Re: [PATCH 1/5] upload-pack: look up "want" lines via commit-graph
From: Derrick Stolee <hidden>
Date: 2022-02-23 14:13:59
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()?
quoted hunk ↗ jump to hunk
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