Fix issue incremental upload can evict textures being drawn

cc/CCPrioritizedTextureManager.h

Index: cc/CCPrioritizedTextureManager.h
diff --git a/cc/CCPrioritizedTextureManager.h b/cc/CCPrioritizedTextureManager.h
index 88a4f45fcfb176186078e1ce0db5b425e4daf285..6a7a1c61031a71122533241f6f3b9dd0e58e1d2a 100644
--- a/cc/CCPrioritizedTextureManager.h
+++ b/cc/CCPrioritizedTextureManager.h
@@ -57,13 +57,9 @@ public:
     void clearPriorities();
 
     void reduceMemoryOnImplThread(size_t limitBytes, CCResourceProvider*);
-    bool evictedBackingsExist() const { return !m_evictedBackings.isEmpty(); }
+    bool linkedEvictedBackingsExist() const;

[epenner, 2012/10/09 17:25:04]

Nit: I was having trouble understanding what this function meant and 'linked' is
kind of an implementation detail. Maybe "backingsWereLost" or something that
that indicates an unexpected eviction has occurred?

[ccameron, 2012/10/09 21:03:56]

I added a comment saying that this returns true if "there exist any textures
that are linked to backings that have had their resources evicted", and some
more detail.

     void getEvictedBackings(BackingVector& evictedBackings);
     void unlinkEvictedBackings(const BackingVector& evictedBackings);
-    // Deletes all evicted backings, unlinking them from their owning textures if needed.
-    // Returns true if this function unlinked any backings from their owning texture while
-    // destroying them.
-    bool deleteEvictedBackings();
 
     bool requestLate(CCPrioritizedTexture*);
 
@@ -76,6 +72,12 @@ public:
     void unregisterTexture(CCPrioritizedTexture*);
     void returnBackingTexture(CCPrioritizedTexture*);
 
+    // Update all backings' priorities from their owning texture.
+    void pushTexturePrioritiesToBackings();
+
+    // Mark all textures' backings as being in the drawing impl tree.
+    void updateBackingsInDrawingImplTree();
+
 private:
     friend class CCPrioritizedTextureTest;
 
@@ -94,25 +96,26 @@ private:
     // Compare backings. Lowest priority first.
     static inline bool compareBackings(CCPrioritizedTexture::Backing* a, CCPrioritizedTexture::Backing* b)
     {
-        int priorityA = a->requestPriorityAtLastPriorityUpdate();
-        int priorityB = b->requestPriorityAtLastPriorityUpdate();
-        if (priorityA != priorityB)
-            return CCPriorityCalculator::priorityIsLower(priorityA, priorityB);
-        bool aboveCutoffA = a->wasAbovePriorityCutoffAtLastPriorityUpdate();
-        bool aboveCutoffB = b->wasAbovePriorityCutoffAtLastPriorityUpdate();
-        if (!aboveCutoffA && aboveCutoffB)
-            return true;
-        if (aboveCutoffA && !aboveCutoffB)
-            return false;
+        // Sort first by priority (note that backings that no longer have owners will 

[epenner, 2012/10/09 17:25:04]

If we make some backings recyclable by intentionally not pushing them into the
tree, then it looks like pushing the new priorities too early will mess with
their eviction order and disable that recycling (the recyclable textures will no
longer be at the beginning of this list). This is why I prefer to think of the
backings being in eviction order, as determined at sync-trees.

Anyway, it's not an issue as it stands since this doesn't keep recycling of
still-linked textures, but it makes me think we may need to revisit this again.

[ccameron, 2012/10/09 21:03:56]

I went ahead and put a "canBeRecycled" test first.

+        // always have the lowest priority)
+        if (a->requestPriorityAtLastPriorityUpdate() != b->requestPriorityAtLastPriorityUpdate())
+            return CCPriorityCalculator::priorityIsLower(a->requestPriorityAtLastPriorityUpdate(), b->requestPriorityAtLastPriorityUpdate());
+        // Then sort by being above or below the priority cutoff.
+        if (a->wasAbovePriorityCutoffAtLastPriorityUpdate() != b->wasAbovePriorityCutoffAtLastPriorityUpdate())
+            return (a->wasAbovePriorityCutoffAtLastPriorityUpdate() < b->wasAbovePriorityCutoffAtLastPriorityUpdate());
+        // Finally sort by being in the impl tree versus being completely unreferenced
+        if (a->inDrawingImplTree() != b->inDrawingImplTree())
+            return (a->inDrawingImplTree() < b->inDrawingImplTree());
         return a < b;
     }
 
     CCPrioritizedTextureManager(size_t maxMemoryLimitBytes, int maxTextureSize, int pool);
 
-    void updateBackingsPriorities();
     void evictBackingsToReduceMemory(size_t limitBytes, EvictionPriorityPolicy, CCResourceProvider*);
     CCPrioritizedTexture::Backing* createBacking(IntSize, GC3Denum format, CCResourceProvider*);
     void evictBackingResource(CCPrioritizedTexture::Backing*, CCResourceProvider*);
+    void deleteUnlinkedEvictedBackings();
+    void sortBackings();
 
 #if !ASSERT_DISABLED
     void assertInvariants();
@@ -136,10 +139,6 @@ private:
     TextureVector m_tempTextureVector;
     BackingVector m_tempBackingVector;
 
-    // Set by the main thread when it adjust priorities in such a way that
-    // the m_backings array's view of priorities is now out of date.
-    bool m_needsUpdateBackingsPrioritites;
-
     DISALLOW_COPY_AND_ASSIGN(CCPrioritizedTextureManager);
 };