Parallel cache - preliminary

src/core/SkGlyphCache.h

Index: src/core/SkGlyphCache.h
diff --git a/src/core/SkGlyphCache.h b/src/core/SkGlyphCache.h
index 4eb6b5bc60a82ad8b2b2fce8ccdd50fcb5043a02..cf64527b492c10a3a09e2fbf611ddd7660736db7 100644
--- a/src/core/SkGlyphCache.h
+++ b/src/core/SkGlyphCache.h
@@ -11,8 +11,11 @@
 #include "SkChunkAlloc.h"
 #include "SkDescriptor.h"
 #include "SkGlyph.h"
+#include "SkMutex.h"
 #include "SkTHash.h"
 #include "SkScalerContext.h"
+#include "SkSharedMutex.h"
+#include "SkSpinlock.h"
 #include "SkTemplates.h"
 #include "SkTDArray.h"
 
@@ -119,12 +122,23 @@ public:
 
     SkScalerContext* getScalerContext() const { return fScalerContext; }
 
+    struct GlyphAndCache {
+        SkGlyphCache* cache;
+        const SkGlyph* glyph;
+    };
+
+    static void OnceFillInImage(GlyphAndCache gc);
+
+    static void OnceFillInPath(GlyphAndCache gc);
+
+    typedef bool (*VisitProc)(const SkGlyphCache*, void*);
+
     /** Find a matching cache entry, and call proc() with it. If none is found create a new one.
         If the proc() returns true, detach the cache and return it, otherwise leave it and return
         nullptr.
     */
     static SkGlyphCache* VisitCache(SkTypeface*, const SkDescriptor* desc,
-                                    bool (*proc)(const SkGlyphCache*, void*),
+                                    VisitProc proc,
                                     void* context);
 
     /** Given a strike that was returned by either VisitCache() or DetachCache() add it back into
@@ -181,18 +195,21 @@ public:
 private:
     friend class SkGlyphCache_Globals;
 
-    enum {
-        kHashBits           = 8,
-        kHashCount          = 1 << kHashBits,
-        kHashMask           = kHashCount - 1
-    };
-
     typedef uint32_t PackedGlyphID;    // glyph-index + subpixel-pos
     typedef uint32_t PackedUnicharID;  // unichar + subpixel-pos
 
     struct CharGlyphRec {
-        PackedUnicharID    fPackedUnicharID;
-        PackedGlyphID      fPackedGlyphID;
+        class HashTraits {
+        public:
+            static PackedUnicharID GetKey(const CharGlyphRec& rec) {
+                return rec.fPackedUnicharID;
+            }
+            static uint32_t Hash(PackedUnicharID unicharID) {
+                return SkChecksum::CheapMix(unicharID);
+            }
+        };
+        PackedUnicharID fPackedUnicharID;
+        PackedGlyphID fPackedGlyphID;
     };
 
     struct AuxProcRec {
@@ -205,6 +222,9 @@ private:
     SkGlyphCache(SkTypeface*, const SkDescriptor*, SkScalerContext*);
     ~SkGlyphCache();
 
+    // Increase the memory used keeping the cache and the global size in sync.
+    void increaseMemoryUsed(size_t used);
+
     // Return the SkGlyph* associated with MakeID. The id parameter is the
     // combined glyph/x/y id generated by MakeID. If it is just a glyph id
     // then x and y are assumed to be zero.
@@ -216,32 +236,45 @@ private:
     // Return a new SkGlyph for the glyph ID and subpixel position id.
     SkGlyph* allocateNewGlyph(PackedGlyphID packedGlyphID);
 
+    // Add the full metrics to an existing glyph.
+    void addFullMetrics(SkGlyph* glyph);
+
     static bool DetachProc(const SkGlyphCache*, void*) { return true; }
 
+    CharGlyphRec PackedUnicharIDtoCharGlyphRec(PackedUnicharID packedUnicharID);
+
     // The id arg is a combined id generated by MakeID.
     CharGlyphRec* getCharGlyphRec(PackedUnicharID id);
 
-    void invokeAndRemoveAuxProcs();
-
     inline static SkGlyphCache* FindTail(SkGlyphCache* head);
 
+    // The following are protected by the SkGlyphCache_Globals fLock mutex.
+    // Note: the following fields are protected by a mutex in a different class.
     SkGlyphCache*          fNext;
     SkGlyphCache*          fPrev;
     SkDescriptor* const    fDesc;
-    SkScalerContext* const fScalerContext;
     SkPaint::FontMetrics   fFontMetrics;
+    int                    fRefCount;
 
+    // The following fields are protected by fMapMutex.
+    mutable SkSharedMutex fMapMutex;
     // Map from a combined GlyphID and sub-pixel position to a SkGlyph.
     SkTHashTable<SkGlyph, PackedGlyphID, SkGlyph::HashTraits> fGlyphMap;
-
     SkChunkAlloc           fGlyphAlloc;
-
-    SkAutoTArray<CharGlyphRec> fPackedUnicharIDToPackedGlyphID;
-
+    typedef SkTHashTable<CharGlyphRec, PackedUnicharID, CharGlyphRec::HashTraits>
+            PackedUnicharIDToPackedGlyphIDMap;
+    SkAutoTDelete<PackedUnicharIDToPackedGlyphIDMap> fPackedUnicharIDToPackedGlyphID;
     // used to track (approx) how much ram is tied-up in this cache
     size_t                 fMemoryUsed;
 
+    // The FScalerMutex protects the following fields. It is mainly used to ensure single-threaded
+    // access to the font scaler, but it also protects the fAuxProcList.
+    mutable SkMutex        fScalerMutex;
+    SkScalerContext* const fScalerContext;
     AuxProcRec*            fAuxProcList;
+
+    // BEWARE: Mutex ordering
+    // If you need to hold both fMapMutex and fScalerMutex then fMapMutex must be held first.
 };
 
 class SkAutoGlyphCacheBase {