On Wed, Aug 10, 2016 at 04:10:02PM +0200, Lars Schneider wrote:
>
> > On 10 Aug 2016, at 15:43, Jeff King <peff@xxxxxxxx> wrote:
> >
> > On Wed, Aug 10, 2016 at 03:04:01PM +0200, larsxschneider@xxxxxxxxx wrote:
> >
> >> +int packet_write_gently_fmt(int fd, const char *fmt, ...)
> >> +{
> >> + static struct strbuf buf = STRBUF_INIT;
> >> + va_list args;
> >> +
> >> + strbuf_reset(&buf);
> >> + va_start(args, fmt);
> >> + format_packet(1, &buf, fmt, args);
> >> + va_end(args);
> >> + packet_trace(buf.buf + 4, buf.len - 4, 1);
> >> + return (write_in_full(fd, buf.buf, buf.len) == buf.len ? 0 : -1);
> >> +}
> >
> > Could the end of this function just be:
> >
> > return packet_write_gently(fd, buf.buf, buf.len);
> >
> > ? I guess we'd prefer to avoid that, because it incurs an extra
> > memmove() of the data.
>
> I don't think the memmove would be that expensive. However, format_packet()
> already creates the packet_header and packet_write_gently would do the same
> again, no?
Yeah, I think you would want extra refactoring to have a shared common
function. I took a stab at it, but the result ends up pretty ugly; the
amount of boilerplate exceeds the duplication here (the really nasty
thing is that format_packet() is hard to split up, because the part you
want to switch out is in the middle, but it needs to keep some context
between the start and the end. In a higher level language you'd pass it
a callback to fill in the strbuf in the middle, but in C that just ends
up horrible).
> > Similarly, I'd think this could share code with the non-gentle form
> > (which should be able to just call this and die() if returns an error).
> > Though sometimes the va_list transformation makes that awkward.
>
> Yeah, the code duplication annoyed me, too. va_list was the reason I did it
> that way. Do you think that is something that needs to be addressed in the
> series?
No, I don't think it needs to be. It's just a case of making sure that
the internals don't grow too crufty and unmanageable for future
maintainability.
-Peff
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