add before&after hooks (#751)

* add before&after hooks

app.go

@@ -80,6 +80,11 @@ func (a *App) Run() error {
 			return srv.Start()
 		})
 	}
+	for _, fn := range a.opts.before {
+		if err := fn(); err != nil {
+			return err
+		}
+	}
 	if a.opts.registrar != nil {
 		if err := a.opts.registrar.Register(a.opts.ctx, a.instance); err != nil {
 			return err
@@ -113,6 +118,11 @@ func (a *App) Stop() error {
 	if a.cancel != nil {
 		a.cancel()
 	}
+	for _, fn := range a.opts.after {
+		if err := fn(); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 

encoding/json/json.go

@@ -44,7 +44,6 @@ func (codec) Unmarshal(data []byte, v interface{}) error {
 		if rv.IsNil() {
 			rv.Set(reflect.New(rv.Type().Elem()))
 			v = rv.Interface()
-			break
 		}
 		rv = rv.Elem()
 	}

options.go

@@ -27,6 +27,9 @@ type options struct {
 	registrar registry.Registrar
 
 	servers []transport.Server
+
+	before []func() error
+	after  []func() error
 }
 
 // ID with service id.
@@ -78,3 +81,13 @@ func Registry(r registry.Registrar) Option {
 func Server(srv ...transport.Server) Option {
 	return func(o *options) { o.servers = srv }
 }
+
+// Before before service starts.
+func Before(fn func() error) Option {
+	return func(o *options) { o.before = append(o.before, fn) }
+}
+
+// After after services stops.
+func After(fn func() error) Option {
+	return func(o *options) { o.after = append(o.after, fn) }
+}