51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package tstest
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import (
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"fmt"
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"runtime"
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"testing"
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"time"
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)
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// MinAllocsPerRun asserts that f can run with no more than target allocations.
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// It runs f up to 1000 times or 5s, whichever happens first.
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// If f has executed more than target allocations on every run, it returns a non-nil error.
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//
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// MinAllocsPerRun sets GOMAXPROCS to 1 during its measurement and restores
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// it before returning.
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func MinAllocsPerRun(t *testing.T, target uint64, f func()) error {
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
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var memstats runtime.MemStats
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var min, max, sum uint64
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start := time.Now()
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var iters int
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for {
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runtime.ReadMemStats(&memstats)
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startMallocs := memstats.Mallocs
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f()
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runtime.ReadMemStats(&memstats)
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mallocs := memstats.Mallocs - startMallocs
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// TODO: if mallocs < target, return an error? See discussion in #3204.
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if mallocs <= target {
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return nil
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}
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if min == 0 || mallocs < min {
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min = mallocs
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}
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if mallocs > max {
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max = mallocs
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}
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sum += mallocs
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iters++
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if iters == 1000 || time.Since(start) > 5*time.Second {
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break
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}
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}
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return fmt.Errorf("min allocs = %d, max allocs = %d, avg allocs/run = %f, want run with <= %d allocs", min, max, float64(sum)/float64(iters), target)
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}
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