test: add test of NaN in map

R=iant, r
CC=golang-dev
https://golang.org/cl/5576071

diff --git a/test/map.go b/test/map.go
index 1c6698629902cdf6e7a9b8664cfa7fcf3107b1ec..821f02ee0a0eb81d21fd1ecf6a1d7222a9b265b1 100644 (file)
--- a/test/map.go
+++ b/test/map.go
@@ -10,6 +10,7 @@ import (
        "fmt"
        "math"
        "strconv"
+       "time"
 )
 
 const count = 100
@@ -27,6 +28,12 @@ func P(a []string) string {
 }
 
 func main() {
+       testbasic()
+       testfloat()
+       testnan()
+}
+
+func testbasic() {
        // Test a map literal.
        mlit := map[string]int{"0": 0, "1": 1, "2": 2, "3": 3, "4": 4}
        for i := 0; i < len(mlit); i++ {
@@ -489,8 +496,6 @@ func main() {
        for _, _ = range mnil {
                panic("range mnil")
        }
-
-       testfloat()
 }
 
 func testfloat() {
@@ -646,3 +651,26 @@ func testfloat() {
                }
        }
 }
+
+func testnan() {
+       // Test that NaNs in maps don't go quadratic.
+       t := func(n int) time.Duration {
+               t0 := 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")
+               }
+               return time.Since(t0)
+       }
+
+       n := 30000 // 0.02 seconds on a MacBook Air
+       t1 := t(n)
+       t2 := t(2 * n)
+       if t2 > 3*t1 { // should be 2x (linear); allow up to 3x
+               fmt.Printf("too slow: %d inserts: %v; %d inserts: %v\n", n, t1, 2*n, t2)
+       }
+}