecaySampleHeap) Push(s expDecaySample) {
n := len(h.s)
h.s = h.s[0 : n+1]
h.s[n] = s
h.up(n)
}
func (h *expDecaySampleHeap) Pop() expDecaySample {
n := len(h.s) - 1
h.s[0], h.s[n] = h.s[n], h.s[0]
h.down(0, n)
n = len(h.s)
s := h.s[n-1]
h.s = h.s[0 : n-1]
return s
}
func (h *expDecaySampleHeap) Size() int {
return len(h.s)
}
func (h *expDecaySampleHeap) Values() []expDecaySample {
return h.s
}
func (h *expDecaySampleHeap) up(j int) {
for {
i := (j - 1) / 2 // parent
if i == j || !(h.s[j].k < h.s[i].k) {
break
}
h.s[i], h.s[j] = h.s[j], h.s[i]
j = i
}
}
func (h *expDecaySampleHeap) down(i, n int) {
for {
j1 := 2*i + 1
if j1 >= n || j1 < 0 { // j1 < 0 after int overflow
break
}
j := j1 // left child
if j2 := j1 + 1; j2 < n && !(h.s[j1].k < h.s[j2].k) {
j = j2 // = 2*i + 2 // right child
}
if !(h.s[j].k < h.s[i].k) {
break
}
h.s[i], h.s[j] = h.s[j], h.s[i]
i = j
}
}
type int64Slice []int64
func (p int64Slice) Len() int { return len(p) }
func (p int64Slice) Less(i, j int) bool { return p[i] < p[j] }
func (p int64Slice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }