mirror of https://github.com/prometheus/prometheus
54 lines
1.0 KiB
Go
54 lines
1.0 KiB
Go
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package remote
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import (
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"sync"
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"sync/atomic"
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"time"
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)
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// ewmaRate tracks an exponentially weighted moving average of a per-second rate.
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type ewmaRate struct {
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newEvents int64
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alpha float64
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interval time.Duration
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lastRate float64
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init bool
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mutex sync.Mutex
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}
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func newEWMARate(alpha float64, interval time.Duration) ewmaRate {
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return ewmaRate{
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alpha: alpha,
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interval: interval,
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}
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}
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// rate returns the per-second rate.
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func (r *ewmaRate) rate() float64 {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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return r.lastRate
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}
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// tick assumes to be called every r.interval.
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func (r *ewmaRate) tick() {
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newEvents := atomic.LoadInt64(&r.newEvents)
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atomic.AddInt64(&r.newEvents, -newEvents)
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instantRate := float64(newEvents) / r.interval.Seconds()
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r.mutex.Lock()
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defer r.mutex.Unlock()
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if r.init {
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r.lastRate += r.alpha * (instantRate - r.lastRate)
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} else {
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r.init = true
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r.lastRate = instantRate
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}
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}
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// inc counts one event.
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func (r *ewmaRate) incr(incr int64) {
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atomic.AddInt64(&r.newEvents, incr)
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}
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