feat: Add Race and RaceWithContext.

Author: ghosind

race.go

@@ -0,0 +1,39 @@
+package async
+
+import (
+	"context"
+	"sync/atomic"
+)
+
+func Race(funcs ...func(context.Context) error) error {
+	return race(context.Background(), funcs...)
+}
+
+func RaceWithContext(ctx context.Context, funcs ...func(context.Context) error) error {
+	return race(ctx, funcs...)
+}
+
+func race(ctx context.Context, funcs ...func(context.Context) error) error {
+	if len(funcs) == 0 {
+		return nil
+	}
+
+	finished := atomic.Bool{}
+	ch := make(chan error)
+	defer close(ch)
+
+	for i := 0; i < len(funcs); i++ {
+		fn := funcs[i]
+
+		go func() {
+			err := fn(ctx)
+			if finished.CompareAndSwap(false, true) {
+				ch <- err
+			}
+		}()
+	}
+
+	err := <-ch
+
+	return err
+}

race_test.go

@@ -0,0 +1,69 @@
+package async
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/ghosind/go-assert"
+)
+
+func TestRaceWithoutFuncs(t *testing.T) {
+	a := assert.New(t)
+
+	err := Race()
+	a.NilNow(err)
+}
+
+func TestRace(t *testing.T) {
+	a := assert.New(t)
+
+	data := make([]bool, 5)
+	funcs := make([]func(context.Context) error, 0, 5)
+	for i := 0; i < 5; i++ {
+		n := i
+		funcs = append(funcs, func(ctx context.Context) error {
+			time.Sleep(time.Duration((n+1)*50) * time.Millisecond)
+			data[n] = true
+			return nil
+		})
+	}
+
+	err := Race(funcs...)
+	a.NilNow(err)
+	a.EqualNow(data, []bool{true, false, false, false, false})
+
+	time.Sleep(300 * time.Millisecond)
+	a.EqualNow(data, []bool{true, true, true, true, true})
+}
+
+func TestRaceWithContext(t *testing.T) {
+	a := assert.New(t)
+
+	data := make([]bool, 5)
+	funcs := make([]func(context.Context) error, 0, 5)
+	for i := 0; i < 5; i++ {
+		n := i
+		funcs = append(funcs, func(ctx context.Context) error {
+			time.Sleep(time.Duration((n+1)*50) * time.Millisecond)
+			select {
+			case <-ctx.Done():
+				return errors.New("timeout")
+			default:
+				data[n] = true
+				return nil
+			}
+		})
+	}
+
+	ctx, canFunc := context.WithTimeout(context.Background(), 170*time.Millisecond)
+	defer canFunc()
+
+	err := RaceWithContext(ctx, funcs...)
+	a.NilNow(err)
+	a.EqualNow(data, []bool{true, false, false, false, false})
+
+	time.Sleep(300 * time.Millisecond)
+	a.EqualNow(data, []bool{true, true, true, false, false})
+}