[Libguestfs] [PATCH libnbd] generator/Go.ml: Simplify copy_uint32_array
Create a slice backed up by the entries pointer, and copy the data with
builtin copy(). This can be 3x times faster but I did not measure it.
Eric posted a similar patch[1] last year, but the patch seems to be
stuck with unrelated incomplete work.
[1] https://listman.redhat.com/archives/libguestfs/2021-December/msg00065.html
Signed-off-by: Nir Soffer <nsoffer(a)redhat.com>
---
generator/GoLang.ml | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/generator/GoLang.ml b/generator/GoLang.ml
index eb3aa263..73838199 100644
--- a/generator/GoLang.ml
+++ b/generator/GoLang.ml
@@ -1,13 +1,13 @@
(* hey emacs, this is OCaml code: -*- tuareg -*- *)
(* nbd client library in userspace: generator
- * Copyright (C) 2013-2020 Red Hat Inc.
+ * Copyright (C) 2013-2022 Red Hat Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
@@ -508,24 +508,24 @@ package libnbd
#include \"wrappers.h\"
*/
import \"C\"
import \"unsafe\"
/* Closures. */
func copy_uint32_array (entries *C.uint32_t, count C.size_t) []uint32 {
ret := make([]uint32, int (count))
- for i := 0; i < int (count); i++ {
- entry := (*C.uint32_t) (unsafe.Pointer(uintptr(unsafe.Pointer(entries)) +
(unsafe.Sizeof(*entries) * uintptr(i))))
- ret[i] = uint32 (*entry)
- }
+ // See https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
+ // TODO: Use unsafe.Slice() when we require Go 1.17.
+ s := (*[1<<30]uint32)(unsafe.Pointer(entries))[:count:count]
+ copy(ret, s)
return ret
}
";
List.iter (
fun { cbname; cbargs } ->
let uname = camel_case cbname in
pr "type %sCallback func (" uname;
let comma = ref false in
List.iter (
--
2.34.1