code review 15570046: test/mapnan: use time.Now instead of syscall.Getrusage

test/mapnan.go

 // +build darwin linux
 // run
 
 // 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.
 
 // Test that NaNs in maps don't go quadratic.
 
 package main
 
 import (
         "fmt"
         "math"
         "time"
-        "syscall"
 )
 
 func main() {
 
         // Test that NaNs in maps don't go quadratic.
         t := func(n int) time.Duration {
-                var u0 syscall.Rusage
-                if err := syscall.Getrusage(0,  &u0); err != nil {
-                        panic(err)
-                }
+                t1 := time.Now()
                 m := map[float64]int{}
                 nan := math.NaN()
                 for i := 0; i < n; i++ {
                         m[nan] = 1
                 }
                 if len(m) != n {
                         panic("wrong size map after nan insertion")
                 }
-                var u1 syscall.Rusage
-                if err := syscall.Getrusage(0,  &u1); err != nil {
-                        panic(err)
-                }
-                return time.Duration(u1.Utime.Nano() - u0.Utime.Nano())
+                return time.Since(t1)
         }
 
         // Depending on the machine and OS, this test might be too fast
         // to measure with accurate enough granularity. On failure,
         // make it run longer, hoping that the timing granularity
         // is eventually sufficient.
 
         n := 30000 // ~8ms user time on a Mid 2011 MacBook Air (1.8 GHz Core i7)
         fails := 0
         for {
                 t1 := t(n)
                 t2 := t(2 * n)
                 // should be 2x (linear); allow up to 3x
                 if t2 < 3*t1 {
                         return
                 }
                 fails++
                 if fails == 6 {
                         panic(fmt.Sprintf("too slow: %d inserts: %v; %d inserts: %v\n", n, t1, 2*n, t2))
                 }
                 if fails < 4 {
                         n *= 2
                 }
         }
 }