fix: Purge cache on memory warning to prevent OOM crashes

packages/skia/apple/MetalContext.h

@@ -38,6 +38,7 @@ class MetalContext {
 public:
   MetalContext(const MetalContext &) = delete;
   MetalContext &operator=(const MetalContext &) = delete;
+  ~MetalContext();
 
   static MetalContext &getInstance() {
     static thread_local MetalContext instance;
@@ -71,13 +72,11 @@ class MetalContext {
     switch (format) {
     case SkiaCVPixelBufferUtils::CVPixelBufferBaseFormat::rgb: {
       // CVPixelBuffer is in any RGB format, single-plane
-      return SkiaCVPixelBufferUtils::RGB::makeSkImageFromCVPixelBuffer(
-          _device, _directContext.get(), sampleBuffer);
+      return SkiaCVPixelBufferUtils::RGB::makeSkImageFromCVPixelBuffer(*this, sampleBuffer);
     }
     case SkiaCVPixelBufferUtils::CVPixelBufferBaseFormat::yuv: {
       // CVPixelBuffer is in any YUV format, multi-plane
-      return SkiaCVPixelBufferUtils::YUV::makeSkImageFromCVPixelBuffer(
-          _device, _directContext.get(), sampleBuffer);
+      return SkiaCVPixelBufferUtils::YUV::makeSkImageFromCVPixelBuffer(*this, sampleBuffer);
     }
     default:
       [[unlikely]] {
@@ -97,12 +96,17 @@ class MetalContext {
                                                 height, useP3ColorSpace);
   }
 
+public:
   GrDirectContext *getDirectContext() { return _directContext.get(); }
+  id<MTLDevice> getDevice() const { return _device; }
+  CVMetalTextureCacheRef getMetalTextureCache();
 
 private:
   id<MTLDevice> _device = nullptr;
   id<MTLCommandQueue> _commandQueue = nullptr;
   sk_sp<GrDirectContext> _directContext = nullptr;
+  CVMetalTextureCacheRef _metalTextureCache = nullptr;
+  id _memoryWarningObserver = nil;
 
   MetalContext();
 };

packages/skia/apple/MetalContext.mm

@@ -3,6 +3,8 @@
 #include "RNSkLog.h"
 
 #import <MetalKit/MetalKit.h>
+#import <UIKit/UIKit.h>
+#import <chrono>
 
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdocumentation"
@@ -17,6 +19,10 @@
 
 #pragma clang diagnostic pop
 
+MetalContext::~MetalContext() {
+  [[NSNotificationCenter defaultCenter] removeObserver:_memoryWarningObserver];
+}
+
 MetalContext::MetalContext() {
   _device = MTLCreateSystemDefaultDevice();
   if (!_device) {
@@ -35,4 +41,33 @@
   if (_directContext == nullptr) {
     RNSkia::RNSkLogger::logToConsole("Couldn't create a Skia Metal Context");
   }
+
+  // Add a memory warning listener to purge cache
+  _memoryWarningObserver = [
+    [NSNotificationCenter defaultCenter]
+      addObserverForName:UIApplicationDidReceiveMemoryWarningNotification
+      object:nil
+      queue:nil
+      usingBlock:^(__unused NSNotification *notification) {
+        // Clean unused Skia textures (cache/GPU)
+        _directContext->performDeferredCleanup(std::chrono::milliseconds(0));
+        if (_metalTextureCache != nil) {
+          // Flush Metal Texture Cache pool (this can have a huge impact)
+          CVMetalTextureCacheFlush(_metalTextureCache, 0);
+        }
+      }
+  ];
+}
+
+
+CVMetalTextureCacheRef MetalContext::getMetalTextureCache() {
+  if (_metalTextureCache == nil) {
+    // Create a new Texture Cache
+    auto result = CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, _device,
+                                            nil, &_metalTextureCache);
+    if (result != kCVReturnSuccess || _metalTextureCache == nil) {
+      throw std::runtime_error("Failed to create Metal Texture Cache!");
+    }
+  }
+  return _metalTextureCache;
 }

packages/skia/apple/SkiaCVPixelBufferUtils.h

@@ -21,6 +21,8 @@
 #import "include/gpu/ganesh/GrYUVABackendTextures.h"
 #pragma clang diagnostic pop
 
+class MetalContext;
+
 /**
  Holds a Metal Texture.
  When the `TextureHolder` is destroyed, the underlying Metal Texture
@@ -84,8 +86,7 @@ class SkiaCVPixelBufferUtils {
      CVPixelBuffer.
      */
     static sk_sp<SkImage>
-    makeSkImageFromCVPixelBuffer(id<MTLDevice> device, GrDirectContext *context,
-                                 CVPixelBufferRef pixelBuffer);
+    makeSkImageFromCVPixelBuffer(MetalContext& context, CVPixelBufferRef pixelBuffer);
 
   private:
     static SkColorType getCVPixelBufferColorType(CVPixelBufferRef pixelBuffer);
@@ -98,8 +99,7 @@ class SkiaCVPixelBufferUtils {
      CVPixelBuffer.
      */
     static sk_sp<SkImage>
-    makeSkImageFromCVPixelBuffer(id<MTLDevice> device, GrDirectContext *context,
-                                 CVPixelBufferRef pixelBuffer);
+    makeSkImageFromCVPixelBuffer(MetalContext& context, CVPixelBufferRef pixelBuffer);
 
   private:
     static SkYUVAInfo::PlaneConfig getPlaneConfig(OSType pixelFormat);
@@ -109,9 +109,7 @@ class SkiaCVPixelBufferUtils {
   };
 
 private:
-  static CVMetalTextureCacheRef getTextureCache(id<MTLDevice> device);
-  static TextureHolder *getSkiaTextureForCVPixelBufferPlane(
-      id<MTLDevice> device, CVPixelBufferRef pixelBuffer, size_t planeIndex);
+  static TextureHolder *getSkiaTextureForCVPixelBufferPlane(MetalContext& context, CVPixelBufferRef pixelBuffer, size_t planeIndex);
   static MTLPixelFormat
   getMTLPixelFormatForCVPixelBufferPlane(CVPixelBufferRef pixelBuffer,
                                          size_t planeIndex);

packages/skia/apple/SkiaCVPixelBufferUtils.mm

@@ -7,6 +7,8 @@
 
 #import "SkiaCVPixelBufferUtils.h"
 
+#import "MetalContext.h"
+
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdocumentation"
 
@@ -133,28 +135,23 @@
   }
 }
 
-sk_sp<SkImage> SkiaCVPixelBufferUtils::RGB::makeSkImageFromCVPixelBuffer(
-    id<MTLDevice> device, GrDirectContext *context,
-    CVPixelBufferRef pixelBuffer) {
+sk_sp<SkImage> SkiaCVPixelBufferUtils::RGB::makeSkImageFromCVPixelBuffer(MetalContext& context, CVPixelBufferRef pixelBuffer) {
   // 1. Get Skia color type for RGB buffer
   SkColorType colorType = getCVPixelBufferColorType(pixelBuffer);
 
   // 2. Get texture, RGB buffers only have one plane
-  TextureHolder *texture = getSkiaTextureForCVPixelBufferPlane(
-      device, pixelBuffer, /* planeIndex */ 0);
+  TextureHolder *texture = getSkiaTextureForCVPixelBufferPlane(context, pixelBuffer, /* planeIndex */ 0);
 
   // 3. Convert to image with manual memory cleanup
   return SkImages::BorrowTextureFrom(
-      context, texture->toGrBackendTexture(), kTopLeft_GrSurfaceOrigin,
+      context.getDirectContext(), texture->toGrBackendTexture(), kTopLeft_GrSurfaceOrigin,
       colorType, kOpaque_SkAlphaType, nullptr,
       [](void *texture) { delete (TextureHolder *)texture; }, (void *)texture);
 }
 
 // pragma MARK: YUV
 
-sk_sp<SkImage> SkiaCVPixelBufferUtils::YUV::makeSkImageFromCVPixelBuffer(
-    id<MTLDevice> device, GrDirectContext *context,
-    CVPixelBufferRef pixelBuffer) {
+sk_sp<SkImage> SkiaCVPixelBufferUtils::YUV::makeSkImageFromCVPixelBuffer(MetalContext& context, CVPixelBufferRef pixelBuffer) {
   // 1. Get all planes (YUV, Y_UV, Y_U_V or Y_U_V_A)
   const size_t planesCount = CVPixelBufferGetPlaneCount(pixelBuffer);
   if (planesCount > SkYUVAInfo::kMaxPlanes) [[unlikely]] {
@@ -168,7 +165,7 @@
 
   for (size_t planeIndex = 0; planeIndex < planesCount; planeIndex++) {
     TextureHolder *textureHolder =
-        getSkiaTextureForCVPixelBufferPlane(device, pixelBuffer, planeIndex);
+        getSkiaTextureForCVPixelBufferPlane(context, pixelBuffer, planeIndex);
     textures[planeIndex] = textureHolder->toGrBackendTexture();
     texturesHolder->addTexture(textureHolder);
   }
@@ -181,7 +178,7 @@
 
   // 4. Wrap into SkImage type with manualy memory cleanup
   return SkImages::TextureFromYUVATextures(
-      context, yuvaTextures, nullptr,
+      context.getDirectContext(), yuvaTextures, nullptr,
       [](void *textureHolders) {
         delete (MultiTexturesHolder *)textureHolders;
       },
@@ -290,9 +287,9 @@
 // pragma MARK: CVPixelBuffer -> Skia Texture
 
 TextureHolder *SkiaCVPixelBufferUtils::getSkiaTextureForCVPixelBufferPlane(
-    id<MTLDevice> device, CVPixelBufferRef pixelBuffer, size_t planeIndex) {
+    MetalContext& context, CVPixelBufferRef pixelBuffer, size_t planeIndex) {
   // 1. Get cache
-  CVMetalTextureCacheRef textureCache = getTextureCache(device);
+  CVMetalTextureCacheRef textureCache = context.getMetalTextureCache();
 
   // 2. Get MetalTexture from CMSampleBuffer
   size_t width = CVPixelBufferGetWidthOfPlane(pixelBuffer, planeIndex);
@@ -314,22 +311,6 @@
   return new TextureHolder(textureHolder);
 }
 
-// pragma MARK: getTextureCache()
-
-CVMetalTextureCacheRef
-SkiaCVPixelBufferUtils::getTextureCache(id<MTLDevice> device) {
-  static CVMetalTextureCacheRef textureCache = nil;
-  if (textureCache == nil) {
-    // Create a new Texture Cache
-    auto result = CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, device,
-                                            nil, &textureCache);
-    if (result != kCVReturnSuccess || textureCache == nil) {
-      throw std::runtime_error("Failed to create Metal Texture Cache!");
-    }
-  }
-  return textureCache;
-}
-
 // pragma MARK: Get CVPixelBuffer MTLPixelFormat
 
 MTLPixelFormat SkiaCVPixelBufferUtils::getMTLPixelFormatForCVPixelBufferPlane(