Factor our mChildrenChanged from doTransaction

We are trying to eliminate the whole doTransaction traversal. Following
queued-transaction changes we can update various values on flinger
directly rather than in-directing through the main-thread.

Test: Existing tests pass. simpleperf
Bug: 186200583
Change-Id: I0536f889602ce0801e9f79881bbe1adb7b163d46

4 files changed, 13 insertions, 11 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index b819dbe7ce..6c9905e7da 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -679,11 +679,6 @@ bool Layer::isSecure() const {
 uint32_t Layer::doTransaction(uint32_t flags) {
     ATRACE_CALL();
 
-    if (mChildrenChanged) {
-        flags |= eVisibleRegion;
-        mChildrenChanged = false;
-    }
-
     // TODO: This is unfortunate.
     mDrawingStateModified = mDrawingState.modified;
     mDrawingState.modified = false;
@@ -1562,7 +1557,7 @@ void Layer::setGameModeForTree(int parentGameMode) {
 }
 
 void Layer::addChild(const sp<Layer>& layer) {
-    mChildrenChanged = true;
+    mFlinger->mSomeChildrenChanged = true;
     setTransactionFlags(eTransactionNeeded);
 
     mCurrentChildren.add(layer);
@@ -1572,7 +1567,7 @@ void Layer::addChild(const sp<Layer>& layer) {
 }
 
 ssize_t Layer::removeChild(const sp<Layer>& layer) {
-    mChildrenChanged = true;
+    mFlinger->mSomeChildrenChanged = true;
     setTransactionFlags(eTransactionNeeded);
 
     layer->setParent(nullptr);
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 9b30fcb315..84d6d3f93e 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -1003,9 +1003,6 @@ protected:
     wp<Layer> mCurrentParent;
     wp<Layer> mDrawingParent;
 
-    // Can only be accessed with the SF state lock held.
-    bool mChildrenChanged{false};
-
     // Window types from WindowManager.LayoutParams
     const InputWindowInfo::Type mWindowType;
 
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index c6841ed6e6..26581a07ea 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2942,6 +2942,11 @@ void SurfaceFlinger::handleTransactionLocked(uint32_t transactionFlags) {
         });
     }
 
+    if (mSomeChildrenChanged) {
+        mVisibleRegionsDirty = true;
+        mSomeChildrenChanged = false;
+    }
+
     // Update transform hint
     if (transactionFlags & (eTransformHintUpdateNeeded | eDisplayTransactionNeeded)) {
         // The transform hint might have changed for some layers
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 22d17eb153..81f569ae9b 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1228,8 +1228,13 @@ private:
     // don't need synchronization
     State mDrawingState{LayerVector::StateSet::Drawing};
     bool mVisibleRegionsDirty = false;
-    // Set during transaction commit stage to track if the input info for a layer has changed.
+
+    // Set during transaction application stage to track if the input info or children
+    // for a layer has changed.
+    // TODO: Also move visibleRegions over to a boolean system.
     bool mInputInfoChanged = false;
+    bool mSomeChildrenChanged;
+
     bool mGeometryInvalid = false;
     bool mAnimCompositionPending = false;