Re: [PATCH] lookup_object: prioritize recently found objects

[Jeff King <peff@peff.net>]

On Thu, May 02, 2013 at 08:44:07AM +0200, Johannes Sixt wrote:

> Am 5/1/2013 22:34, schrieb Jeff King:
> >  struct object *lookup_object(const unsigned char *sha1)
> >  {
> > -	unsigned int i;
> > +	unsigned int i, first;
> >  	struct object *obj;
> >  
> >  	if (!obj_hash)
> >  		return NULL;
> >  
> > -	i = hashtable_index(sha1);
> > +	first = i = hashtable_index(sha1);
> >  	while ((obj = obj_hash[i]) != NULL) {
> >  		if (!hashcmp(sha1, obj->sha1))
> >  			break;
> > @@ -85,6 +85,11 @@ struct object *lookup_object(const unsigned char *sha1)
> >  		if (i == obj_hash_size)
> >  			i = 0;
> >  	}
> > +	if (obj && i != first) {
> > +		struct object *tmp = obj_hash[i];
> > +		obj_hash[i] = obj_hash[first];
> > +		obj_hash[first] = tmp;
> > +	}
> >  	return obj;
> >  }
> 
> This is one of the places where I think the code does not speak for itself
> and a comment is warranted: The new if statement is not about correctness,
> but about optimization:

I figured the lengthy description in the commit message would be
sufficient, but I don't mind adding something like your suggestion to
point readers of the code in the right direction when they see it.

-Peff