test/mapnan.go: add regression test for non-empty interfaces.
LGTM=rsc, khr
R=rsc, khr, bradfitz
CC=golang-codereviews
https://golang.org/cl/126720043
diff --git a/test/maplinear.go b/test/maplinear.go
new file mode 100644
index 0000000..56e5095
--- /dev/null
+++ b/test/maplinear.go
@@ -0,0 +1,143 @@
+// +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 maps don't go quadratic for NaNs and other values.
+
+package main
+
+import (
+ "fmt"
+ "math"
+ "time"
+)
+
+// checkLinear asserts that the running time of f(n) is in O(n).
+// tries is the initial number of iterations.
+func checkLinear(typ string, tries int, f func(n int)) {
+ // 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.
+
+ timeF := func(n int) time.Duration {
+ t1 := time.Now()
+ f(n)
+ return time.Since(t1)
+ }
+
+ t0 := time.Now()
+
+ n := tries
+ fails := 0
+ for {
+ t1 := timeF(n)
+ t2 := timeF(2 * n)
+
+ // should be 2x (linear); allow up to 3x
+ if t2 < 3*t1 {
+ if false {
+ fmt.Println(typ, "\t", time.Since(t0))
+ }
+ return
+ }
+ fails++
+ if fails == 6 {
+ panic(fmt.Sprintf("%s: too slow: %d inserts: %v; %d inserts: %v\n",
+ typ, n, t1, 2*n, t2))
+ }
+ if fails < 4 {
+ n *= 2
+ }
+ }
+}
+
+type I interface {
+ f()
+}
+
+type C int
+
+func (C) f() {}
+
+func main() {
+ // NaNs. ~31ms on a 1.6GHz Zeon.
+ checkLinear("NaN", 30000, func(n int) {
+ 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")
+ }
+ })
+
+ // ~6ms on a 1.6GHz Zeon.
+ checkLinear("eface", 10000, func(n int) {
+ m := map[interface{}]int{}
+ for i := 0; i < n; i++ {
+ m[i] = 1
+ }
+ })
+
+ // ~7ms on a 1.6GHz Zeon.
+ // Regression test for CL 119360043.
+ checkLinear("iface", 10000, func(n int) {
+ m := map[I]int{}
+ for i := 0; i < n; i++ {
+ m[C(i)] = 1
+ }
+ })
+
+ // ~6ms on a 1.6GHz Zeon.
+ checkLinear("int", 10000, func(n int) {
+ m := map[int]int{}
+ for i := 0; i < n; i++ {
+ m[i] = 1
+ }
+ })
+
+ // ~18ms on a 1.6GHz Zeon.
+ checkLinear("string", 10000, func(n int) {
+ m := map[string]int{}
+ for i := 0; i < n; i++ {
+ m[fmt.Sprint(i)] = 1
+ }
+ })
+
+ // ~6ms on a 1.6GHz Zeon.
+ checkLinear("float32", 10000, func(n int) {
+ m := map[float32]int{}
+ for i := 0; i < n; i++ {
+ m[float32(i)] = 1
+ }
+ })
+
+ // ~6ms on a 1.6GHz Zeon.
+ checkLinear("float64", 10000, func(n int) {
+ m := map[float64]int{}
+ for i := 0; i < n; i++ {
+ m[float64(i)] = 1
+ }
+ })
+
+ // ~22ms on a 1.6GHz Zeon.
+ checkLinear("complex64", 10000, func(n int) {
+ m := map[complex64]int{}
+ for i := 0; i < n; i++ {
+ m[complex(float32(i), float32(i))] = 1
+ }
+ })
+
+ // ~32ms on a 1.6GHz Zeon.
+ checkLinear("complex128", 10000, func(n int) {
+ m := map[complex128]int{}
+ for i := 0; i < n; i++ {
+ m[complex(float64(i), float64(i))] = 1
+ }
+ })
+}
