Bug 1670014 - Delay querying buffer age until it is actually needed. r=sotaro

Currently we query the backbuffer age in
RenderCompositor::BeginFrame(). Querying the age on android requires
the driver to dequeue a new backbuffer. By doing this right at the
start of the frame, we may cause the driver to block until a buffer is
ready.

We don't actually need the buffer age until part way through
rendering, in Renderer::composite_simple(), by which point there is a
better chance the buffer is available. So move the query to there instead.

Differential Revision: https://phabricator.services.mozilla.com/D92950

gfx/webrender_bindings/RenderCompositorEGL.cpp

@@ -59,9 +59,7 @@ EGLSurface RenderCompositorEGL::CreateEGLSurface() {
 
 RenderCompositorEGL::RenderCompositorEGL(
     RefPtr<widget::CompositorWidget> aWidget)
-    : RenderCompositor(std::move(aWidget)),
-      mEGLSurface(EGL_NO_SURFACE),
-      mBufferAge(0) {}
+    : RenderCompositor(std::move(aWidget)), mEGLSurface(EGL_NO_SURFACE) {}
 
 RenderCompositorEGL::~RenderCompositorEGL() {
 #ifdef MOZ_WIDGET_ANDROID
@@ -91,9 +89,6 @@ bool RenderCompositorEGL::BeginFrame() {
   gl()->MakeCurrent();  // DestroyUnused can change the current context!
 #endif
 
-  // sets 0 if buffer_age is not supported
-  mBufferAge = gl::GLContextEGL::Cast(gl())->GetBufferAge();
-
   return true;
 }
 
@@ -238,7 +233,7 @@ bool RenderCompositorEGL::UsePartialPresent() {
   return gfx::gfxVars::WebRenderMaxPartialPresentRects() > 0;
 }
 
-bool RenderCompositorEGL::RequestFullRender() { return mBufferAge == 0; }
+bool RenderCompositorEGL::RequestFullRender() { return false; }
 
 uint32_t RenderCompositorEGL::GetMaxPartialPresentRects() {
   return gfx::gfxVars::WebRenderMaxPartialPresentRects();
@@ -248,7 +243,9 @@ bool RenderCompositorEGL::ShouldDrawPreviousPartialPresentRegions() {
   return true;
 }
 
-size_t RenderCompositorEGL::GetBufferAge() const { return mBufferAge; }
+size_t RenderCompositorEGL::GetBufferAge() const {
+  return gl::GLContextEGL::Cast(gl())->GetBufferAge();
+}
 
 void RenderCompositorEGL::SetBufferDamageRegion(const wr::DeviceIntRect* aRects,
                                                 size_t aNumRects) {

gfx/webrender_bindings/RenderCompositorEGL.h

@@ -59,8 +59,6 @@ class RenderCompositorEGL : public RenderCompositor {
   LayoutDeviceIntSize mEGLSurfaceSize;
 #endif
 
-  EGLint mBufferAge;
-
   // FileDescriptor of release fence.
   // Release fence is a fence that is used for waiting until usage/composite of
   // AHardwareBuffer is ended. The fence is delivered to client side via

gfx/webrender_bindings/RenderCompositorOGL.cpp

@@ -34,7 +34,7 @@ UniquePtr<RenderCompositor> RenderCompositorOGL::Create(
 
 RenderCompositorOGL::RenderCompositorOGL(
     RefPtr<gl::GLContext>&& aGL, RefPtr<widget::CompositorWidget>&& aWidget)
-    : RenderCompositor(std::move(aWidget)), mGL(aGL), mBufferAge(0) {
+    : RenderCompositor(std::move(aWidget)), mGL(aGL) {
   MOZ_ASSERT(mGL);
 
   mIsEGL = aGL->GetContextType() == mozilla::gl::GLContextType::EGL;
@@ -57,11 +57,6 @@ bool RenderCompositorOGL::BeginFrame() {
 
   mGL->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mGL->GetDefaultFramebuffer());
 
-  if (mIsEGL) {
-    // sets 0 if buffer_age is not supported
-    mBufferAge = gl::GLContextEGL::Cast(gl())->GetBufferAge();
-  }
-
   return true;
 }
 
@@ -112,9 +107,7 @@ uint32_t RenderCompositorOGL::GetMaxPartialPresentRects() {
   return mIsEGL ? gfx::gfxVars::WebRenderMaxPartialPresentRects() : 0;
 }
 
-bool RenderCompositorOGL::RequestFullRender() {
-  return mIsEGL && (mBufferAge == 0);
-}
+bool RenderCompositorOGL::RequestFullRender() { return false; }
 
 bool RenderCompositorOGL::UsePartialPresent() {
   return mIsEGL && gfx::gfxVars::WebRenderMaxPartialPresentRects() > 0;
@@ -126,7 +119,7 @@ bool RenderCompositorOGL::ShouldDrawPreviousPartialPresentRegions() {
 
 size_t RenderCompositorOGL::GetBufferAge() const {
   if (mIsEGL) {
-    return mBufferAge;
+    return gl::GLContextEGL::Cast(gl())->GetBufferAge();
   }
   return 0;
 }

gfx/webrender_bindings/RenderCompositorOGL.h

@@ -44,7 +44,6 @@ class RenderCompositorOGL : public RenderCompositor {
  protected:
   RefPtr<gl::GLContext> mGL;
   bool mIsEGL;
-  EGLint mBufferAge;
 };
 
 }  // namespace wr