From 55a625bfb88e35971014dbdd1c48528e729fc553 Mon Sep 17 00:00:00 2001
From: Andrew Newdigate <andrew@troupe.co>
Date: Tue, 9 May 2017 06:14:00 +0100
Subject: Use process groups and kill the entire group on context cancel

---
 internal/helper/command.go               | 52 +++++++++++++++++++++++++++++---
 internal/helper/command_wrapper_go1.6.go | 44 ---------------------------
 internal/helper/command_wrapper_go17.go  | 14 ---------
 3 files changed, 47 insertions(+), 63 deletions(-)
 delete mode 100644 internal/helper/command_wrapper_go1.6.go
 delete mode 100644 internal/helper/command_wrapper_go17.go

diff --git a/internal/helper/command.go b/internal/helper/command.go
index 5b9288757..fd10c5039 100644
--- a/internal/helper/command.go
+++ b/internal/helper/command.go
@@ -3,6 +3,7 @@ package helper
 import (
 	"fmt"
 	"io"
+	"log"
 	"os"
 	"os/exec"
 	"syscall"
@@ -70,6 +71,15 @@ func NewCommand(cmd *exec.Cmd, stdin io.Reader, stdout io.Writer, env ...string)
 	return command, nil
 }
 
+func cleanUpProcessGroupNoWait(cmd *exec.Cmd) {
+	process := cmd.Process
+	if process != nil && process.Pid > 0 {
+		// Send SIGTERM to the process group of cmd
+		syscall.Kill(-process.Pid, syscall.SIGTERM)
+	}
+
+}
+
 // CleanUpProcessGroup will send a SIGTERM signal to the process group
 // belonging to the `cmd` process
 func CleanUpProcessGroup(cmd *exec.Cmd) {
@@ -77,11 +87,7 @@ func CleanUpProcessGroup(cmd *exec.Cmd) {
 		return
 	}
 
-	process := cmd.Process
-	if process != nil && process.Pid > 0 {
-		// Send SIGTERM to the process group of cmd
-		syscall.Kill(-process.Pid, syscall.SIGTERM)
-	}
+	cleanUpProcessGroupNoWait(cmd)
 
 	// reap our child process
 	cmd.Wait()
@@ -101,3 +107,39 @@ func ExitStatus(err error) (int, bool) {
 
 	return waitStatus.ExitStatus(), true
 }
+
+// CommandWrapper ensures that the command is executed within a context,
+// and ensures that the process group is terminated with the
+func CommandWrapper(ctx context.Context, name string, arg ...string) *exec.Cmd {
+	command := exec.Command(name, arg...)
+
+	if ctx != nil {
+		// Create a channel to listen to the command completion
+		done := make(chan error, 1)
+		go func() {
+			done <- command.Wait()
+		}()
+
+		// Wait for the process to shutdown or the
+		// context to be complete
+		go func() {
+			select {
+			case <-ctx.Done():
+				log.Printf("Context done, killing process")
+				cleanUpProcessGroupNoWait(command)
+
+			case err := <-done:
+				if err != nil {
+					log.Printf("process done with error = %v", err)
+				} else {
+					log.Print("process done gracefully without error")
+				}
+				cleanUpProcessGroupNoWait(command)
+
+			}
+
+		}()
+	}
+
+	return command
+}
diff --git a/internal/helper/command_wrapper_go1.6.go b/internal/helper/command_wrapper_go1.6.go
deleted file mode 100644
index c063a9a37..000000000
--- a/internal/helper/command_wrapper_go1.6.go
+++ /dev/null
@@ -1,44 +0,0 @@
-// +build !go1.7
-
-package helper
-
-import (
-	"log"
-	"os/exec"
-
-	"golang.org/x/net/context"
-)
-
-// CommandWrapper handles context until we compile using Go 1.7
-func CommandWrapper(ctx context.Context, name string, arg ...string) *exec.Cmd {
-	command := exec.Command(name, arg...)
-
-	if ctx != nil {
-		// Create a channel to listen to the command completion
-		done := make(chan error, 1)
-		go func() {
-			done <- command.Wait()
-		}()
-
-		// Wait for the process to shutdown or the
-		// context to be complete
-		go func() {
-			select {
-			case <-ctx.Done():
-				log.Printf("Context done, killing process")
-				command.Process.Kill()
-
-			case err := <-done:
-				if err != nil {
-					log.Printf("process done with error = %v", err)
-				} else {
-					log.Print("process done gracefully without error")
-				}
-
-			}
-
-		}()
-	}
-
-	return command
-}
diff --git a/internal/helper/command_wrapper_go17.go b/internal/helper/command_wrapper_go17.go
deleted file mode 100644
index c381331b5..000000000
--- a/internal/helper/command_wrapper_go17.go
+++ /dev/null
@@ -1,14 +0,0 @@
-//+build go1.7
-
-package helper
-
-import (
-	"os/exec"
-
-	"golang.org/x/net/context"
-)
-
-// CommandWrapper handles context until we compile using Go 1.7
-func CommandWrapper(ctx context.Context, name string, arg ...string) *exec.Cmd {
-	return exec.CommandContext(ctx, name, arg...)
-}
-- 
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