From: Patrick Steinhardt <ps@pks.im>
To: git@vger.kernel.org
Cc: "Jeff King" <peff@peff.net>,
"Felipe Contreras" <felipe.contreras@gmail.com>,
"SZEDER Gábor" <szeder.dev@gmail.com>,
"Chris Torek" <chris.torek@gmail.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Junio C Hamano" <gitster@pobox.com>,
"Taylor Blau" <me@ttaylorr.com>
Subject: [PATCH v5 5/5] revision: avoid hitting packfiles when commits are in commit-graph
Date: Mon, 9 Aug 2021 10:12:03 +0200 [thread overview]
Message-ID: <fdb1fa9d574a27500df7f16a165997a41a8cc8e8.1628496539.git.ps@pks.im> (raw)
In-Reply-To: <cover.1628496538.git.ps@pks.im>
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When queueing references in git-rev-list(1), we try to optimize parsing
of commits via the commit-graph. To do so, we first look up the object's
type, and if it is a commit we call `repo_parse_commit()` instead of
`parse_object()`. This is quite inefficient though given that we're
always uncompressing the object header in order to determine the type.
Instead, we can opportunistically search the commit-graph for the object
ID: in case it's found, we know it's a commit and can directly fill in
the commit object without having to uncompress the object header.
Expose a new function `lookup_commit_in_graph()`, which tries to find a
commit in the commit-graph by ID, and convert `get_reference()` to use
this function. This provides a big performance win in cases where we
load references in a repository with lots of references pointing to
commits. The following has been executed in a real-world repository with
about 2.2 million refs:
Benchmark #1: HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev
Time (mean ± σ): 4.458 s ± 0.044 s [User: 4.115 s, System: 0.342 s]
Range (min … max): 4.409 s … 4.534 s 10 runs
Benchmark #2: HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev
Time (mean ± σ): 3.089 s ± 0.015 s [User: 2.768 s, System: 0.321 s]
Range (min … max): 3.061 s … 3.105 s 10 runs
Summary
'HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev' ran
1.44 ± 0.02 times faster than 'HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev'
Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
commit-graph.c | 24 ++++++++++++++++++++++++
commit-graph.h | 8 ++++++++
revision.c | 18 ++++++++----------
3 files changed, 40 insertions(+), 10 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 8c4c7262c8..00614acd65 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -891,6 +891,30 @@ static int find_commit_pos_in_graph(struct commit *item, struct commit_graph *g,
}
}
+struct commit *lookup_commit_in_graph(struct repository *repo, const struct object_id *id)
+{
+ struct commit *commit;
+ uint32_t pos;
+
+ if (!repo->objects->commit_graph)
+ return NULL;
+ if (!search_commit_pos_in_graph(id, repo->objects->commit_graph, &pos))
+ return NULL;
+ if (!repo_has_object_file(repo, id))
+ return NULL;
+
+ commit = lookup_commit(repo, id);
+ if (!commit)
+ return NULL;
+ if (commit->object.parsed)
+ return commit;
+
+ if (!fill_commit_in_graph(repo, commit, repo->objects->commit_graph, pos))
+ return NULL;
+
+ return commit;
+}
+
static int parse_commit_in_graph_one(struct repository *r,
struct commit_graph *g,
struct commit *item)
diff --git a/commit-graph.h b/commit-graph.h
index 96c24fb577..04a94e1830 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -40,6 +40,14 @@ int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
*/
int parse_commit_in_graph(struct repository *r, struct commit *item);
+/*
+ * Look up the given commit ID in the commit-graph. This will only return a
+ * commit if the ID exists both in the graph and in the object database such
+ * that we don't return commits whose object has been pruned. Otherwise, this
+ * function returns `NULL`.
+ */
+struct commit *lookup_commit_in_graph(struct repository *repo, const struct object_id *id);
+
/*
* It is possible that we loaded commit contents from the commit buffer,
* but we also want to ensure the commit-graph content is correctly
diff --git a/revision.c b/revision.c
index 80a59896b9..0dabb5a0bc 100644
--- a/revision.c
+++ b/revision.c
@@ -360,20 +360,18 @@ static struct object *get_reference(struct rev_info *revs, const char *name,
unsigned int flags)
{
struct object *object;
+ struct commit *commit;
/*
- * If the repository has commit graphs, repo_parse_commit() avoids
- * reading the object buffer, so use it whenever possible.
+ * If the repository has commit graphs, we try to opportunistically
+ * look up the object ID in those graphs. Like this, we can avoid
+ * parsing commit data from disk.
*/
- if (oid_object_info(revs->repo, oid, NULL) == OBJ_COMMIT) {
- struct commit *c = lookup_commit(revs->repo, oid);
- if (!repo_parse_commit(revs->repo, c))
- object = (struct object *) c;
- else
- object = NULL;
- } else {
+ commit = lookup_commit_in_graph(revs->repo, oid);
+ if (commit)
+ object = &commit->object;
+ else
object = parse_object(revs->repo, oid);
- }
if (!object) {
if (revs->ignore_missing)
--
2.32.0
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prev parent reply other threads:[~2021-08-09 8:12 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-28 5:33 [PATCH v2 0/3] Speed up connectivity checks via bitmaps Patrick Steinhardt
2021-06-28 5:33 ` [PATCH v2 1/3] p5400: add perf tests for git-receive-pack(1) Patrick Steinhardt
2021-06-28 7:49 ` Ævar Arnfjörð Bjarmason
2021-06-29 6:18 ` Patrick Steinhardt
2021-06-29 12:09 ` Ævar Arnfjörð Bjarmason
2021-06-28 5:33 ` [PATCH v2 2/3] receive-pack: skip connectivity checks on delete-only commands Patrick Steinhardt
2021-06-28 8:00 ` Ævar Arnfjörð Bjarmason
2021-06-28 8:06 ` Ævar Arnfjörð Bjarmason
2021-06-29 6:26 ` Patrick Steinhardt
2021-06-30 1:31 ` Jeff King
2021-06-30 1:35 ` Jeff King
2021-06-30 13:52 ` Patrick Steinhardt
2021-06-28 5:33 ` [PATCH v2 3/3] connected: implement connectivity check using bitmaps Patrick Steinhardt
2021-06-28 20:23 ` Taylor Blau
2021-06-29 22:44 ` Taylor Blau
2021-06-30 2:04 ` Jeff King
2021-06-30 3:07 ` Taylor Blau
2021-06-30 5:45 ` Jeff King
2021-07-02 17:44 ` Taylor Blau
2021-07-02 21:21 ` Jeff King
2021-06-30 1:51 ` Jeff King
2021-07-20 14:26 ` Patrick Steinhardt
2021-08-02 9:37 ` [PATCH v3 0/4] Speed up connectivity checks Patrick Steinhardt
2021-08-02 9:38 ` [PATCH v3 1/4] connected: do not sort input revisions Patrick Steinhardt
2021-08-02 12:49 ` Ævar Arnfjörð Bjarmason
2021-08-03 8:50 ` Patrick Steinhardt
2021-08-04 11:01 ` Ævar Arnfjörð Bjarmason
2021-08-02 19:00 ` Junio C Hamano
2021-08-03 8:55 ` Patrick Steinhardt
2021-08-03 21:47 ` Junio C Hamano
2021-08-02 9:38 ` [PATCH v3 2/4] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-02 12:53 ` Ævar Arnfjörð Bjarmason
2021-08-02 9:38 ` [PATCH v3 3/4] revision: avoid loading object headers multiple times Patrick Steinhardt
2021-08-02 12:55 ` Ævar Arnfjörð Bjarmason
2021-08-05 10:12 ` Patrick Steinhardt
2021-08-02 19:40 ` Junio C Hamano
2021-08-03 9:07 ` Patrick Steinhardt
2021-08-06 14:17 ` Patrick Steinhardt
2021-08-02 9:38 ` [PATCH v3 4/4] revision: avoid hitting packfiles when commits are in commit-graph Patrick Steinhardt
2021-08-02 20:01 ` Junio C Hamano
2021-08-03 9:16 ` Patrick Steinhardt
2021-08-03 21:56 ` Junio C Hamano
2021-08-05 11:01 ` Patrick Steinhardt
2021-08-05 16:16 ` Junio C Hamano
2021-08-04 10:51 ` Ævar Arnfjörð Bjarmason
2021-08-05 11:25 ` [PATCH v4 0/6] Speed up connectivity checks Patrick Steinhardt
2021-08-05 11:25 ` [PATCH v4 1/6] revision: separate walk and unsorted flags Patrick Steinhardt
2021-08-05 18:47 ` Junio C Hamano
2021-08-05 11:25 ` [PATCH v4 2/6] connected: do not sort input revisions Patrick Steinhardt
2021-08-05 18:44 ` Junio C Hamano
2021-08-06 6:00 ` Patrick Steinhardt
2021-08-06 16:50 ` Junio C Hamano
2021-08-05 11:25 ` [PATCH v4 3/6] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-05 11:25 ` [PATCH v4 4/6] revision: avoid loading object headers multiple times Patrick Steinhardt
2021-08-05 11:25 ` [PATCH v4 5/6] commit-graph: split out function to search commit position Patrick Steinhardt
2021-08-05 11:25 ` [PATCH v4 6/6] revision: avoid hitting packfiles when commits are in commit-graph Patrick Steinhardt
2021-08-09 8:00 ` [PATCH v5 0/5] Speed up connectivity checks Patrick Steinhardt
2021-08-09 8:02 ` Patrick Steinhardt
2021-08-09 8:11 ` Patrick Steinhardt
2021-08-09 8:11 ` [PATCH v5 1/5] revision: separate walk and unsorted flags Patrick Steinhardt
2021-08-09 8:11 ` [PATCH v5 2/5] connected: do not sort input revisions Patrick Steinhardt
2021-08-09 8:11 ` [PATCH v5 3/5] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-09 8:11 ` [PATCH v5 4/5] commit-graph: split out function to search commit position Patrick Steinhardt
2021-08-09 8:12 ` Patrick Steinhardt [this message]
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