Re: [PATCH 04/16] Add embedded list interface (header only)

Hi,

On Tuesday, June 19, 2012 09:59:48 PM Marko Kreen wrote:
> On Wed, Jun 13, 2012 at 2:28 PM, Andres Freund <andres(at)2ndquadrant(dot)com>
wrote:
> > +/*
> > + * removes a node from a list
> > + * Attention: O(n)
> > + */
> > +static inline void ilist_s_remove(ilist_s_head *head,
> > + ilist_s_node *node)
> > +{
> > + ilist_s_node *last = &head->head;
> > + ilist_s_node *cur;
> > +#ifndef NDEBUG
> > + bool found = false;
> > +#endif
> > + while ((cur = last->next))
> > + {
> > + if (cur == node)
> > + {
> > + last->next = cur->next;
> > +#ifndef NDEBUG
> > + found = true;
> > +#endif
> > + break;
> > + }
> > + last = cur;
> > + }
> > + assert(found);
> > +}
>
> This looks weird.
>
> In cyclic list removal is:
>
> node->prev->next = node->next;
> node->next->prev = node->prev;
>
> And thats it.
Thats the single linked list, not the double linked one. Thats why it has a
O(n) warning tacked on...

The double linked one is just as you said:
/*
* removes a node from a list
*/
static inline void ilist_d_remove(unused_attr ilist_d_head *head, ilist_d_node
*node)
{
ilist_d_check(head);
node->prev->next = node->next;
node->next->prev = node->prev;
ilist_d_check(head);
}

Greetings,

Andres

--
Andres Freund http://www.2ndQuadrant.com/
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