Layer: Use raw pointers for Current/Drawing parent

We should only be reading/writing this from the main thread
and likewise we only delete layers on the main thread and
so using raw pointers and managing the lifetime from the
Layer destructor will be safe. This significantly decreases
overhead in various code that traverses via parent (getAlpha,
isVisible, etc...).

Test: Existing tests pass. simpleperf
Bug: 186200583
Change-Id: I45745f7c865177ddfe9105d1440a9fa8f3470823

1 files changed, 44 insertions, 33 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 4f4a897084..5707c67a56 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -179,9 +179,23 @@ Layer::~Layer() {
     if (mDrawingState.sidebandStream != nullptr) {
         mFlinger->mTunnelModeEnabledReporter->decrementTunnelModeCount();
     }
+
     if (mHadClonedChild) {
         mFlinger->mNumClones--;
     }
+
+    for (auto const& child : mCurrentChildren) {
+        if (child->mCurrentParent == this) child->mCurrentParent = nullptr;
+        if (child->mDrawingParent == this) {
+            child->mDrawingParent = nullptr;
+        }
+    }
+    for (auto const& child : mDrawingChildren) {
+        if (child->mCurrentParent == this) child->mCurrentParent = nullptr;
+        if (child->mDrawingParent == this) {
+            child->mDrawingParent = nullptr;
+        }
+    }
 }
 
 LayerCreationArgs::LayerCreationArgs(SurfaceFlinger* flinger, sp<Client> client, std::string name,
@@ -237,7 +251,7 @@ void Layer::removeFromCurrentState() {
 }
 
 sp<Layer> Layer::getRootLayer() {
-    sp<Layer> parent = getParent();
+    auto parent = getParent();
     if (parent == nullptr) {
         return this;
     }
@@ -662,7 +676,7 @@ bool Layer::isSecure() const {
         return true;
     }
 
-    const auto p = mDrawingParent.promote();
+    const auto p = mDrawingParent;
     return (p != nullptr) ? p->isSecure() : false;
 }
 
@@ -845,7 +859,7 @@ bool Layer::isTrustedOverlay() const {
     if (getDrawingState().isTrustedOverlay) {
         return true;
     }
-    const auto& p = mDrawingParent.promote();
+    const auto p = mDrawingParent;
     return (p != nullptr) && p->isTrustedOverlay();
 }
 
@@ -1025,7 +1039,7 @@ int32_t Layer::getFrameRateSelectionPriority() const {
         return mDrawingState.frameRateSelectionPriority;
     }
     // If not, search whether its parents have it set.
-    sp<Layer> parent = getParent();
+    auto parent = getParent();
     if (parent != nullptr) {
         return parent->getFrameRateSelectionPriority();
     }
@@ -1038,10 +1052,11 @@ bool Layer::isLayerFocusedBasedOnPriority(int32_t priority) {
 };
 
 ui::LayerStack Layer::getLayerStack() const {
-    if (const auto parent = mDrawingParent.promote()) {
-        return parent->getLayerStack();
+    auto p = mDrawingParent;
+    if (p == nullptr) {
+        return getDrawingState().layerStack;
     }
-    return getDrawingState().layerStack;
+    return mDrawingParent->getLayerStack();
 }
 
 bool Layer::setShadowRadius(float shadowRadius) {
@@ -1086,7 +1101,7 @@ StretchEffect Layer::getStretchEffect() const {
         return mDrawingState.stretchEffect;
     }
 
-    sp<Layer> parent = getParent();
+    auto parent = mDrawingParent;
     if (parent != nullptr) {
         auto effect = parent->getStretchEffect();
         if (effect.hasEffect()) {
@@ -1301,7 +1316,7 @@ Layer::FrameRate Layer::getFrameRateForLayerTree() const {
 
 bool Layer::isHiddenByPolicy() const {
     const State& s(mDrawingState);
-    const auto& parent = mDrawingParent.promote();
+    auto parent = mDrawingParent;
     if (parent != nullptr && parent->isHiddenByPolicy()) {
         return true;
     }
@@ -1348,7 +1363,7 @@ LayerDebugInfo Layer::getLayerDebugInfo(const DisplayDevice* display) const {
     LayerDebugInfo info;
     const State& ds = getDrawingState();
     info.mName = getName();
-    sp<Layer> parent = mDrawingParent.promote();
+    auto parent = mDrawingParent;
     info.mParentName = parent ? parent->getName() : "none"s;
     info.mType = getType();
     info.mTransparentRegion = ds.activeTransparentRegion_legacy;
@@ -1580,7 +1595,7 @@ ssize_t Layer::removeChild(const sp<Layer>& layer) {
 
 void Layer::setChildrenDrawingParent(const sp<Layer>& newParent) {
     for (const sp<Layer>& child : mDrawingChildren) {
-        child->mDrawingParent = newParent;
+        child->mDrawingParent = newParent.get();
         child->computeBounds(newParent->mBounds, newParent->mEffectiveTransform,
                              newParent->mEffectiveShadowRadius);
     }
@@ -1600,7 +1615,7 @@ bool Layer::reparent(const sp<IBinder>& newParentHandle) {
         }
     }
 
-    sp<Layer> parent = getParent();
+    auto parent = getParent();
     if (parent != nullptr) {
         parent->removeChild(this);
     }
@@ -1635,7 +1650,7 @@ bool Layer::setColorTransform(const mat4& matrix) {
 
 mat4 Layer::getColorTransform() const {
     mat4 colorTransform = mat4(getDrawingState().colorTransform);
-    if (sp<Layer> parent = mDrawingParent.promote(); parent != nullptr) {
+    if (auto parent = mDrawingParent; parent != nullptr) {
         colorTransform = parent->getColorTransform() * colorTransform;
     }
     return colorTransform;
@@ -1643,7 +1658,7 @@ mat4 Layer::getColorTransform() const {
 
 bool Layer::hasColorTransform() const {
     bool hasColorTransform = getDrawingState().hasColorTransform;
-    if (sp<Layer> parent = mDrawingParent.promote(); parent != nullptr) {
+    if (auto parent = mDrawingParent; parent != nullptr) {
         hasColorTransform = hasColorTransform || parent->hasColorTransform();
     }
     return hasColorTransform;
@@ -1657,7 +1672,7 @@ bool Layer::isLegacyDataSpace() const {
 }
 
 void Layer::setParent(const sp<Layer>& layer) {
-    mCurrentParent = layer;
+    mCurrentParent = layer.get();
 }
 
 int32_t Layer::getZ(LayerVector::StateSet) const {
@@ -1861,7 +1876,7 @@ ui::Transform Layer::getTransform() const {
 }
 
 half Layer::getAlpha() const {
-    const auto& p = mDrawingParent.promote();
+    auto p = mDrawingParent;
 
     half parentAlpha = (p != nullptr) ? p->getAlpha() : 1.0_hf;
     return parentAlpha * getDrawingState().color.a;
@@ -1872,7 +1887,7 @@ ui::Transform::RotationFlags Layer::getFixedTransformHint() const {
     if (fixedTransformHint != ui::Transform::ROT_INVALID) {
         return fixedTransformHint;
     }
-    const auto& p = mCurrentParent.promote();
+    auto p = mCurrentParent;
     if (!p) return fixedTransformHint;
     return p->getFixedTransformHint();
 }
@@ -1883,7 +1898,7 @@ half4 Layer::getColor() const {
 }
 
 int32_t Layer::getBackgroundBlurRadius() const {
-    const auto& p = mDrawingParent.promote();
+    auto p = mDrawingParent;
 
     half parentAlpha = (p != nullptr) ? p->getAlpha() : 1.0_hf;
     return parentAlpha * getDrawingState().backgroundBlurRadius;
@@ -1901,9 +1916,8 @@ const std::vector<BlurRegion> Layer::getBlurRegions() const {
 Layer::RoundedCornerState Layer::getRoundedCornerState() const {
     // Get parent settings
     RoundedCornerState parentSettings;
-    const auto& parent = mDrawingParent.promote();
-    if (parent != nullptr) {
-        parentSettings = parent->getRoundedCornerState();
+    if (mDrawingParent != nullptr) {
+        parentSettings = mDrawingParent->getRoundedCornerState();
         if (parentSettings.radius > 0) {
             ui::Transform t = getActiveTransform(getDrawingState());
             t = t.inverse();
@@ -2119,7 +2133,7 @@ void Layer::writeToProtoCommonState(LayerProto* layerInfo, LayerVector::StateSet
         LayerProtoHelper::writeToProtoDeprecated(requestedTransform,
                                                  layerInfo->mutable_requested_transform());
 
-        auto parent = useDrawing ? mDrawingParent.promote() : mCurrentParent.promote();
+        auto parent = useDrawing ? mDrawingParent : mCurrentParent;
         if (parent != nullptr) {
             layerInfo->set_parent(parent->sequence);
         } else {
@@ -2266,9 +2280,9 @@ void Layer::fillInputFrameInfo(WindowInfo& info, const ui::Transform& displayTra
 }
 
 void Layer::fillTouchOcclusionMode(WindowInfo& info) {
-    sp<Layer> p = this;
+    Layer* p = this;
     while (p != nullptr && !p->hasInputInfo()) {
-        p = p->mDrawingParent.promote();
+        p = p->mDrawingParent;
     }
     if (p != nullptr) {
         info.touchOcclusionMode = p->mDrawingState.inputInfo.touchOcclusionMode;
@@ -2280,9 +2294,8 @@ gui::DropInputMode Layer::getDropInputMode() const {
     if (mode == gui::DropInputMode::ALL) {
         return mode;
     }
-    sp<Layer> parent = mDrawingParent.promote();
-    if (parent) {
-        gui::DropInputMode parentMode = parent->getDropInputMode();
+    if (mDrawingParent) {
+        gui::DropInputMode parentMode = mDrawingParent->getDropInputMode();
         if (parentMode != gui::DropInputMode::NONE) {
             return parentMode;
         }
@@ -2309,8 +2322,7 @@ void Layer::handleDropInputMode(gui::WindowInfo& info) const {
     }
 
     // Check if the parent has set an alpha on the layer
-    sp<Layer> parent = mDrawingParent.promote();
-    if (parent && parent->getAlpha() != 1.0_hf) {
+    if (mDrawingParent && mDrawingParent->getAlpha() != 1.0_hf) {
         info.inputFeatures |= WindowInfo::Feature::DROP_INPUT;
         ALOGV("Dropping input for %s as requested by policy because alpha=%f", getDebugName(),
               static_cast<float>(getAlpha()));
@@ -2408,10 +2420,10 @@ sp<Layer> Layer::getClonedRoot() {
     if (mClonedChild != nullptr) {
         return this;
     }
-    if (mDrawingParent == nullptr || mDrawingParent.promote() == nullptr) {
+    if (mDrawingParent == nullptr) {
         return nullptr;
     }
-    return mDrawingParent.promote()->getClonedRoot();
+    return mDrawingParent->getClonedRoot();
 }
 
 bool Layer::hasInputInfo() const {
@@ -2598,8 +2610,7 @@ bool Layer::isInternalDisplayOverlay() const {
         return true;
     }
 
-    sp<Layer> parent = mDrawingParent.promote();
-    return parent && parent->isInternalDisplayOverlay();
+    return mDrawingParent && mDrawingParent->isInternalDisplayOverlay();
 }
 
 void Layer::setClonedChild(const sp<Layer>& clonedChild) {