Make upb::SymbolTable no longer reference-counted.

This transitions it from shared ownership to unique
ownership.

5 files changed, 32 insertions, 77 deletions

diff --git a/upb/bindings/lua/def.c b/upb/bindings/lua/def.c
index 638abb6..5133831 100644
--- a/upb/bindings/lua/def.c
+++ b/upb/bindings/lua/def.c
@@ -1090,50 +1090,35 @@ static const struct luaL_Reg lupb_filedef_m[] = {
 
 /* lupb_symtab ****************************************************************/
 
-/* Inherits a ref on the symtab.
- * Checks that narg is a proper lupb_symtab object.  If it is, leaves its
- * metatable on the stack for cache lookups/updates. */
-const upb_symtab *lupb_symtab_check(lua_State *L, int narg) {
-  return lupb_refcounted_check(L, narg, LUPB_SYMTAB);
-}
-
-static upb_symtab *lupb_symtab_checkmutable(lua_State *L, int narg) {
-  const upb_symtab *s = lupb_symtab_check(L, narg);
-  if (upb_symtab_isfrozen(s))
-    luaL_error(L, "not allowed on frozen value");
-  return (upb_symtab*)s;
-}
-
-void lupb_symtab_pushwrapper(lua_State *L, const upb_symtab *s,
-                             const void *ref_donor) {
-  lupb_refcounted_pushwrapper(L, upb_symtab_upcast(s), LUPB_SYMTAB, ref_donor,
-                              sizeof(void *));
-}
+typedef struct {
+  upb_symtab *symtab;
+} lupb_symtab;
 
-void lupb_symtab_pushnewrapper(lua_State *L, const upb_symtab *s,
-                               const void *ref_donor) {
-  lupb_refcounted_pushnewrapper(L, upb_symtab_upcast(s), LUPB_SYMTAB,
-                                ref_donor);
+upb_symtab *lupb_symtab_check(lua_State *L, int narg) {
+  lupb_symtab *lsymtab = luaL_checkudata(L, narg, LUPB_SYMTAB);
+  if (!lsymtab->symtab) {
+    luaL_error(L, "called into dead object");
+  }
+  return lsymtab->symtab;
 }
 
 static int lupb_symtab_new(lua_State *L) {
-  upb_symtab *s = upb_symtab_new(&s);
-  lupb_symtab_pushnewrapper(L, s, &s);
+  lupb_symtab *lsymtab = lua_newuserdata(L, sizeof(*lsymtab));
+  lsymtab->symtab = upb_symtab_new();
+  luaL_getmetatable(L, LUPB_SYMTAB);
+  lua_setmetatable(L, -2);
   return 1;
 }
 
-static int lupb_symtab_freeze(lua_State *L) {
-  upb_symtab_freeze(lupb_symtab_checkmutable(L, 1));
+static int lupb_symtab_gc(lua_State *L) {
+  lupb_symtab *lsymtab = luaL_checkudata(L, 1, LUPB_SYMTAB);
+  upb_symtab_free(lsymtab->symtab);
+  lsymtab->symtab = NULL;
   return 0;
 }
 
-static int lupb_symtab_isfrozen(lua_State *L) {
-  lua_pushboolean(L, upb_symtab_isfrozen(lupb_symtab_check(L, 1)));
-  return 1;
-}
-
 static int lupb_symtab_add(lua_State *L) {
-  upb_symtab *s = lupb_symtab_checkmutable(L, 1);
+  upb_symtab *s = lupb_symtab_check(L, 1);
   int n;
   upb_def **defs;
 
@@ -1161,7 +1146,7 @@ static int lupb_symtab_add(lua_State *L) {
 }
 
 static int lupb_symtab_addfile(lua_State *L) {
-  upb_symtab *s = lupb_symtab_checkmutable(L, 1);
+  upb_symtab *s = lupb_symtab_check(L, 1);
   upb_filedef *f = lupb_filedef_checkmutable(L, 2);
   CHK(upb_symtab_addfile(s, f, &status));
   return 0;
@@ -1201,14 +1186,12 @@ static const struct luaL_Reg lupb_symtab_m[] = {
   {"add", lupb_symtab_add},
   {"add_file", lupb_symtab_addfile},
   {"defs", lupb_symtab_defs},
-  {"freeze", lupb_symtab_freeze},
-  {"is_frozen", lupb_symtab_isfrozen},
   {"lookup", lupb_symtab_lookup},
   {NULL, NULL}
 };
 
 static const struct luaL_Reg lupb_symtab_mm[] = {
-  {"__gc", lupb_refcounted_gc},
+  {"__gc", lupb_symtab_gc},
   {NULL, NULL}
 };
 
diff --git a/upb/bindings/lua/upb.h b/upb/bindings/lua/upb.h
index 84212c5..88a201c 100644
--- a/upb/bindings/lua/upb.h
+++ b/upb/bindings/lua/upb.h
@@ -101,7 +101,7 @@ void *lupb_refcounted_check(lua_State *L, int narg, const char *type);
 const upb_msgdef *lupb_msgdef_check(lua_State *L, int narg);
 const upb_enumdef *lupb_enumdef_check(lua_State *L, int narg);
 const upb_fielddef *lupb_fielddef_check(lua_State *L, int narg);
-const upb_symtab *lupb_symtab_check(lua_State *L, int narg);
+upb_symtab *lupb_symtab_check(lua_State *L, int narg);
 
 void lupb_refcounted_pushnewrapper(lua_State *L, const upb_refcounted *obj,
                                    const char *type, const void *ref_donor);
diff --git a/upb/def.c b/upb/def.c
index 45cd362..39d8c08 100644
--- a/upb/def.c
+++ b/upb/def.c
@@ -2142,8 +2142,7 @@ bool upb_filedef_adddep(upb_filedef *f, const upb_filedef *dep) {
   }
 }
 
-static void upb_symtab_free(upb_refcounted *r) {
-  upb_symtab *s = (upb_symtab*)r;
+void upb_symtab_free(upb_symtab *s) {
   upb_strtable_iter i;
   upb_strtable_begin(&i, &s->symtab);
   for (; !upb_strtable_done(&i); upb_strtable_next(&i)) {
@@ -2154,32 +2153,16 @@ static void upb_symtab_free(upb_refcounted *r) {
   upb_gfree(s);
 }
 
-upb_symtab *upb_symtab_new(const void *owner) {
-  static const struct upb_refcounted_vtbl vtbl = {NULL, &upb_symtab_free};
-
+upb_symtab *upb_symtab_new() {
   upb_symtab *s = upb_gmalloc(sizeof(*s));
   if (!s) {
     return NULL;
   }
 
-  upb_refcounted_init(upb_symtab_upcast_mutable(s), &vtbl, owner);
   upb_strtable_init(&s->symtab, UPB_CTYPE_PTR);
   return s;
 }
 
-void upb_symtab_freeze(upb_symtab *s) {
-  upb_refcounted *r;
-  bool ok;
-
-  UPB_ASSERT(!upb_symtab_isfrozen(s));
-  r = upb_symtab_upcast_mutable(s);
-  /* The symtab does not take ref2's (see refcounted.h) on the defs, because
-   * defs cannot refer back to the table and therefore cannot create cycles.  So
-   * 0 will suffice for maxdepth here. */
-  ok = upb_refcounted_freeze(&r, 1, NULL, 0);
-  UPB_ASSERT(ok);
-}
-
 const upb_def *upb_symtab_lookup(const upb_symtab *s, const char *sym) {
   upb_value v;
   upb_def *ret = upb_strtable_lookup(&s->symtab, sym, &v) ?
@@ -2352,7 +2335,6 @@ static bool symtab_add(upb_symtab *s, upb_def *const*defs, size_t n,
     return true;
   }
 
-  UPB_ASSERT(!upb_symtab_isfrozen(s));
   if (!upb_strtable_init(&addtab, UPB_CTYPE_PTR)) {
     upb_status_seterrmsg(status, "out of memory");
     return false;
diff --git a/upb/def.h b/upb/def.h
index b2c42a6..b99dcb0 100644
--- a/upb/def.h
+++ b/upb/def.h
@@ -44,8 +44,7 @@ UPB_DECLARE_DERIVED_TYPE(upb::OneofDef, upb::RefCounted, upb_oneofdef,
                          upb_refcounted)
 UPB_DECLARE_DERIVED_TYPE(upb::FileDef, upb::RefCounted, upb_filedef,
                          upb_refcounted)
-UPB_DECLARE_DERIVED_TYPE(upb::SymbolTable, upb::RefCounted,
-                         upb_symtab, upb_refcounted)
+UPB_DECLARE_TYPE(upb::SymbolTable, upb_symtab)
 
 
 /* The maximum message depth that the type graph can have.  This is a resource
@@ -1434,10 +1433,8 @@ class upb::SymbolTable {
  public:
   /* Returns a new symbol table with a single ref owned by "owner."
    * Returns NULL if memory allocation failed. */
-  static reffed_ptr<SymbolTable> New();
-
-  /* Include RefCounted base methods. */
-  UPB_REFCOUNTED_CPPMETHODS
+  static SymbolTable* New();
+  static void Free(upb::SymbolTable* table);
 
   /* For all lookup functions, the returned pointer is not owned by the
    * caller; it may be invalidated by any non-const call or unref of the
@@ -1527,11 +1524,8 @@ UPB_BEGIN_EXTERN_C
 
 /* Native C API. */
 
-/* Include refcounted methods like upb_symtab_ref(). */
-UPB_REFCOUNTED_CMETHODS(upb_symtab, upb_symtab_upcast)
-
-upb_symtab *upb_symtab_new(const void *owner);
-void upb_symtab_freeze(upb_symtab *s);
+upb_symtab *upb_symtab_new();
+void upb_symtab_free(upb_symtab* s);
 const upb_def *upb_symtab_resolve(const upb_symtab *s, const char *base,
                                   const char *sym);
 const upb_def *upb_symtab_lookup(const upb_symtab *s, const char *sym);
@@ -1562,13 +1556,11 @@ UPB_END_EXTERN_C
 #ifdef __cplusplus
 /* C++ inline wrappers. */
 namespace upb {
-inline reffed_ptr<SymbolTable> SymbolTable::New() {
-  upb_symtab *s = upb_symtab_new(&s);
-  return reffed_ptr<SymbolTable>(s, &s);
+inline SymbolTable* SymbolTable::New() {
+  return upb_symtab_new();
 }
-
-inline void SymbolTable::Freeze() {
-  return upb_symtab_freeze(this);
+inline void SymbolTable::Free(SymbolTable* s) {
+  upb_symtab_free(s);
 }
 inline const Def *SymbolTable::Resolve(const char *base,
                                        const char *sym) const {
diff --git a/upb/msg.c b/upb/msg.c
index 517b814..5fa9bc8 100644
--- a/upb/msg.c
+++ b/upb/msg.c
@@ -350,7 +350,6 @@ upb_msgfactory *upb_msgfactory_new(const upb_symtab *symtab) {
   upb_msgfactory *ret = upb_gmalloc(sizeof(*ret));
 
   ret->symtab = symtab;
-  upb_symtab_ref(ret->symtab, &ret->symtab);
   upb_inttable_init(&ret->layouts, UPB_CTYPE_PTR);
   upb_inttable_init(&ret->mergehandlers, UPB_CTYPE_CONSTPTR);
 
@@ -373,7 +372,6 @@ void upb_msgfactory_free(upb_msgfactory *f) {
 
   upb_inttable_uninit(&f->layouts);
   upb_inttable_uninit(&f->mergehandlers);
-  upb_symtab_unref(f->symtab, &f->symtab);
   upb_gfree(f);
 }