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https://github.com/golang/go
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65 lines
1.3 KiB
Go
65 lines
1.3 KiB
Go
// +build darwin linux
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// run
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test that NaNs in maps don't go quadratic.
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package main
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import (
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"fmt"
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"math"
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"time"
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"syscall"
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)
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func main() {
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// Test that NaNs in maps don't go quadratic.
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t := func(n int) time.Duration {
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var u0 syscall.Rusage
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if err := syscall.Getrusage(0, &u0); err != nil {
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panic(err)
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}
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m := map[float64]int{}
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nan := math.NaN()
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for i := 0; i < n; i++ {
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m[nan] = 1
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}
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if len(m) != n {
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panic("wrong size map after nan insertion")
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}
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var u1 syscall.Rusage
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if err := syscall.Getrusage(0, &u1); err != nil {
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panic(err)
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}
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return time.Duration(u1.Utime.Nano() - u0.Utime.Nano())
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}
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// Depending on the machine and OS, this test might be too fast
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// to measure with accurate enough granularity. On failure,
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// make it run longer, hoping that the timing granularity
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// is eventually sufficient.
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n := 30000 // ~8ms user time on a Mid 2011 MacBook Air (1.8 GHz Core i7)
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fails := 0
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for {
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t1 := t(n)
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t2 := t(2 * n)
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// should be 2x (linear); allow up to 3x
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if t2 < 3*t1 {
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return
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}
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fails++
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if fails == 6 {
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panic(fmt.Sprintf("too slow: %d inserts: %v; %d inserts: %v\n", n, t1, 2*n, t2))
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}
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if fails < 4 {
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n *= 2
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}
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}
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}
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