[PATCH v1 09/12] box: use own vtab per each function object

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

Tarantool functions used to refer to a static func_vtab object
based on it's type. With this patch, each function has own vtab
object, so it's virtual method may be overridden.
It is required to call builtin functions in func_call directly
in further patches.

Needed for #4113, #2200, #2233
---
 src/box/func.c     | 8 +++-----
 src/box/func.h     | 2 +-
 src/box/lua/call.c | 8 ++------
 src/box/sql/func.c | 3 +--
 4 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/src/box/func.c b/src/box/func.c
index 8d93a83b2..e36649d15 100644
--- a/src/box/func.c
+++ b/src/box/func.c
@@ -437,7 +437,7 @@ func_c_new(struct func_def *def)
 		diag_set(OutOfMemory, sizeof(*func), "malloc", "func");
 		return NULL;
 	}
-	func->base.vtab = &func_c_vtab;
+	func->base.vtab = func_c_vtab;
 	func->func = NULL;
 	func->module = NULL;
 	return &func->base;
@@ -462,7 +462,6 @@ func_c_unload(struct func_c *func)
 static void
 func_c_destroy(struct func *base)
 {
-	assert(base->vtab == &func_c_vtab);
 	assert(base != NULL && base->def->language == FUNC_LANGUAGE_C);
 	struct func_c *func = (struct func_c *) base;
 	func_c_unload(func);
@@ -505,7 +504,6 @@ func_c_load(struct func_c *func)
 int
 func_c_call(struct func *base, struct port *args, struct port *ret)
 {
-	assert(base->vtab == &func_c_vtab);
 	assert(base != NULL && base->def->language == FUNC_LANGUAGE_C);
 	struct func_c *func = (struct func_c *) base;
 	if (func->func == NULL) {
@@ -551,7 +549,7 @@ void
 func_delete(struct func *func)
 {
 	struct func_def *def = func->def;
-	func->vtab->destroy(func);
+	func->vtab.destroy(func);
 	free(def);
 }
 
@@ -617,7 +615,7 @@ func_call(struct func *base, struct port *args, struct port *ret)
 		}
 		fiber_set_user(fiber(), &base->owner_credentials);
 	}
-	int rc = base->vtab->call(base, args, ret);
+	int rc = base->vtab.call(base, args, ret);
 	/* Restore the original user */
 	if (orig_credentials)
 		fiber_set_user(fiber(), orig_credentials);
diff --git a/src/box/func.h b/src/box/func.h
index 2236fd873..7e4dd37a3 100644
--- a/src/box/func.h
+++ b/src/box/func.h
@@ -72,7 +72,7 @@ struct func_vtab {
 struct func {
 	struct func_def *def;
 	/** Virtual method table. */
-	const struct func_vtab *vtab;
+	struct func_vtab vtab;
 	/**
 	 * Authentication id of the owner of the function,
 	 * used for set-user-id functions.
diff --git a/src/box/lua/call.c b/src/box/lua/call.c
index 4297218cd..752f05745 100644
--- a/src/box/lua/call.c
+++ b/src/box/lua/call.c
@@ -708,14 +708,14 @@ func_lua_new(struct func_def *def)
 	}
 	if (def->body != NULL) {
 		func->base.def = def;
-		func->base.vtab = &func_persistent_lua_vtab;
+		func->base.vtab = func_persistent_lua_vtab;
 		if (func_persistent_lua_load(func) != 0) {
 			free(func);
 			return NULL;
 		}
 	} else {
 		func->lua_ref = LUA_REFNIL;
-		func->base.vtab = &func_lua_vtab;
+		func->base.vtab = func_lua_vtab;
 	}
 	return &func->base;
 }
@@ -724,7 +724,6 @@ static void
 func_lua_destroy(struct func *func)
 {
 	assert(func != NULL && func->def->language == FUNC_LANGUAGE_LUA);
-	assert(func->vtab == &func_lua_vtab);
 	free(func);
 }
 
@@ -732,7 +731,6 @@ static inline int
 func_lua_call(struct func *func, struct port *args, struct port *ret)
 {
 	assert(func != NULL && func->def->language == FUNC_LANGUAGE_LUA);
-	assert(func->vtab == &func_lua_vtab);
 	return box_lua_call(func->def->name, func->def->name_len, args, ret);
 }
 
@@ -752,7 +750,6 @@ func_persistent_lua_destroy(struct func *base)
 {
 	assert(base != NULL && base->def->language == FUNC_LANGUAGE_LUA &&
 	       base->def->body != NULL);
-	assert(base->vtab == &func_persistent_lua_vtab);
 	struct func_lua *func = (struct func_lua *) base;
 	func_persistent_lua_unload(func);
 	free(func);
@@ -763,7 +760,6 @@ func_persistent_lua_call(struct func *base, struct port *args, struct port *ret)
 {
 	assert(base != NULL && base->def->language == FUNC_LANGUAGE_LUA &&
 	       base->def->body != NULL);
-	assert(base->vtab == &func_persistent_lua_vtab);
 	struct func_lua *func = (struct func_lua *)base;
 	struct execute_lua_ctx ctx;
 	ctx.lua_ref = func->lua_ref;
diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index ce28fc960..e137f6999 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -2192,14 +2192,13 @@ func_sql_builtin_new(struct func_def *def)
 	}
 	/** Don't export SQL builtins in Lua for now. */
 	def->exports.lua = false;
-	func->base.vtab = &func_sql_builtin_vtab;
+	func->base.vtab = func_sql_builtin_vtab;
 	return &func->base;
 }
 
 static void
 func_sql_builtin_destroy(struct func *base)
 {
-	assert(base->vtab == &func_sql_builtin_vtab);
 	assert(base != NULL && base->def->language == FUNC_LANGUAGE_SQL_BUILTIN);
 	free(base);
 }
-- 
2.21.0