buffered: Avoid creating func objects whenever possible

Fixes #1220

internal/buffered/command.go

@@ -64,16 +64,14 @@ func getDelayedFuncsAndClearSlow() []func() error {
 	return nil
 }
 
+// maybeCanAddDelayedCommand returns false if the delayed commands cannot be added.
+// Otherwise, maybeCanAddDelayedCommand's returning value is not determined.
+// For example, maybeCanAddDelayedCommand can return true even when flusing is being processed.
+func maybeCanAddDelayedCommand() bool {
+	return atomic.LoadUint32(&delayedCommandsFlushed) == 0
+}
+
 func tryAddDelayedCommand(f func(obj interface{}) error, ondelayed func() interface{}) bool {
-	if atomic.LoadUint32(&delayedCommandsFlushed) == 0 {
-		// Outline the slow-path to expect the fast-path is inlined.
-		return tryAddDelayedCommandSlow(f, ondelayed)
-	}
-
-	return false
-}
-
-func tryAddDelayedCommandSlow(f func(obj interface{}) error, ondelayed func() interface{}) bool {
 	delayedCommandsM.Lock()
 	defer delayedCommandsM.Unlock()
 

internal/buffered/image.go

@@ -55,12 +55,14 @@ func NewImage(width, height int, volatile bool) *Image {
 }
 
 func (i *Image) initialize(width, height int, volatile bool) {
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			i.initialize(width, height, volatile)
 			return nil
 		}, nil) {
 			return
 		}
+	}
 	i.img = mipmap.New(width, height, volatile)
 	i.width = width
 	i.height = height
@@ -73,12 +75,14 @@ func NewScreenFramebufferImage(width, height int) *Image {
 }
 
 func (i *Image) initializeAsScreenFramebuffer(width, height int) {
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			i.initializeAsScreenFramebuffer(width, height)
 			return nil
 		}, nil) {
 			return
 		}
+	}
 
 	i.img = mipmap.NewScreenFramebufferMipmap(width, height)
 	i.width = width
@@ -114,12 +118,14 @@ func (i *Image) resolvePendingFill() {
 }
 
 func (i *Image) MarkDisposed() {
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			i.MarkDisposed()
 			return nil
 		}, nil) {
 			return
 		}
+	}
 	i.invalidatePendingPixels()
 	i.img.MarkDisposed()
 }
@@ -165,12 +171,14 @@ func (i *Image) Dump(name string, blackbg bool) error {
 }
 
 func (i *Image) Fill(clr color.RGBA) {
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			i.Fill(clr)
 			return nil
 		}, nil) {
 			return
 		}
+	}
 
 	// Defer filling the image so that successive fillings will be merged into one (#1134).
 	i.invalidatePendingPixels()
@@ -183,6 +191,7 @@ func (i *Image) ReplacePixels(pix []byte, x, y, width, height int) error {
 		panic(fmt.Sprintf("buffered: len(pix) was %d but must be %d", len(pix), l))
 	}
 
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(copied interface{}) error {
 			i.ReplacePixels(copied.([]byte), x, y, width, height)
 			return nil
@@ -193,6 +202,7 @@ func (i *Image) ReplacePixels(pix []byte, x, y, width, height int) error {
 		}) {
 			return nil
 		}
+	}
 
 	if x == 0 && y == 0 && width == i.width && height == i.height {
 		i.invalidatePendingPixels()
@@ -238,12 +248,14 @@ func (i *Image) DrawImage(src *Image, bounds image.Rectangle, a, b, c, d, tx, ty
 		Ty: ty,
 	}
 
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			i.drawImage(src, bounds, g, colorm, mode, filter)
 			return nil
 		}, nil) {
 			return
 		}
+	}
 
 	i.drawImage(src, bounds, g, colorm, mode, filter)
 }
@@ -275,6 +287,7 @@ func (i *Image) DrawTriangles(src *Image, vertices []float32, indices []uint16,
 		}
 	}
 
+	if maybeCanAddDelayedCommand() {
 		if tryAddDelayedCommand(func(obj interface{}) error {
 			// Arguments are not copied. Copying is the caller's responsibility.
 			i.DrawTriangles(src, vertices, indices, colorm, mode, filter, address, shader, uniforms)
@@ -282,6 +295,7 @@ func (i *Image) DrawTriangles(src *Image, vertices []float32, indices []uint16,
 		}, nil) {
 			return
 		}
+	}
 
 	for _, src := range srcs {
 		src.resolvePendingPixels(true)