gcc/testsuite/go.test/test/mapnan.go

   1 // +build darwin linux
   2 // run
   3
   4 // Copyright 2013 The Go Authors. All rights reserved.
   5 // Use of this source code is governed by a BSD-style
   6 // license that can be found in the LICENSE file.
   7
   8 // Test that NaNs in maps don't go quadratic.
   9
  10 package main
  11
  12 import (
  13         "fmt"
  14         "math"
  15         "time"
  16 )
  17
  18 func main() {
  19
  20         // Test that NaNs in maps don't go quadratic.
  21         t := func(n int) time.Duration {
  22                 t1 := time.Now()
  23                 m := map[float64]int{}
  24                 nan := math.NaN()
  25                 for i := 0; i < n; i++ {
  26                         m[nan] = 1
  27                 }
  28                 if len(m) != n {
  29                         panic("wrong size map after nan insertion")
  30                 }
  31                 return time.Since(t1)
  32         }
  33
  34         // Depending on the machine and OS, this test might be too fast
  35         // to measure with accurate enough granularity. On failure,
  36         // make it run longer, hoping that the timing granularity
  37         // is eventually sufficient.
  38
  39         n := 30000 // ~8ms user time on a Mid 2011 MacBook Air (1.8 GHz Core i7)
  40         fails := 0
  41         for {
  42                 t1 := t(n)
  43                 t2 := t(2 * n)
  44                 // should be 2x (linear); allow up to 3x
  45                 if t2 < 3*t1 {
  46                         return
  47                 }
  48                 fails++
  49                 if fails == 6 {
  50                         panic(fmt.Sprintf("too slow: %d inserts: %v; %d inserts: %v\n", n, t1, 2*n, t2))
  51                 }
  52                 if fails < 4 {
  53                         n *= 2
  54                 }
  55         }
  56 }