add counting to glyphcache, and refactor some for clarity

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 "SkTLS.h"
+
+#ifndef SK_DEFAULT_FONT_CACHE_COUNT_LIMIT
+    #define SK_DEFAULT_FONT_CACHE_COUNT_LIMIT   8

[bungeman-skia, 2013/09/25 14:46:07]

8 seems rather small, though I suppose one hardly ever cycles through more than
8 strikes in any useful manner.

[reed1, 2013/09/25 17:30:31]

Doh! I had set it to 8 just for testing. I'll reset it to a more normal value
(e.g. 512 was my first thought).

+#endif
+
+#ifndef SK_DEFAULT_FONT_CACHE_LIMIT
+    #define SK_DEFAULT_FONT_CACHE_LIMIT     (2 * 1024 * 1024)
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
+class SkMutex;
+
+class SkGlyphCache_Globals {
+public:
+    enum UseMutex {
+        kNo_UseMutex,  // thread-local cache

[bungeman-skia, 2013/09/25 14:46:07]

These enum names seem a bit silly in that you've named them No and Yes, but then
have short comments as to what thy really mean. More confusingly it changes the
meaning of the fCacheSizeLimit since with the 'mutex' path the limits are per
process and with 'tls' they're per thread. Also, whether or not a mutex is used
seems like an implementation detail that doesn't need to be exposed. It seems
like the values are more

enum CacheLocality {
    kThread_CacheLocality,
    kProcess_CacheLocality,
}

+        kYes_UseMutex  // shared cache
+    };
+    
+    SkGlyphCache_Globals(UseMutex um) {
+        fHead = NULL;
+        fTotalMemoryUsed = 0;
+        fCacheSizeLimit = SK_DEFAULT_FONT_CACHE_LIMIT;
+        fCacheCount = 0;
+        fCacheCountLimit = SK_DEFAULT_FONT_CACHE_COUNT_LIMIT;
+    
+        fMutex = (kYes_UseMutex == um) ? SkNEW(SkMutex) : NULL;
+    }
+    
+    ~SkGlyphCache_Globals() {
+        SkGlyphCache* cache = fHead;
+        while (cache) {
+            SkGlyphCache* next = cache->fNext;
+            SkDELETE(cache);
+            cache = next;
+        }
+        
+        SkDELETE(fMutex);
+    }
+    
+    // call when SkGlyphCache is constructed
+    void registerCache(SkGlyphCache*);
+    // call when SkGlyphCache is destroyed
+    void unregisterCache(SkGlyphCache*);
+
+    SkMutex*        fMutex;

[bungeman-skia, 2013/09/25 14:46:07]

SkAutoTDelete<SkMutex> ?

+    SkGlyphCache*   fHead;
+    size_t          fTotalMemoryUsed;
+    
+#ifdef SK_DEBUG
+    void validate() const;
+#else
+    void validate() const {}
+#endif
+
+    int     getCacheCountLimit() const { return fCacheCountLimit; }
+    void    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;
+    }
+
+    void    purgeAll(); // does not change budget
+
+    // call when a glyphcache is available for caching (i.e. not in use)
+    void attachCache(SkGlyphCache*);
+
+    // can return NULL
+    static SkGlyphCache_Globals* FindTLS() {
+        return (SkGlyphCache_Globals*)SkTLS::Find(CreateTLS);
+    }
+    
+    static SkGlyphCache_Globals& GetTLS() {
+        return *(SkGlyphCache_Globals*)SkTLS::Get(CreateTLS, DeleteTLS);
+    }
+    
+    static void DeleteTLS() { SkTLS::Delete(CreateTLS); }
+    
+private:
+    size_t  fCacheSizeLimit;
+    int32_t fCacheCount;
+    int32_t fCacheCountLimit;
+    
+    // Checkout budgets, modulated by the specified min-bytes-needed-to-purge,
+    // and attempt to purge caches to match.
+    // Returns number of bytes freed.
+    size_t internalPurge(size_t minBytesNeeded = 0);
+
+    static void* CreateTLS() {
+        return SkNEW_ARGS(SkGlyphCache_Globals, (kNo_UseMutex));
+    }
+    
+    static void DeleteTLS(void* ptr) {
+        SkDELETE((SkGlyphCache_Globals*)ptr);
+    }
+};
+
+#endif