From c591ea41856af8152cb33f5435f686e3ea090f88 Mon Sep 17 00:00:00 2001
From: Andrey Nering <andrey.nering@gmail.com>
Date: Wed, 12 Apr 2017 20:53:41 -0300
Subject: [PATCH] Use context together with errgroup

This will let other deps to be killed when one of the deps returns an
error.

Before this change, the process could keep running even after Task
exited.
---
 task.go  | 20 ++++++++++----------
 watch.go |  5 +++--
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/task.go b/task.go
index 692331e4..5fae5c4e 100644
--- a/task.go
+++ b/task.go
@@ -77,20 +77,20 @@ func Run() {
 	}
 
 	for _, a := range args {
-		if err = RunTask(a); err != nil {
+		if err = RunTask(context.Background(), a); err != nil {
 			log.Fatal(err)
 		}
 	}
 }
 
 // RunTask runs a task by its name
-func RunTask(name string) error {
+func RunTask(ctx context.Context, name string) error {
 	t, ok := Tasks[name]
 	if !ok {
 		return &taskNotFoundError{name}
 	}
 
-	if err := t.runDeps(); err != nil {
+	if err := t.runDeps(ctx); err != nil {
 		return err
 	}
 
@@ -100,20 +100,20 @@ func RunTask(name string) error {
 	}
 
 	for i := range t.Cmds {
-		if err := t.runCommand(i); err != nil {
+		if err := t.runCommand(ctx, i); err != nil {
 			return &taskRunError{name, err}
 		}
 	}
 	return nil
 }
 
-func (t *Task) runDeps() error {
+func (t *Task) runDeps(ctx context.Context) error {
 	vars, err := t.handleVariables()
 	if err != nil {
 		return err
 	}
 
-	var g errgroup.Group
+	g, ctx := errgroup.WithContext(ctx)
 
 	for _, d := range t.Deps {
 		dep := d
@@ -124,7 +124,7 @@ func (t *Task) runDeps() error {
 				return err
 			}
 
-			if err = RunTask(dep); err != nil {
+			if err = RunTask(ctx, dep); err != nil {
 				return err
 			}
 			return nil
@@ -155,7 +155,7 @@ func (t *Task) isUpToDate() bool {
 	return generatesMinTime.After(sourcesMaxTime)
 }
 
-func (t *Task) runCommand(i int) error {
+func (t *Task) runCommand(ctx context.Context, i int) error {
 	vars, err := t.handleVariables()
 	if err != nil {
 		return err
@@ -167,7 +167,7 @@ func (t *Task) runCommand(i int) error {
 
 	if strings.HasPrefix(c, "^") {
 		c = strings.TrimPrefix(c, "^")
-		if err = RunTask(c); err != nil {
+		if err = RunTask(ctx, c); err != nil {
 			return err
 		}
 		return nil
@@ -177,7 +177,7 @@ func (t *Task) runCommand(i int) error {
 	if err != nil {
 		return err
 	}
-	cmd := execext.NewCommand(context.Background(), c)
+	cmd := execext.NewCommand(ctx, c)
 	if dir != "" {
 		cmd.Dir = dir
 	}
diff --git a/watch.go b/watch.go
index 8117276c..0e9d5181 100644
--- a/watch.go
+++ b/watch.go
@@ -1,6 +1,7 @@
 package task
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"strings"
@@ -16,7 +17,7 @@ func WatchTasks(args []string) error {
 
 	// run tasks on init
 	for _, a := range args {
-		if err := RunTask(a); err != nil {
+		if err := RunTask(context.Background(), a); err != nil {
 			fmt.Println(err)
 			break
 		}
@@ -42,7 +43,7 @@ loop:
 		select {
 		case <-watcher.Events:
 			for _, a := range args {
-				if err := RunTask(a); err != nil {
+				if err := RunTask(context.Background(), a); err != nil {
 					fmt.Println(err)
 					continue loop
 				}