On 2/23/2022 7:35 AM, Patrick Steinhardt wrote:
> The following benchmark is executed in a repository with a huge number
> of references. It uses cached request from git-fetch(1) as input and
> contains about 876,000 "want" lines:
>
> Benchmark 1: git-upload-pack (HEAD~)
> Time (mean ± σ): 7.113 s ± 0.028 s [User: 6.900 s, System: 0.662 s]
> Range (min … max): 7.072 s … 7.168 s 10 runs
>
> Benchmark 2: git-upload-pack (HEAD)
> Time (mean ± σ): 6.622 s ± 0.061 s [User: 6.452 s, System: 0.650 s]
> Range (min … max): 6.535 s … 6.727 s 10 runs
>
> Summary
> 'git-upload-pack (HEAD)' ran
> 1.07 ± 0.01 times faster than 'git-upload-pack (HEAD~)'
Nice!
> - o = parse_object(the_repository, &oid);
> + commit = lookup_commit_in_graph(the_repository, &oid);
> + if (commit)
> + o = &commit->object;
> + else
> + o = parse_object(the_repository, &oid);
> +
This is a neat trick. I see that we've also done this trick in
revision.c:get_reference(). Perhaps it is worth creating a helper,
maybe named parse_probably_commit()?
> if (!o) {
> packet_writer_error(writer,
> "upload-pack: not our ref %s",
> @@ -1434,7 +1440,7 @@ static int parse_want_ref(struct packet_writer *writer, const char *line,
> if (skip_prefix(line, "want-ref ", &refname_nons)) {
> struct object_id oid;
> struct string_list_item *item;
> - struct object *o;
> + struct object *o = NULL;
> struct strbuf refname = STRBUF_INIT;
>
> strbuf_addf(&refname, "%s%s", get_git_namespace(), refname_nons);
> @@ -1448,7 +1454,15 @@ static int parse_want_ref(struct packet_writer *writer, const char *line,
> item = string_list_append(wanted_refs, refname_nons);
> item->util = oiddup(&oid);
>
> - o = parse_object_or_die(&oid, refname_nons);
> + if (!starts_with(refname_nons, "refs/tags/")) {
> + struct commit *commit = lookup_commit_in_graph(the_repository, &oid);
> + if (commit)
> + o = &commit->object;
> + }
> +
> + if (!o)
> + o = parse_object_or_die(&oid, refname_nons);
> +
Even here, we _could_ use a parse_probably_commit() helper
inside the if (!starts_with(...)) block, even though we would
still need the if (!o) check later.
Thanks,
-Stolee
