From c7ca30a5337cb660e650d51ddd17d389909357c2 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 12 Aug 2018 13:46:53 -0700
Subject: [PATCH] [ot/ft] Port font_funcs statis to lazy-loader

---
 src/hb-ft.cc                | 56 ++++++++++++++++++-------------------
 src/hb-machinery-private.hh | 14 ++++++++++
 src/hb-ot-font.cc           | 51 +++++++++++++++------------------
 3 files changed, 63 insertions(+), 58 deletions(-)

diff --git a/src/hb-ft.cc b/src/hb-ft.cc
index 5ab2a8879..c58cd87c2 100644
--- a/src/hb-ft.cc
+++ b/src/hb-ft.cc
@@ -32,6 +32,7 @@
 #include "hb-ft.h"
 
 #include "hb-font-private.hh"
+#include "hb-machinery-private.hh"
 
 #include FT_ADVANCES_H
 #include FT_MULTIPLE_MASTERS_H
@@ -416,30 +417,13 @@ hb_ft_get_font_h_extents (hb_font_t *font HB_UNUSED,
   return true;
 }
 
-static hb_atomic_ptr_t<hb_font_funcs_t> static_ft_funcs;
+static void free_static_ft_funcs (void);
 
-#ifdef HB_USE_ATEXIT
-static
-void free_static_ft_funcs (void)
+static struct hb_ft_font_funcs_lazy_loader_t : hb_font_funcs_lazy_loader_t<hb_ft_font_funcs_lazy_loader_t>
 {
-retry:
-  hb_font_funcs_t *ft_funcs = static_ft_funcs.get ();
-  if (unlikely (!static_ft_funcs.cmpexch (ft_funcs, nullptr)))
-    goto retry;
-
-  hb_font_funcs_destroy (ft_funcs);
-}
-#endif
-
-static void
-_hb_ft_font_set_funcs (hb_font_t *font, FT_Face ft_face, bool unref)
-{
-retry:
-  hb_font_funcs_t *funcs = static_ft_funcs.get ();
-
-  if (unlikely (!funcs))
+  static inline hb_font_funcs_t *create (void)
   {
-    funcs = hb_font_funcs_create ();
+    hb_font_funcs_t *funcs = hb_font_funcs_create ();
 
     hb_font_funcs_set_font_h_extents_func (funcs, hb_ft_get_font_h_extents, nullptr, nullptr);
     //hb_font_funcs_set_font_v_extents_func (funcs, hb_ft_get_font_v_extents, nullptr, nullptr);
@@ -458,21 +442,35 @@ retry:
 
     hb_font_funcs_make_immutable (funcs);
 
-    if (unlikely (!static_ft_funcs. cmpexch (nullptr, funcs)))
-    {
-      hb_font_funcs_destroy (funcs);
-      goto retry;
-    }
+#ifdef HB_USE_ATEXIT
+    atexit (free_static_ft_funcs);
+#endif
+
+    return funcs;
+  }
+} static_ft_funcs;
 
 #ifdef HB_USE_ATEXIT
-    atexit (free_static_ft_funcs); /* First person registers atexit() callback. */
+static
+void free_static_ft_funcs (void)
+{
+  static_ft_funcs.fini ();
+}
 #endif
-  };
 
+static hb_font_funcs_t *
+_hb_ft_get_font_funcs (void)
+{
+  return const_cast<hb_font_funcs_t *> (static_ft_funcs.get ());
+}
+
+static void
+_hb_ft_font_set_funcs (hb_font_t *font, FT_Face ft_face, bool unref)
+{
   bool symbol = ft_face->charmap && ft_face->charmap->encoding == FT_ENCODING_MS_SYMBOL;
 
   hb_font_set_funcs (font,
-		     funcs,
+		     _hb_ft_get_font_funcs (),
 		     _hb_ft_font_create (ft_face, symbol, unref),
 		     _hb_ft_font_destroy);
 }
diff --git a/src/hb-machinery-private.hh b/src/hb-machinery-private.hh
index 873596de3..b26ca710e 100644
--- a/src/hb-machinery-private.hh
+++ b/src/hb-machinery-private.hh
@@ -749,6 +749,20 @@ struct hb_table_lazy_loader_t : hb_lazy_loader_t<hb_table_lazy_loader_t<T, Where
   }
 };
 
+template <typename Subclass>
+struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<Subclass,
+						       void, 0,
+						       hb_font_funcs_t>
+{
+  static inline void destroy (hb_font_funcs_t *p)
+  {
+    hb_font_funcs_destroy (p);
+  }
+  static inline const hb_font_funcs_t *get_null (void)
+  {
+      return hb_font_funcs_get_empty ();
+  }
+};
 template <typename Subclass>
 struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<Subclass,
 							 void, 0,
diff --git a/src/hb-ot-font.cc b/src/hb-ot-font.cc
index 0284a45bd..1fb18c487 100644
--- a/src/hb-ot-font.cc
+++ b/src/hb-ot-font.cc
@@ -29,6 +29,7 @@
 #include "hb-ot.h"
 
 #include "hb-font-private.hh"
+#include "hb-machinery-private.hh"
 
 #include "hb-ot-cmap-table.hh"
 #include "hb-ot-glyf-table.hh"
@@ -225,30 +226,14 @@ hb_ot_get_font_v_extents (hb_font_t *font,
   return ot_font->v_metrics.has_font_extents;
 }
 
-static hb_atomic_ptr_t <hb_font_funcs_t> static_ot_funcs;
 
-#ifdef HB_USE_ATEXIT
-static
-void free_static_ot_funcs (void)
+static void free_static_ot_funcs (void);
+
+static struct hb_ot_font_funcs_lazy_loader_t : hb_font_funcs_lazy_loader_t<hb_ot_font_funcs_lazy_loader_t>
 {
-retry:
-  hb_font_funcs_t *ot_funcs = static_ot_funcs.get ();
-  if (unlikely (!static_ot_funcs.cmpexch (ot_funcs, nullptr)))
-    goto retry;
-
-  hb_font_funcs_destroy (ot_funcs);
-}
-#endif
-
-static hb_font_funcs_t *
-_hb_ot_get_font_funcs (void)
-{
-retry:
-  hb_font_funcs_t *funcs = static_ot_funcs.get ();
-
-  if (unlikely (!funcs))
+  static inline hb_font_funcs_t *create (void)
   {
-    funcs = hb_font_funcs_create ();
+    hb_font_funcs_t *funcs = hb_font_funcs_create ();
 
     hb_font_funcs_set_font_h_extents_func (funcs, hb_ot_get_font_h_extents, nullptr, nullptr);
     hb_font_funcs_set_font_v_extents_func (funcs, hb_ot_get_font_v_extents, nullptr, nullptr);
@@ -267,18 +252,26 @@ retry:
 
     hb_font_funcs_make_immutable (funcs);
 
-    if (unlikely (!static_ot_funcs.cmpexch (nullptr, funcs)))
-    {
-      hb_font_funcs_destroy (funcs);
-      goto retry;
-    }
+#ifdef HB_USE_ATEXIT
+    atexit (free_static_ot_funcs);
+#endif
+
+    return funcs;
+  }
+} static_ot_funcs;
 
 #ifdef HB_USE_ATEXIT
-    atexit (free_static_ot_funcs); /* First person registers atexit() callback. */
+static
+void free_static_ot_funcs (void)
+{
+  static_ot_funcs.fini ();
+}
 #endif
-  };
 
-  return funcs;
+static hb_font_funcs_t *
+_hb_ot_get_font_funcs (void)
+{
+  return const_cast<hb_font_funcs_t *> (static_ot_funcs.get ());
 }