57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
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package stati
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import (
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"math"
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"golang.org/x/xerrors"
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)
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type Histogram struct {
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Buckets []float64
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Counts []uint64
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}
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// NewHistogram creates a histograme with buckets defined as:
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// {x > -Inf, x >= buckets[0], x >= buckets[1], ..., x >= buckets[i]}
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func NewHistogram(buckets []float64) (*Histogram, error) {
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if len(buckets) == 0 {
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return nil, xerrors.Errorf("empty buckets")
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}
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prev := buckets[0]
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for i, v := range buckets[1:] {
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if v < prev {
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return nil, xerrors.Errorf("bucket at index %d is smaller than previous %f < %f", i+1, v, prev)
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}
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prev = v
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}
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h := &Histogram{
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Buckets: append([]float64{math.Inf(-1)}, buckets...),
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Counts: make([]uint64, len(buckets)+1),
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}
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return h, nil
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}
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func (h *Histogram) Observe(x float64) {
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for i, b := range h.Buckets {
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if x >= b {
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h.Counts[i]++
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} else {
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break
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}
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}
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}
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func (h *Histogram) Total() uint64 {
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return h.Counts[0]
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}
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func (h *Histogram) Get(i int) uint64 {
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if i >= len(h.Counts)-2 {
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return h.Counts[i]
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}
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return h.Counts[i+1] - h.Counts[i+2]
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}
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func (h *Histogram) GetRatio(i int) float64 {
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return float64(h.Get(i)) / float64(h.Total())
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}
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