From 8ed119e3f60099d7c232a30efa9d474aff3bc8db Mon Sep 17 00:00:00 2001
From: Darien Raymond <admin@v2ray.com>
Date: Sun, 5 Aug 2018 17:56:49 +0200
Subject: [PATCH] make sure err is propagated

---
 common/task/task.go | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/common/task/task.go b/common/task/task.go
index f79e5610a..5a6763959 100644
--- a/common/task/task.go
+++ b/common/task/task.go
@@ -88,8 +88,8 @@ func OnFailure(task Task) ExecutionOption {
 	}
 }
 
-func Single(task Task, opts ExecutionOption) Task {
-	return Run(append([]ExecutionOption{Sequential(task)}, opts)...)
+func Single(task Task, opts ...ExecutionOption) Task {
+	return Run(append([]ExecutionOption{Sequential(task)}, opts...)...)
 }
 
 func Run(opts ...ExecutionOption) Task {
@@ -120,14 +120,17 @@ func executeParallel(ctx context.Context, tasks []Task) error {
 
 	for _, task := range tasks {
 		<-s.Wait()
-		go func(f func() error) {
-			if err := f(); err != nil {
-				select {
-				case done <- err:
-				default:
-				}
+		go func(f Task) {
+			err := f()
+			if err == nil {
+				s.Signal()
+				return
+			}
+
+			select {
+			case done <- err:
+			default:
 			}
-			s.Signal()
 		}(task)
 	}