Creating a version of fyne.Do that does not wait

driver.go

@@ -47,11 +47,11 @@ type Driver interface {
 	// Since: 2.5
 	SetDisableScreenBlanking(bool)
 
-	// DoFromGoroutine provides a way to queue a function that is running on a goroutine back to
-	// the central thread for Fyne updates.
+	// DoFromGoroutine provides a way to queue a function `fn` that is running on a goroutine back to
+	// the central thread for Fyne updates, waiting for it to return if `wait` is true.
 	// The driver provides the implementation normally accessed through [fyne.Do].
 	// This is required when background tasks want to execute code safely in the graphical context.
 	//
 	// Since: 2.6
-	DoFromGoroutine(func())
+	DoFromGoroutine(fn func(), wait bool)
 }

internal/app/lifecycle.go

@@ -106,9 +106,9 @@ func (l *Lifecycle) QueueEvent(fn func()) {
 
 // RunEventQueue runs the event queue. This should called inside a go routine.
 // This function blocks.
-func (l *Lifecycle) RunEventQueue(run func(func())) {
+func (l *Lifecycle) RunEventQueue(run func(func(), bool)) {
 	for fn := range l.eventQueue.Out() {
-		run(fn)
+		run(fn, true)
 	}
 }
 

internal/app/lifecycle_test.go

@@ -17,7 +17,7 @@ func TestLifecycle(t *testing.T) {
 
 	var entered, exited, start, stop, hookedStop, called bool
 	life.InitEventQueue()
-	go life.RunEventQueue(func(fn func()) {
+	go life.RunEventQueue(func(fn func(), _ bool) {
 		fn()
 	})
 	life.QueueEvent(func() { called = true })

internal/driver/glfw/driver.go

@@ -56,9 +56,9 @@ func toOSIcon(icon []byte) ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
-func (d *gLDriver) DoFromGoroutine(f func()) {
+func (d *gLDriver) DoFromGoroutine(f func(), wait bool) {
 	async.EnsureNotMain(func() {
-		runOnMain(f)
+		runOnMainWithWait(f, wait)
 	})
 }
 

internal/driver/glfw/loop.go

@@ -31,19 +31,28 @@ func init() {
 
 // force a function f to run on the main thread
 func runOnMain(f func()) {
+	runOnMainWithWait(f, true)
+}
+
+// force a function f to run on the main thread and specify if we should wait for it to return
+func runOnMainWithWait(f func(), wait bool) {
 	// If we are on main just execute - otherwise add it to the main queue and wait.
 	// The "running" variable is normally false when we are on the main thread.
 	if !running.Load() {
 		f()
 		return
 	}
 
-	done := common.DonePool.Get()
-	defer common.DonePool.Put(done)
+	var done chan struct{}
+	if wait {
+		done = common.DonePool.Get()
+		defer common.DonePool.Put(done)
+	}
 
 	funcQueue <- funcData{f: f, done: done}
-
-	<-done
+	if wait {
+		<-done
+	}
 }
 
 // Preallocate to avoid allocations on every drawSingleFrame.
@@ -110,7 +119,9 @@ func (d *gLDriver) runGL() {
 			return
 		case f := <-funcQueue:
 			f.f()
-			f.done <- struct{}{}
+			if f.done != nil {
+				f.done <- struct{}{}
+			}
 		case <-eventTick.C:
 			d.pollEvents()
 			for i := 0; i < len(d.windows); i++ {

internal/driver/glfw/window.go

@@ -867,11 +867,7 @@ func (w *window) Context() any {
 
 func (w *window) runOnMainWhenCreated(fn func()) {
 	if w.view() != nil {
-		if async.IsMainGoroutine() {
-			fn()
-			return
-		}
-		fyne.Do(fn)
+		async.EnsureMain(fn)
 		return
 	}
 

internal/driver/mobile/canvas.go

@@ -407,7 +407,7 @@ func (c *canvas) waitForDoubleTap(co fyne.CanvasObject, ev *fyne.PointEvent, tap
 		c.touchCancelFunc = nil
 		c.touchLastTapped = nil
 		c.touchCancelLock.Unlock()
-	})
+	}, true)
 }
 
 func (c *canvas) windowHeadIsDisplacing() bool {

internal/driver/mobile/canvas_test.go

@@ -142,7 +142,7 @@ func Test_canvas_Focusable(t *testing.T) {
 		c.tapUp(pos, 0, func(wid fyne.Tappable, ev *fyne.PointEvent) {
 			wid.Tapped(ev)
 		}, nil, nil, nil)
-	})
+	}, true)
 
 	waitAndCheck(tapDoubleDelay/time.Millisecond+150, func() {
 		assert.Equal(t, 1, content.focusedTimes)
@@ -154,7 +154,7 @@ func Test_canvas_Focusable(t *testing.T) {
 		c.tapUp(pos, 1, func(wid fyne.Tappable, ev *fyne.PointEvent) {
 			wid.Tapped(ev)
 		}, nil, nil, nil)
-	})
+	}, true)
 	waitAndCheck(tapDoubleDelay/time.Millisecond+150, func() {
 		assert.Equal(t, 1, content.focusedTimes)
 		assert.Equal(t, 0, content.unfocusedTimes)
@@ -177,7 +177,7 @@ func Test_canvas_Focusable(t *testing.T) {
 		c.tapDown(fyne.NewPos(10, 10), 2)
 		assert.Equal(t, 1, content.focusedTimes)
 		assert.Equal(t, 1, content.unfocusedTimes)
-	})
+	}, true)
 }
 
 func Test_canvas_InteractiveArea(t *testing.T) {
@@ -534,7 +534,7 @@ func waitAndCheck(msWait time.Duration, fn func()) {
 			fn()
 
 			waitForCheck <- struct{}{}
-		})
+		}, true)
 	}()
 	<-waitForCheck
 }

internal/driver/mobile/driver.go

@@ -72,17 +72,24 @@ func init() {
 	runtime.LockOSThread()
 }
 
-func (d *driver) DoFromGoroutine(fn func()) {
+func (d *driver) DoFromGoroutine(fn func(), wait bool) {
 	async.EnsureNotMain(func() {
-		done := common.DonePool.Get()
-		defer common.DonePool.Put(done)
+		var done chan struct{}
+		if wait {
+			done = common.DonePool.Get()
+			defer common.DonePool.Put(done)
+		}
 
 		d.queuedFuncs.In() <- func() {
 			fn()
-			done <- struct{}{}
+			if wait {
+				done <- struct{}{}
+			}
 		}
 
-		<-done
+		if wait {
+			<-done
+		}
 	})
 }
 
@@ -446,11 +453,11 @@ func (d *driver) tapUpCanvas(w *window, x, y float32, tapID touch.Sequence) {
 
 				d.DoFromGoroutine(func() {
 					wid.Dragged(ev)
-				})
+				}, true)
 				time.Sleep(time.Millisecond * 16)
 			}
 
-			d.DoFromGoroutine(wid.DragEnd)
+			d.DoFromGoroutine(wid.DragEnd, true)
 		}()
 	})
 }

test/app.go

@@ -253,7 +253,7 @@ func (s *testSettings) apply() {
 		cache.ResetThemeCaches()
 		intapp.ApplySettings(s, s.app)
 		s.app.propertyLock.Unlock()
-	})
+	}, false)
 
 	s.app.propertyLock.Lock()
 	s.app.appliedTheme = s.Theme()

test/driver.go

@@ -50,7 +50,8 @@ func NewDriverWithPainter(painter SoftwarePainter) fyne.Driver {
 	return &driver{painter: painter}
 }
 
-func (d *driver) DoFromGoroutine(f func()) {
+// DoFromGoroutine on a test driver ignores the wait flag as our threading is simple
+func (d *driver) DoFromGoroutine(f func(), _ bool) {
 	// Tests all run on a single (but potentially different per-test) thread
 	async.EnsureNotMain(f)
 }

thread.go

@@ -6,5 +6,15 @@ package fyne
 //
 // Since: 2.6
 func Do(fn func()) {
-	CurrentApp().Driver().DoFromGoroutine(fn)
+	CurrentApp().Driver().DoFromGoroutine(fn, true)
+}
+
+// DoAsync is used to execute a specified function in the main Fyne runtime context without waiting.
+// This is required when a background process wishes to adjust graphical elements of a running app.
+// Developers should use this only from within goroutines they have created and when the result does not have to
+// be waited for.
+//
+// Since: 2.6
+func DoAsync(fn func()) {
+	CurrentApp().Driver().DoFromGoroutine(fn, false)
 }