[PATCH v2 1/5] upload-pack: look up "want" lines via commit-graph
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Mar 1, 2022, 09:33 UTC
- Message-ID
- <b5c696bd8e4b33e782e4837ad5051268e35f9828.1646127015.git.ps@pks.im>
- In-Reply-To
- <cover.1646127015.git.ps@pks.im>
During packfile negotiation the client will send "want" and "want-ref" lines to the server to tell it which objects it is interested in. The server-side parses each of those and looks them up to see whether it actually has requested objects. This lookup is performed by calling `parse_object()` directly, which thus hits the object database. In the general case though most of the objects the client requests will be commits. We can thus try to look up the object via the commit-graph opportunistically, which is much faster than doing the same via the object database.
Refactor parsing of both "want" and "want-ref" lines to do so.
The following benchmark is executed in a repository with a huge number of references. It uses cached request from git-fetch(1) as input to git-upload-pack(1) that contains about 876,000 "want" lines:
Benchmark 1: 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: 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
'HEAD' ran
1.07 ± 0.01 times faster than 'HEAD~'Signed-off-by: Patrick Steinhardt <ps@pks.im> --- upload-pack.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/upload-pack.c b/upload-pack.c index 8acc98741b..3a851b3606 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -1400,13 +1400,19 @@ static int parse_want(struct packet_writer *writer, const char *line, const char *arg; if (skip_prefix(line, "want ", &arg)) { struct object_id oid; + struct commit *commit; struct object *o; if (get_oid_hex(arg, &oid)) die("git upload-pack: protocol error, " "expected to get oid, not '%s'", line); - 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); + 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); + if (!(o->flags & WANTED)) { o->flags |= WANTED; add_object_array(o, NULL, want_obj);
-- 2.35.1