Track pendingBuffer count in RequestedLayerState

Allows for easier retrieval without added lock contention.
RequestedLayerState stores a pointer to the original
buffer count from legacy layer.

Bug: b/294922229
Test: presubmit
Flag: EXEMPT, mechanical refactor
Change-Id: Iaab1b2214cc670f6e2d385ba4aba31e635a34030

Author: Melody Hsu

services/surfaceflinger/FrontEnd/LayerCreationArgs.h

@@ -61,6 +61,7 @@ struct LayerCreationArgs {
     ui::LayerStack layerStackToMirror = ui::INVALID_LAYER_STACK;
     uint32_t parentId = UNASSIGNED_LAYER_ID;
     uint32_t layerIdToMirror = UNASSIGNED_LAYER_ID;
+    std::atomic<int32_t>* pendingBuffers = 0;
 };
 
 } // namespace android::surfaceflinger

services/surfaceflinger/FrontEnd/RequestedLayerState.cpp

@@ -56,7 +56,8 @@ RequestedLayerState::RequestedLayerState(const LayerCreationArgs& args)
         ownerUid(args.ownerUid),
         ownerPid(args.ownerPid),
         parentId(args.parentId),
-        layerIdToMirror(args.layerIdToMirror) {
+        layerIdToMirror(args.layerIdToMirror),
+        pendingBuffers(args.pendingBuffers) {
     layerId = static_cast<int32_t>(args.sequence);
     changes |= RequestedLayerState::Changes::Created;
     metadata.merge(args.metadata);

services/surfaceflinger/FrontEnd/RequestedLayerState.h

@@ -131,6 +131,7 @@ struct RequestedLayerState : layer_state_t {
     uint64_t barrierFrameNumber = 0;
     uint32_t barrierProducerId = 0;
     std::string debugName;
+    std::atomic<int32_t>* pendingBuffers = 0;
 
     // book keeping states
     bool handleAlive = true;

services/surfaceflinger/Layer.cpp

@@ -1347,7 +1347,7 @@ Rect Layer::computeBufferCrop(const State& s) {
 }
 
 void Layer::decrementPendingBufferCount() {
-    int32_t pendingBuffers = --mPendingBufferTransactions;
+    int32_t pendingBuffers = --mPendingBuffers;
     tracePendingBufferCount(pendingBuffers);
 }
 

services/surfaceflinger/Layer.h

@@ -369,7 +369,7 @@ class Layer : public virtual RefBase {
 
     // See mPendingBufferTransactions
     void decrementPendingBufferCount();
-    std::atomic<int32_t>* getPendingBufferCounter() { return &mPendingBufferTransactions; }
+    std::atomic<int32_t>* getPendingBufferCounter() { return &mPendingBuffers; }
     std::string getPendingBufferCounterName() { return mBlastTransactionName; }
     void callReleaseBufferCallback(const sp<ITransactionCompletedListener>& listener,
                                    const sp<GraphicBuffer>& buffer, uint64_t framenumber,
@@ -562,7 +562,7 @@ class Layer : public virtual RefBase {
     //     - If the integer increases, a buffer arrived at the server.
     //     - If the integer decreases in latchBuffer, that buffer was latched
     //     - If the integer decreases in setBuffer, a buffer was dropped
-    std::atomic<int32_t> mPendingBufferTransactions{0};
+    std::atomic<int32_t> mPendingBuffers{0};
 
     // Contains requested position and matrix updates. This will be applied if the client does
     // not specify a destination frame.

services/surfaceflinger/SurfaceFlinger.cpp

@@ -5181,6 +5181,7 @@ status_t SurfaceFlinger::createLayer(LayerCreationArgs& args, gui::CreateSurface
                 std::string counterName = layer->getPendingBufferCounterName();
                 mBufferCountTracker.add(LayerHandle::getLayerId(outResult.handle), counterName,
                                         pendingBufferCounter);
+                args.pendingBuffers = pendingBufferCounter;
             }
         } break;
         default: