diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index 0ff5eca..1747294 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -1030,10 +1030,9 @@
         }
     }
 
-    base::unique_fd readyFence;
     if (!hasClientComposition) {
         setExpensiveRenderingExpected(false);
-        return readyFence;
+        return base::unique_fd();
     }
 
     ALOGV("hasClientComposition");
@@ -1073,7 +1072,7 @@
                                                    clientCompositionLayers)) {
             outputCompositionState.reusedClientComposition = true;
             setExpensiveRenderingExpected(false);
-            return readyFence;
+            return base::unique_fd();
         }
         mClientCompositionRequestCache->add(tex->getBuffer()->getId(), clientCompositionDisplay,
                                             clientCompositionLayers);
@@ -1107,9 +1106,11 @@
     // probably to encapsulate the output buffer into a structure that dispatches resource cleanup
     // over to RenderEngine, in which case this flag can be removed from the drawLayers interface.
     const bool useFramebufferCache = outputState.layerFilter.toInternalDisplay;
-    status_t status =
-            renderEngine.drawLayers(clientCompositionDisplay, clientCompositionLayerPointers, tex,
-                                    useFramebufferCache, std::move(fd), &readyFence);
+    auto [status, drawFence] =
+            renderEngine
+                    .drawLayers(clientCompositionDisplay, clientCompositionLayerPointers, tex,
+                                useFramebufferCache, std::move(fd))
+                    .get();
 
     if (status != NO_ERROR && mClientCompositionRequestCache) {
         // If rendering was not successful, remove the request from the cache.
@@ -1117,15 +1118,15 @@
     }
 
     auto& timeStats = getCompositionEngine().getTimeStats();
-    if (readyFence.get() < 0) {
+    if (drawFence.get() < 0) {
         timeStats.recordRenderEngineDuration(renderEngineStart, systemTime());
     } else {
         timeStats.recordRenderEngineDuration(renderEngineStart,
                                              std::make_shared<FenceTime>(
-                                                     new Fence(dup(readyFence.get()))));
+                                                     new Fence(dup(drawFence.get()))));
     }
 
-    return readyFence;
+    return std::move(drawFence);
 }
 
 std::vector<LayerFE::LayerSettings> Output::generateClientCompositionRequests(
diff --git a/services/surfaceflinger/CompositionEngine/src/planner/CachedSet.cpp b/services/surfaceflinger/CompositionEngine/src/planner/CachedSet.cpp
index ccacdfb..5bbd58e 100644
--- a/services/surfaceflinger/CompositionEngine/src/planner/CachedSet.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/planner/CachedSet.cpp
@@ -272,12 +272,12 @@
         bufferFence.reset(texture->getReadyFence()->dup());
     }
 
-    base::unique_fd drawFence;
-    status_t result =
-            renderEngine.drawLayers(displaySettings, layerSettingsPointers, texture->get(), false,
-                                    std::move(bufferFence), &drawFence);
+    auto [status, drawFence] = renderEngine
+                                       .drawLayers(displaySettings, layerSettingsPointers,
+                                                   texture->get(), false, std::move(bufferFence))
+                                       .get();
 
-    if (result == NO_ERROR) {
+    if (status == NO_ERROR) {
         mDrawFence = new Fence(drawFence.release());
         mOutputSpace = outputState.framebufferSpace;
         mTexture = texture;
diff --git a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
index 6c510eb..a904c7d 100644
--- a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
@@ -35,6 +35,7 @@
 #include "CallOrderStateMachineHelper.h"
 #include "MockHWC2.h"
 #include "RegionMatcher.h"
+#include "TestUtils.h"
 #include "renderengine/ExternalTexture.h"
 
 namespace android::compositionengine {
@@ -3119,9 +3120,14 @@
             .WillRepeatedly(Return());
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, IsEmpty(), _, false, _, _))
-            .WillRepeatedly(Return(NO_ERROR));
-
+    EXPECT_CALL(mRenderEngine, drawLayers(_, IsEmpty(), _, false, _))
+            .WillRepeatedly([&](const renderengine::DisplaySettings&,
+                                const std::vector<const renderengine::LayerSettings*>&,
+                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                                base::unique_fd &&)
+                                    -> std::future<renderengine::RenderEngineResult> {
+                return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
+            });
     verify().execute().expectAFenceWasReturned();
 }
 
@@ -3146,8 +3152,14 @@
                     }));
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _, _))
-            .WillRepeatedly(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _))
+            .WillRepeatedly([&](const renderengine::DisplaySettings&,
+                                const std::vector<const renderengine::LayerSettings*>&,
+                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                                base::unique_fd &&)
+                                    -> std::future<renderengine::RenderEngineResult> {
+                return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
+            });
 
     verify().execute().expectAFenceWasReturned();
 }
@@ -3175,8 +3187,14 @@
                     }));
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, true, _, _))
-            .WillRepeatedly(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, true, _))
+            .WillRepeatedly([&](const renderengine::DisplaySettings&,
+                                const std::vector<const renderengine::LayerSettings*>&,
+                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                                base::unique_fd &&)
+                                    -> std::future<renderengine::RenderEngineResult> {
+                return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
+            });
 
     verify().execute().expectAFenceWasReturned();
 }
@@ -3199,9 +3217,12 @@
             .WillRepeatedly(Return());
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _, _))
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _))
             .Times(2)
-            .WillOnce(Return(NO_ERROR));
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     verify().execute().expectAFenceWasReturned();
     EXPECT_FALSE(mOutput.mState.reusedClientComposition);
@@ -3228,8 +3249,9 @@
             .WillRepeatedly(Return());
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _, _))
-            .WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     EXPECT_CALL(mOutput, setExpensiveRenderingExpected(false));
 
     verify().execute().expectAFenceWasReturned();
@@ -3263,8 +3285,14 @@
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_))
             .WillOnce(Return(mOutputBuffer))
             .WillOnce(Return(otherOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _, _))
-            .WillRepeatedly(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _))
+            .WillRepeatedly([&](const renderengine::DisplaySettings&,
+                                const std::vector<const renderengine::LayerSettings*>&,
+                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                                base::unique_fd &&)
+                                    -> std::future<renderengine::RenderEngineResult> {
+                return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
+            });
 
     verify().execute().expectAFenceWasReturned();
     EXPECT_FALSE(mOutput.mState.reusedClientComposition);
@@ -3293,10 +3321,12 @@
             .WillRepeatedly(Return());
 
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _, _))
-            .WillOnce(Return(NO_ERROR));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r3)), _, false, _, _))
-            .WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r2)), _, false, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, ElementsAre(Pointee(r1), Pointee(r3)), _, false, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     verify().execute().expectAFenceWasReturned();
     EXPECT_FALSE(mOutput.mState.reusedClientComposition);
@@ -3345,8 +3375,9 @@
     struct ExpectDisplaySettingsState
           : public CallOrderStateMachineHelper<TestType, ExpectDisplaySettingsState> {
         auto thenExpectDisplaySettingsUsed(renderengine::DisplaySettings settings) {
-            EXPECT_CALL(getInstance()->mRenderEngine, drawLayers(settings, _, _, false, _, _))
-                    .WillOnce(Return(NO_ERROR));
+            EXPECT_CALL(getInstance()->mRenderEngine, drawLayers(settings, _, _, false, _))
+                    .WillOnce(Return(ByMove(futureOf<renderengine::RenderEngineResult>(
+                            {NO_ERROR, base::unique_fd()}))));
             return nextState<ExecuteState>();
         }
     };
@@ -3444,8 +3475,15 @@
         EXPECT_CALL(mOutput, appendRegionFlashRequests(RegionEq(kDebugRegion), _))
                 .WillRepeatedly(Return());
         EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _, _))
-                .WillRepeatedly(Return(NO_ERROR));
+        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _))
+                .WillRepeatedly(
+                        [&](const renderengine::DisplaySettings&,
+                            const std::vector<const renderengine::LayerSettings*>&,
+                            const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                            base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
+                            return futureOf<renderengine::RenderEngineResult>(
+                                    {NO_ERROR, base::unique_fd()});
+                        });
     }
 
     Layer mLayer1;
@@ -3497,7 +3535,9 @@
     EXPECT_CALL(*mRenderSurface, setProtected(true));
     // Must happen after setting the protected content state.
     EXPECT_CALL(*mRenderSurface, dequeueBuffer(_)).WillRepeatedly(Return(mOutputBuffer));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     mOutput.composeSurfaces(kDebugRegion, kDefaultRefreshArgs);
 }
@@ -3567,7 +3607,9 @@
     InSequence seq;
 
     EXPECT_CALL(mOutput, setExpensiveRenderingExpected(true));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     mOutput.composeSurfaces(kDebugRegion, kDefaultRefreshArgs);
 }
@@ -3584,7 +3626,9 @@
                                     /*zIsOverridden*/ false, /*isPeekingThrough*/ false));
         EXPECT_CALL(mOutput, generateClientCompositionRequests(_, kDefaultOutputDataspace))
                 .WillOnce(Return(std::vector<LayerFE::LayerSettings>{}));
-        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _, _)).WillOnce(Return(NO_ERROR));
+        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, false, _))
+                .WillOnce(Return(ByMove(futureOf<renderengine::RenderEngineResult>(
+                        {NO_ERROR, base::unique_fd()}))));
         EXPECT_CALL(mOutput, getOutputLayerCount()).WillRepeatedly(Return(1u));
         EXPECT_CALL(mOutput, getOutputLayerOrderedByZByIndex(0u))
                 .WillRepeatedly(Return(&mLayer.outputLayer));
diff --git a/services/surfaceflinger/CompositionEngine/tests/TestUtils.h b/services/surfaceflinger/CompositionEngine/tests/TestUtils.h
new file mode 100644
index 0000000..c80fde6
--- /dev/null
+++ b/services/surfaceflinger/CompositionEngine/tests/TestUtils.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <future>
+
+namespace android::compositionengine {
+namespace {
+
+template <class T>
+std::future<T> futureOf(T obj) {
+    std::promise<T> resultPromise;
+    std::future<T> resultFuture = resultPromise.get_future();
+    resultPromise.set_value(std::move(obj));
+    return resultFuture;
+}
+} // namespace
+} // namespace android::compositionengine
diff --git a/services/surfaceflinger/CompositionEngine/tests/planner/CachedSetTest.cpp b/services/surfaceflinger/CompositionEngine/tests/planner/CachedSetTest.cpp
index ec81322..818334d 100644
--- a/services/surfaceflinger/CompositionEngine/tests/planner/CachedSetTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/planner/CachedSetTest.cpp
@@ -27,6 +27,8 @@
 #include <utils/Errors.h>
 #include <memory>
 
+#include "tests/TestUtils.h"
+
 namespace android::compositionengine {
 using namespace std::chrono_literals;
 
@@ -342,10 +344,11 @@
     clientCompList2.push_back({});
     clientCompList2[0].alpha = 0.75f;
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings& displaySettings,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> size_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings& displaySettings,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         EXPECT_EQ(mOutputState.framebufferSpace.content, displaySettings.physicalDisplay);
         EXPECT_EQ(mOutputState.layerStackSpace.content, displaySettings.clip);
         EXPECT_EQ(ui::Transform::toRotationFlags(mOutputState.framebufferSpace.orientation),
@@ -353,8 +356,7 @@
         EXPECT_EQ(0.5f, layers[0]->alpha);
         EXPECT_EQ(0.75f, layers[1]->alpha);
         EXPECT_EQ(ui::Dataspace::SRGB, displaySettings.outputDataspace);
-
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
     EXPECT_CALL(*layerFE1,
@@ -363,7 +365,7 @@
     EXPECT_CALL(*layerFE2,
                 prepareClientCompositionList(ClientCompositionTargetSettingsSecureEq(false)))
             .WillOnce(Return(clientCompList2));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     mOutputState.isSecure = false;
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
     expectReadyBuffer(cachedSet);
@@ -394,10 +396,11 @@
     clientCompList2.push_back({});
     clientCompList2[0].alpha = 0.75f;
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings& displaySettings,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> size_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings& displaySettings,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         EXPECT_EQ(mOutputState.framebufferSpace.content, displaySettings.physicalDisplay);
         EXPECT_EQ(mOutputState.layerStackSpace.content, displaySettings.clip);
         EXPECT_EQ(ui::Transform::toRotationFlags(mOutputState.framebufferSpace.orientation),
@@ -406,7 +409,7 @@
         EXPECT_EQ(0.75f, layers[1]->alpha);
         EXPECT_EQ(ui::Dataspace::SRGB, displaySettings.outputDataspace);
 
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
     EXPECT_CALL(*layerFE1,
@@ -415,7 +418,7 @@
     EXPECT_CALL(*layerFE2,
                 prepareClientCompositionList(ClientCompositionTargetSettingsSecureEq(true)))
             .WillOnce(Return(clientCompList2));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     mOutputState.isSecure = true;
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
     expectReadyBuffer(cachedSet);
@@ -448,10 +451,11 @@
 
     mOutputState.framebufferSpace = ProjectionSpace(ui::Size(10, 20), Rect(2, 3, 10, 5));
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings& displaySettings,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> size_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings& displaySettings,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         EXPECT_EQ(mOutputState.framebufferSpace.content, displaySettings.physicalDisplay);
         EXPECT_EQ(mOutputState.layerStackSpace.content, displaySettings.clip);
         EXPECT_EQ(ui::Transform::toRotationFlags(mOutputState.framebufferSpace.orientation),
@@ -460,12 +464,12 @@
         EXPECT_EQ(0.75f, layers[1]->alpha);
         EXPECT_EQ(ui::Dataspace::SRGB, displaySettings.outputDataspace);
 
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
     EXPECT_CALL(*layerFE1, prepareClientCompositionList(_)).WillOnce(Return(clientCompList1));
     EXPECT_CALL(*layerFE2, prepareClientCompositionList(_)).WillOnce(Return(clientCompList2));
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
     expectReadyBuffer(cachedSet);
 
@@ -650,10 +654,11 @@
     EXPECT_CALL(*layerFE2, prepareClientCompositionList(_)).WillOnce(Return(clientCompList2));
     EXPECT_CALL(*layerFE3, prepareClientCompositionList(_)).WillOnce(Return(clientCompList3));
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings&,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> size_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings&,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         // If the highlight layer is enabled, it will increase the size by 1.
         // We're interested in the third layer either way.
         EXPECT_GE(layers.size(), 4u);
@@ -673,10 +678,10 @@
             EXPECT_EQ(1.0f, holePunchBackgroundSettings->alpha);
         }
 
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
 }
 
@@ -710,10 +715,11 @@
     EXPECT_CALL(*layerFE2, prepareClientCompositionList(_)).WillOnce(Return(clientCompList2));
     EXPECT_CALL(*layerFE3, prepareClientCompositionList(_)).WillOnce(Return(clientCompList3));
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings&,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> size_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings&,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         // If the highlight layer is enabled, it will increase the size by 1.
         // We're interested in the third layer either way.
         EXPECT_GE(layers.size(), 4u);
@@ -734,10 +740,10 @@
             EXPECT_EQ(1.0f, holePunchBackgroundSettings->alpha);
         }
 
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
 }
 
@@ -859,10 +865,11 @@
                                 BackgroundBlurOnly)))
             .WillOnce(Return(clientCompList3));
 
-    const auto drawLayers = [&](const renderengine::DisplaySettings&,
-                                const std::vector<const renderengine::LayerSettings*>& layers,
-                                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
-                                base::unique_fd&&, base::unique_fd*) -> int32_t {
+    const auto drawLayers =
+            [&](const renderengine::DisplaySettings&,
+                const std::vector<const renderengine::LayerSettings*>& layers,
+                const std::shared_ptr<renderengine::ExternalTexture>&, const bool,
+                base::unique_fd &&) -> std::future<renderengine::RenderEngineResult> {
         // If the highlight layer is enabled, it will increase the size by 1.
         // We're interested in the third layer either way.
         EXPECT_GE(layers.size(), 3u);
@@ -871,10 +878,10 @@
         EXPECT_EQ(half3(0.0f, 0.0f, 0.0f), blurSettings->source.solidColor);
         EXPECT_EQ(0.0f, blurSettings->alpha);
 
-        return NO_ERROR;
+        return futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()});
     };
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Invoke(drawLayers));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).WillOnce(Invoke(drawLayers));
     cachedSet.render(mRenderEngine, mTexturePool, mOutputState);
 }
 
diff --git a/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp b/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
index fc9d0dd..77d038d 100644
--- a/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/planner/FlattenerTest.cpp
@@ -26,6 +26,8 @@
 #include <renderengine/mock/RenderEngine.h>
 #include <chrono>
 
+#include "tests/TestUtils.h"
+
 namespace android::compositionengine {
 using namespace std::chrono_literals;
 using impl::planner::CachedSet;
@@ -166,7 +168,9 @@
 
 void FlattenerTest::expectAllLayersFlattened(const std::vector<const LayerState*>& layers) {
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -400,7 +404,9 @@
     // caleed for Layer2 and Layer3
     layerState1->resetFramesSinceBufferUpdate();
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -422,7 +428,9 @@
     layerState1->incrementFramesSinceBufferUpdate();
     mTime += 200ms;
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -473,7 +481,9 @@
     // called for Layer1 and Layer2
     layerState3->resetFramesSinceBufferUpdate();
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -486,7 +496,9 @@
     EXPECT_EQ(nullptr, overrideBuffer5);
 
     // Layers 1 and 2 will be flattened a new drawFrame would be called for Layer4 and Layer5
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -514,8 +526,9 @@
 
     layerState3->incrementFramesSinceBufferUpdate();
     mTime += 200ms;
-
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -569,7 +582,9 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     // This will render a CachedSet.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
@@ -579,7 +594,7 @@
 
     // This time we merge the CachedSet in, so we have a new hash, and we should
     // only have two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -631,7 +646,9 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     // This will render a CachedSet.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
@@ -641,7 +658,7 @@
 
     // This time we merge the CachedSet in, so we have a new hash, and we should
     // only have two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -701,14 +718,16 @@
 
     // This will render a CachedSet of layer 0. Though it is just one layer, it satisfies the
     // exception that there would be a hole punch above it.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
     EXPECT_EQ(nullptr, overrideBuffer0);
 
     // This time we merge the CachedSet in and we should still have only two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -751,7 +770,9 @@
     layerState3->resetFramesSinceBufferUpdate();
 
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -795,7 +816,9 @@
     layerState1->resetFramesSinceBufferUpdate();
 
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillRepeatedly(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillRepeatedly(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -847,7 +870,9 @@
     layerState1->resetFramesSinceBufferUpdate();
 
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -894,7 +919,9 @@
     layerStateWithBlurBehind->resetFramesSinceBufferUpdate();
 
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -935,7 +962,9 @@
     // Mark the layers inactive
     mTime += 200ms;
     // layers would be flattened but the buffer would not be overridden
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
 
     initializeOverrideBuffer(layers);
     EXPECT_EQ(getNonBufferHash(layers),
@@ -947,7 +976,7 @@
 
     // Simulate attempting to render prior to merging the new cached set with the layer stack.
     // Here we should not try to re-render.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We provide the override buffer now that it's rendered
@@ -992,13 +1021,15 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     for (size_t i = 0; i < kMaxDeferRenderAttempts; i++) {
-        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+        EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
         mFlattener->renderCachedSets(mOutputState,
                                      std::chrono::steady_clock::now() -
                                              (kCachedSetRenderDuration + 10ms));
     }
 
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState,
                                  std::chrono::steady_clock::now() -
                                          (kCachedSetRenderDuration + 10ms));
@@ -1032,7 +1063,9 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     // This will render a CachedSet.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
@@ -1042,7 +1075,7 @@
 
     // This time we merge the CachedSet in, so we have a new hash, and we should
     // only have two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -1081,7 +1114,9 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     // This will render a CachedSet.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
@@ -1091,7 +1126,7 @@
 
     // This time we merge the CachedSet in, so we have a new hash, and we should
     // only have two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
@@ -1130,7 +1165,9 @@
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));
 
     // This will render a CachedSet.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).WillOnce(Return(NO_ERROR));
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _))
+            .WillOnce(Return(ByMove(
+                    futureOf<renderengine::RenderEngineResult>({NO_ERROR, base::unique_fd()}))));
     mFlattener->renderCachedSets(mOutputState, std::nullopt);
 
     // We've rendered a CachedSet, but we haven't merged it in.
@@ -1140,7 +1177,7 @@
 
     // This time we merge the CachedSet in, so we have a new hash, and we should
     // only have two sets.
-    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _, _)).Times(0);
+    EXPECT_CALL(mRenderEngine, drawLayers(_, _, _, _, _)).Times(0);
     initializeOverrideBuffer(layers);
     EXPECT_NE(getNonBufferHash(layers),
               mFlattener->flattenLayers(layers, getNonBufferHash(layers), mTime));