Change SkResourceCache to take a Visitor inside its find().

src/core/SkBitmapCache.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkResourceCache.h"
 #include "SkMipMap.h"
@@ skipping 41 matching lines @@
               const SkBitmap& result)
         : fKey(genID, scaleX, scaleY, bounds)
         , fBitmap(result)
     {}
 
     BitmapKey   fKey;
     SkBitmap    fBitmap;
 
     virtual const Key& getKey() const SK_OVERRIDE { return fKey; }
     virtual size_t bytesUsed() const SK_OVERRIDE { return sizeof(fKey) + fBitmap.getSize(); }
+
+    static bool Visitor(const SkResourceCache::Rec& baseRec, void* contextBitmap) {
+        const BitmapRec& rec = static_cast<const BitmapRec&>(baseRec);
+        SkBitmap* result = (SkBitmap*)contextBitmap;
+
+        *result = rec.fBitmap;
+        result->lockPixels();
+        return SkToBool(result->getPixels());
+    }
 };
 
-static bool find_and_return(const BitmapKey& key, SkBitmap* result) {
-    const BitmapRec* rec = (BitmapRec*)SkResourceCache::FindAndLock(key);
-    if (rec) {
-        *result = rec->fBitmap;
-        SkResourceCache::Unlock(rec);
-
-        result->lockPixels();
-        if (result->getPixels()) {
-            return true;
-        }
-
-        SkResourceCache::Remove(rec);
-        result->reset();
-        // fall-through to false
-    }
-    return false;
-}
-
 bool SkBitmapCache::Find(const SkBitmap& src, SkScalar invScaleX, SkScalar invScaleY,
                          SkBitmap* result) {
     if (0 == invScaleX || 0 == invScaleY) {
         // degenerate, and the key we use for mipmaps
         return false;
     }
     BitmapKey key(src.getGenerationID(), invScaleX, invScaleY, get_bounds_from_bitmap(src));
-    return find_and_return(key, result);
+    return SkResourceCache::Find(key, BitmapRec::Visitor, result);
 }
 
 void SkBitmapCache::Add(const SkBitmap& src, SkScalar invScaleX, SkScalar invScaleY,
                         const SkBitmap& result) {
     if (0 == invScaleX || 0 == invScaleY) {
         // degenerate, and the key we use for mipmaps
         return;
     }
     SkASSERT(result.isImmutable());
     SkResourceCache::Add(SkNEW_ARGS(BitmapRec, (src.getGenerationID(), invScaleX, invScaleY,
                                                 get_bounds_from_bitmap(src), result)));
 }
 
 bool SkBitmapCache::Find(uint32_t genID, const SkIRect& subset, SkBitmap* result) {
     BitmapKey key(genID, SK_Scalar1, SK_Scalar1, subset);
-    return find_and_return(key, result);
+    return SkResourceCache::Find(key, BitmapRec::Visitor, result);
 }
 
 bool SkBitmapCache::Add(uint32_t genID, const SkIRect& subset, const SkBitmap& result) {
     SkASSERT(result.isImmutable());
 
     if (subset.isEmpty()
         || subset.top() < 0
         || subset.left() < 0
         || result.width() != subset.width()
         || result.height() != subset.height()) {
@@ skipping 15 matching lines @@
 
     virtual ~MipMapRec() {
         fMipMap->unref();
     }
 
     BitmapKey       fKey;
     const SkMipMap* fMipMap;
 
     virtual const Key& getKey() const SK_OVERRIDE { return fKey; }
     virtual size_t bytesUsed() const SK_OVERRIDE { return sizeof(fKey) + fMipMap->getSize(); }
+
+    static bool Visitor(const SkResourceCache::Rec& baseRec, void* contextMip) {
+        const MipMapRec& rec = static_cast<const MipMapRec&>(baseRec);
+        const SkMipMap** result = (const SkMipMap**)contextMip;
+        
+        *result = SkRef(rec.fMipMap);
+        // mipmaps don't use the custom allocator yet, so we don't need to check pixels
+        return true;
+    }
 };
 
-
 const SkMipMap* SkMipMapCache::FindAndRef(const SkBitmap& src) {
     BitmapKey key(src.getGenerationID(), 0, 0, get_bounds_from_bitmap(src));
-    const MipMapRec* rec = (MipMapRec*)SkResourceCache::FindAndLock(key);
-    const SkMipMap* result = NULL;
-    if (rec) {
-        result = SkRef(rec->fMipMap);
-        SkResourceCache::Unlock(rec);
+    const SkMipMap* result;
+    if (!SkResourceCache::Find(key, MipMapRec::Visitor, &result)) {
+        result = NULL;
     }
     return result;
 }
 
 void SkMipMapCache::Add(const SkBitmap& src, const SkMipMap* result) {
     if (result) {
         SkResourceCache::Add(SkNEW_ARGS(MipMapRec, (src, result)));
     }
 }