[pulseaudio-discuss] [PATCH 15/21] dynarray: Reimplement with nicer semantics

[Tanu Kaskinen]

On Wed, 2013-06-26 at 12:34 +0200, David Henningsson wrote:
> On 06/26/2013 12:22 PM, Tanu Kaskinen wrote:
> > On Wed, 2013-06-26 at 11:48 +0200, David Henningsson wrote:
> >> On 06/19/2013 05:40 PM, Tanu Kaskinen wrote:
> >>> A dynamic array is a nice simple container, but the old interface
> >>> wasn't quite what I wanted it to be. I like GLib's way of providing
> >>> the free callback at the container creation time, because that way
> >>> the free callback doesn't have to be given every time something is
> >>> removed from the array.
> >>>
> >>> The allocation pattern was changed too: instead of increasing the
> >>> array size always by 25 when the array gets full, the size gets
> >>> doubled now.
> >>
> >> Not sure if you need this now that the node ownership stuff is changed,
> >
> > I guess I don't need this now, but I'd still like to have this change in
> > dynarray. Is it OK for you?
> 
> Yes, I'm okay with the rest of the changes. I noticed that dynarray_get 
> semantics changed for getting element outside the array - I'm okay with 
> the change but please go through the callers thoroughly to make sure we 
> don't get assertion failures when we shouldn't.
> 
> >> but anyway, it makes sense to have both (new_size = old_size * 2 + 25),
> >> both as an optimisation in the beginning, and especially so if
> >> n_allocated ever gets down to zero (I don't know if that can happen).
> >
> > n_allocated never decreases (at the moment anyway - I could implement
> > that if there is demand).
> >
> > I see the point of optimizing in the beginning. Currently the array
> > starts with allocated size of 1, so reallocations will happen when the
> > size reaches 2, 3, 5, 9, 17, 33... Starting with size 25 would perhaps
> > be better.
> >
> 
> So if we start with n_allocated = 25 and increase with max(n_allocated * 
> 2, 25), does that work for you?

Sure. It's only a safety mechanism against future bugs (for the case
when n_allocated goes to 0), but I'm OK with that.

-- 
Tanu