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report accurate mean instead of an approximation #744

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Nov 22, 2017
Merged

report accurate mean instead of an approximation #744

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6 changes: 5 additions & 1 deletion stats/latencyhistogram15s32.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package stats

import (
"sync/atomic"
"time"

"github.com/Dieterbe/artisanalhistogram/hist15s"
Expand All @@ -10,6 +11,7 @@ import (
type LatencyHistogram15s32 struct {
hist hist15s.Hist15s
since time.Time
sum uint64 // in micros. to generate more accurate mean
}

func NewLatencyHistogram15s32(name string) *LatencyHistogram15s32 {
Expand All @@ -21,6 +23,7 @@ func NewLatencyHistogram15s32(name string) *LatencyHistogram15s32 {
}

func (l *LatencyHistogram15s32) Value(t time.Duration) {
atomic.AddUint64(&l.sum, uint64(t.Nanoseconds()/1000))
l.hist.AddDuration(t)
}

Expand All @@ -30,8 +33,9 @@ func (l *LatencyHistogram15s32) ReportGraphite(prefix, buf []byte, now time.Time
// for now, only report the summaries :(
r, ok := l.hist.Report(snap)
if ok {
sum := atomic.SwapUint64(&l.sum, 0)
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you are reseting sum to 0 on every flush, but not count.

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r.Count comes from the report which comes from the histogram snapshot. the histogram is reset when snapshot is taken

buf = WriteUint32(buf, prefix, []byte("latency.min.gauge32"), r.Min/1000, now)
buf = WriteUint32(buf, prefix, []byte("latency.mean.gauge32"), r.Mean/1000, now)
buf = WriteUint32(buf, prefix, []byte("latency.mean.gauge32"), uint32((sum / uint64(r.Count) / 1000)), now)
buf = WriteUint32(buf, prefix, []byte("latency.median.gauge32"), r.Median/1000, now)
buf = WriteUint32(buf, prefix, []byte("latency.p75.gauge32"), r.P75/1000, now)
buf = WriteUint32(buf, prefix, []byte("latency.p90.gauge32"), r.P90/1000, now)
Expand Down