First patch for async renderengine.

1. return a std::future object from DrawLayers() instead to make it
asynchronously
2. retire drawFence value from drawLayers() parameter list.

Bug: 180657548
Test: android.hardware.graphics.composer@2.2-vts, libcompositionengine_test, libsurfaceflinger_unittest and
librenderengine_test pass

Change-Id: If63c11762d1cce7b053cc72aaeaed6dd7904877f
diff --git a/libs/renderengine/RenderEngine.cpp b/libs/renderengine/RenderEngine.cpp
index 0c5a851..2174df5 100644
--- a/libs/renderengine/RenderEngine.cpp
+++ b/libs/renderengine/RenderEngine.cpp
@@ -95,5 +95,16 @@
                         "output buffer not gpu writeable");
 }
 
+std::future<RenderEngineResult> RenderEngine::drawLayers(
+        const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+        const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+        base::unique_fd&& bufferFence) {
+    const auto resultPromise = std::make_shared<std::promise<RenderEngineResult>>();
+    std::future<RenderEngineResult> resultFuture = resultPromise->get_future();
+    drawLayersInternal(std::move(resultPromise), display, layers, buffer, useFramebufferCache,
+                       std::move(bufferFence));
+    return resultFuture;
+}
+
 } // namespace renderengine
 } // namespace android
diff --git a/libs/renderengine/gl/GLESRenderEngine.cpp b/libs/renderengine/gl/GLESRenderEngine.cpp
index b1e1014..2375cb7 100644
--- a/libs/renderengine/gl/GLESRenderEngine.cpp
+++ b/libs/renderengine/gl/GLESRenderEngine.cpp
@@ -1078,15 +1078,16 @@
     return image;
 }
 
-status_t GLESRenderEngine::drawLayers(const DisplaySettings& display,
-                                      const std::vector<const LayerSettings*>& layers,
-                                      const std::shared_ptr<ExternalTexture>& buffer,
-                                      const bool useFramebufferCache, base::unique_fd&& bufferFence,
-                                      base::unique_fd* drawFence) {
+void GLESRenderEngine::drawLayersInternal(
+        const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+        const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+        const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+        base::unique_fd&& bufferFence) {
     ATRACE_CALL();
     if (layers.empty()) {
         ALOGV("Drawing empty layer stack");
-        return NO_ERROR;
+        resultPromise->set_value({NO_ERROR, base::unique_fd()});
+        return;
     }
 
     if (bufferFence.get() >= 0) {
@@ -1100,7 +1101,8 @@
 
     if (buffer == nullptr) {
         ALOGE("No output buffer provided. Aborting GPU composition.");
-        return BAD_VALUE;
+        resultPromise->set_value({BAD_VALUE, base::unique_fd()});
+        return;
     }
 
     validateOutputBufferUsage(buffer->getBuffer());
@@ -1128,7 +1130,8 @@
             ALOGE("Failed to bind framebuffer! Aborting GPU composition for buffer (%p).",
                   buffer->getBuffer()->handle);
             checkErrors();
-            return fbo->getStatus();
+            resultPromise->set_value({fbo->getStatus(), base::unique_fd()});
+            return;
         }
         setViewportAndProjection(display.physicalDisplay, display.clip);
     } else {
@@ -1139,7 +1142,8 @@
             ALOGE("Failed to prepare blur filter! Aborting GPU composition for buffer (%p).",
                   buffer->getBuffer()->handle);
             checkErrors();
-            return status;
+            resultPromise->set_value({status, base::unique_fd()});
+            return;
         }
     }
 
@@ -1172,7 +1176,8 @@
                 ALOGE("Failed to render blur effect! Aborting GPU composition for buffer (%p).",
                       buffer->getBuffer()->handle);
                 checkErrors("Can't render first blur pass");
-                return status;
+                resultPromise->set_value({status, base::unique_fd()});
+                return;
             }
 
             if (blurLayers.size() == 0) {
@@ -1194,7 +1199,8 @@
                 ALOGE("Failed to bind framebuffer! Aborting GPU composition for buffer (%p).",
                       buffer->getBuffer()->handle);
                 checkErrors("Can't bind native framebuffer");
-                return status;
+                resultPromise->set_value({status, base::unique_fd()});
+                return;
             }
 
             status = mBlurFilter->render(blurLayersSize > 1);
@@ -1202,7 +1208,8 @@
                 ALOGE("Failed to render blur effect! Aborting GPU composition for buffer (%p).",
                       buffer->getBuffer()->handle);
                 checkErrors("Can't render blur filter");
-                return status;
+                resultPromise->set_value({status, base::unique_fd()});
+                return;
             }
         }
 
@@ -1289,30 +1296,31 @@
         }
     }
 
-    if (drawFence != nullptr) {
-        *drawFence = flush();
-    }
+    base::unique_fd drawFence = flush();
+
     // If flush failed or we don't support native fences, we need to force the
     // gl command stream to be executed.
-    if (drawFence == nullptr || drawFence->get() < 0) {
+    if (drawFence.get() < 0) {
         bool success = finish();
         if (!success) {
             ALOGE("Failed to flush RenderEngine commands");
             checkErrors();
             // Chances are, something illegal happened (either the caller passed
             // us bad parameters, or we messed up our shader generation).
-            return INVALID_OPERATION;
+            resultPromise->set_value({INVALID_OPERATION, std::move(drawFence)});
+            return;
         }
         mLastDrawFence = nullptr;
     } else {
         // The caller takes ownership of drawFence, so we need to duplicate the
         // fd here.
-        mLastDrawFence = new Fence(dup(drawFence->get()));
+        mLastDrawFence = new Fence(dup(drawFence.get()));
     }
     mPriorResourcesCleaned = false;
 
     checkErrors();
-    return NO_ERROR;
+    resultPromise->set_value({NO_ERROR, std::move(drawFence)});
+    return;
 }
 
 void GLESRenderEngine::setViewportAndProjection(Rect viewport, Rect clip) {
diff --git a/libs/renderengine/gl/GLESRenderEngine.h b/libs/renderengine/gl/GLESRenderEngine.h
index 14627ce..c4adfdf 100644
--- a/libs/renderengine/gl/GLESRenderEngine.h
+++ b/libs/renderengine/gl/GLESRenderEngine.h
@@ -63,11 +63,6 @@
     bool isProtected() const override { return mInProtectedContext; }
     bool supportsProtectedContent() const override;
     void useProtectedContext(bool useProtectedContext) override;
-    status_t drawLayers(const DisplaySettings& display,
-                        const std::vector<const LayerSettings*>& layers,
-                        const std::shared_ptr<ExternalTexture>& buffer,
-                        const bool useFramebufferCache, base::unique_fd&& bufferFence,
-                        base::unique_fd* drawFence) override;
     void cleanupPostRender() override;
     int getContextPriority() override;
     bool supportsBackgroundBlur() override { return mBlurFilter != nullptr; }
@@ -107,6 +102,11 @@
             EXCLUDES(mRenderingMutex);
     void unmapExternalTextureBuffer(const sp<GraphicBuffer>& buffer) EXCLUDES(mRenderingMutex);
     bool canSkipPostRenderCleanup() const override;
+    void drawLayersInternal(const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+                            const DisplaySettings& display,
+                            const std::vector<const LayerSettings*>& layers,
+                            const std::shared_ptr<ExternalTexture>& buffer,
+                            const bool useFramebufferCache, base::unique_fd&& bufferFence) override;
 
 private:
     friend class BindNativeBufferAsFramebuffer;
diff --git a/libs/renderengine/include/renderengine/RenderEngine.h b/libs/renderengine/include/renderengine/RenderEngine.h
index 967cf5d..701c1f2 100644
--- a/libs/renderengine/include/renderengine/RenderEngine.h
+++ b/libs/renderengine/include/renderengine/RenderEngine.h
@@ -68,6 +68,7 @@
 class Mesh;
 class Texture;
 struct RenderEngineCreationArgs;
+struct RenderEngineResult;
 
 namespace threaded {
 class RenderEngineThreaded;
@@ -156,17 +157,12 @@
     // parameter does nothing.
     // @param bufferFence Fence signalling that the buffer is ready to be drawn
     // to.
-    // @param drawFence A pointer to a fence, which will fire when the buffer
-    // has been drawn to and is ready to be examined. The fence will be
-    // initialized by this method. The caller will be responsible for owning the
-    // fence.
-    // @return An error code indicating whether drawing was successful. For
-    // now, this always returns NO_ERROR.
-    virtual status_t drawLayers(const DisplaySettings& display,
-                                const std::vector<const LayerSettings*>& layers,
-                                const std::shared_ptr<ExternalTexture>& buffer,
-                                const bool useFramebufferCache, base::unique_fd&& bufferFence,
-                                base::unique_fd* drawFence) = 0;
+    // @return A future object of RenderEngineResult struct indicating whether
+    // drawing was successful in async mode.
+    virtual std::future<RenderEngineResult> drawLayers(
+            const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+            const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+            base::unique_fd&& bufferFence);
 
     // Clean-up method that should be called on the main thread after the
     // drawFence returned by drawLayers fires. This method will free up
@@ -232,6 +228,12 @@
     friend class threaded::RenderEngineThreaded;
     friend class RenderEngineTest_cleanupPostRender_cleansUpOnce_Test;
     const RenderEngineType mRenderEngineType;
+
+    virtual void drawLayersInternal(
+            const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+            const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+            const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+            base::unique_fd&& bufferFence) = 0;
 };
 
 struct RenderEngineCreationArgs {
@@ -318,6 +320,13 @@
             RenderEngine::RenderEngineType::SKIA_GL_THREADED;
 };
 
+struct RenderEngineResult {
+    // status indicates if drawing is successful
+    status_t status;
+    // drawFence will fire when the buffer has been drawn to and is ready to be examined.
+    base::unique_fd drawFence;
+};
+
 } // namespace renderengine
 } // namespace android
 
diff --git a/libs/renderengine/include/renderengine/mock/RenderEngine.h b/libs/renderengine/include/renderengine/mock/RenderEngine.h
index 0be3ba6..a7e6809 100644
--- a/libs/renderengine/include/renderengine/mock/RenderEngine.h
+++ b/libs/renderengine/include/renderengine/mock/RenderEngine.h
@@ -47,10 +47,15 @@
     MOCK_METHOD1(useProtectedContext, void(bool));
     MOCK_METHOD0(cleanupPostRender, void());
     MOCK_CONST_METHOD0(canSkipPostRenderCleanup, bool());
-    MOCK_METHOD6(drawLayers,
-                 status_t(const DisplaySettings&, const std::vector<const LayerSettings*>&,
-                          const std::shared_ptr<ExternalTexture>&, const bool, base::unique_fd&&,
-                          base::unique_fd*));
+    MOCK_METHOD5(drawLayers,
+                 std::future<RenderEngineResult>(const DisplaySettings&,
+                                                 const std::vector<const LayerSettings*>&,
+                                                 const std::shared_ptr<ExternalTexture>&,
+                                                 const bool, base::unique_fd&&));
+    MOCK_METHOD6(drawLayersInternal,
+                 void(const std::shared_ptr<std::promise<RenderEngineResult>>&&,
+                      const DisplaySettings&, const std::vector<const LayerSettings*>&,
+                      const std::shared_ptr<ExternalTexture>&, const bool, base::unique_fd&&));
     MOCK_METHOD0(cleanFramebufferCache, void());
     MOCK_METHOD0(getContextPriority, int());
     MOCK_METHOD0(supportsBackgroundBlur, bool());
diff --git a/libs/renderengine/skia/Cache.cpp b/libs/renderengine/skia/Cache.cpp
index 01df6a6..e796f66 100644
--- a/libs/renderengine/skia/Cache.cpp
+++ b/libs/renderengine/skia/Cache.cpp
@@ -95,7 +95,6 @@
             .alpha = 1,
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer, &caster};
     // Four combinations of settings are used (two transforms here, and drawShadowLayers is
     // called with two different destination data spaces) They're all rounded rect.
@@ -116,7 +115,7 @@
         layer.geometry.positionTransform = transform;
         caster.geometry.positionTransform = transform;
         renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                                base::unique_fd(), &drawFence);
+                                 base::unique_fd());
     }
 }
 
@@ -141,7 +140,6 @@
                                           }},
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
     for (auto dataspace : {kDestDataSpace, kOtherDataSpace}) {
         layer.sourceDataspace = dataspace;
@@ -155,7 +153,7 @@
                 for (auto alpha : {half(.2f), half(1.0f)}) {
                     layer.alpha = alpha;
                     renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                                             base::unique_fd(), &drawFence);
+                                             base::unique_fd());
                 }
             }
         }
@@ -178,14 +176,13 @@
             .alpha = 0.5,
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
     for (auto transform : {mat4(), kScaleAndTranslate}) {
         layer.geometry.positionTransform = transform;
         for (float roundedCornersRadius : {0.0f, 50.f}) {
             layer.geometry.roundedCornersRadius = roundedCornersRadius;
             renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                                     base::unique_fd(), &drawFence);
+                                     base::unique_fd());
         }
     }
 }
@@ -204,13 +201,12 @@
             .skipContentDraw = true,
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
     // Different blur code is invoked for radii less and greater than 30 pixels
     for (int radius : {9, 60}) {
         layer.backgroundBlurRadius = radius;
         renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                                 base::unique_fd(), &drawFence);
+                                 base::unique_fd());
     }
 }
 
@@ -246,7 +242,6 @@
                     },
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
     for (auto pixelSource : {bufferSource, bufferOpaque, colorSource}) {
         layer.source = pixelSource;
@@ -258,7 +253,7 @@
                 for (float alpha : {0.5f, 1.f}) {
                     layer.alpha = alpha,
                     renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                                             base::unique_fd(), &drawFence);
+                                             base::unique_fd());
                 }
             }
         }
@@ -294,10 +289,8 @@
 
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
-    renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                             base::unique_fd(), &drawFence);
+    renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache, base::unique_fd());
 }
 
 static void drawHolePunchLayer(SkiaRenderEngine* renderengine, const DisplaySettings& display,
@@ -324,10 +317,8 @@
 
     };
 
-    base::unique_fd drawFence;
     auto layers = std::vector<const LayerSettings*>{&layer};
-    renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                            base::unique_fd(), &drawFence);
+    renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache, base::unique_fd());
 }
 
 //
@@ -436,8 +427,10 @@
                 .source = PixelSource{.solidColor = half3(0.f, 0.f, 0.f)},
         };
         auto layers = std::vector<const LayerSettings*>{&layer};
-        renderengine->drawLayers(display, layers, dstTexture, kUseFrameBufferCache,
-                             base::unique_fd(), nullptr); // null drawFence makes it synchronous
+        // call get() to make it synchronous
+        renderengine
+                ->drawLayers(display, layers, dstTexture, kUseFrameBufferCache, base::unique_fd())
+                .get();
 
         const nsecs_t timeAfter = systemTime();
         const float compileTimeMs = static_cast<float>(timeAfter - timeBefore) / 1.0E6;
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.cpp b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
index 9fbbdc3..052c61f 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.cpp
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
@@ -713,17 +713,18 @@
     return roundedRect;
 }
 
-status_t SkiaGLRenderEngine::drawLayers(const DisplaySettings& display,
-                                        const std::vector<const LayerSettings*>& layers,
-                                        const std::shared_ptr<ExternalTexture>& buffer,
-                                        const bool /*useFramebufferCache*/,
-                                        base::unique_fd&& bufferFence, base::unique_fd* drawFence) {
+void SkiaGLRenderEngine::drawLayersInternal(
+        const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+        const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+        const std::shared_ptr<ExternalTexture>& buffer, const bool /*useFramebufferCache*/,
+        base::unique_fd&& bufferFence) {
     ATRACE_NAME("SkiaGL::drawLayers");
 
     std::lock_guard<std::mutex> lock(mRenderingMutex);
     if (layers.empty()) {
         ALOGV("Drawing empty layer stack");
-        return NO_ERROR;
+        resultPromise->set_value({NO_ERROR, base::unique_fd()});
+        return;
     }
 
     if (bufferFence.get() >= 0) {
@@ -736,7 +737,8 @@
     }
     if (buffer == nullptr) {
         ALOGE("No output buffer provided. Aborting GPU composition.");
-        return BAD_VALUE;
+        resultPromise->set_value({BAD_VALUE, base::unique_fd()});
+        return;
     }
 
     validateOutputBufferUsage(buffer->getBuffer());
@@ -765,7 +767,8 @@
     SkCanvas* dstCanvas = mCapture->tryCapture(dstSurface.get());
     if (dstCanvas == nullptr) {
         ALOGE("Cannot acquire canvas from Skia.");
-        return BAD_VALUE;
+        resultPromise->set_value({BAD_VALUE, base::unique_fd()});
+        return;
     }
 
     // setup color filter if necessary
@@ -1094,13 +1097,11 @@
         activeSurface->flush();
     }
 
-    if (drawFence != nullptr) {
-        *drawFence = flush();
-    }
+    base::unique_fd drawFence = flush();
 
     // If flush failed or we don't support native fences, we need to force the
     // gl command stream to be executed.
-    bool requireSync = drawFence == nullptr || drawFence->get() < 0;
+    bool requireSync = drawFence.get() < 0;
     if (requireSync) {
         ATRACE_BEGIN("Submit(sync=true)");
     } else {
@@ -1112,11 +1113,13 @@
         ALOGE("Failed to flush RenderEngine commands");
         // Chances are, something illegal happened (either the caller passed
         // us bad parameters, or we messed up our shader generation).
-        return INVALID_OPERATION;
+        resultPromise->set_value({INVALID_OPERATION, std::move(drawFence)});
+        return;
     }
 
     // checkErrors();
-    return NO_ERROR;
+    resultPromise->set_value({NO_ERROR, std::move(drawFence)});
+    return;
 }
 
 inline SkRect SkiaGLRenderEngine::getSkRect(const FloatRect& rect) {
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.h b/libs/renderengine/skia/SkiaGLRenderEngine.h
index cc91948..0b46705 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.h
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.h
@@ -54,11 +54,6 @@
     ~SkiaGLRenderEngine() override EXCLUDES(mRenderingMutex);
 
     std::future<void> primeCache() override;
-    status_t drawLayers(const DisplaySettings& display,
-                        const std::vector<const LayerSettings*>& layers,
-                        const std::shared_ptr<ExternalTexture>& buffer,
-                        const bool useFramebufferCache, base::unique_fd&& bufferFence,
-                        base::unique_fd* drawFence) override;
     void cleanupPostRender() override;
     void cleanFramebufferCache() override{};
     int getContextPriority() override;
@@ -77,6 +72,11 @@
     void mapExternalTextureBuffer(const sp<GraphicBuffer>& buffer, bool isRenderable) override;
     void unmapExternalTextureBuffer(const sp<GraphicBuffer>& buffer) override;
     bool canSkipPostRenderCleanup() const override;
+    void drawLayersInternal(const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+                            const DisplaySettings& display,
+                            const std::vector<const LayerSettings*>& layers,
+                            const std::shared_ptr<ExternalTexture>& buffer,
+                            const bool useFramebufferCache, base::unique_fd&& bufferFence) override;
 
 private:
     static EGLConfig chooseEglConfig(EGLDisplay display, int format, bool logConfig);
diff --git a/libs/renderengine/skia/SkiaRenderEngine.h b/libs/renderengine/skia/SkiaRenderEngine.h
index 7cd9eca..f61653b 100644
--- a/libs/renderengine/skia/SkiaRenderEngine.h
+++ b/libs/renderengine/skia/SkiaRenderEngine.h
@@ -44,14 +44,6 @@
     virtual void deleteTextures(size_t /*count*/, uint32_t const* /*names*/) override{};
     virtual bool isProtected() const override { return false; } // mInProtectedContext; }
     virtual bool supportsProtectedContent() const override { return false; };
-    virtual status_t drawLayers(const DisplaySettings& /*display*/,
-                                const std::vector<const LayerSettings*>& /*layers*/,
-                                const std::shared_ptr<ExternalTexture>& /*buffer*/,
-                                const bool /*useFramebufferCache*/,
-                                base::unique_fd&& /*bufferFence*/,
-                                base::unique_fd* /*drawFence*/) override {
-        return 0;
-    };
     virtual int getContextPriority() override { return 0; }
     virtual void assertShadersCompiled(int numShaders) {}
     virtual int reportShadersCompiled() { return 0; }
@@ -60,6 +52,14 @@
     virtual void mapExternalTextureBuffer(const sp<GraphicBuffer>& /*buffer*/,
                                           bool /*isRenderable*/) override = 0;
     virtual void unmapExternalTextureBuffer(const sp<GraphicBuffer>& /*buffer*/) override = 0;
+
+    virtual void drawLayersInternal(
+            const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+            const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+            const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+            base::unique_fd&& bufferFence) override {
+        resultPromise->set_value({NO_ERROR, base::unique_fd()});
+    };
 };
 
 } // namespace skia
diff --git a/libs/renderengine/tests/RenderEngineTest.cpp b/libs/renderengine/tests/RenderEngineTest.cpp
index 33053a0..b3b726d 100644
--- a/libs/renderengine/tests/RenderEngineTest.cpp
+++ b/libs/renderengine/tests/RenderEngineTest.cpp
@@ -419,9 +419,10 @@
 
     void invokeDraw(renderengine::DisplaySettings settings,
                     std::vector<const renderengine::LayerSettings*> layers) {
-        base::unique_fd fence;
-        status_t status =
-                mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd(), &fence);
+        std::future<renderengine::RenderEngineResult> result =
+                mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd());
+        ASSERT_TRUE(result.valid());
+        auto [status, fence] = result.get();
 
         int fd = fence.release();
         if (fd >= 0) {
@@ -1312,9 +1313,11 @@
     layer.geometry.boundaries = fullscreenRect().toFloatRect();
     BufferSourceVariant<ForceOpaqueBufferVariant>::fillColor(layer, 1.0f, 0.0f, 0.0f, this);
     layers.push_back(&layer);
-    base::unique_fd fence;
-    status_t status = mRE->drawLayers(settings, layers, nullptr, true, base::unique_fd(), &fence);
+    std::future<renderengine::RenderEngineResult> result =
+            mRE->drawLayers(settings, layers, nullptr, true, base::unique_fd());
 
+    ASSERT_TRUE(result.valid());
+    auto [status, _] = result.get();
     ASSERT_EQ(BAD_VALUE, status);
 }
 
@@ -1333,7 +1336,10 @@
     layer.alpha = 1.0;
     layers.push_back(&layer);
 
-    status_t status = mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd(), nullptr);
+    std::future<renderengine::RenderEngineResult> result =
+            mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd());
+    ASSERT_TRUE(result.valid());
+    auto [status, _] = result.get();
     ASSERT_EQ(NO_ERROR, status);
     expectBufferColor(fullscreenRect(), 255, 0, 0, 255);
 }
@@ -1360,7 +1366,10 @@
     layer.alpha = 1.0;
     layers.push_back(&layer);
 
-    status_t status = mRE->drawLayers(settings, layers, mBuffer, false, base::unique_fd(), nullptr);
+    std::future<renderengine::RenderEngineResult> result =
+            mRE->drawLayers(settings, layers, mBuffer, false, base::unique_fd());
+    ASSERT_TRUE(result.valid());
+    auto [status, _] = result.get();
     ASSERT_EQ(NO_ERROR, status);
     ASSERT_FALSE(mGLESRE->isFramebufferImageCachedForTesting(mBuffer->getBuffer()->getId()));
     expectBufferColor(fullscreenRect(), 255, 0, 0, 255);
@@ -1760,10 +1769,17 @@
     layer.alpha = 1.0;
     layers.push_back(&layer);
 
-    base::unique_fd fenceOne;
-    mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd(), &fenceOne);
-    base::unique_fd fenceTwo;
-    mRE->drawLayers(settings, layers, mBuffer, true, std::move(fenceOne), &fenceTwo);
+    std::future<renderengine::RenderEngineResult> resultOne =
+            mRE->drawLayers(settings, layers, mBuffer, true, base::unique_fd());
+    ASSERT_TRUE(resultOne.valid());
+    auto [statusOne, fenceOne] = resultOne.get();
+    ASSERT_EQ(NO_ERROR, statusOne);
+
+    std::future<renderengine::RenderEngineResult> resultTwo =
+            mRE->drawLayers(settings, layers, mBuffer, true, std::move(fenceOne));
+    ASSERT_TRUE(resultTwo.valid());
+    auto [statusTwo, fenceTwo] = resultTwo.get();
+    ASSERT_EQ(NO_ERROR, statusTwo);
 
     const int fd = fenceTwo.get();
     if (fd >= 0) {
diff --git a/libs/renderengine/tests/RenderEngineThreadedTest.cpp b/libs/renderengine/tests/RenderEngineThreadedTest.cpp
index 830f463..99250c1 100644
--- a/libs/renderengine/tests/RenderEngineThreadedTest.cpp
+++ b/libs/renderengine/tests/RenderEngineThreadedTest.cpp
@@ -169,6 +169,7 @@
     status_t result = mThreadedRE->supportsBackgroundBlur();
     ASSERT_EQ(true, result);
 }
+
 TEST_F(RenderEngineThreadedTest, drawLayers) {
     renderengine::DisplaySettings settings;
     std::vector<const renderengine::LayerSettings*> layers;
@@ -177,17 +178,22 @@
                                            renderengine::ExternalTexture::Usage::READABLE |
                                                    renderengine::ExternalTexture::Usage::WRITEABLE);
     base::unique_fd bufferFence;
-    base::unique_fd drawFence;
 
-    EXPECT_CALL(*mRenderEngine, drawLayers)
-            .WillOnce([](const renderengine::DisplaySettings&,
-                         const std::vector<const renderengine::LayerSettings*>&,
-                         const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                         base::unique_fd&&, base::unique_fd*) -> status_t { return NO_ERROR; });
+    EXPECT_CALL(*mRenderEngine, drawLayersInternal)
+            .WillOnce([&](const std::shared_ptr<std::promise<renderengine::RenderEngineResult>>&&
+                                  resultPromise,
+                          const renderengine::DisplaySettings&,
+                          const std::vector<const renderengine::LayerSettings*>&,
+                          const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                          base::unique_fd &&) -> void {
+                resultPromise->set_value({NO_ERROR, base::unique_fd()});
+            });
 
-    status_t result = mThreadedRE->drawLayers(settings, layers, buffer, false,
-                                              std::move(bufferFence), &drawFence);
-    ASSERT_EQ(NO_ERROR, result);
+    std::future<renderengine::RenderEngineResult> result =
+            mThreadedRE->drawLayers(settings, layers, buffer, false, std::move(bufferFence));
+    ASSERT_TRUE(result.valid());
+    auto [status, _] = result.get();
+    ASSERT_EQ(NO_ERROR, status);
 }
 
 } // namespace android
diff --git a/libs/renderengine/threaded/RenderEngineThreaded.cpp b/libs/renderengine/threaded/RenderEngineThreaded.cpp
index 8e666d5..9a8201f 100644
--- a/libs/renderengine/threaded/RenderEngineThreaded.cpp
+++ b/libs/renderengine/threaded/RenderEngineThreaded.cpp
@@ -304,27 +304,33 @@
     return mRenderEngine->canSkipPostRenderCleanup();
 }
 
-status_t RenderEngineThreaded::drawLayers(const DisplaySettings& display,
-                                          const std::vector<const LayerSettings*>& layers,
-                                          const std::shared_ptr<ExternalTexture>& buffer,
-                                          const bool useFramebufferCache,
-                                          base::unique_fd&& bufferFence,
-                                          base::unique_fd* drawFence) {
+void RenderEngineThreaded::drawLayersInternal(
+        const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+        const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+        const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+        base::unique_fd&& bufferFence) {
+    resultPromise->set_value({NO_ERROR, base::unique_fd()});
+    return;
+}
+
+std::future<RenderEngineResult> RenderEngineThreaded::drawLayers(
+        const DisplaySettings& display, const std::vector<const LayerSettings*>& layers,
+        const std::shared_ptr<ExternalTexture>& buffer, const bool useFramebufferCache,
+        base::unique_fd&& bufferFence) {
     ATRACE_CALL();
-    std::promise<status_t> resultPromise;
-    std::future<status_t> resultFuture = resultPromise.get_future();
+    const auto resultPromise = std::make_shared<std::promise<RenderEngineResult>>();
+    std::future<RenderEngineResult> resultFuture = resultPromise->get_future();
     {
         std::lock_guard lock(mThreadMutex);
-        mFunctionCalls.push([&resultPromise, &display, &layers, &buffer, useFramebufferCache,
-                             &bufferFence, &drawFence](renderengine::RenderEngine& instance) {
+        mFunctionCalls.push([resultPromise, &display, &layers, &buffer, useFramebufferCache,
+                             &bufferFence](renderengine::RenderEngine& instance) {
             ATRACE_NAME("REThreaded::drawLayers");
-            status_t status = instance.drawLayers(display, layers, buffer, useFramebufferCache,
-                                                  std::move(bufferFence), drawFence);
-            resultPromise.set_value(status);
+            instance.drawLayersInternal(std::move(resultPromise), display, layers, buffer,
+                                        useFramebufferCache, std::move(bufferFence));
         });
     }
     mCondition.notify_one();
-    return resultFuture.get();
+    return resultFuture;
 }
 
 void RenderEngineThreaded::cleanFramebufferCache() {
diff --git a/libs/renderengine/threaded/RenderEngineThreaded.h b/libs/renderengine/threaded/RenderEngineThreaded.h
index b197df7..2303caa 100644
--- a/libs/renderengine/threaded/RenderEngineThreaded.h
+++ b/libs/renderengine/threaded/RenderEngineThreaded.h
@@ -56,11 +56,11 @@
     void useProtectedContext(bool useProtectedContext) override;
     void cleanupPostRender() override;
 
-    status_t drawLayers(const DisplaySettings& display,
-                        const std::vector<const LayerSettings*>& layers,
-                        const std::shared_ptr<ExternalTexture>& buffer,
-                        const bool useFramebufferCache, base::unique_fd&& bufferFence,
-                        base::unique_fd* drawFence) override;
+    std::future<RenderEngineResult> drawLayers(const DisplaySettings& display,
+                                               const std::vector<const LayerSettings*>& layers,
+                                               const std::shared_ptr<ExternalTexture>& buffer,
+                                               const bool useFramebufferCache,
+                                               base::unique_fd&& bufferFence) override;
 
     void cleanFramebufferCache() override;
     int getContextPriority() override;
@@ -71,6 +71,11 @@
     void mapExternalTextureBuffer(const sp<GraphicBuffer>& buffer, bool isRenderable) override;
     void unmapExternalTextureBuffer(const sp<GraphicBuffer>& buffer) override;
     bool canSkipPostRenderCleanup() const override;
+    void drawLayersInternal(const std::shared_ptr<std::promise<RenderEngineResult>>&& resultPromise,
+                            const DisplaySettings& display,
+                            const std::vector<const LayerSettings*>& layers,
+                            const std::shared_ptr<ExternalTexture>& buffer,
+                            const bool useFramebufferCache, base::unique_fd&& bufferFence) override;
 
 private:
     void threadMain(CreateInstanceFactory factory);