Re: Remove TO DO in jfs_xtree.c

[Dave Kleikamp <dave.kleikamp@oracle.com>]

On 12/27/2014 06:58 PM, nick wrote:
> Greetings Dave,
> I am wondering why there is a TO DO above this code:
>         * ToDo:  tlocks should be on doubly-linked list, so we can
>         * quickly remove it and add it to the end.

I'm sure the idea was to avoid the for loop needed to find the previous
entry in the linked list. A doubly-linked list makes it much simpler to
remove an item from an arbitrary position in the list.

>         */
> 
>        /*
>        * Move parent page's tlock to the end of the tid's tlock list
>        */
>        if (log && mp->lid && (tblk->last != mp->lid) &&
>            lid_to_tlock(mp->lid)->tid) {
>                lid_t lid = mp->lid;
>                 struct tlock *prev;
> 
>              tlck = lid_to_tlock(lid);
> 
>              if (tblk->next == lid)
>                        tblk->next = tlck->next;
>              else {
>                        for (prev = lid_to_tlock(tblk->next);
>                              prev->next != lid;
>                             prev = lid_to_tlock(prev->next)) {
>                               assert(prev->next);
>                       }
>                         prev->next = tlck->next;
>               }
>               lid_to_tlock(tblk->last)->next = lid;
>               tlck->next = 0;
>                tblk->last = lid;
>        }
> As this code clearly moves the locks onto a linked list. Therefore I am recommend we remove this
> TO DO as this is clearly misleading and no longer needed.

That comment has been in the code forever and I don't have any intention
of changing things, but I don't think it's wrong. I don't mind removing
it, though. jfs has been barely maintained and there is a ton of cleanup
that can be done if someone were willing to take the time to do it.

Thanks,
Shaggy