Fix race condition

Bug: 17372309

 AnimationContext::startFrame() happens both with and without
 the UI thread lock. Pass the TraversalMode into it so
 that ThreadedRenderer's subclass can correctly decide
 when it is safe to push over mPendingAnimatingRenderNodes, as doing
 so outside of the lock is Very Bad.

Change-Id: Ife5dd3a2b46b0a207cd9234c159a674afdbf5efd

core/jni/android_view_ThreadedRenderer.cpp

@@ -158,9 +158,11 @@ public:
 
     // Marks the start of a frame, which will update the frame time and move all
     // next frame animations into the current frame
-    virtual void startFrame() {
-        mRootNode->doAttachAnimatingNodes(this);
-        AnimationContext::startFrame();
+    virtual void startFrame(TreeInfo::TraversalMode mode) {
+        if (mode == TreeInfo::MODE_FULL) {
+            mRootNode->doAttachAnimatingNodes(this);
+        }
+        AnimationContext::startFrame(mode);
     }
 
     // Runs any animations still left in mCurrentFrameAnimations

libs/hwui/AnimationContext.cpp

@@ -17,7 +17,6 @@
 
 #include "Animator.h"
 #include "RenderNode.h"
-#include "TreeInfo.h"
 #include "renderthread/TimeLord.h"
 
 namespace android {
@@ -34,7 +33,7 @@ AnimationContext::~AnimationContext() {
 }
 
 void AnimationContext::destroy() {
-    startFrame();
+    startFrame(TreeInfo::MODE_RT_ONLY);
     while (mCurrentFrameAnimations.mNextHandle) {
         AnimationHandle* current = mCurrentFrameAnimations.mNextHandle;
         AnimatorManager& animators = current->mRenderNode->animators();
@@ -55,7 +54,7 @@ void AnimationContext::addAnimationHandle(AnimationHandle* handle) {
     handle->insertAfter(&mNextFrameAnimations);
 }
 
-void AnimationContext::startFrame() {
+void AnimationContext::startFrame(TreeInfo::TraversalMode mode) {
     LOG_ALWAYS_FATAL_IF(mCurrentFrameAnimations.mNextHandle,
             "Missed running animations last frame!");
     AnimationHandle* head = mNextFrameAnimations.mNextHandle;

libs/hwui/AnimationContext.h

@@ -20,6 +20,7 @@
 #include <utils/RefBase.h>
 #include <utils/StrongPointer.h>
 
+#include "TreeInfo.h"
 #include "renderthread/TimeLord.h"
 #include "utils/Macros.h"
 
@@ -30,7 +31,6 @@ class AnimationContext;
 class AnimationListener;
 class BaseRenderNodeAnimator;
 class RenderNode;
-class TreeInfo;
 
 /*
  * AnimationHandle is several classes merged into one.
@@ -90,7 +90,7 @@ public:
 
     // Marks the start of a frame, which will update the frame time and move all
     // next frame animations into the current frame
-    ANDROID_API virtual void startFrame();
+    ANDROID_API virtual void startFrame(TreeInfo::TraversalMode mode);
 
     // Runs any animations still left in mCurrentFrameAnimations that were not run
     // as part of the standard RenderNode:prepareTree pass.

libs/hwui/renderthread/CanvasContext.cpp

@@ -150,7 +150,7 @@ void CanvasContext::prepareTree(TreeInfo& info) {
     if (mPrefetechedLayers.size() && info.mode == TreeInfo::MODE_FULL) {
         info.canvasContext = this;
     }
-    mAnimationContext->startFrame();
+    mAnimationContext->startFrame(info.mode);
     mRootRenderNode->prepareTree(info);
     mAnimationContext->runRemainingAnimations(info);