Re: [PATCH 1/1] sha1-file: split OBJECT_INFO_FOR_PREFETCH
- From
Junio C Hamano <gitster@pobox.com>
- Date
- May 28, 2019, 20:31 UTC
- Message-ID
- <xmqqblzm1fuc.fsf@gitster-ct.c.googlers.com>
- In-Reply-To
- <2737e62966cae2f00d75a93446bad76e5816d07e.1559056745.git.gitgitgadget@gmail.com>
"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
Show 12 quoted lines
> From: Derrick Stolee <dstolee@microsoft.com> > > The OBJECT_INFO_FOR_PREFETCH bitflag was added to sha1-file.c in 0f4a4fb1 > (sha1-file: support OBJECT_INFO_FOR_PREFETCH, 2019-03-29) and is used to > prevent the fetch_objects() method when enabled. > > However, there is a problem with the current use. The definition of > OBJECT_INFO_FOR_PREFETCH is given by adding 32 to OBJECT_INFO_QUICK. This is > clearly stated above the definition (in a comment) that this is so > OBJECT_INFO_FOR_PREFETCH implies OBJECT_INFO_QUICK. The problem is that using > "flag & OBJECT_INFO_FOR_PREFETCH" means that OBJECT_INFO_QUICK also implies > OBJECT_INFO_FOR_PREFETCH.
So the right test to see prefetch is in effect is not
if (!!(flag & TWO_BITS))
but to use
if ((flag & TWO_BITS) == TWO_BITS)
instead?
> Split out the single bit from OBJECT_INFO_FOR_PREFETCH into a new > OBJECT_INFO_SKIP_FETCH_OBJECT as the single bit and keep > OBJECT_INFO_FOR_PREFETCH as the union of two flags. This allows a clearer use > of flag checking while also keeping the implication of OBJECT_INFO_QUICK.
OK, I guess that would work and with far less damage to the existing code.
Show 42 quoted lines
>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
> object-store.h | 10 +++++++---
> sha1-file.c | 2 +-
> 2 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/object-store.h b/object-store.h
> index dd3f9b75f0..c90628d839 100644
> --- a/object-store.h
> +++ b/object-store.h
> @@ -282,10 +282,14 @@ struct object_info {
> #define OBJECT_INFO_IGNORE_LOOSE 16
> /*
> * Do not attempt to fetch the object if missing (even if fetch_is_missing is
> - * nonzero). This is meant for bulk prefetching of missing blobs in a partial
> - * clone. Implies OBJECT_INFO_QUICK.
> + * nonzero).
> */
> -#define OBJECT_INFO_FOR_PREFETCH (32 + OBJECT_INFO_QUICK)
> +#define OBJECT_INFO_SKIP_FETCH_OBJECT 32
> +/*
> + * This is meant for bulk prefetching of missing blobs in a partial
> + * clone. Implies OBJECT_INFO_SKIP_FETCH_OBJECT and OBJECT_INFO_QUICK
> + */
> +#define OBJECT_INFO_FOR_PREFETCH (OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK)
>
> int oid_object_info_extended(struct repository *r,
> const struct object_id *,
> diff --git a/sha1-file.c b/sha1-file.c
> index ad02649124..0299fdd516 100644
> --- a/sha1-file.c
> +++ b/sha1-file.c
> @@ -1371,7 +1371,7 @@ int oid_object_info_extended(struct repository *r, const struct object_id *oid,
> /* Check if it is a missing object */
> if (fetch_if_missing && repository_format_partial_clone &&
> !already_retried && r == the_repository &&
> - !(flags & OBJECT_INFO_FOR_PREFETCH)) {
> + !(flags & OBJECT_INFO_SKIP_FETCH_OBJECT)) {
> /*
> * TODO Investigate having fetch_object() return
> * TODO error/success and stopping the music here.