Port math table to hb_lazy_table_loader_t

src/hb-open-type-private.hh

@@ -1064,6 +1064,7 @@ struct SortedArrayOf : ArrayOf<Type, LenType>
 
 /* Lazy struct and blob loaders. */
 
+/* Logic is shared between hb_lazy_loader_t and hb_lazy_table_loader_t */
 template <typename T>
 struct hb_lazy_loader_t
 {
@@ -1082,7 +1083,7 @@ struct hb_lazy_loader_t
     }
   }
 
-  inline const T* operator-> (void) const
+  inline const T* get (void) const
   {
   retry:
     T *p = (T *) hb_atomic_ptr_get (&instance);
@@ -1103,11 +1104,17 @@ struct hb_lazy_loader_t
     return p;
   }
 
+  inline const T* operator-> (void) const
+  {
+    return get ();
+  }
+
   private:
   hb_face_t *face;
   T *instance;
 };
 
+/* Logic is shared between hb_lazy_loader_t and hb_lazy_table_loader_t */
 template <typename T>
 struct hb_lazy_table_loader_t
 {
@@ -1123,14 +1130,14 @@ struct hb_lazy_table_loader_t
     hb_blob_destroy (blob);
   }
 
-  inline const T* operator-> (void) const
+  inline const T* get (void) const
   {
   retry:
-    T *p = (T *) hb_atomic_ptr_get (&instance);
+    const T *p = (T *) hb_atomic_ptr_get (&instance);
     if (unlikely (!p))
     {
       hb_blob_t *blob_ = OT::Sanitizer<T>::sanitize (face->reference_table (T::tableTag));
-      p = OT::Sanitizer<T>::lock_instance (blob);
+      p = OT::Sanitizer<T>::lock_instance (blob_);
       if (!hb_atomic_ptr_cmpexch (const_cast<T **>(&instance), NULL, p))
       {
 	hb_blob_destroy (blob_);
@@ -1141,10 +1148,15 @@ struct hb_lazy_table_loader_t
     return p;
   }
 
+  inline const T* operator-> (void) const
+  {
+    return get();
+  }
+
   private:
   hb_face_t *face;
   T *instance;
-  hb_blob_t *blob;
+  mutable hb_blob_t *blob;
 };
 
 

src/hb-ot-layout-private.hh

@@ -34,6 +34,7 @@
 #include "hb-font-private.hh"
 #include "hb-buffer-private.hh"
 #include "hb-set-private.hh"
+#include "hb-open-type-private.hh"
 
 
 /* Private API corresponding to hb-ot-layout.h: */
@@ -153,12 +154,11 @@ struct hb_ot_layout_t
   hb_blob_t *gdef_blob;
   hb_blob_t *gsub_blob;
   hb_blob_t *gpos_blob;
-  hb_blob_t *math_blob;
 
   const struct OT::GDEF *gdef;
   const struct OT::GSUB *gsub;
   const struct OT::GPOS *gpos;
-  const struct OT::MATH *math;
+  OT::hb_lazy_table_loader_t<struct OT::MATH> math;
 
   unsigned int gsub_lookup_count;
   unsigned int gpos_lookup_count;

src/hb-ot-layout.cc

@@ -60,9 +60,7 @@ _hb_ot_layout_create (hb_face_t *face)
   layout->gpos_blob = OT::Sanitizer<OT::GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
   layout->gpos = OT::Sanitizer<OT::GPOS>::lock_instance (layout->gpos_blob);
 
-  /* The MATH table is rarely used, so only try and load it in _get_math. */
-  layout->math_blob = NULL;
-  layout->math = NULL;
+  layout->math.init (face);
 
   {
     /*
@@ -181,7 +179,8 @@ _hb_ot_layout_destroy (hb_ot_layout_t *layout)
   hb_blob_destroy (layout->gdef_blob);
   hb_blob_destroy (layout->gsub_blob);
   hb_blob_destroy (layout->gpos_blob);
-  hb_blob_destroy (layout->math_blob);
+
+  layout->math.fini ();
 
   free (layout);
 }

src/hb-ot-math.cc

@@ -37,22 +37,7 @@ _get_math (hb_face_t *face)
 
   hb_ot_layout_t * layout = hb_ot_layout_from_face (face);
 
-retry:
-  const OT::MATH *math = (const OT::MATH *) hb_atomic_ptr_get (&layout->math);
-
-  if (unlikely (!math))
-  {
-    hb_blob_t *blob = OT::Sanitizer<OT::MATH>::sanitize (face->reference_table (HB_OT_TAG_MATH));
-    math = OT::Sanitizer<OT::MATH>::lock_instance (blob);
-    if (!hb_atomic_ptr_cmpexch (&layout->math, NULL, math))
-    {
-      hb_blob_destroy (blob);
-      goto retry;
-    }
-    layout->math_blob = blob;
-  }
-
-  return *math;
+  return *(layout->math.get ());
 }
 
 /*