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mirror of https://github.com/golang/go synced 2024-11-19 18:24:39 -07:00
go/src/testing/allocs.go
Brad Fitzpatrick 5fea2ccc77 all: single space after period.
The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.

This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:

$ perl -i -npe 's,^(\s*// .+[a-z]\.)  +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.)  +([A-Z])')
$ go test go/doc -update

Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Day <djd@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-03-02 00:13:47 +00:00

46 lines
1.4 KiB
Go

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package testing
import (
"runtime"
)
// AllocsPerRun returns the average number of allocations during calls to f.
// Although the return value has type float64, it will always be an integral value.
//
// To compute the number of allocations, the function will first be run once as
// a warm-up. The average number of allocations over the specified number of
// runs will then be measured and returned.
//
// AllocsPerRun sets GOMAXPROCS to 1 during its measurement and will restore
// it before returning.
func AllocsPerRun(runs int, f func()) (avg float64) {
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
// Warm up the function
f()
// Measure the starting statistics
var memstats runtime.MemStats
runtime.ReadMemStats(&memstats)
mallocs := 0 - memstats.Mallocs
// Run the function the specified number of times
for i := 0; i < runs; i++ {
f()
}
// Read the final statistics
runtime.ReadMemStats(&memstats)
mallocs += memstats.Mallocs
// Average the mallocs over the runs (not counting the warm-up).
// We are forced to return a float64 because the API is silly, but do
// the division as integers so we can ask if AllocsPerRun()==1
// instead of AllocsPerRun()<2.
return float64(mallocs / uint64(runs))
}