Correctly pass screenshot fences to transaction callbacks
In some instances, a screenshot may be captured before a layer has a
release callback registered. This can happen when a new buffer has
not yet been transacted before a screenshot is captured. This causes the
screenshot fence to be dropped and the possibility of tearing when
capturing a screenshot while continuously rendering.
To resolve this, buffer screenshot fences into a list of future fences
when there is no callback registered, and merge those fences when
dispatching the release callback.
Bug: 302703346
Test: SurfaceViewTests#testMovingWhiteSurfaceView 100 times
Change-Id: I91aec3cdb0973092d48cd77e59dd3999e9d9e847
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index c8b1059..219a8e2 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -78,11 +78,13 @@
#include "SurfaceFlinger.h"
#include "TimeStats/TimeStats.h"
#include "TunnelModeEnabledReporter.h"
+#include "Utils/FenceUtils.h"
#define DEBUG_RESIZE 0
#define EARLY_RELEASE_ENABLED false
namespace android {
+using namespace std::chrono_literals;
namespace {
constexpr int kDumpTableRowLength = 159;
@@ -2911,7 +2913,8 @@
}
void Layer::onLayerDisplayed(ftl::SharedFuture<FenceResult> futureFenceResult,
- ui::LayerStack layerStack) {
+ ui::LayerStack layerStack,
+ std::function<FenceResult(FenceResult)>&& continuation) {
// If we are displayed on multiple displays in a single composition cycle then we would
// need to do careful tracking to enable the use of the mLastClientCompositionFence.
// For example we can only use it if all the displays are client comp, and we need
@@ -2946,11 +2949,41 @@
break;
}
}
+
+ if (!FlagManager::getInstance().screenshot_fence_preservation() && continuation) {
+ futureFenceResult = ftl::Future(futureFenceResult).then(std::move(continuation)).share();
+ }
+
if (ch != nullptr) {
ch->previousReleaseCallbackId = mPreviousReleaseCallbackId;
ch->previousReleaseFences.emplace_back(std::move(futureFenceResult));
ch->name = mName;
+ } else if (FlagManager::getInstance().screenshot_fence_preservation()) {
+ // If we didn't get a release callback yet, e.g. some scenarios when capturing screenshots
+ // asynchronously, then make sure we don't drop the fence.
+ mAdditionalPreviousReleaseFences.emplace_back(std::move(futureFenceResult),
+ std::move(continuation));
+ std::vector<FenceAndContinuation> mergedFences;
+ sp<Fence> prevFence = nullptr;
+ // For a layer that's frequently screenshotted, try to merge fences to make sure we don't
+ // grow unbounded.
+ for (const auto& futureAndContinution : mAdditionalPreviousReleaseFences) {
+ auto result = futureAndContinution.future.wait_for(0s);
+ if (result != std::future_status::ready) {
+ mergedFences.emplace_back(futureAndContinution);
+ continue;
+ }
+
+ mergeFence(getDebugName(), futureAndContinution.chain().get().value_or(Fence::NO_FENCE),
+ prevFence);
+ }
+ if (prevFence != nullptr) {
+ mergedFences.emplace_back(ftl::yield(FenceResult(std::move(prevFence))).share());
+ }
+
+ mAdditionalPreviousReleaseFences.swap(mergedFences);
}
+
if (mBufferInfo.mBuffer) {
mPreviouslyPresentedLayerStacks.push_back(layerStack);
}
@@ -3440,6 +3473,15 @@
handle->acquireTimeOrFence = mCallbackHandleAcquireTimeOrFence;
handle->frameNumber = mDrawingState.frameNumber;
handle->previousFrameNumber = mDrawingState.previousFrameNumber;
+ if (FlagManager::getInstance().screenshot_fence_preservation() &&
+ mPreviousReleaseBufferEndpoint == handle->listener) {
+ // Add fences from previous screenshots now so that they can be dispatched to the
+ // client.
+ for (const auto& futureAndContinution : mAdditionalPreviousReleaseFences) {
+ handle->previousReleaseFences.emplace_back(futureAndContinution.chain());
+ }
+ mAdditionalPreviousReleaseFences.clear();
+ }
// Store so latched time and release fence can be set
mDrawingState.callbackHandles.push_back(handle);