From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 4/4] v2writable: short-circuit is_ancestor check on equality
Date: Thu, 30 May 2019 06:52:27 +0000 [thread overview]
Message-ID: <20190530065227.17641-5-e@80x24.org> (raw)
In-Reply-To: <20190530065227.17641-1-e@80x24.org>
We don't need to use git to check ancestry if object IDs
match on a string comparison.
This saves 100ms or so and brings down the ~0.5s no-op time on
lore.kernel.org/lkml down to ~0.4s.
---
lib/PublicInbox/V2Writable.pm | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index fd93ac2..76844cd 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -831,6 +831,12 @@ sub log_range ($$$$$) {
return $tip; # all of it
};
+ # fast equality check to avoid (v)fork+execve overhead
+ if ($cur eq $tip) {
+ $sync->{ranges}->[$i] = undef;
+ return;
+ }
+
my $range = "$cur..$tip";
$pr->("$i.git checking contiguity... ") if $pr;
if (is_ancestor($git, $cur, $tip)) { # common case
--
EW
prev parent reply other threads:[~2019-05-30 6:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 6:52 [PATCH 0/4] v2writable: speedup no-op -index invocation Eric Wong
2019-05-30 6:52 ` [PATCH 1/4] v2writable: split off unindex_range mapping Eric Wong
2019-05-30 6:52 ` [PATCH 2/4] v2writable: hoist out index_epoch sub Eric Wong
2019-05-30 6:52 ` [PATCH 3/4] v2writable: avoid mm_tmp creation without regen Eric Wong
2019-05-30 6:52 ` Eric Wong [this message]
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