158 lines
3.5 KiB
Go
158 lines
3.5 KiB
Go
package metrics
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import (
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"fmt"
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"io"
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"math"
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"sync"
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"time"
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"github.com/valyala/histogram"
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)
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const defaultSummaryWindow = 5 * time.Minute
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var defaultSummaryQuantiles = []float64{0.5, 0.9, 0.97, 0.99, 1}
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// Summary implements summary.
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type Summary struct {
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mu sync.Mutex
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curr *histogram.Fast
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next *histogram.Fast
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quantiles []float64
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quantileValues []float64
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}
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// NewSummary creates and returns new summary with the given name.
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//
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// name must be valid Prometheus-compatible metric with possible lables.
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// For instance,
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//
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// * foo
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// * foo{bar="baz"}
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// * foo{bar="baz",aaa="b"}
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//
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// The returned summary is safe to use from concurrent goroutines.
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func NewSummary(name string) *Summary {
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return NewSummaryExt(name, defaultSummaryWindow, defaultSummaryQuantiles)
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}
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// NewSummaryExt creates and returns new summary with the given name,
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// window and quantiles.
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//
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// name must be valid Prometheus-compatible metric with possible lables.
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// For instance,
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//
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// * foo
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// * foo{bar="baz"}
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// * foo{bar="baz",aaa="b"}
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//
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// The returned summary is safe to use from concurrent goroutines.
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func NewSummaryExt(name string, window time.Duration, quantiles []float64) *Summary {
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validateQuantiles(quantiles)
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s := &Summary{
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curr: histogram.NewFast(),
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next: histogram.NewFast(),
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quantiles: quantiles,
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quantileValues: make([]float64, len(quantiles)),
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}
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registerSummary(s, window)
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registerMetric(name, s)
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for i, q := range quantiles {
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quantileValueName := addTag(name, fmt.Sprintf(`quantile="%g"`, q))
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qv := &quantileValue{
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s: s,
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idx: i,
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}
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registerMetric(quantileValueName, qv)
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}
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return s
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}
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func validateQuantiles(quantiles []float64) {
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for _, q := range quantiles {
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if q < 0 || q > 1 {
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panic(fmt.Errorf("BUG: quantile must be in the range [0..1]; got %v", q))
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}
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}
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}
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// Update updates the summary.
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func (s *Summary) Update(v float64) {
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s.mu.Lock()
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s.curr.Update(v)
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s.next.Update(v)
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s.mu.Unlock()
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}
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// UpdateDuration updates request duration based on the given startTime.
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func (s *Summary) UpdateDuration(startTime time.Time) {
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d := time.Since(startTime).Seconds()
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s.Update(d)
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}
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func (s *Summary) marshalTo(prefix string, w io.Writer) {
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// Just update s.quantileValues and don't write anything to w.
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// s.quantileValues will be marshaled later via quantileValue.marshalTo.
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s.updateQuantiles()
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}
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func (s *Summary) updateQuantiles() {
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s.mu.Lock()
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s.quantileValues = s.curr.Quantiles(s.quantileValues[:0], s.quantiles)
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s.mu.Unlock()
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}
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type quantileValue struct {
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s *Summary
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idx int
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}
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func (qv *quantileValue) marshalTo(prefix string, w io.Writer) {
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qv.s.mu.Lock()
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v := qv.s.quantileValues[qv.idx]
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qv.s.mu.Unlock()
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if !math.IsNaN(v) {
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fmt.Fprintf(w, "%s %g\n", prefix, v)
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}
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}
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func addTag(name, tag string) string {
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if len(name) == 0 || name[len(name)-1] != '}' {
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return fmt.Sprintf("%s{%s}", name, tag)
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}
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return fmt.Sprintf("%s,%s}", name[:len(name)-1], tag)
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}
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func registerSummary(s *Summary, window time.Duration) {
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summariesLock.Lock()
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summaries[window] = append(summaries[window], s)
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if len(summaries[window]) == 1 {
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go summariesSwapCron(window)
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}
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summariesLock.Unlock()
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}
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func summariesSwapCron(window time.Duration) {
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for {
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time.Sleep(window / 2)
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summariesLock.Lock()
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for _, s := range summaries[window] {
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s.mu.Lock()
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tmp := s.curr
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s.curr = s.next
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s.next = tmp
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s.next.Reset()
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s.mu.Unlock()
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}
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summariesLock.Unlock()
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}
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}
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var (
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summaries = map[time.Duration][]*Summary{}
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summariesLock sync.Mutex
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)
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