notify resource caches when pixelref genID goes stale

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 15 matching lines @@
     }
     SkIPoint origin = bm.pixelRefOrigin();
     return SkIRect::MakeXYWH(origin.fX, origin.fY, bm.width(), bm.height());
 }
 
 namespace {
 static unsigned gBitmapKeyNamespaceLabel;
 
 struct BitmapKey : public SkResourceCache::Key {
 public:
-    BitmapKey(uint32_t genID, SkScalar scaleX, SkScalar scaleY, const SkIRect& bounds)
-    : fGenID(genID)
-    , fScaleX(scaleX)
-    , fScaleY(scaleY)
-    , fBounds(bounds)
+    BitmapKey(uint32_t genID, SkScalar sx, SkScalar sy, const SkIRect& bounds)
+        : fGenID(genID)
+        , fScaleX(sx)
+        , fScaleY(sy)
+        , fBounds(bounds)
     {
         this->init(&gBitmapKeyNamespaceLabel,
                    sizeof(fGenID) + sizeof(fScaleX) + sizeof(fScaleY) + sizeof(fBounds));
     }
 
     uint32_t    fGenID;
     SkScalar    fScaleX;
     SkScalar    fScaleY;
     SkIRect     fBounds;
 };
 
-//////////////////////////////////////////////////////////////////////////////////////////
-
 struct BitmapRec : public SkResourceCache::Rec {
     BitmapRec(uint32_t genID, SkScalar scaleX, SkScalar scaleY, const SkIRect& bounds,
               const SkBitmap& result)
         : fKey(genID, scaleX, scaleY, bounds)
         , fBitmap(result)
     {}
 
-    BitmapKey   fKey;
-    SkBitmap    fBitmap;
-
     const Key& getKey() const SK_OVERRIDE { return fKey; }
     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 SkResourceCache::PurgeVisitorResult PurgeGenID(const SkResourceCache::Rec& baseRec,
+                                                          void* contextGenID) {
+        const BitmapRec& rec = static_cast<const BitmapRec&>(baseRec);
+        uintptr_t genID = (uintptr_t)contextGenID;
+        if (rec.fKey.fGenID == genID) {
+            return SkResourceCache::kPurgeAndContinue_PurgeVisitorResult;
+        } else {
+            return SkResourceCache::kRetainAndContinue_PurgeVisitorResult;
+        }
+    }
+
+private:
+    BitmapKey   fKey;
+    SkBitmap    fBitmap;
 };
 } // namespace
 
 #define CHECK_LOCAL(localCache, localName, globalName, ...) \
     ((localCache) ? localCache->localName(__VA_ARGS__) : SkResourceCache::globalName(__VA_ARGS__))
 
 bool SkBitmapCache::Find(const SkBitmap& src, SkScalar invScaleX, SkScalar invScaleY, SkBitmap* result,
                          SkResourceCache* localCache) {
     if (0 == invScaleX || 0 == invScaleY) {
         // degenerate, and the key we use for mipmaps
@@ skipping 33 matching lines @@
         || result.width() != subset.width()
         || result.height() != subset.height()) {
         return false;
     } else {
         BitmapRec* rec = SkNEW_ARGS(BitmapRec, (genID, SK_Scalar1, SK_Scalar1, subset, result));
 
         CHECK_LOCAL(localCache, add, Add, rec);
         return true;
     }
 }
+
+void SkBitmapCache::NotifyGenIDStale(uint32_t genID) {
+    SkResourceCache::Purge(&gBitmapKeyNamespaceLabel, BitmapRec::PurgeGenID,
+                           (void*)((uintptr_t)genID));
+}
+
 //////////////////////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////////////////
+
+namespace {
+static unsigned gMipMapKeyNamespaceLabel;
+
+struct MipMapKey : public SkResourceCache::Key {
+public:
+    MipMapKey(uint32_t genID, const SkIRect& bounds) : fGenID(genID), fBounds(bounds) {
+        this->init(&gMipMapKeyNamespaceLabel, sizeof(fGenID) + sizeof(fBounds));
+    }
+
+    uint32_t    fGenID;
+    SkIRect     fBounds;
+};
 
 struct MipMapRec : public SkResourceCache::Rec {
     MipMapRec(const SkBitmap& src, const SkMipMap* result)
-        : fKey(src.getGenerationID(), 0, 0, get_bounds_from_bitmap(src))
+        : fKey(src.getGenerationID(), get_bounds_from_bitmap(src))
         , fMipMap(result)
     {
         fMipMap->attachToCacheAndRef();
     }
 
     virtual ~MipMapRec() {
         fMipMap->detachFromCacheAndUnref();
     }
 
     const Key& getKey() const SK_OVERRIDE { return fKey; }
     size_t bytesUsed() const SK_OVERRIDE { return sizeof(fKey) + fMipMap->size(); }
 
     static bool Visitor(const SkResourceCache::Rec& baseRec, void* contextMip) {
         const MipMapRec& rec = static_cast<const MipMapRec&>(baseRec);
         const SkMipMap* mm = SkRef(rec.fMipMap);
         // the call to ref() above triggers a "lock" in the case of discardable memory,
         // which means we can now check for null (in case the lock failed).
         if (NULL == mm->data()) {
             mm->unref();    // balance our call to ref()
             return false;
         }
         // the call must call unref() when they are done.
         *(const SkMipMap**)contextMip = mm;
         return true;
     }
 
+    static SkResourceCache::PurgeVisitorResult PurgeGenID(const SkResourceCache::Rec& baseRec,
+                                                          void* contextGenID) {
+        const MipMapRec& rec = static_cast<const MipMapRec&>(baseRec);
+        uintptr_t genID = (uintptr_t)contextGenID;
+        if (rec.fKey.fGenID == genID) {
+            return SkResourceCache::kPurgeAndContinue_PurgeVisitorResult;
+        } else {
+            return SkResourceCache::kRetainAndContinue_PurgeVisitorResult;
+        }
+    }
+
 private:
-    BitmapKey       fKey;
+    MipMapKey       fKey;
     const SkMipMap* fMipMap;
 };
+}
 
 const SkMipMap* SkMipMapCache::FindAndRef(const SkBitmap& src, SkResourceCache* localCache) {
     BitmapKey key(src.getGenerationID(), 0, 0, get_bounds_from_bitmap(src));
-    const SkMipMap* result;
+    const SkMipMap* result = NULL;  // if we never get called, we want to see a NULL.
 
     if (!CHECK_LOCAL(localCache, find, Find, key, MipMapRec::Visitor, &result)) {
         result = NULL;
     }
     return result;
 }
 
 static SkResourceCache::DiscardableFactory get_fact(SkResourceCache* localCache) {
     return localCache ? localCache->GetDiscardableFactory()
                       : SkResourceCache::GetDiscardableFactory();
 }
 
 const SkMipMap* SkMipMapCache::AddAndRef(const SkBitmap& src, SkResourceCache* localCache) {
     SkMipMap* mipmap = SkMipMap::Build(src, get_fact(localCache));
     if (mipmap) {
         MipMapRec* rec = SkNEW_ARGS(MipMapRec, (src, mipmap));
         CHECK_LOCAL(localCache, add, Add, rec);
     }
     return mipmap;
 }
 
+void SkMipMapCache::NotifyGenIDStale(uint32_t genID) {
+    SkResourceCache::Purge(&gMipMapKeyNamespaceLabel, MipMapRec::PurgeGenID,
+                           (void*)((uintptr_t)genID));
+}