File size: 1,881 Bytes
e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | // Copyright 2024 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.
package race_test
import (
"runtime"
"sync/atomic"
"testing"
)
type Seq2[T1, T2 any] func(yield func(T1, T2) bool)
// ofSliceIndex returns a Seq over the elements of s. It is equivalent
// to range s, except that it splits s into two halves and iterates
// in two separate goroutines. This is racy if yield is racy, and yield
// will be racy if it contains an early exit.
func ofSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
return func(yield func(int, T) bool) {
c := make(chan bool, 2)
var done atomic.Bool
go func() {
for i := 0; i < len(s)/2; i++ {
if !done.Load() && !yield(i, s[i]) {
done.Store(true)
c <- false
}
}
c <- true
}()
go func() {
for i := len(s) / 2; i < len(s); i++ {
if !done.Load() && !yield(i, s[i]) {
done.Store(true)
c <- false
}
}
c <- true
return
}()
if !<-c {
return
}
<-c
}
}
// foo is racy, or not, depending on the value of v
// (0-4 == racy, otherwise, not racy).
func foo(v int) int64 {
var asum atomic.Int64
for i, x := range ofSliceIndex([]int64{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
if i%5 == v {
break
}
asum.Add(x) // don't race on asum
runtime.Gosched()
}
return 100 + asum.Load()
}
// TestRaceRangeFuncIterator races because x%5 can be equal to 4,
// therefore foo can early exit.
func TestRaceRangeFuncIterator(t *testing.T) {
t.Skip("#72925: uncaught panic ends tests")
x := foo(4)
t.Logf("foo(4)=%d", x)
}
// TestNoRaceRangeFuncIterator does not race because x%5 is never 5,
// therefore foo's loop will not exit early, and this it will not race.
func TestNoRaceRangeFuncIterator(t *testing.T) {
t.Skip("#72925: unexpected data race")
x := foo(5)
t.Logf("foo(5)=%d", x)
}
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