Sync WebGL and acc canvas content with fences when available

Author: magomez

Source/WebCore/platform/graphics/cairo/ImageBufferCairoGLSurfaceBackend.cpp

@@ -224,7 +224,9 @@ void ImageBufferCairoGLSurfaceBackend::swapBuffersIfNeeded()
         ASSERT(is<TextureMapperPlatformLayerProxyGL>(proxy));
 
         Locker locker { proxy.lock() };
-        downcast<TextureMapperPlatformLayerProxyGL>(proxy).pushNextBuffer(makeUnique<TextureMapperPlatformLayerBuffer>(m_textures[1], backendSize, TextureMapperGL::ShouldBlend, GL_RGBA), false);
+        auto layerBuffer = makeUnique<TextureMapperPlatformLayerBuffer>(m_textures[1], backendSize, TextureMapperGL::ShouldBlend, GL_RGBA);
+        layerBuffer->addFenceSyncIfAvailable();
+        downcast<TextureMapperPlatformLayerProxyGL>(proxy).pushNextBuffer(WTFMove(layerBuffer), false);
     }
 
     if (previousActiveContext)

Source/WebCore/platform/graphics/nicosia/texmap/NicosiaGCGLLayer.cpp

@@ -132,7 +132,9 @@ void GCGLLayer::swapBuffersIfNeeded()
         auto& proxy = downcast<Nicosia::ContentLayerTextureMapperImpl>(m_contentLayer->impl()).proxy();
         Locker locker { proxy.lock() };
         ASSERT(is<TextureMapperPlatformLayerProxyGL>(proxy));
-        downcast<TextureMapperPlatformLayerProxyGL>(proxy).pushNextBuffer(makeUnique<TextureMapperPlatformLayerBuffer>(m_context.m_compositorTexture, textureSize, flags, m_context.m_internalColorFormat), false);
+        auto layerBuffer = makeUnique<TextureMapperPlatformLayerBuffer>(m_context.m_compositorTexture, textureSize, flags, m_context.m_internalColorFormat);
+        layerBuffer->addFenceSyncIfAvailable();
+        downcast<TextureMapperPlatformLayerProxyGL>(proxy).pushNextBuffer(WTFMove(layerBuffer), false);
     }
 
     m_context.markLayerComposited();

Source/WebCore/platform/graphics/texmap/TextureMapperPlatformLayerBuffer.cpp

@@ -58,6 +58,8 @@ TextureMapperPlatformLayerBuffer::TextureMapperPlatformLayerBuffer(TextureVarian
 
 TextureMapperPlatformLayerBuffer::~TextureMapperPlatformLayerBuffer()
 {
+    if (m_sync)
+        glDeleteSync(static_cast<GLsync>(m_sync));
 }
 
 bool TextureMapperPlatformLayerBuffer::canReuseWithoutReset(const IntSize& size, GLint internalFormat)
@@ -129,6 +131,13 @@ void TextureMapperPlatformLayerBuffer::paintToTextureMapper(TextureMapper& textu
         m_unmanagedBufferDataHolder->waitForCPUSync();
 #endif // USE(GSTREAMER_GL)
 
+    if (m_sync) {
+        glWaitSync(static_cast<GLsync>(m_sync), 0, GL_TIMEOUT_IGNORED);
+        glDeleteSync(static_cast<GLsync>(m_sync));
+        glFlush();
+        m_sync = nullptr;
+    }
+
     WTF::switchOn(m_variant,
         [&](const RGBTexture& texture) {
             ASSERT(texture.id);
@@ -176,6 +185,16 @@ bool TextureMapperPlatformLayerBuffer::isHolePunchBuffer()
     return (m_extraFlags & TextureMapperGL::ShouldNotBlend) && !m_texture;
 }
 
+void TextureMapperPlatformLayerBuffer::addFenceSyncIfAvailable()
+{
+    unsigned version = GLContext::current()->version();
+    if (version >= 300 && glFenceSync) {
+        // GLES 3, so fences are available and we can use them.
+        m_sync = static_cast<void*>(glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0));
+        glFlush();
+    }
+}
+
 } // namespace WebCore
 
 #endif // USE(COORDINATED_GRAPHICS)

Source/WebCore/platform/graphics/texmap/TextureMapperPlatformLayerBuffer.h

@@ -102,6 +102,8 @@ class TextureMapperPlatformLayerBuffer : public TextureMapperPlatformLayer {
     const TextureVariant& textureVariant() const { return m_variant; }
     IntSize size() const { return m_size; }
 
+    void addFenceSyncIfAvailable();
+
 protected:
     TextureVariant m_variant;
 
@@ -115,6 +117,7 @@ class TextureMapperPlatformLayerBuffer : public TextureMapperPlatformLayer {
     bool m_hasManagedTexture;
     std::unique_ptr<UnmanagedBufferDataHolder> m_unmanagedBufferDataHolder;
     std::unique_ptr<HolePunchClient> m_holePunchClient;
+    void* m_sync { nullptr };
 };
 
 } // namespace WebCore