Subject: Re: [PATCH v5 08/16] refs: stop re-verifying common prefixes for availability

From: shejialuo <[email-masked]>
Date: Wed, 12 Mar 2025 21:22:59 +0800

On Thu, Mar 06, 2025 at 04:08:39PM +0100, Patrick Steinhardt wrote:
>  refs.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/refs.c b/refs.c
> index 5a9b0f2fa1e..eaf41421f50 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -2476,6 +2476,7 @@ int refs_verify_refnames_available(struct ref_store *refs,
>  {
>  	struct strbuf dirname = STRBUF_INIT;
>  	struct strbuf referent = STRBUF_INIT;
> +	struct strset dirnames;
>  	int ret = -1;
>  
>  	/*
> @@ -2485,6 +2486,8 @@ int refs_verify_refnames_available(struct ref_store *refs,
>  
>  	assert(err);
>  
> +	strset_init(&dirnames);
> +
>  	for (size_t i = 0; i < refnames->nr; i++) {
>  		const char *refname = refnames->items[i].string;
>  		const char *extra_refname;
> @@ -2514,6 +2517,14 @@ int refs_verify_refnames_available(struct ref_store *refs,
>  			if (skip && string_list_has_string(skip, dirname.buf))
>  				continue;
>  
> +			/*
> +			 * If we've already seen the directory we don't need to
> +			 * process it again. Skip it to avoid checking checking
> +			 * common prefixes like "refs/heads/" repeatedly.
> +			 */
> +			if (!strset_add(&dirnames, dirname.buf))
> +				continue;
> +

Reading here, I think we should not sort the refnames for "reftable"
backend. Anyway, really a nice job for optimizing the speed.

>  			if (!initial_transaction &&
>  			    !refs_read_raw_ref(refs, dirname.buf, &oid, &referent,
>  					       &type, &ignore_errno)) {
> @@ -2574,6 +2585,7 @@ int refs_verify_refnames_available(struct ref_store *refs,
>  cleanup:
>  	strbuf_release(&referent);
>  	strbuf_release(&dirname);
> +	strset_clear(&dirnames);
>  	return ret;
>  }
>  
> 
> -- 
> 2.49.0.rc0.416.g627208d89d.dirty
>