DO NOT MERGE: BufferStateLayer: Mirror BufferQueue behavior in fence merging am: 92c2976f7c
Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1538645
Change-Id: Ifc2f0f65ed0405861b14fc54a3053497488f81fc
diff --git a/services/surfaceflinger/BufferStateLayer.cpp b/services/surfaceflinger/BufferStateLayer.cpp
index 41dd7bf..d94347a 100644
--- a/services/surfaceflinger/BufferStateLayer.cpp
+++ b/services/surfaceflinger/BufferStateLayer.cpp
@@ -66,10 +66,70 @@
}
}
+status_t BufferStateLayer::addReleaseFence(const sp<CallbackHandle>& ch,
+ const sp<Fence>& fence) {
+ if (ch == nullptr) {
+ return OK;
+ }
+ if (!ch->previousReleaseFence.get()) {
+ ch->previousReleaseFence = fence;
+ return OK;
+ }
+
+ // Below logic is lifted from ConsumerBase.cpp:
+ // Check status of fences first because merging is expensive.
+ // Merging an invalid fence with any other fence results in an
+ // invalid fence.
+ auto currentStatus = ch->previousReleaseFence->getStatus();
+ if (currentStatus == Fence::Status::Invalid) {
+ ALOGE("Existing fence has invalid state, layer: %s", mName.c_str());
+ return BAD_VALUE;
+ }
+
+ auto incomingStatus = fence->getStatus();
+ if (incomingStatus == Fence::Status::Invalid) {
+ ALOGE("New fence has invalid state, layer: %s", mName.c_str());
+ ch->previousReleaseFence = fence;
+ return BAD_VALUE;
+ }
+
+ // If both fences are signaled or both are unsignaled, we need to merge
+ // them to get an accurate timestamp.
+ if (currentStatus == incomingStatus) {
+ char fenceName[32] = {};
+ snprintf(fenceName, 32, "%.28s", mName.c_str());
+ sp<Fence> mergedFence = Fence::merge(
+ fenceName, ch->previousReleaseFence, fence);
+ if (!mergedFence.get()) {
+ ALOGE("failed to merge release fences, layer: %s", mName.c_str());
+ // synchronization is broken, the best we can do is hope fences
+ // signal in order so the new fence will act like a union
+ ch->previousReleaseFence = fence;
+ return BAD_VALUE;
+ }
+ ch->previousReleaseFence = mergedFence;
+ } else if (incomingStatus == Fence::Status::Unsignaled) {
+ // If one fence has signaled and the other hasn't, the unsignaled
+ // fence will approximately correspond with the correct timestamp.
+ // There's a small race if both fences signal at about the same time
+ // and their statuses are retrieved with unfortunate timing. However,
+ // by this point, they will have both signaled and only the timestamp
+ // will be slightly off; any dependencies after this point will
+ // already have been met.
+ ch->previousReleaseFence = fence;
+ }
+ // else if (currentStatus == Fence::Status::Unsignaled) is a no-op.
+
+ return OK;
+}
+
// -----------------------------------------------------------------------
// Interface implementation for Layer
// -----------------------------------------------------------------------
void BufferStateLayer::onLayerDisplayed(const sp<Fence>& releaseFence) {
+ if (!releaseFence->isValid()) {
+ return;
+ }
// The previous release fence notifies the client that SurfaceFlinger is done with the previous
// buffer that was presented on this layer. The first transaction that came in this frame that
// replaced the previous buffer on this layer needs this release fence, because the fence will
@@ -86,12 +146,17 @@
// buffer. It replaces the buffer in the second transaction. The buffer in the second
// transaction will now no longer be presented so it is released immediately and the third
// transaction doesn't need a previous release fence.
+ sp<CallbackHandle> ch;
for (auto& handle : mDrawingState.callbackHandles) {
if (handle->releasePreviousBuffer) {
- handle->previousReleaseFence = releaseFence;
+ ch = handle;
break;
}
}
+ auto status = addReleaseFence(ch, releaseFence);
+ if (status != OK) {
+ ALOGE("Failed to add release fence for layer %s", getName().c_str());
+ }
mPreviousReleaseFence = releaseFence;
diff --git a/services/surfaceflinger/BufferStateLayer.h b/services/surfaceflinger/BufferStateLayer.h
index 00fa7f7..2430c4e 100644
--- a/services/surfaceflinger/BufferStateLayer.h
+++ b/services/surfaceflinger/BufferStateLayer.h
@@ -120,6 +120,8 @@
bool updateFrameEventHistory(const sp<Fence>& acquireFence, nsecs_t postedTime,
nsecs_t requestedPresentTime);
+ status_t addReleaseFence(const sp<CallbackHandle>& ch, const sp<Fence>& releaseFence);
+
uint64_t getFrameNumber(nsecs_t expectedPresentTime) const override;
bool getAutoRefresh() const override;