Re: [PATCH v2 12/19] streaming: rely on object sources to create object stream

> Patrick Steinhardt <ps@pks.im> writes:
> > @@ -463,30 +461,15 @@ static int istream_source(struct odb_read_stream **out,
> >  			  struct repository *r,
> >  			  const struct object_id *oid)
> >  {
> > -	unsigned long size;
> > -	int status;
> > -	struct object_info oi = OBJECT_INFO_INIT;
> > -
> > -	oi.sizep = &size;
> > -	status = odb_read_object_info_extended(r->objects, oid, &oi, 0);
> > -	if (status < 0)
> > -		return status;
> > +	struct odb_source *source;
> >  
> > -	switch (oi.whence) {
> > -	case OI_LOOSE:
> > -		if (open_istream_loose(out, r, oid) < 0)
> > -			break;
> > -		return 0;
> > -	case OI_PACKED:
> > -		if (oi.u.packed.is_delta ||
> > -		    repo_settings_get_big_file_threshold(the_repository) >= size ||
> > -		    open_istream_pack_non_delta(out, r, oid, oi.u.packed.pack,
> > -						oi.u.packed.offset) < 0)
> > -			break;
> > +	if (!open_istream_pack_non_delta(out, r->objects, oid))
> >  		return 0;
> > -	default:
> > -		break;
> > -	}
> > +
> > +	odb_prepare_alternates(r->objects);
> > +	for (source = r->objects->sources; source; source = source->next)
> > +		if (!open_istream_loose(out, source, oid))
> > +			return 0;
> 
> Hmph.
> 
> Earlier we let odb_read_object_info_extended() decide which one of
> the duplicated objects (e.g., perhaps a loose object is still there
> after packing), and then used the one it picked.  I think the
> odb_read_object_info_extended() encodes a particular order with with
> solid reasons like "do in-core cached one first", "favor objects in
> pack over loose ones".
> 
> Now we instead let the first one with the object in the linked list
> of sources, which may be different, unless the linked list is
> created with the same "why one source needs to be given precedence
> over the others" reasoning.
> 
> I do not know if/how it matters, this somewhat changes the
> semantics, no?