Re: [PATCH 1/2] Have a filter_start/filter_end API.

[Alex Riesen <raa.lkml@gmail.com>]

Pierre Habouzit, Mon, Oct 08, 2007 09:29:47 +0200:
> On Sun, Oct 07, 2007 at 09:50:41PM +0000, Alex Riesen wrote:
> > Pierre Habouzit, Sun, Oct 07, 2007 18:52:18 +0200:
> > > Though, those are both things that I find ugly to "know" in convert.c.
> > > How things are allocated in strbufs is one of the few things we don't
> > > want to assume anywhere outside of the strbuf module.
> >
> > src is outside of strbuf scope. It is not internal to struct strbuf.
> > The caller must already know if it is inside of the given strbuf
> > instance.
> >
> > need_realloc is covered by make_room, isn't it?
> 
>   Internally yes, but make_room may move the buffer, if that happens,
> there is nothing we can do, in the case where we point inside (or at the
> begining of - fwiw it's the same here) the buffer

update the outside pointer you can. But I actually lost all interest:
personally I never use the filters and deeply despise the reasons
caused their existence.

> > I'd suggest just fix the caller, it is simple in convert.c: just use
> > ret, which contains exactly this information. If you insist on editing
> > in-place, which makes your routines really need the in-placeability
> > informaion. Just give it to them, better explicitely. All of this
> > makes the routines very convert.c specific, which is the reason why I
> > argument to have them just there and nowhere else.
> > 
> > Alternatively, one can memdup ->buf (as it is the input for next
> > filter) every time a filter modifies it (which is safe, but simple,
> > slow, requires memory, and may fragment heap):
> 
>   This is exactly what we are trying to avoid with the current form.

I take this suggestion back. Do not use memdup, as it is slow,
requires lots of memory and may fragment heap. Sorry for repeating.

> Given how you try to micro-optimize strbuf_cmp I'm a bit lost here…
> 

I didn't. It just happened. If I _wanted_ to optimize anything I
wouldn't start with a function which is used exactly one time in a
program with a name like "rerere" which is not even used in default
configuration.