Re: [PATCH 2/8] packfile: always declare object info to be OI_PACKED

[Junio C Hamano <gitster@pobox.com>]

Patrick Steinhardt <ps@pks.im> writes:

> When reading object info via a packfile we yield one of two types:
>
>   - The object can either be OI_PACKED, which is what a caller would
>     typically expect.
>
>   - Or it can be OI_DBCACHED if it is stored in the delta base cache.
>
> The latter really is an implementation detail though, and callers
> typically don't care at all about the difference. Furthermore, the
> information whether or not it is part of the delta base cache can
> already be derived via the `is_delta` field, so the fact that we discern
> between OI_PACKED and OI_DBCACHED only further complicates the
> interface.

If this were "and no existing callers check at all", it would be
trivial to decide for this change.  In fact you do say that but in a
weaker form just below.

> Drop the OI_DBCACHED enum completely. There don't seem to be any callers
> that care about the distinction.

"git grep OI_DBCACHED" shows only a single hit, which is what you
are getting rid of in this patch, but I cannot claim that we did a
sufficient audit, as this change will break code paths that check if
they got OI_PACKED and do something differently (or if what they got
is different from OI_PACKED, for that matter).

>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  odb.h      | 1 -
>  packfile.c | 3 +--
>  2 files changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/odb.h b/odb.h
> index 014cd9585a..73b0b87ad5 100644
> --- a/odb.h
> +++ b/odb.h
> @@ -330,7 +330,6 @@ struct object_info {
>  		OI_CACHED,
>  		OI_LOOSE,
>  		OI_PACKED,
> -		OI_DBCACHED
>  	} whence;
>  	union {
>  		/*
> diff --git a/packfile.c b/packfile.c
> index c88bd92619..79ad9d7179 100644
> --- a/packfile.c
> +++ b/packfile.c
> @@ -1656,8 +1656,7 @@ int packed_object_info(struct repository *r, struct packed_git *p,
>  			oidclr(oi->delta_base_oid, p->repo->hash_algo);
>  	}
>  
> -	oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
> -							  OI_PACKED;
> +	oi->whence = OI_PACKED;
>  
>  out:
>  	unuse_pack(&w_curs);