Revert "internal/graphicsdriver/metal: add in-flight semaphore"

This reverts commit db9ca28598.

Reason: This didn't seem to change the situation.

Updates #3278

internal/graphicsdriver/metal/graphics_darwin.go

@@ -15,7 +15,6 @@
 package metal
 
 import (
-	"context"
 	"fmt"
 	"image"
 	"math"
@@ -24,7 +23,6 @@ import (
 	"unsafe"
 
 	"github.com/ebitengine/purego/objc"
-	"golang.org/x/sync/semaphore"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/cocoa"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
@@ -46,9 +44,6 @@ type Graphics struct {
 	rce  mtl.RenderCommandEncoder
 	dsss map[stencilMode]mtl.DepthStencilState
 
-	cbCompletedBlock  objc.Block
-	inFlightSemaphore *semaphore.Weighted
-
 	screenDrawable ca.MetalDrawable
 
 	buffers       map[mtl.CommandBuffer][]mtl.Buffer
@@ -108,8 +103,7 @@ func NewGraphics(colorSpace graphicsdriver.ColorSpace) (graphicsdriver.Graphics,
 	}
 
 	g := &Graphics{
-		colorSpace:        colorSpace,
-		inFlightSemaphore: semaphore.NewWeighted(maximumDrawableCount),
+		colorSpace: colorSpace,
 	}
 
 	if runtime.GOOS != "ios" {
@@ -119,11 +113,6 @@ func NewGraphics(colorSpace graphicsdriver.ColorSpace) (graphicsdriver.Graphics,
 			return nil, err
 		}
 	}
-
-	g.cbCompletedBlock = objc.NewBlock(func(self objc.Block, _ objc.ID) {
-		g.inFlightSemaphore.Release(1)
-	})
-
 	return g, nil
 }
 
@@ -839,25 +828,14 @@ func (i *Image) mtlTexture() mtl.Texture {
 	if i.screen {
 		g := i.graphics
 		if g.screenDrawable == (ca.MetalDrawable{}) {
-			// Wait for the inflight semaphore to be available.
-			_ = g.inFlightSemaphore.Acquire(context.Background(), 1)
-
 			i.graphics.view.waitForDisplayLinkOutputCallback()
 			drawable := g.view.nextDrawable()
 			if drawable == (ca.MetalDrawable{}) {
-				g.inFlightSemaphore.Release(1)
 				return mtl.Texture{}
 			}
 			g.screenDrawable = drawable
-
 			// After nextDrawable, it is expected some command buffers are completed.
 			g.gcBuffers()
-
-			// Set the completed handler to release the semaphore when the command buffer is completed.
-			if g.cb == (mtl.CommandBuffer{}) {
-				g.cb = g.cq.CommandBuffer()
-			}
-			g.cb.AddCompletedHandler(g.cbCompletedBlock)
 		}
 		return g.screenDrawable.Texture()
 	}

internal/graphicsdriver/metal/mtl/mtl_darwin.go

@@ -563,7 +563,6 @@ var (
 	sel_replaceRegion_mipmapLevel_withBytes_bytesPerRow                                                                               = objc.RegisterName("replaceRegion:mipmapLevel:withBytes:bytesPerRow:")
 	sel_getBytes_bytesPerRow_fromRegion_mipmapLevel                                                                                   = objc.RegisterName("getBytes:bytesPerRow:fromRegion:mipmapLevel:")
 	sel_respondsToSelector                                                                                                            = objc.RegisterName("respondsToSelector:")
-	sel_addCompletedHandler                                                                                                           = objc.RegisterName("addCompletedHandler:")
 )
 
 // CreateSystemDefaultDevice returns the preferred system default Metal device.
@@ -844,13 +843,6 @@ func (cb CommandBuffer) WaitUntilScheduled() {
 	cb.commandBuffer.Send(sel_waitUntilScheduled)
 }
 
-// AddCompletedHandler registers a completion handler the GPU device calls immediately after the GPU finishes running the commands in the command buffer.
-//
-// Reference: https://developer.apple.com/documentation/metal/mtlcommandbuffer/addcompletedhandler(_:)
-func (cb CommandBuffer) AddCompletedHandler(block objc.Block) {
-	cb.commandBuffer.Send(sel_addCompletedHandler, block)
-}
-
 // RenderCommandEncoderWithDescriptor creates a render command encoder from a descriptor.
 //
 // Reference: https://developer.apple.com/documentation/metal/mtlcommandbuffer/1442999-rendercommandencoderwithdescript?language=objc.