golang allocs 代码
文件路径：/src/testing/allocs.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))
}