nit: fix with-node

1. It doesn't return an error and we weren't checking it anyways.
2. Avoid a goroutine unless we need it.

basic.go

@@ -51,7 +51,7 @@ func NewBus() event.Bus {
 	}
 }
 
-func (b *basicBus) withNode(typ reflect.Type, cb func(*node), async func(*node)) error {
+func (b *basicBus) withNode(typ reflect.Type, cb func(*node), async func(*node)) {
 	b.lk.Lock()
 
 	n, ok := b.nodes[typ]
@@ -65,12 +65,14 @@ func (b *basicBus) withNode(typ reflect.Type, cb func(*node), async func(*node))
 
 	cb(n)
 
-	go func() {
-		defer n.lk.Unlock()
-		async(n)
-	}()
-
-	return nil
+	if async == nil {
+		n.lk.Unlock()
+	} else {
+		go func() {
+			defer n.lk.Unlock()
+			async(n)
+		}()
+	}
 }
 
 func (b *basicBus) tryDropNode(typ reflect.Type) {
@@ -104,9 +106,21 @@ func (s *sub) Out() <-chan interface{} {
 }
 
 func (s *sub) Close() error {
-	close(s.ch)
+	stop := make(chan struct{})
+	go func() {
+		for {
+			select {
+			case <-s.ch:
+			case <-stop:
+				close(s.ch)
+				return
+			}
+		}
+	}()
+
 	for _, n := range s.nodes {
 		n.lk.Lock()
+
 		for i := 0; i < len(n.sinks); i++ {
 			if n.sinks[i] == s.ch {
 				n.sinks[i], n.sinks[len(n.sinks)-1] = n.sinks[len(n.sinks)-1], nil
@@ -114,12 +128,16 @@ func (s *sub) Close() error {
 				break
 			}
 		}
+
 		tryDrop := len(n.sinks) == 0 && atomic.LoadInt32(&n.nEmitters) == 0
+
 		n.lk.Unlock()
+
 		if tryDrop {
 			s.dropper(n.typ)
 		}
 	}
+	close(stop)
 	return nil
 }
 
@@ -129,7 +147,7 @@ var _ event.Subscription = (*sub)(nil)
 // publishers to get blocked. CancelFunc is guaranteed to return after last send
 // to the channel
 func (b *basicBus) Subscribe(evtTypes interface{}, opts ...event.SubscriptionOpt) (_ event.Subscription, err error) {
-	var settings subSettings
+	settings := subSettings(subSettingsDefault)
 	for _, opt := range opts {
 		if err := opt(&settings); err != nil {
 			return nil, err
@@ -148,14 +166,16 @@ func (b *basicBus) Subscribe(evtTypes interface{}, opts ...event.SubscriptionOpt
 		dropper: b.tryDropNode,
 	}
 
+	for _, etyp := range types {
+		if reflect.TypeOf(etyp).Kind() != reflect.Ptr {
+			return nil, errors.New("subscribe called with non-pointer type")
+		}
+	}
+
 	for i, etyp := range types {
 		typ := reflect.TypeOf(etyp)
 
-		if typ.Kind() != reflect.Ptr {
-			return nil, errors.New("subscribe called with non-pointer type")
-		}
-
-		err = b.withNode(typ.Elem(), func(n *node) {
+		b.withNode(typ.Elem(), func(n *node) {
 			n.sinks = append(n.sinks, out.ch)
 			out.nodes[i] = n
 		}, func(n *node) {
@@ -184,6 +204,7 @@ func (b *basicBus) Subscribe(evtTypes interface{}, opts ...event.SubscriptionOpt
 // emit(EventT{})
 func (b *basicBus) Emitter(evtType interface{}, opts ...event.EmitterOpt) (e event.Emitter, err error) {
 	var settings emitterSettings
+
 	for _, opt := range opts {
 		if err := opt(&settings); err != nil {
 			return nil, err
@@ -196,11 +217,11 @@ func (b *basicBus) Emitter(evtType interface{}, opts ...event.EmitterOpt) (e eve
 	}
 	typ = typ.Elem()
 
-	err = b.withNode(typ, func(n *node) {
+	b.withNode(typ, func(n *node) {
 		atomic.AddInt32(&n.nEmitters, 1)
 		n.keepLast = n.keepLast || settings.makeStateful
 		e = &emitter{n: n, typ: typ, dropper: b.tryDropNode}
-	}, func(_ *node) {})
+	}, nil)
 	return
 }
 
@@ -229,9 +250,9 @@ func newNode(typ reflect.Type) *node {
 }
 
 func (n *node) emit(event interface{}) {
-	eval := reflect.ValueOf(event)
-	if eval.Type() != n.typ {
-		panic(fmt.Sprintf("Emit called with wrong type. expected: %s, got: %s", n.typ, eval.Type()))
+	typ := reflect.TypeOf(event)
+	if typ != n.typ {
+		panic(fmt.Sprintf("Emit called with wrong type. expected: %s, got: %s", n.typ, typ))
 	}
 
 	n.lk.RLock()

basic_test.go

@@ -25,6 +25,17 @@ func (EventA) String() string {
 	return "Oh, Hello"
 }
 
+func TestDefaultSubIsBuffered(t *testing.T) {
+	bus := NewBus()
+	s, err := bus.Subscribe(new(EventA))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cap(s.(*sub).ch) == 0 {
+		t.Fatalf("without any options subscribe should be buffered. was %d", cap(s.(*sub).ch))
+	}
+}
+
 func TestEmit(t *testing.T) {
 	bus := NewBus()
 	sub, err := bus.Subscribe(new(EventA))
@@ -297,6 +308,49 @@ func TestStateful(t *testing.T) {
 	}
 }
 
+func TestCloseBlocking(t *testing.T) {
+	bus := NewBus()
+	em, err := bus.Emitter(new(EventB))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	sub, err := bus.Subscribe(new(EventB))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	go func() {
+		em.Emit(EventB(159))
+	}()
+
+	time.Sleep(10 * time.Millisecond) // make sure that emit is blocked
+
+	sub.Close() // cancel sub
+}
+
+func panicOnTimeout(d time.Duration) {
+	<-time.After(d)
+	panic("timeout reached")
+}
+
+func TestSubFailFully(t *testing.T) {
+	bus := NewBus()
+	em, err := bus.Emitter(new(EventB))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = bus.Subscribe([]interface{}{new(EventB), 5})
+	if err == nil || err.Error() != "subscribe called with non-pointer type" {
+		t.Fatal(err)
+	}
+
+	go panicOnTimeout(5 * time.Second)
+
+	em.Emit(EventB(159)) // will hang if sub doesn't fail properly
+}
+
 func testMany(t testing.TB, subs, emits, msgs int, stateful bool) {
 	if race.WithRace() && subs+emits > 5000 {
 		t.SkipNow()

opts.go

@@ -4,6 +4,10 @@ type subSettings struct {
 	buffer int
 }
 
+var subSettingsDefault = subSettings{
+	buffer: 16,
+}
+
 func BufSize(n int) func(interface{}) error {
 	return func(s interface{}) error {
 		s.(*subSettings).buffer = n