Re: [PATCH] clean: use warning_errno() when appropriate

From: Jeff King <peff@peff.net>
Date: Feb 13, 2017, 21:10 UTC
Message-ID: <20170213211051.vsnnrtcsvuvfcwyk@sigill.intra.peff.net>
In-Reply-To: <xmqqk28tddwo.fsf@gitster.mtv.corp.google.com>

On Mon, Feb 13, 2017 at 12:38:47PM -0800, Junio C Hamano wrote:

Show 11 quoted lines

> Jeff King <peff@peff.net> writes:
> 
> > I wonder if xmalloc() should be the one doing the saved_errno trick.
> > After all, it has only two outcomes: we successfully allocated the
> > memory, or we called die().
> 
> I would be lying if I said I did not considered it when I wrote the
> message you are responding to, but I rejected it because that would
> be optimizing for a wrong case, in that most callers of xmalloc()
> and friends do not do so in the error codepath, and we would be
> penalizing them by doing the saved_errno dance unconditionally.

Yes, that also occurred to me. I'm not sure if two integer swaps is enough to care about when compared to the cost of a malloc(), though.

IOW, I think this may be a case where we should be optimizing for programmer time (fewer lines of code, and one less thing to worry about in the callers) versus squeezing out every instruction.

-Peff