fix: AnyOf return first not err result or first err if all err

api.go

@@ -70,13 +70,24 @@ type AnyResult[T any] struct {
 }
 
 func AnyOf[T any](fs ...*Future[T]) *Future[AnyResult[T]] {
+	var counter int32
 	var done uint32
+	var errIndex int32 = -1
 	s := &state[AnyResult[T]]{}
 	for i, f := range fs {
 		i := i
 		f.state.subscribe(func(val T, err error) {
-			if atomic.CompareAndSwapUint32(&done, 0, 1) {
-				s.set(AnyResult[T]{Index: i, Val: val, Err: err}, nil)
+			if err == nil {
+				if atomic.CompareAndSwapUint32(&done, 0, 1) {
+					s.set(AnyResult[T]{Index: i, Val: val, Err: err}, nil)
+				}
+			} else {
+				atomic.CompareAndSwapInt32(&errIndex, -1, int32(i))
+				if atomic.AddInt32(&counter, 1) == int32(len(fs)) {
+					idx := atomic.LoadInt32(&errIndex)
+					fval, ferr := fs[idx].Get()
+					s.set(AnyResult[T]{Index: int(idx), Val: fval, Err: ferr}, nil)
+				}
 			}
 		})
 	}

api_test.go

@@ -235,6 +235,9 @@ func TestAnyOf(t *testing.T) {
 		i := i
 		fs[i] = Async(func() (int, error) {
 			time.Sleep(time.Duration(vals[i]) * time.Millisecond)
+			if i != target && rand.Intn(2) == 0 { // random error
+				return 0, errFoo
+			}
 			return vals[i], nil
 		})
 	}
@@ -246,7 +249,7 @@ func TestAnyOf(t *testing.T) {
 	assert.Equal(t, nil, r.Err)
 }
 
-func TestAnyOfWhenErrFirst(t *testing.T) {
+func TestAnyOfWhenAllErr(t *testing.T) {
 	target := rand.Intn(10)
 	vals := make([]int, 10)
 	for i := 0; i < len(vals); i++ {
@@ -261,11 +264,11 @@ func TestAnyOfWhenErrFirst(t *testing.T) {
 	for i := 0; i < 10; i++ {
 		i := i
 		fs[i] = Async(func() (int, error) {
-			time.Sleep(time.Duration(vals[i]) * time.Millisecond)
 			if i == target {
 				return 0, errFoo
 			}
-			return vals[i], nil
+			time.Sleep(time.Duration(vals[i]) * time.Millisecond)
+			return 0, errFoo
 		})
 	}
 	f := AnyOf(fs...)