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12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152// Copyright (c) Tailscale Inc & contributors// SPDX-License-Identifier: BSD-3-Clause
package tstest
import ( "fmt" "runtime" "time"
"tailscale.com/util/testenv")
// MinAllocsPerRun asserts that f can run with no more than target allocations.// It runs f up to 1000 times or 5s, whichever happens first.// If f has executed more than target allocations on every run, it returns a non-nil error.//// MinAllocsPerRun sets GOMAXPROCS to 1 during its measurement and restores// it before returning.func MinAllocsPerRun(t testenv.TB, target uint64, f func()) error { defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
var memstats runtime.MemStats var min, max, sum uint64 start := time.Now() var iters int for { runtime.ReadMemStats(&memstats) startMallocs := memstats.Mallocs f() runtime.ReadMemStats(&memstats) mallocs := memstats.Mallocs - startMallocs // TODO: if mallocs < target, return an error? See discussion in #3204. if mallocs <= target { return nil } if min == 0 || mallocs < min { min = mallocs } if mallocs > max { max = mallocs } sum += mallocs iters++ if iters == 1000 || time.Since(start) > 5*time.Second { break } }
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)}