Parallel cache - preliminary

src/core/SkGlyphCache_Globals.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGlyphCache_Globals_DEFINED
 #define SkGlyphCache_Globals_DEFINED
 
 #include "SkGlyphCache.h"
 #include "SkMutex.h"
 #include "SkSpinlock.h"
 #include "SkTLS.h"
 
 #ifndef SK_DEFAULT_FONT_CACHE_COUNT_LIMIT
     #define SK_DEFAULT_FONT_CACHE_COUNT_LIMIT   2048
 #endif
 
 #ifndef SK_DEFAULT_FONT_CACHE_LIMIT
     #define SK_DEFAULT_FONT_CACHE_LIMIT     (2 * 1024 * 1024)
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 class SkGlyphCache_Globals {
 public:
     SkGlyphCache_Globals() {
+
         fHead = nullptr;
-        fTotalMemoryUsed = 0;
+        fTotalMemoryUsed.store(0);
         fCacheSizeLimit = SK_DEFAULT_FONT_CACHE_LIMIT;
         fCacheCount = 0;
         fCacheCountLimit = SK_DEFAULT_FONT_CACHE_COUNT_LIMIT;
     }
 
     ~SkGlyphCache_Globals() {
         SkGlyphCache* cache = fHead;
         while (cache) {
             SkGlyphCache* next = cache->fNext;
             delete cache;
             cache = next;
         }
     }
 
     SkSpinlock     fLock;
 
     SkGlyphCache* internalGetHead() const { return fHead; }
     SkGlyphCache* internalGetTail() const;
 
-    size_t getTotalMemoryUsed() const { return fTotalMemoryUsed; }
+    size_t getTotalMemoryUsed() const { return fTotalMemoryUsed.load(); }
+    void increaseTotalMemoryUsed(size_t increase) { fTotalMemoryUsed.fetch_add(increase);}
     int getCacheCountUsed() const { return fCacheCount; }
 
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 
     int getCacheCountLimit() const { return fCacheCountLimit; }
     int setCacheCountLimit(int limit);
 
     size_t  getCacheSizeLimit() const { return fCacheSizeLimit; }
     size_t  setCacheSizeLimit(size_t limit);
 
     // returns true if this cache is over-budget either due to size limit
     // or count limit.
     bool isOverBudget() const {
         return fCacheCount > fCacheCountLimit ||
-               fTotalMemoryUsed > fCacheSizeLimit;
+               fTotalMemoryUsed.load() > fCacheSizeLimit;
     }
 
     void purgeAll(); // does not change budget
 
     // call when a glyphcache is available for caching (i.e. not in use)
-    void attachCacheToHead(SkGlyphCache*);
+    void internalAttachCacheToHead(SkGlyphCache*);
 
     // can only be called when the mutex is already held
-    void internalDetachCache(SkGlyphCache*);
-    void internalAttachCacheToHead(SkGlyphCache*);
-
-private:
-    SkGlyphCache* fHead;
-    size_t  fTotalMemoryUsed;
-    size_t  fCacheSizeLimit;
-    int32_t fCacheCountLimit;
-    int32_t fCacheCount;
+    void internalMoveToHead(SkGlyphCache *);
 
     // Checkout budgets, modulated by the specified min-bytes-needed-to-purge,
     // and attempt to purge caches to match.
     // Returns number of bytes freed.
+    void internalDetachCache(SkGlyphCache* cache);
     size_t internalPurge(size_t minBytesNeeded = 0);
+
+private:
+    SkGlyphCache*    fHead;
+    SkAtomic<size_t> fTotalMemoryUsed;
+    size_t           fCacheSizeLimit;
+    int32_t          fCacheCountLimit;
+    int32_t          fCacheCount;
+
 };
 
 #endif