最近查看openvswitch的代码，发现有个函数怎么都找不到：ovsrec_open_vswitch_set_bridges

最后通过汇编发现它还调用ovsdb_idl_txn_write函数。反向搜索终于找到了定义：

ovsdb/ovsdb-idlc.in

 * This function is rarely useful, since it is easier to access the value* directly through the "%(c)s" member in %(s)s. */
const struct ovsdb_datum *
%(s)s_get_%(c)s(const struct %(s)s *row,
\tenum ovsdb_atomic_type key_type OVS_UNUSED%(v)s)
{ovs_assert(key_type == %(kt)s);%(vt)sreturn ovsdb_idl_read(&row->header_, &%(s)s_col_%(c)s);
}""" % {'t': tableName, 's': structName, 'c': columnName,'kt': column.type.key.toAtomicType(),'v': valueParam, 'vt': valueType, 'vc': valueComment})# Set functions.for columnName, column in sorted_columns(table):if column.extensions.get('synthetic'):continuetype = column.typecomment, members = cMembers(prefix, tableName, columnName,column, True)if type.is_smap():print(comment)print("""void
%(s)s_set_%(c)s(const struct %(s)s *row, const struct smap *%(c)s)
{struct ovsdb_datum datum;if (%(c)s) {ovsdb_datum_from_smap(&datum, %(c)s);} else {ovsdb_datum_init_empty(&datum);}ovsdb_idl_txn_write(&row->header_,&%(s)s_col_%(c)s,&datum);
}

如果不熟悉这个代码，还真是不好找。原来还以为是宏定义出来的代码，现在看是中间穿插了一个代码自动生成层。