From: Jeff King <peff@peff.net>
Date: Tue, 08 Aug 2017 22:52:31 GMT
Subject: Re: [PATCH] sha1_file: avoid comparison if no packed hash matches the first byte
Message-ID: <20170808225231.3l7gyoxxvghsvtv7@sigill.intra.peff.net>
In-Reply-To: <xmqq3791adfi.fsf@gitster.mtv.corp.google.com>

On Tue, Aug 08, 2017 at 03:43:13PM -0700, Junio C Hamano wrote:

> > @@ -2812,7 +2812,7 @@ off_t find_pack_entry_one(const unsigned char *sha1,
> >  			hi = mi;
> >  		else
> >  			lo = mi+1;
> > -	} while (lo < hi);
> > +	}
> >  	return 0;
> >  }
> 
> Interesting.  I see that we still have the conditional code to call
> out to sha1-lookup.c::sha1_entry_pos().  Do we need a similar change
> over there, I wonder?  Alternatively, as we have had the experimental
> sha1-lookup.c::sha1_entry_pos() long enough without anybody using it,
> perhaps we should write it off as a failed experiment and retire it?

There is also sha1_pos(), which seems to have the same problem (and is
used in several places).

-Peff