Adding bulk plot reffer to cached textblobs

src/gpu/GrBatchAtlas.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrBatchAtlas_DEFINED
 #define GrBatchAtlas_DEFINED
 
@@ skipping 22 matching lines @@
     // the eviction
     typedef void (*EvictionFunc)(GrBatchAtlas::AtlasID, void*);
 
     GrBatchAtlas(GrTexture*, int numPlotsX, int numPlotsY);
     ~GrBatchAtlas();
 
     // Adds a width x height subimage to the atlas. Upon success it returns
     // the containing GrPlot and absolute location in the backing texture.
     // NULL is returned if the subimage cannot fit in the atlas.
     // If provided, the image data will be written to the CPU-side backing bitmap.
+    // NOTE: If the client intends to refer to the atlas, they should immediately call 'setUseToken'
+    // with the currentToken from the batch target, otherwise the next call to addToAtlas might
+    // cause an eviction
     bool addToAtlas(AtlasID*, GrBatchTarget*, int width, int height, const void* image,
                     SkIPoint16* loc);
 
     GrTexture* getTexture() const { return fTexture; }
 
     uint64_t atlasGeneration() const { return fAtlasGeneration; }
     bool hasID(AtlasID id);
-    void setLastRefToken(AtlasID id, BatchToken batchToken);
+
+    // To ensure the atlas does not evict a given entry, the client must set the last use token
+    void setLastUseToken(AtlasID id, BatchToken batchToken);
     void registerEvictionCallback(EvictionFunc func, void* userData) {
         EvictionData* data = fEvictionCallbacks.append();
         data->fFunc = func;
         data->fData = userData;
     }
 
+    /*
+     * A class which can be handed back to GrBatchAtlas for updating in bulk last use tokens.

[robertphillips, 2015/04/07 12:18:33]

Maybe a comment re the maxplots limit (e.g., for the current use cases 32 is
enough. If in the future this is insufficient ...) ?

+     */
+    class BulkUseTokenUpdater {
+    public:
+        BulkUseTokenUpdater() : fPlotAlreadyUpdated(0) {}
+        void add(AtlasID id) {
+            int index = GrBatchAtlas::GetIndexFromID(id);
+            if (!this->find(index)) {
+                this->set(index);
+            }
+        }
+
+        void reset() {
+            fPlotsToUpdate.reset();
+            fPlotAlreadyUpdated = 0;
+        }
+
+    private:
+        bool find(int index) const {

[robertphillips, 2015/04/07 12:18:33]

SkASSERT(index < kMaxPlots); ?

+            return (fPlotAlreadyUpdated >> index) & 1;
+        }
+        void set(int index) {
+            SkASSERT(!this->find(index));
+            fPlotAlreadyUpdated = fPlotAlreadyUpdated | (1 << index);
+            fPlotsToUpdate.push_back(index);
+        }
+
+        static const int kMaxPlots = 32;
+        uint32_t fPlotAlreadyUpdated;
+        SkSTArray<4, int, true> fPlotsToUpdate;
+
+        friend class GrBatchAtlas;
+    };
+
+    void setLastUseTokenBulk(const BulkUseTokenUpdater& reffer, BatchToken);
+
 private:
-    int getIndexFromID(AtlasID id) {
+    static int GetIndexFromID(AtlasID id) {
         return id & 0xffff;
     }
 
-    int getGenerationFromID(AtlasID id) {
+    static int GetGenerationFromID(AtlasID id) {
         return (id >> 16) & 0xffff;
     }
 
     inline void updatePlot(GrBatchTarget*, AtlasID*, BatchPlot*);
 
     inline void makeMRU(BatchPlot* plot);
 
     inline void processEviction(AtlasID);
 
     GrTexture* fTexture;
@@ skipping 10 matching lines @@
     };
 
     SkTDArray<EvictionData> fEvictionCallbacks;
     // allocated array of GrBatchPlots
     SkAutoTUnref<BatchPlot>* fPlotArray;
     // LRU list of GrPlots (MRU at head - LRU at tail)
     GrBatchPlotList fPlotList;
 };
 
 #endif