commit b17c62120b646f378c0b842b3d7fcce8a5540e3e
author Dominik Laskowski <domlaskowski@google.com> Mon May 09 09:36:19 2022 -0700
committer Dominik Laskowski <domlaskowski@google.com> Mon May 16 08:13:29 2022 -0700
tree 13f01098a51f9c387d3e8c87683f55ef40de4ba4
parent bb448ce9aa521f9574d94c9ec2d57eb7d37382cb

FTL: Yield futures without overhead

ftl::yield, which lifts T to std::future<T>, incurs the cost of
allocating, ref counting, and locking the latter's shared state.

Consolidate the existing std::future extensions into ftl::Future,
and optimize ftl::yield by including static storage for T within.

Bug: 232436803
Test: simpleperf (-31% cycles in postFramebuffer)
Change-Id: I9a7ca7de17e7af10515de97d2f6a0dfa24e35d7a

services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp

diff --git a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
index 784abea..deaea87 100644
--- a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
@@ -3189,15 +3189,15 @@
     // would not survive certain calls like Fence::merge() which would return a
     // new instance.
     EXPECT_CALL(*mLayer1.layerFE, onLayerDisplayed(_))
-            .WillOnce([&layer1Fence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&layer1Fence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(layer1Fence), futureFenceResult.get());
             });
     EXPECT_CALL(*mLayer2.layerFE, onLayerDisplayed(_))
-            .WillOnce([&layer2Fence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&layer2Fence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(layer2Fence), futureFenceResult.get());
             });
     EXPECT_CALL(*mLayer3.layerFE, onLayerDisplayed(_))
-            .WillOnce([&layer3Fence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&layer3Fence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(layer3Fence), futureFenceResult.get());
             });
 
@@ -3256,15 +3256,15 @@
 
     // Each released layer should be given the presentFence.
     EXPECT_CALL(*releasedLayer1, onLayerDisplayed(_))
-            .WillOnce([&presentFence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&presentFence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(presentFence), futureFenceResult.get());
             });
     EXPECT_CALL(*releasedLayer2, onLayerDisplayed(_))
-            .WillOnce([&presentFence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&presentFence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(presentFence), futureFenceResult.get());
             });
     EXPECT_CALL(*releasedLayer3, onLayerDisplayed(_))
-            .WillOnce([&presentFence](std::shared_future<FenceResult> futureFenceResult) {
+            .WillOnce([&presentFence](ftl::SharedFuture<FenceResult> futureFenceResult) {
                 EXPECT_EQ(FenceResult(presentFence), futureFenceResult.get());
             });