Re: [PATCH] builtin/refs: add '--skip-reflog' flag to bypass reflog migration

> While this behavior is desirable for most client-side repositories,
> server-side repositories typically don't use reflogs and the migration
> of these entries is unnecessary overhead.
> 
> Add a '--skip-reflog' flag to the migrate subcommand to make reflog
> migration optional. This is particularly useful for server-side
> migrations where reflogs are not needed, improving migration performance
> in these scenarios.

> 
> Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
> ---
> ---
>  builtin/refs.c          |  3 +++
>  refs.c                  |  8 +++++---
>  refs.h                  |  5 ++++-
>  t/t1460-refs-migrate.sh | 17 +++++++++++++++--
>  4 files changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/builtin/refs.c b/builtin/refs.c
> index a29f19583474518ee0942ea53c39cbdf9661c5e2..30be0254c14dd3d07693d70c25dddc9990756e9c 100644
> --- a/builtin/refs.c
> +++ b/builtin/refs.c
> @@ -30,6 +30,9 @@ static int cmd_refs_migrate(int argc, const char **argv, const char *prefix,
>  		OPT_BIT(0, "dry-run", &flags,
>  			N_("perform a non-destructive dry-run"),
>  			REPO_MIGRATE_REF_STORAGE_FORMAT_DRYRUN),
> +		OPT_BIT(0, "skip-reflog", &flags,
> +			N_("skip migrating reflogs"),
> +			REPO_MIGRATE_REF_STORAGE_FORMAT_SKIP_REFLOG),
>  		OPT_END(),
>  	};
>  	struct strbuf errbuf = STRBUF_INIT;
> diff --git a/refs.c b/refs.c
> index f4094a326a9f88f979654b668cc9c3d27d83cb5d..5e8f5c06fa68d16c93ee11edd9742995eea994b6 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -3035,9 +3035,11 @@ int repo_migrate_ref_storage_format(struct repository *repo,
>  	if (ret < 0)
>  		goto done;
>  
> -	ret = refs_for_each_reflog(old_refs, migrate_one_reflog, &data);
> -	if (ret < 0)
> -		goto done;
> +	if (!(flags & REPO_MIGRATE_REF_STORAGE_FORMAT_SKIP_REFLOG)) {
> +		ret = refs_for_each_reflog(old_refs, migrate_one_reflog, &data);
> +		if (ret < 0)
> +			goto done;
> +	}

>  
>  	ret = ref_transaction_commit(transaction, errbuf);
>  	if (ret < 0)
> diff --git a/refs.h b/refs.h
> index a0cdd99250e8286b55808b697b0a94afac5d8319..ccee8fc6705e6e93a1c6234e7395180f8dfd815b 100644
> --- a/refs.h
> +++ b/refs.h
> @@ -1157,8 +1157,11 @@ int is_pseudo_ref(const char *refname);
>   *   - REPO_MIGRATE_REF_STORAGE_FORMAT_DRYRUN: perform a dry-run migration
>   *     without touching the main repository. The result will be written into a
>   *     temporary ref storage directory.
> + *
> + *   - REPO_MIGRATE_REF_STORAGE_FORMAT_SKIP_REFLOG: skip migration of reflogs.
>   */
> -#define REPO_MIGRATE_REF_STORAGE_FORMAT_DRYRUN (1 << 0)
> +#define REPO_MIGRATE_REF_STORAGE_FORMAT_DRYRUN      (1 << 0)
> +#define REPO_MIGRATE_REF_STORAGE_FORMAT_SKIP_REFLOG (1 << 1)
>  
>  /*
>   * Migrate the ref storage format used by the repository to the
> diff --git a/t/t1460-refs-migrate.sh b/t/t1460-refs-migrate.sh
> index a6d9b35a46eb59350aa0d59d982a2fbfaecf1448..9059d4c4121842a9d2e77dc4e54c537eeff8afab 100755
> --- a/t/t1460-refs-migrate.sh
> +++ b/t/t1460-refs-migrate.sh
> @@ -9,14 +9,16 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
>  
>  # Migrate the provided repository from one format to the other and
>  # verify that the references and logs are migrated over correctly.
> -# Usage: test_migration <repo> <format> <skip_reflog_verify>
> +# Usage: test_migration <repo> <format> <skip_reflog_verify> <...options>
>  #   <repo> is the relative path to the repo to be migrated.
>  #   <format> is the ref format to be migrated to.
>  #   <skip_reflog_verify> (true or false) whether to skip reflog verification.
> +#   <...options> are other options be passed directly to 'git refs migrate'.
>  test_migration () {
>  	repo=$1 &&
>  	format=$2 &&
>  	skip_reflog_verify=${3:-false} &&
> +	shift $(( $# >= 3 ? 3 : 2 )) &&
>  	git -C "$repo" for-each-ref --include-root-refs \
>  		--format='%(refname) %(objectname) %(symref)' >expect &&
>  	if ! $skip_reflog_verify
> @@ -25,7 +27,7 @@ test_migration () {
>  	   git -C "$repo" reflog list >expect_log_list
>  	fi &&
>  
> -	git -C "$repo" refs migrate --ref-format="$2" &&
> +	git -C "$repo" refs migrate --ref-format="$format" $@ &&
>  
>  	git -C "$repo" for-each-ref --include-root-refs \
>  		--format='%(refname) %(objectname) %(symref)' >actual &&
> @@ -241,6 +243,17 @@ do
>  				test_cmp expect.reflog actual.reflog
>  			)
>  		'
> +
> +		test_expect_success "$from_format -> $to_format: skip reflog with --skip-reflog" '
> +			test_when_finished "rm -rf repo" &&
> +			git init --ref-format=$from_format repo &&
> +			test_commit -C repo initial &&
> +			# we see that the repository contains reflogs.
> +			test 2 = $(git -C repo reflog --all | wc -l) &&
> +			test_migration repo "$to_format" true --skip-reflog &&
> +			# there should be no reflogs post migration.
> +			test 0 = $(git -C repo reflog --all | wc -l)
> +		'
>  	done
>  done
>  
> 
> ---
> 
> base-commit: bc204b742735ae06f65bb20291c95985c9633b7f
> change-id: 20250207-477-refs-migrate-add-a-flag-to-ignore-reflogs-during-migration-8066f6df50ac
> 
> Thanks
> - Karthik
> 
>