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// +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)
}
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())
}
// 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
}
}
}
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