user/dev discussion of public-inbox itself
 help / color / Atom feed
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
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


      parent reply index

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]

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

  List information: http://public-inbox.org/README

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190530065227.17641-5-e@80x24.org \
    --to=e@80x24.org \
    --cc=meta@public-inbox.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

user/dev discussion of public-inbox itself

Archives are clonable:
	git clone --mirror http://public-inbox.org/meta
	git clone --mirror http://czquwvybam4bgbro.onion/meta
	git clone --mirror http://hjrcffqmbrq6wope.onion/meta
	git clone --mirror http://ou63pmih66umazou.onion/meta

Example config snippet for mirrors

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.mail.public-inbox.meta
	nntp://ou63pmih66umazou.onion/inbox.comp.mail.public-inbox.meta
	nntp://czquwvybam4bgbro.onion/inbox.comp.mail.public-inbox.meta
	nntp://hjrcffqmbrq6wope.onion/inbox.comp.mail.public-inbox.meta
	nntp://news.gmane.io/gmane.mail.public-inbox.general

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git