64 lines
1.4 KiB
Go
64 lines
1.4 KiB
Go
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package peer
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import (
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"sync"
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"time"
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)
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// LatencyEWMASmooting governs the decay of the EWMA (the speed
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// at which it changes). This must be a normalized (0-1) value.
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// 1 is 100% change, 0 is no change.
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var LatencyEWMASmoothing = 0.1
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// Metrics is just an object that tracks metrics
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// across a set of peers.
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type Metrics interface {
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// RecordLatency records a new latency measurement
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RecordLatency(ID, time.Duration)
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// LatencyEWMA returns an exponentially-weighted moving avg.
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// of all measurements of a peer's latency.
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LatencyEWMA(ID) time.Duration
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}
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type metrics struct {
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latmap map[ID]time.Duration
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latmu sync.RWMutex
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}
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func NewMetrics() Metrics {
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return &metrics{
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latmap: make(map[ID]time.Duration),
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}
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}
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// RecordLatency records a new latency measurement
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func (m *metrics) RecordLatency(p ID, next time.Duration) {
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nextf := float64(next)
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s := LatencyEWMASmoothing
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if s > 1 || s < 0 {
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s = 0.1 // ignore the knob. it's broken. look, it jiggles.
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}
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m.latmu.Lock()
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ewma, found := m.latmap[p]
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ewmaf := float64(ewma)
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if !found {
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m.latmap[p] = next // when no data, just take it as the mean.
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} else {
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nextf = ((1.0 - s) * ewmaf) + (s * nextf)
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m.latmap[p] = time.Duration(nextf)
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}
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m.latmu.Unlock()
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}
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// LatencyEWMA returns an exponentially-weighted moving avg.
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// of all measurements of a peer's latency.
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func (m *metrics) LatencyEWMA(p ID) time.Duration {
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m.latmu.RLock()
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lat := m.latmap[p]
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m.latmu.RUnlock()
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return time.Duration(lat)
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}
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