mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
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111 lines
2.8 KiB
Go
111 lines
2.8 KiB
Go
package streamaggr
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import (
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"math"
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"sync"
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"sync/atomic"
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"time"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
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)
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// stddevAggrState calculates output=stddev, e.g. the average value over input samples.
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type stddevAggrState struct {
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m sync.Map
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intervalSecs uint64
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lastPushTimestamp atomic.Uint64
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}
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type stddevStateValue struct {
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mu sync.Mutex
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count float64
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avg float64
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q float64
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deleted bool
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}
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func newStddevAggrState(interval time.Duration) *stddevAggrState {
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return &stddevAggrState{
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intervalSecs: roundDurationToSecs(interval),
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}
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}
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func (as *stddevAggrState) pushSample(_, outputKey string, value float64) {
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again:
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v, ok := as.m.Load(outputKey)
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if !ok {
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// The entry is missing in the map. Try creating it.
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v = &stddevStateValue{}
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vNew, loaded := as.m.LoadOrStore(outputKey, v)
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if loaded {
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// Use the entry created by a concurrent goroutine.
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v = vNew
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}
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}
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sv := v.(*stddevStateValue)
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sv.mu.Lock()
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deleted := sv.deleted
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if !deleted {
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// See `Rapid calculation methods` at https://en.wikipedia.org/wiki/Standard_deviation
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sv.count++
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avg := sv.avg + (value-sv.avg)/sv.count
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sv.q += (value - sv.avg) * (value - avg)
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sv.avg = avg
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}
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sv.mu.Unlock()
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if deleted {
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// The entry has been deleted by the concurrent call to appendSeriesForFlush
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// Try obtaining and updating the entry again.
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goto again
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}
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}
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func (as *stddevAggrState) appendSeriesForFlush(ctx *flushCtx) {
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currentTime := fasttime.UnixTimestamp()
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currentTimeMsec := int64(currentTime) * 1000
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m := &as.m
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m.Range(func(k, v interface{}) bool {
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// Atomically delete the entry from the map, so new entry is created for the next flush.
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m.Delete(k)
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sv := v.(*stddevStateValue)
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sv.mu.Lock()
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stddev := math.Sqrt(sv.q / sv.count)
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// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
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sv.deleted = true
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sv.mu.Unlock()
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key := k.(string)
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ctx.appendSeries(key, as.getOutputName(), currentTimeMsec, stddev)
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return true
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})
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as.lastPushTimestamp.Store(currentTime)
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}
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func (as *stddevAggrState) getOutputName() string {
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return "stddev"
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}
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func (as *stddevAggrState) getStateRepresentation(suffix string) aggrStateRepresentation {
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metrics := make([]aggrStateRepresentationMetric, 0)
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as.m.Range(func(k, v any) bool {
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value := v.(*stddevStateValue)
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value.mu.Lock()
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defer value.mu.Unlock()
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if value.deleted {
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return true
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}
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metrics = append(metrics, aggrStateRepresentationMetric{
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metric: getLabelsStringFromKey(k.(string), suffix, as.getOutputName()),
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currentValue: math.Sqrt(value.q / value.count),
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samplesCount: uint64(value.count),
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})
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return true
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})
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return aggrStateRepresentation{
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intervalSecs: as.intervalSecs,
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lastPushTimestamp: as.lastPushTimestamp.Load(),
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metrics: metrics,
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}
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}
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