From: Kristian Høgsberg <krh@redhat.com>
Date: Tue, 31 Jul 2007 15:33:52 GMT
Subject: Re: [PATCH 3/5] Add strbuf_printf() to do formatted printing to a strbuf.
Message-ID: <1185896032.11086.57.camel@hinata.boston.redhat.com>
In-Reply-To: <Pine.LNX.4.64.0707311554220.14781@racer.site>

On Tue, 2007-07-31 at 15:55 +0100, Johannes Schindelin wrote:
> Hi,
> 
> On Tue, 31 Jul 2007, Kristian H?gsberg wrote:
> 
> > On Mon, 2007-07-30 at 21:36 -0700, Junio C Hamano wrote:
> > > Kristian Høgsberg <krh@redhat.com> writes:
> > > 
> > > > +static void inline strbuf_grow(struct strbuf *sb, size_t extra)
> > > > +{
> > > > +	while (sb->alloc < sb->len + extra)
> > > >  		sb->alloc = sb->alloc * 3 / 2 + 16;
> > > > +	sb->buf = xrealloc(sb->buf, sb->alloc);
> > > > +}
> > > 
> > > Somehow this while () loop to compute the growth factor bothers
> > > me but that is probably a minor detail.
> > 
> > Think of it as a more efficient way of adding one character at a time :)
> > And it's logarithmic in the number of extra bytes.  By the way, I
> > normally just double the size in these cases, which gives you amortized
> > linear performance for adding to the buffer.  What's behind the * 3 / 2
> > idea?
> 
> But why not
> 
> 	sb->alloc = alloc_nr(sb->len + extra);

That should work, or even ALLOC_GROW, I guess.  Didn't know about those
macros.  But still, why not just double the size?

Kristian