From: "Kristofer Karlsson via GitGitGadget" <gitgitgadget@gmail•com>
To: git@vger•kernel.org
Cc: Kristofer Karlsson <krka@spotify•com>,
Kristofer Karlsson <krka@spotify•com>
Subject: [PATCH 1/3] commit-reach: deduplicate queue entries in paint_down_to_common
Date: Sun, 24 May 2026 17:42:18 +0000 [thread overview]
Message-ID: <1d3751569ba3a5f0c353fb468578d6c5bcd0b738.1779644541.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.2124.git.1779644541.gitgitgadget@gmail.com>
From: Kristofer Karlsson <krka@spotify•com>
paint_down_to_common() can enqueue the same commit multiple times
when it is reached through different parents with different flag
combinations. Add an ENQUEUED flag to track whether a commit is
currently in the priority queue, and skip it if already present.
This change is performance-neutral on its own: the O(n)
queue_has_nonstale() scan still dominates the per-iteration cost.
However, the deduplication guarantee (each commit appears in the
queue at most once) is a prerequisite for the next commit, which
replaces that scan with an O(1) nonstale counter.
Signed-off-by: Kristofer Karlsson <krka@spotify•com>
---
commit-reach.c | 19 +++++++++++++++----
object.h | 2 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/commit-reach.c b/commit-reach.c
index d3a9b3ed6f..c16d4b061c 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -17,8 +17,9 @@
#define PARENT2 (1u<<17)
#define STALE (1u<<18)
#define RESULT (1u<<19)
+#define ENQUEUED (1u<<20)
-static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
+static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT | ENQUEUED);
static int compare_commits_by_gen(const void *_a, const void *_b)
{
@@ -39,6 +40,14 @@ static int compare_commits_by_gen(const void *_a, const void *_b)
return 0;
}
+static void maybe_enqueue(struct prio_queue *queue, struct commit *c)
+{
+ if (c->object.flags & ENQUEUED)
+ return;
+ c->object.flags |= ENQUEUED;
+ prio_queue_put(queue, c);
+}
+
static int queue_has_nonstale(struct prio_queue *queue)
{
for (size_t i = 0; i < queue->nr; i++) {
@@ -70,11 +79,11 @@ static int paint_down_to_common(struct repository *r,
commit_list_append(one, result);
return 0;
}
- prio_queue_put(&queue, one);
+ maybe_enqueue(&queue, one);
for (i = 0; i < n; i++) {
twos[i]->object.flags |= PARENT2;
- prio_queue_put(&queue, twos[i]);
+ maybe_enqueue(&queue, twos[i]);
}
while (queue_has_nonstale(&queue)) {
@@ -83,6 +92,8 @@ static int paint_down_to_common(struct repository *r,
int flags;
timestamp_t generation = commit_graph_generation(commit);
+ commit->object.flags &= ~ENQUEUED;
+
if (min_generation && generation > last_gen)
BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
generation, last_gen,
@@ -124,7 +135,7 @@ static int paint_down_to_common(struct repository *r,
oid_to_hex(&p->object.oid));
}
p->object.flags |= flags;
- prio_queue_put(&queue, p);
+ maybe_enqueue(&queue, p);
}
}
diff --git a/object.h b/object.h
index d814647ebe..05cbf728e9 100644
--- a/object.h
+++ b/object.h
@@ -74,7 +74,7 @@ void object_array_init(struct object_array *array);
* bundle.c: 16
* http-push.c: 11-----14
* commit-graph.c: 15
- * commit-reach.c: 16-----19
+ * commit-reach.c: 16-------20
* builtin/last-modified.c: 1617
* sha1-name.c: 20
* list-objects-filter.c: 21
--
gitgitgadget
next prev parent reply other threads:[~2026-05-24 17:42 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-24 17:42 [PATCH 0/3] commit-reach: replace queue_has_nonstale with a counter Kristofer Karlsson via GitGitGadget
2026-05-24 17:42 ` Kristofer Karlsson via GitGitGadget [this message]
2026-05-24 23:40 ` [PATCH 1/3] commit-reach: deduplicate queue entries in paint_down_to_common Junio C Hamano
2026-05-25 1:43 ` Derrick Stolee
2026-05-25 6:50 ` Kristofer Karlsson
2026-05-25 7:17 ` Junio C Hamano
2026-05-25 7:53 ` Kristofer Karlsson
2026-05-25 10:02 ` Jeff King
2026-05-25 7:01 ` Jeff King
2026-05-25 7:15 ` Jeff King
2026-05-24 17:42 ` [PATCH 2/3] commit-reach: optimize queue scan " Kristofer Karlsson via GitGitGadget
2026-05-25 1:59 ` Derrick Stolee
2026-05-25 8:54 ` Kristofer Karlsson
2026-05-24 17:42 ` [PATCH 3/3] commit-reach: optimize queue scan in ahead_behind Kristofer Karlsson via GitGitGadget
2026-05-25 7:11 ` Jeff King
2026-05-25 6:47 ` [PATCH 0/3] commit-reach: replace queue_has_nonstale with a counter Jeff King
2026-05-25 7:59 ` Kristofer Karlsson
2026-05-25 8:38 ` Junio C Hamano
2026-05-25 9:55 ` Jeff King
2026-05-25 10:47 ` Kristofer Karlsson
2026-05-25 14:28 ` [PATCH v2 0/3] commit-reach: replace queue_has_nonstale() scan with O(1) tracking Kristofer Karlsson via GitGitGadget
2026-05-25 14:28 ` [PATCH v2 1/3] object.h: fix stale entries in object flag allocation table Kristofer Karlsson via GitGitGadget
2026-05-25 14:28 ` [PATCH v2 2/3] commit-reach: deduplicate queue entries in paint_down_to_common Kristofer Karlsson via GitGitGadget
2026-05-25 22:50 ` Junio C Hamano
2026-05-26 6:57 ` Kristofer Karlsson
2026-05-25 14:28 ` [PATCH v2 3/3] commit-reach: replace queue_has_nonstale() scan with O(1) tracking Kristofer Karlsson via GitGitGadget
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1d3751569ba3a5f0c353fb468578d6c5bcd0b738.1779644541.git.gitgitgadget@gmail.com \
--to=gitgitgadget@gmail$(echo .)com \
--cc=git@vger$(echo .)kernel.org \
--cc=krka@spotify$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox