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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| package pd | ||
|
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||
| import ( | ||
| "fmt" | ||
| "strings" | ||
| "sync/atomic" | ||
| "time" | ||
|
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| "github.com/pingcap/log" | ||
| "go.uber.org/zap" | ||
| ) | ||
|
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| type Histogram struct { | ||
| buckets []int | ||
| sum float64 | ||
| sumSquare float64 | ||
| count int | ||
| interval float64 | ||
| cutoff float64 | ||
| } | ||
|
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| func NewHistogram(interval float64, bucketsCount int, cutoff float64) *Histogram { | ||
| return &Histogram{ | ||
| buckets: make([]int, bucketsCount), | ||
| interval: interval, | ||
| count: 0, | ||
| cutoff: cutoff, | ||
| } | ||
| } | ||
|
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| func (h *Histogram) Observe(value float64) { | ||
| if value >= h.cutoff { | ||
| return | ||
| } | ||
|
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| index := int(value / h.interval) | ||
| for index >= len(h.buckets) { | ||
| h.buckets = append(h.buckets, 0) | ||
| } | ||
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| h.buckets[index]++ | ||
| h.count++ | ||
| h.sum += value | ||
| h.sumSquare += value * value | ||
| } | ||
|
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| func (h *Histogram) GetPercentile(p float64) float64 { | ||
| if h.count == 0 { | ||
| return 0 | ||
| } | ||
| limit := float64(h.count) * p | ||
| result := 0. | ||
| for i := 0; i < len(h.buckets); i += 1 { | ||
| samplesInBucket := float64(h.buckets[i]) | ||
| if samplesInBucket >= limit { | ||
| result += limit / samplesInBucket * h.interval | ||
| break | ||
| } | ||
| result += h.interval | ||
| limit -= samplesInBucket | ||
| } | ||
| return result | ||
| } | ||
|
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| func (h *Histogram) GetAvg() float64 { | ||
| return h.sum / float64(h.count) | ||
| } | ||
|
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| func (h *Histogram) String() string { | ||
| sb := &strings.Builder{} | ||
| _, err := fmt.Fprintf(sb, "{ count: %v, sum: %v, sum_square: %v, interval: %v, buckets.len: %v, buckets: [", h.count, h.sum, h.sumSquare, h.interval, len(h.buckets)) | ||
| if err != nil { | ||
| panic("unreachable") | ||
| } | ||
|
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| if len(h.buckets) > 0 { | ||
| put := func(value, count int) { | ||
| if count == 1 { | ||
| _, err = fmt.Fprintf(sb, "%v;", value) | ||
| } else { | ||
| _, err = fmt.Fprintf(sb, "%v,%v;", value, count) | ||
| } | ||
| if err != nil { | ||
| panic("unreachable") | ||
| } | ||
| } | ||
|
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| lastValue := h.buckets[0] | ||
| lastValueCount := 1 | ||
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| for i := 1; i < len(h.buckets); i++ { | ||
| if h.buckets[i] == lastValue { | ||
| lastValueCount++ | ||
| continue | ||
| } | ||
|
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| put(lastValue, lastValueCount) | ||
| lastValue = h.buckets[i] | ||
| lastValueCount = 1 | ||
| } | ||
|
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| put(lastValue, lastValueCount) | ||
| } | ||
|
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| _, err = sb.WriteString("] }") | ||
| if err != nil { | ||
| panic("unreachable") | ||
| } | ||
|
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| return sb.String() | ||
| } | ||
|
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| func (h *Histogram) Clear() { | ||
| h.sum = 0 | ||
| h.sumSquare = 0 | ||
| h.count = 0 | ||
| for i := 0; i < len(h.buckets); i++ { | ||
| h.buckets[i] = 0 | ||
| } | ||
| } | ||
|
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| type AutoDumpHistogram struct { | ||
| name string | ||
| mainHistogram *Histogram | ||
| backHistogram *Histogram | ||
| accumulated *Histogram | ||
| isDumping atomic.Bool | ||
| lastDumpHistogramTime time.Time | ||
| dumpInterval time.Duration | ||
| } | ||
|
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| func NewAutoDumpingHistogram(name string, interval float64, bucketsCount int, cutoff float64, dumpInterval time.Duration) *AutoDumpHistogram { | ||
| return &AutoDumpHistogram{ | ||
| name: name, | ||
| mainHistogram: NewHistogram(interval, bucketsCount, cutoff), | ||
| backHistogram: NewHistogram(interval, bucketsCount, cutoff), | ||
| accumulated: NewHistogram(interval, bucketsCount, cutoff), | ||
| lastDumpHistogramTime: time.Now(), | ||
| dumpInterval: dumpInterval, | ||
| } | ||
| } | ||
|
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| func (h *AutoDumpHistogram) Observe(value float64, now time.Time) { | ||
| // Not thread-safe. | ||
| h.mainHistogram.Observe(value) | ||
| if now.Sub(h.lastDumpHistogramTime) >= h.dumpInterval && !h.isDumping.Load() { | ||
| h.isDumping.Store(true) | ||
| h.mainHistogram, h.backHistogram = h.backHistogram, h.mainHistogram | ||
| h.lastDumpHistogramTime = now | ||
| go h.dump(now) | ||
| } | ||
| } | ||
|
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| func (h *AutoDumpHistogram) dump(now time.Time) { | ||
| defer h.isDumping.Store(false) | ||
|
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| h.accumulated.sum += h.backHistogram.sum | ||
| h.accumulated.sumSquare += h.backHistogram.sumSquare | ||
| h.accumulated.count += h.backHistogram.count | ||
| for i := 0; i < len(h.accumulated.buckets) && i < len(h.backHistogram.buckets); i++ { | ||
| h.accumulated.buckets[i] += h.backHistogram.buckets[i] | ||
| } | ||
| if len(h.backHistogram.buckets) > len(h.accumulated.buckets) { | ||
| h.accumulated.buckets = append(h.accumulated.buckets, h.backHistogram.buckets[len(h.accumulated.buckets):]...) | ||
| } | ||
|
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| log.Info("dumping histogram", zap.String("name", h.name), zap.Time("time", now), zap.Stringer("histogram", h.accumulated)) | ||
|
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| h.backHistogram.Clear() | ||
| } |
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