On Fri, Aug 20 2021, Patrick Steinhardt wrote:
> [[PGP Signed Part:Undecided]]
> When updating local refs after the fetch has transferred all objects, we
> do an object existence test as a safety guard to avoid updating a ref to
> an object which we don't have. We do so via `oid_object_info()`: if it
> returns an error, then we know the object does not exist.
>
> One side effect of `oid_object_info()` is that it parses the object's
> type, and to do so it must unpack the object header. This is completely
> pointless: we don't care for the type, but only want to assert that the
> object exists.
>
> Refactor the code to use `repo_has_object_file()`, which both makes the
> code's intent clearer and is also faster because it does not unpack
> object headers. In a real-world repo with 2.3M refs, this results in a
> small speedup when doing a mirror-fetch:
>
> Benchmark #1: HEAD~: git-fetch
> Time (mean ± σ): 33.686 s ± 0.176 s [User: 30.119 s, System: 5.262 s]
> Range (min … max): 33.512 s … 33.944 s 5 runs
>
> Benchmark #2: HEAD: git-fetch
> Time (mean ± σ): 31.247 s ± 0.195 s [User: 28.135 s, System: 5.066 s]
> Range (min … max): 30.948 s … 31.472 s 5 runs
>
> Summary
> 'HEAD: git-fetch' ran
> 1.08 ± 0.01 times faster than 'HEAD~: git-fetch'
>
> Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
> ---
> builtin/fetch.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/builtin/fetch.c b/builtin/fetch.c
> index 73f5b286d5..5fd0f7c791 100644
> --- a/builtin/fetch.c
> +++ b/builtin/fetch.c
> @@ -846,13 +846,11 @@ static int update_local_ref(struct ref *ref,
> int summary_width)
> {
> struct commit *current = NULL, *updated;
> - enum object_type type;
> struct branch *current_branch = branch_get(NULL);
> const char *pretty_ref = prettify_refname(ref->name);
> int fast_forward = 0;
>
> - type = oid_object_info(the_repository, &ref->new_oid, NULL);
> - if (type < 0)
> + if (!repo_has_object_file(the_repository, &ref->new_oid))
> die(_("object %s not found"), oid_to_hex(&ref->new_oid));
>
> if (oideq(&ref->old_oid, &ref->new_oid)) {
I tried grepping the source for any other candidates for a migration to
repo_has_object_file(), but this is the only "type = oid_object_info" I
could find that didn't care about the type, perhaps there's some callers
of *_extended() that could be moved over, but that's less likely, and I
didn't check...
