Also throttling repetitive events to focus and widgets.

container/container.go

@@ -250,11 +250,15 @@ func (c *Container) Subscribe(eds *event.DistributionSystem) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
+	// maxReps is the maximum number of repetitive events towards widgets
+	// before we throttle them.
+	const maxReps = 10
+
 	root := rootCont(c)
 	// Subscriber the container itself in order to track keyboard focus.
 	eds.Subscribe([]terminalapi.Event{&terminalapi.Mouse{}}, func(ev terminalapi.Event) {
 		root.updateFocus(ev.(*terminalapi.Mouse))
-	})
+	}, event.MaxRepetitive(0)) // One event is enough to change the focus.
 
 	// Subscribe any widgets that specify Keyboard or Mouse in their options.
 	var errStr string
@@ -266,7 +270,7 @@ func (c *Container) Subscribe(eds *event.DistributionSystem) {
 					if err := c.keyboardToWidget(ev.(*terminalapi.Keyboard)); err != nil {
 						eds.Event(terminalapi.NewErrorf("failed to send keyboard event %v to widget %T: %v", ev, c.opts.widget, err))
 					}
-				})
+				}, event.MaxRepetitive(maxReps))
 			}
 
 			if wOpt.WantMouse {
@@ -274,7 +278,7 @@ func (c *Container) Subscribe(eds *event.DistributionSystem) {
 					if err := c.mouseToWidget(ev.(*terminalapi.Mouse)); err != nil {
 						eds.Event(terminalapi.NewErrorf("failed to send mouse event %v to widget %T: %v", ev, c.opts.widget, err))
 					}
-				})
+				}, event.MaxRepetitive(maxReps))
 			}
 		}
 		return nil

container/focus_test.go

@@ -294,8 +294,9 @@ func TestFocusTrackerMouse(t *testing.T) {
 	tests := []struct {
 		desc string
 		// Can be either the mouse event or a time.Duration to pause for.
-		events      []*terminalapi.Mouse
-		wantFocused contLoc
+		events        []*terminalapi.Mouse
+		wantFocused   contLoc
+		wantProcessed int
 	}{
 		{
 			desc:        "initially the root is focused",
@@ -307,7 +308,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: image.Point{0, 0}, Button: mouse.ButtonLeft},
 				{Position: image.Point{1, 1}, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocLeft,
+			wantFocused:   contLocLeft,
+			wantProcessed: 2,
 		},
 		{
 			desc: "click and release moves focus to the right",
@@ -315,7 +317,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: image.Point{5, 5}, Button: mouse.ButtonLeft},
 				{Position: image.Point{6, 6}, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocRight,
+			wantFocused:   contLocRight,
+			wantProcessed: 2,
 		},
 		{
 			desc: "click in the same container is a no-op",
@@ -325,7 +328,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideRight, Button: mouse.ButtonLeft},
 				{Position: insideRight, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocRight,
+			wantFocused:   contLocRight,
+			wantProcessed: 4,
 		},
 		{
 			desc: "click in the same container and release never happens",
@@ -334,7 +338,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideLeft, Button: mouse.ButtonLeft},
 				{Position: insideLeft, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocLeft,
+			wantFocused:   contLocLeft,
+			wantProcessed: 3,
 		},
 		{
 			desc: "click in the same container, release elsewhere",
@@ -342,7 +347,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideRight, Button: mouse.ButtonLeft},
 				{Position: insideLeft, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocRoot,
+			wantFocused:   contLocRoot,
+			wantProcessed: 2,
 		},
 		{
 			desc: "other buttons are ignored",
@@ -354,7 +360,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideLeft, Button: mouse.ButtonWheelUp},
 				{Position: insideLeft, Button: mouse.ButtonWheelDown},
 			},
-			wantFocused: contLocRoot,
+			wantFocused:   contLocRoot,
+			wantProcessed: 6,
 		},
 		{
 			desc: "moving mouse with pressed button and then releasing moves focus",
@@ -363,7 +370,8 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: image.Point{1, 1}, Button: mouse.ButtonLeft},
 				{Position: image.Point{2, 2}, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocLeft,
+			wantFocused:   contLocLeft,
+			wantProcessed: 3,
 		},
 		{
 			desc: "click ignored if followed by another click of the same button elsewhere",
@@ -371,9 +379,9 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideRight, Button: mouse.ButtonLeft},
 				{Position: insideLeft, Button: mouse.ButtonLeft},
 				{Position: insideRight, Button: mouse.ButtonRelease},
-				{Position: insideRight, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocRoot,
+			wantFocused:   contLocRoot,
+			wantProcessed: 3,
 		},
 		{
 			desc: "click ignored if followed by another click of a different button",
@@ -381,9 +389,9 @@ func TestFocusTrackerMouse(t *testing.T) {
 				{Position: insideRight, Button: mouse.ButtonLeft},
 				{Position: insideRight, Button: mouse.ButtonMiddle},
 				{Position: insideRight, Button: mouse.ButtonRelease},
-				{Position: insideRight, Button: mouse.ButtonRelease},
 			},
-			wantFocused: contLocRoot,
+			wantFocused:   contLocRoot,
+			wantProcessed: 3,
 		},
 	}
 
@@ -406,7 +414,7 @@ func TestFocusTrackerMouse(t *testing.T) {
 				eds.Event(ev)
 			}
 			if err := testevent.WaitFor(5*time.Second, func() error {
-				if got, want := eds.Processed(), len(tc.events); got != want {
+				if got, want := eds.Processed(), tc.wantProcessed; got != want {
 					return fmt.Errorf("the event distribution system processed %d events, want %d", got, want)
 				}
 				return nil

event/event_test.go

@@ -37,6 +37,10 @@ const (
 
 	// receiverModeBlock tells the receiver to block on the call to receive.
 	receiverModeBlock
+
+	// receiverModePause tells the receiver to pause before starting to
+	// receive.
+	receiverModePause
 )
 
 // receiver receives events from the distribution system.
@@ -48,6 +52,9 @@ type receiver struct {
 
 	// events are the received events.
 	events []terminalapi.Event
+
+	// resumed indicates if the receiver was resumed.
+	resumed bool
 }
 
 // newReceiver returns a new event receiver.
@@ -64,12 +71,14 @@ func (r *receiver) receive(ev terminalapi.Event) {
 		for {
 			time.Sleep(1 * time.Minute)
 		}
-	default:
-		r.mu.Lock()
-		defer r.mu.Unlock()
-
-		r.events = append(r.events, ev)
+	case receiverModePause:
+		time.Sleep(3 * time.Second)
 	}
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.events = append(r.events, ev)
 }
 
 // getEvents returns the received events.
@@ -273,7 +282,7 @@ func TestDistributionSystem(t *testing.T) {
 					opts: []SubscribeOption{
 						MaxRepetitive(0),
 					},
-					rec: newReceiver(receiverModeReceive),
+					rec: newReceiver(receiverModePause),
 					want: map[terminalapi.Event]bool{
 						&terminalapi.Keyboard{Key: keyboard.KeyEsc}:   true,
 						&terminalapi.Keyboard{Key: keyboard.KeyEnter}: true,
@@ -301,7 +310,7 @@ func TestDistributionSystem(t *testing.T) {
 
 			for i, sc := range tc.subCase {
 				gotEv := map[terminalapi.Event]bool{}
-				err := testevent.WaitFor(5*time.Second, func() error {
+				err := testevent.WaitFor(10*time.Second, func() error {
 					ev := sc.rec.getEvents()
 					want := len(sc.want)
 					switch got := len(ev); {