Ian Romanick <i...@freedesktop.org> writes: >> For what it's worth, I'm strongly in favour of using these >> kernel-style lists instead of exec_list. The kernel ones seem much >> less confusing. > > Huh? They're practically identical. The only difference is the > kernel-style lists have a single sentinel node, and that node is > impossible to identify "in a crowd." The exec_lists use two sentinel > nodes, and those nodes have one pointer of overlapping storage (head > and tail are the next and prev pointers of one node, and tail and > tail_pred are the next and prev pointers of the other). I thought > there was some ASCII art in list.h that showed this, but that appears > to not be the case...
Yes, I understand how they work. But you have to admit that the magic of making the end sentinel overlap with the head sentinel is a bit more difficult to get your head around then just having a single sentinel. At least personally I found that more confusing. > This gives some convenience that you can walk through a list from any > node in the list without having a pointer to the list itself. I don't > know if we still do, but there used to be a few places where we took > advantage of that. Ok, that is a good point. However if we can't find any examples of where we are doing this then maybe it isn't all that important. A counter advantage of the kernel-style lists is that the sentinel is slightly smaller (one fewer pointer). That might be an important consideration if you're using them to build up a tree structure with a lot of lists, like an AST. However the main advantage for me is that saying “they're easy, they're just like in the kernel and Wayland” is a lot more likely to have meaning for someone than saying “they're just like on the Amiga”! Regards, - Neil _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
