From 27bc1ca5d17a1f401f4be0829cb5f9cb3fefc1ec Mon Sep 17 00:00:00 2001
From: Ross Hammermeister <glitch17@gmail.com>
Date: Wed, 13 Nov 2019 13:50:04 -0700
Subject: [PATCH] Add flag to allow tasks provided on the command line to be
 run in parallel

---
 cmd/task/task.go |  3 +++
 task.go          | 13 ++++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/cmd/task/task.go b/cmd/task/task.go
index b71023ac..3ae8dcd8 100644
--- a/cmd/task/task.go
+++ b/cmd/task/task.go
@@ -58,6 +58,7 @@ func main() {
 		silent      bool
 		dry         bool
 		summary     bool
+		parallel    bool
 		dir         string
 		entrypoint  string
 		output      string
@@ -71,6 +72,7 @@ func main() {
 	pflag.BoolVarP(&watch, "watch", "w", false, "enables watch of the given task")
 	pflag.BoolVarP(&verbose, "verbose", "v", false, "enables verbose mode")
 	pflag.BoolVarP(&silent, "silent", "s", false, "disables echoing")
+	pflag.BoolVarP(&parallel, "parallel", "p", false, "executes tasks provided on command line in parallel")
 	pflag.BoolVar(&dry, "dry", false, "compiles and prints tasks in the order that they would be run, without executing them")
 	pflag.BoolVar(&summary, "summary", false, "show summary about a task")
 	pflag.StringVarP(&dir, "dir", "d", "", "sets directory of execution")
@@ -114,6 +116,7 @@ func main() {
 		Dry:        dry,
 		Entrypoint: entrypoint,
 		Summary:    summary,
+		Parallel:   parallel,
 
 		Stdin:  os.Stdin,
 		Stdout: os.Stdout,
diff --git a/task.go b/task.go
index 83198192..1c3cd383 100644
--- a/task.go
+++ b/task.go
@@ -41,6 +41,7 @@ type Executor struct {
 	Silent     bool
 	Dry        bool
 	Summary    bool
+	Parallel   bool
 
 	Stdin  io.Reader
 	Stdout io.Writer
@@ -77,12 +78,18 @@ func (e *Executor) Run(ctx context.Context, calls ...taskfile.Call) error {
 		return e.watchTasks(calls...)
 	}
 
+	g, ctx := errgroup.WithContext(ctx)
 	for _, c := range calls {
-		if err := e.RunTask(ctx, c); err != nil {
-			return err
+		c := c
+		if e.Parallel {
+			g.Go(func() error { return e.RunTask(ctx, c) })
+		} else {
+			if err := e.RunTask(ctx, c); err != nil {
+				return err
+			}
 		}
 	}
-	return nil
+	return g.Wait()
 }
 
 // Setup setups Executor's internal state