Refactor(engine): add StartOrFatal/StopOrFatal wrappers (#552)

* Feat(engine): make Start/Stop return error instead of log.Fatalf (#550)

* Refactor(engine): add StartOrFatal/StopOrFatal wrappers

---------

Co-authored-by: Jason Lyu <xjasonlyu@gmail.com>

engine/engine.go

@@ -42,20 +42,6 @@ var (
 	_icmpHandler adapter.NetworkHandler
 )
 
-// Start starts the default engine up.
-func Start() {
-	if err := start(); err != nil {
-		log.Fatalf("[ENGINE] failed to start: %v", err)
-	}
-}
-
-// Stop shuts the default engine down.
-func Stop() {
-	if err := stop(); err != nil {
-		log.Fatalf("[ENGINE] failed to stop: %v", err)
-	}
-}
-
 // Insert loads *Key to the default engine.
 func Insert(k *Key) {
 	_engineMu.Lock()
@@ -70,7 +56,8 @@ func SetICMPHandler(h adapter.NetworkHandler) {
 	_engineMu.Unlock()
 }
 
-func start() error {
+// Start starts the default engine up.
+func Start() error {
 	_engineMu.Lock()
 	defer _engineMu.Unlock()
 
@@ -90,7 +77,16 @@ func start() error {
 	return nil
 }
 
-func stop() (err error) {
+// StartOrFatal starts the default engine up, and exits the
+// process if it fails.
+func StartOrFatal() {
+	if err := Start(); err != nil {
+		log.Fatalf("[ENGINE] failed to start: %v", err)
+	}
+}
+
+// Stop shuts the default engine down.
+func Stop() error {
 	_engineMu.Lock()
 	if _defaultDevice != nil {
 		_defaultDevice.Close()
@@ -103,6 +99,14 @@ func stop() (err error) {
 	return nil
 }
 
+// StopOrFatal shuts the default engine down, and exits the
+// process if it fails.
+func StopOrFatal() {
+	if err := Stop(); err != nil {
+		log.Fatalf("[ENGINE] failed to stop: %v", err)
+	}
+}
+
 func execCommand(cmd string) error {
 	parts, err := shlex.Split(cmd)
 	if err != nil {

main.go

@@ -61,8 +61,8 @@ func main() {
 
 	engine.Insert(key)
 
-	engine.Start()
-	defer engine.Stop()
+	engine.StartOrFatal()
+	defer engine.StopOrFatal()
 
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)