[tarantool-patches] Re: [PATCH v5 3/5] sql: create method dump_lua for port_sql

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Thanks for the patch! See 7 comments below.

On 22/12/2018 14:31, imeevma@tarantool.org wrote:
> This patch creates the dump_lua method for port_sql. It also
> defines a new function box.sql.new_execute(), which will be
> converted to box.sql.execute().
> 
> Part of #3505
> ---
>   src/box/execute.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>   src/box/lua/sql.c | 25 +++++++++++++++++
>   2 files changed, 108 insertions(+), 1 deletion(-)
> 
> diff --git a/src/box/execute.c b/src/box/execute.c
> index b07de28..3cbee4f 100644
> --- a/src/box/execute.c
> +++ b/src/box/execute.c
> @@ -674,6 +675,87 @@ finish:
>   	return rc;
>   }
>   
> +/**
> + * Push a metadata of the prepared statement to Lua stack.
> + *
> + * @param stmt Prepared statement.
> + * @param L Lua stack.
> + * @param column_count Statement's column count.
> + */
> +static inline void
> +lua_sql_get_description(struct sqlite3_stmt *stmt, struct lua_State *L,
> +			int column_count)
> +{
> +	assert(column_count > 0);
> +	lua_createtable(L, column_count, 0);
> +	for (int i = 0; i < column_count; ++i) {
> +		lua_createtable(L, 2, 0);
> +		const char *name = sqlite3_column_name(stmt, i);
> +		const char *type = sqlite3_column_datatype(stmt, i);
> +		/*
> +		 * Can not fail, since all column names are
> +		 * preallocated during prepare phase and the
> +		 * column_name simply returns them.
> +		 */
> +		assert(name != NULL);
> +		lua_pushlstring(L, name, strlen(name));
> +		lua_setfield(L, -2, "name");
> +		lua_pushlstring(L, type, strlen(type));

1. Use lua_pushstring.

> +		lua_setfield(L, -2, "type");
> +		lua_rawseti(L, -2, i + 1);
> +	}
> +	lua_setfield(L, -2, "metadata");

2. It is strange, that this function creates a table and sets it
as a member of some externally created table. Please, move this line
to a caller function.

> +}
> +
> +/**
> + * Dump a built response into Lua stack. The response is
> + * destroyed.
> + *
> + * @param port port with EXECUTE response.
> + * @param L Lua stack.
> + */
> +static void
> +port_sql_dump_lua(struct port *port, struct lua_State *L)
> +{
> +	assert(port->vtab == &port_sql_vtab);
> +	sqlite3 *db = sql_get();
> +	struct sqlite3_stmt *stmt = ((struct port_sql *)port)->stmt;
> +	int column_count = sqlite3_column_count(stmt);
> +	if (column_count > 0) {
> +		int keys = 2;
> +		lua_createtable(L, 0, keys);

3. Just inline keys 2.

> +		lua_sql_get_description(stmt, L, column_count);
> +		port_tuple_vtab.dump_lua(port, L);
> +		lua_setfield(L, -2, "rows");
> +	} else {
> +		assert(((struct port_tuple *)port)->size == 0);
> +		struct stailq *autoinc_id_list =
> +			vdbe_autoinc_id_list((struct Vdbe *)stmt);
> +
> +		int dynamic_keys = stailq_empty(autoinc_id_list) ? 0 : 1;
> +		lua_createtable(L, 1, dynamic_keys);

4. Why 1 array element? And why do you separate fixed/optional keys?
lua_createtable does not take statis/dynamic key count. It takes
array/map key count.

> +
> +		luaL_pushuint64(L, db->nChange);
> +		lua_setfield(L, -2, "rowcount");
> +
> +		if (!stailq_empty(autoinc_id_list)) {
> +			lua_newtable(L);
> +			int i = 1;
> +			struct autoinc_id_entry *id_entry;
> +			stailq_foreach_entry(id_entry, autoinc_id_list, link) {
> +				if (id_entry->id >= 0)
> +					luaL_pushuint64(L, id_entry->id);
> +				else
> +					luaL_pushint64(L, id_entry->id);
> +				lua_rawseti(L, -2, i++);
> +			}
> +			lua_setfield(L, -2, "autoincrement_ids");
> +		}
> +	}
> +	port_destroy(port);
> +	sqlite3_finalize(stmt);

5. I think, port_sql_destroy should call sqlite3_finalize.

> +}
> +
>   static void
>   port_sql_destroy(struct port *base)
>   {
> diff --git a/src/box/lua/sql.c b/src/box/lua/sql.c
> index 6923666..318f331 100644
> --- a/src/box/lua/sql.c
> +++ b/src/box/lua/sql.c
> @@ -111,6 +112,29 @@ sqlerror:
>   }
>   
>   static int
> +lbox_execute(struct lua_State *L)
> +{
> +	struct sql_bind *bind = NULL;
> +	int bind_count = 0;
> +	size_t length;
> +	struct port port;
> +
> +	struct sqlite3 *db = sql_get();
> +	if (db == NULL)
> +		return luaL_error(L, "not ready");

6. Impossible. It isn't?

> +
> +	const char *sql = lua_tolstring(L, 1, &length);
> +	if (sql == NULL)
> +		return luaL_error(L, "usage: box.execute(sqlstring)");

7. Please, start message with a capital letter.

> +
> +	if (sql_prepare_and_execute(sql, length, bind, bind_count, &port,
> +				    &fiber()->gc) != 0)
> +		return luaT_error(L);
> +	port_dump_lua(&port, L);
> +	return 1;
> +}
> +
> +static int
>   lua_sql_debug(struct lua_State *L)
>   {
>   	struct info_handler info;