Re: [PATCH RFC] Let pseudo->users loop on duplicate version of list

[Christopher Li <sparse@chrisli.org>]

On Tue, Jul 11, 2017 at 2:04 PM, Dibyendu Majumdar
<mobile@majumdar.org.uk> wrote:
> I think that duplicating a list because that list is being modified is
> quite a sensible thing to do. My only suggestion would be that perhaps
> you could have a dup() step that is separate so that you can use the
> normal iterator macro after duplicating.

So are you suggesting some thing like this:

struct ptr_list *dup_list = NULL:
concat_ptr_list(orign_list, &dup_list);
FOR_EACH_PTR(dup_list, ptr) {
...
} END_FOR_EACH_PTR(ptr);
free_ptr_list(dup_list);

I think that should work. But it come with a price
allocating and freeing the list (otherwise it is a memory leak).

Also run slightly slower. My current way will only duplicate
the list struct one at a time. It never duplicate the full list.
It has fixed memory usage, no allocating, no duplicate of
the ->next and ->prev pointer.

So what macro do you have in mind? I think any thing modify
the duplicate list does not make sense.

On thing I can do is rename the __list into __orig, then rename
__dup into __list. Then most of the list macro using __list should
work. It also means I have to use END_FOR_EACH_PTR_DUP()
as well.


Chris