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047df28b88
Fix #5455 The `math/rand.Rand` type is not safe for concurrent access. Concurrent measurements, and therefore concurrent exemplar computation, are allowed. Ensure this concurrent design does not lead to data races with `rng`.
68 lines
1.4 KiB
Go
68 lines
1.4 KiB
Go
// Copyright The OpenTelemetry Authors
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// SPDX-License-Identifier: Apache-2.0
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package exemplar
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import (
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"context"
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"math"
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"slices"
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"sync"
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"testing"
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"github.com/stretchr/testify/assert"
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)
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func TestFixedSize(t *testing.T) {
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t.Run("Int64", ReservoirTest[int64](func(n int) (Reservoir, int) {
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return FixedSize(n), n
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}))
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t.Run("Float64", ReservoirTest[float64](func(n int) (Reservoir, int) {
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return FixedSize(n), n
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}))
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}
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func TestFixedSizeSamplingCorrectness(t *testing.T) {
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intensity := 0.1
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sampleSize := 1000
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data := make([]float64, sampleSize*1000)
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for i := range data {
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// Generate exponentially distributed data.
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data[i] = (-1.0 / intensity) * math.Log(random())
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}
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// Sort to test position bias.
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slices.Sort(data)
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r := FixedSize(sampleSize)
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for _, value := range data {
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r.Offer(context.Background(), staticTime, NewValue(value), nil)
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}
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var sum float64
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for _, m := range r.(*randRes).store {
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sum += m.Value.Float64()
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}
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mean := sum / float64(sampleSize)
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// Check the intensity/rate of the sampled distribution is preserved
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// ensuring no bias in our random sampling algorithm.
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assert.InDelta(t, 1/mean, intensity, 0.02) // Within 5σ.
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}
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func TestRandomConcurrentSafe(t *testing.T) {
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const goRoutines = 10
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var wg sync.WaitGroup
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for n := 0; n < goRoutines; n++ {
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wg.Add(1)
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go func() {
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defer wg.Done()
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_ = random()
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}()
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}
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wg.Wait()
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}
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