Re: [PATCH v4 4/6] box: export registered functions in box.func folder

[Vladimir Davydov <vdavydov.dev@gmail.com>]

On Sun, Jun 23, 2019 at 04:57:55PM +0300, Kirill Shcherbatov wrote:
> diff --git a/src/box/lua/call.c b/src/box/lua/call.c
> index 8b7223a7c..8c70c1088 100644
> --- a/src/box/lua/call.c
> +++ b/src/box/lua/call.c
> @@ -284,8 +287,13 @@ port_lua_create(struct port *port, struct lua_State *L)
>  }
>  
>  struct execute_lua_ctx {
> -	const char *name;
> -	uint32_t name_len;
> +	union {
> +		struct {
> +			const char *name;
> +			uint32_t name_len;
> +		};
> +		struct mpstream *stream;
> +	};
>  	struct port *args;
>  };
>  
> @@ -340,58 +348,56 @@ execute_lua_eval(lua_State *L)
>  static int
>  encode_lua_call(lua_State *L)
>  {
> -	struct port_lua *port = (struct port_lua *) lua_topointer(L, -1);
> +	struct execute_lua_ctx *ctx =
> +		(struct execute_lua_ctx *) lua_topointer(L, 1);

Using the same struct for executing a function and encoding its result
looks ugly. I introduced a separate struct for this - see my changes
below - and pushed the patch to master.

diff --git a/src/box/lua/call.c b/src/box/lua/call.c
index 8c70c108..b308924c 100644
--- a/src/box/lua/call.c
+++ b/src/box/lua/call.c
@@ -287,13 +287,8 @@ port_lua_create(struct port *port, struct lua_State *L)
 }
 
 struct execute_lua_ctx {
-	union {
-		struct {
-			const char *name;
-			uint32_t name_len;
-		};
-		struct mpstream *stream;
-	};
+	const char *name;
+	uint32_t name_len;
 	struct port *args;
 };
 
@@ -345,22 +340,26 @@ execute_lua_eval(lua_State *L)
 	return lua_gettop(L);
 }
 
+struct encode_lua_ctx {
+	struct port_lua *port;
+	struct mpstream *stream;
+};
+
 static int
 encode_lua_call(lua_State *L)
 {
-	struct execute_lua_ctx *ctx =
-		(struct execute_lua_ctx *) lua_topointer(L, 1);
+	struct encode_lua_ctx *ctx =
+		(struct encode_lua_ctx *) lua_topointer(L, 1);
 	/*
 	 * Add all elements from Lua stack to the buffer.
 	 *
 	 * TODO: forbid explicit yield from __serialize or __index here
 	 */
 	struct luaL_serializer *cfg = luaL_msgpack_default;
-	struct port_lua *port = (struct port_lua *) ctx->args;
-	int size = lua_gettop(port->L);
+	int size = lua_gettop(ctx->port->L);
 	for (int i = 1; i <= size; ++i)
-		luamp_encode(port->L, cfg, ctx->stream, i);
-	port->size = size;
+		luamp_encode(ctx->port->L, cfg, ctx->stream, i);
+	ctx->port->size = size;
 	mpstream_flush(ctx->stream);
 	return 0;
 }
@@ -368,16 +367,15 @@ encode_lua_call(lua_State *L)
 static int
 encode_lua_call_16(lua_State *L)
 {
-	struct execute_lua_ctx *ctx =
-		(struct execute_lua_ctx *) lua_topointer(L, 1);
+	struct encode_lua_ctx *ctx =
+		(struct encode_lua_ctx *) lua_topointer(L, 1);
 	/*
 	 * Add all elements from Lua stack to the buffer.
 	 *
 	 * TODO: forbid explicit yield from __serialize or __index here
 	 */
 	struct luaL_serializer *cfg = luaL_msgpack_default;
-	struct port_lua *port = (struct port_lua *) ctx->args;
-	port->size = luamp_encode_call_16(port->L, cfg, ctx->stream);
+	ctx->port->size = luamp_encode_call_16(ctx->port->L, cfg, ctx->stream);
 	mpstream_flush(ctx->stream);
 	return 0;
 }
@@ -392,8 +390,8 @@ port_lua_do_dump(struct port *base, struct mpstream *stream,
 	 * Use the same global state, assuming the encoder doesn't
 	 * yield.
 	 */
-	struct execute_lua_ctx ctx;
-	ctx.args = base;
+	struct encode_lua_ctx ctx;
+	ctx.port = port;
 	ctx.stream = stream;
 	struct lua_State *L = tarantool_L;
 	int top = lua_gettop(L);