Fix memory leak. (#140)

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/redrawer/MetalRedrawer.kt

@@ -16,7 +16,7 @@ import javax.swing.SwingUtilities.getRootPane
 
 internal class MetalRedrawer(
     private val layer: SkiaLayer,
-    private val properties: SkiaLayerProperties
+    properties: SkiaLayerProperties
 ) : Redrawer {
     private var isDisposed = false
     private var disposeLock = Any()
@@ -58,6 +58,8 @@ internal class MetalRedrawer(
     }
 
     private suspend fun draw() {
+        withContext(Dispatchers.IO) {
+            val handle = startRendering()
             if (layer.prepareDrawContext()) {
                 // 2,3 GHz 8-Core Intel Core i9
                 //
@@ -70,26 +72,27 @@ internal class MetalRedrawer(
                 //
                 // Executors.newSingleThreadExecutor().asCoroutineDispatcher(): 50 FPS, 150% CPU
                 // Dispatchers.IO: 50 FPS, 200% CPU
-            withContext(Dispatchers.IO) {
                 synchronized(disposeLock) {
                     if (!isDisposed) {
                         layer.draw()
                     }
                 }
             }
+            endRendering(handle)
+        }
         // When window is not visible - it doesn't make sense to redraw fast to avoid battery drain.
         // In theory, we could be more precise, and just suspend rendering in
         // `NSWindowDidChangeOcclusionStateNotification`, but current approach seems to work as well in practise.
         if (isOccluded(windowHandle))
             delay(300)
     }
-    }
 
     override fun syncSize() {
         val rootPane = getRootPane(layer)
         val globalPosition = convertPoint(layer, layer.x, layer.y, rootPane)
         setContentScale(device, layer.contentScale)
-        resizeLayers(device,
+        resizeLayers(
+            device,
             globalPosition.x,
             rootPane.height - globalPosition.y - layer.height,
             layer.width.coerceAtLeast(0),
@@ -130,4 +133,6 @@ internal class MetalRedrawer(
     private external fun isOccluded(window: Long): Boolean
     private external fun getAdapterName(device: Long): String
     private external fun getAdapterMemorySize(device: Long): Long
+    private external fun startRendering(): Long
+    private external fun endRendering(handle: Long)
 }

skiko/src/jvmMain/objectiveC/macos/MetalRedrawer.mm

@@ -101,17 +101,30 @@ JNIEXPORT jlong JNICALL Java_org_jetbrains_skiko_redrawer_MetalRedrawer_makeMeta
     MetalDevice *device = (MetalDevice *) devicePtr;
     GrBackendRenderTarget* renderTarget = NULL;
 
-    @autoreleasepool {
     id<CAMetalDrawable> currentDrawable = [device.layer nextDrawable];
     if (!currentDrawable) return 0;
     device.drawableHandle = currentDrawable;
     GrMtlTextureInfo info;
     info.fTexture.retain(currentDrawable.texture);
     renderTarget = new GrBackendRenderTarget(width, height, 0, info);
-    }
     return (jlong) renderTarget;
 }
 
+extern "C" void* objc_autoreleasePoolPush(void);
+extern "C" void objc_autoreleasePoolPop(void*);
+
+JNIEXPORT jlong JNICALL Java_org_jetbrains_skiko_redrawer_MetalRedrawer_startRendering(
+    JNIEnv * env, jobject redrawer)
+{
+    return (jlong)objc_autoreleasePoolPush();
+}
+
+JNIEXPORT void JNICALL Java_org_jetbrains_skiko_redrawer_MetalRedrawer_endRendering(
+    JNIEnv * env, jobject redrawer, jlong handle)
+{
+    objc_autoreleasePoolPop((void*)handle);
+}
+
 BOOL isUsingIntegratedGPU() {
     kern_return_t kernResult = 0;
     io_iterator_t iterator = IO_OBJECT_NULL;
@@ -241,18 +254,13 @@ JNIEXPORT void JNICALL Java_org_jetbrains_skiko_redrawer_MetalRedrawer_finishFra
 
     id<CAMetalDrawable> currentDrawable = device.drawableHandle;
 
+    if (currentDrawable) {
         id<MTLCommandBuffer> commandBuffer = [device.queue commandBuffer];
         commandBuffer.label = @"Present";
-
-    [currentDrawable addPresentedHandler:^(id<MTLDrawable> dr) {
-         CFRelease(currentDrawable);
-    }];
         [commandBuffer presentDrawable:currentDrawable];
         [commandBuffer commit];
-
         device.drawableHandle = nil;
-
-    currentDrawable = nil;
+    }
 }
 
 JNIEXPORT void JNICALL Java_org_jetbrains_skiko_redrawer_MetalRedrawer_disposeDevice(