Re: [WIP 1/2] pack-objects: rename want_.* to ignore_.*

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 2, 2017, 03:45 UTC
Message-ID: <xmqqwp8vyrv1.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <5e8aebf2726481ef63838291c32e07439289d922.1496361873.git.jonathantanmy@google.com>

Jonathan Tan <jonathantanmy@google.com> writes:

> Currently, pack-objects conflates the concepts of "ignoring an object"
> and "including it in to_pack".

Hmph, that statement is a hard to read and agree to. I thought an ignored object that is not going to be packed is one that won't hit to_pack?

I agree that "including to to_pack" and "actually appearing in the resulting pack" are three different things, though. Preferred base objects that are used when constructing a thin pack are thrown into to_pack because they need to participate in the delta base selection computation, but by definition they shouldn't be contained in the resulting pack (hence, nr_result is not incremented for them).

Show 6 quoted lines

> This is fine for now, but a subsequent
> commit will introduce the concept of an object that cannot be completely
> ignored, but should not be included in to_pack either. To separate these
> concepts, restrict want_found_object() and want_object_in_pack() to only
> indicate if the object is to be ignored. This is done by renaming these
> methods and swapping the meanings of the return values 0 and 1.

I am a bit confused by your reasoning. I guess it will become clearer if I knew exactly what you mean by "ignoring". It is not like "pretend as if it didn't exist in the rev-list --objects output we are working off of".

Show 5 quoted lines

> We also take the opportunity to use the terminology "preferred_base"
> instead of "excluded" in these methods. It is true that preferred bases
> are not included in the final packfile generation, but at this point in
> the code, there is no exclusion taking place - on the contrary, if
> something is "excluded", it is in fact guaranteed to be in to_pack.

This one I can understand.

> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
> ---
>  builtin/pack-objects.c | 50 +++++++++++++++++++++++++-------------------------
>  1 file changed, 25 insertions(+), 25 deletions(-)

Without understanding why this change is desirable, I can tell that overall this does not change the behaviour, which is good ;-).