From: Jeff King <peff@peff.net>
Date: Tue, 30 Jun 2015 19:22:15 GMT
Subject: Re: [PATCH 3/3] introduce "format" date-mode
Message-ID: <20150630192215.GB6845@peff.net>
In-Reply-To: <CAPig+cSJXZjrZ=OcV+C6bkCEHQFrw35-cjQ3At_Qo5KrpYxaQA@mail.gmail.com>

On Tue, Jun 30, 2015 at 02:13:53PM -0400, Eric Sunshine wrote:

> Sorry, I meant that the interpolation expense of "%s ". A cheaper (but
> more verbose) alternative might be:
> 
>     size_t n = strlen(fmt);
>     const char *f = xmalloc(n + 2);
>     strcpy(f, fmt);
>     f[n] = ' ';
>     f[n + 1] = '\0';
>     ...
>     free(f);
> 
> or something similar.

I think you're probably getting into premature optimization here. Using
strbuf_vaddf should be within the same order of magnitude of
instructions (and I think we should almost never hit this code path
anyway, because we'll be reading into a static strbuf generally which
will come pre-sized to hold a date).

-Peff