From: Eric Wong <e@80x24.org>
Date: Sat, 30 Sep 2023 15:20:40 +0000 (+0000)
Subject: git+gcf2client: switch to level-triggered wakeups
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f5ac9b00bc95de4a5f4f06266d3a2eb5424e24a;p=thirdparty%2Fpublic-inbox.git

git+gcf2client: switch to level-triggered wakeups

Instead of using ->requeue to emulate level-triggered wakeups in
userspace, just use level-triggered wakeups in the kernel to
save some user time at the expense of system (kernel) time.  Of
course, the ready list implementation in the kernel via C is
faster than a Perl one on our end.

We must still use requeue if we've got buffered data, however.

Followup-to: 1181a7e6a853 (listener: switch to level-triggered epoll)
---

diff --git a/lib/PublicInbox/Gcf2Client.pm b/lib/PublicInbox/Gcf2Client.pm
index 8f4427876..8ac44a5e5 100644
--- a/lib/PublicInbox/Gcf2Client.pm
+++ b/lib/PublicInbox/Gcf2Client.pm
@@ -9,7 +9,7 @@ use PublicInbox::Git;
 use PublicInbox::Gcf2; # fails if Inline::C or libgit2-dev isn't available
 use PublicInbox::Spawn qw(spawn);
 use Socket qw(AF_UNIX SOCK_STREAM);
-use PublicInbox::Syscall qw(EPOLLIN EPOLLET);
+use PublicInbox::Syscall qw(EPOLLIN);
 use PublicInbox::ProcessPipe;
 
 # fields:
@@ -35,7 +35,7 @@ sub new  {
 	my $sock = PublicInbox::ProcessPipe->maybe_new($pid, $s1);
 	$self->{inflight} = [];
 	$self->{epwatch} = \undef; # for Git->cleanup
-	$self->SUPER::new($sock, EPOLLIN|EPOLLET);
+	$self->SUPER::new($sock, EPOLLIN);
 }
 
 sub gcf2_async ($$$;$) {
diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 3062f293f..5003be537 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -650,15 +650,16 @@ sub event_step {
 	if ($inflight && @$inflight) {
 		$self->cat_async_step($inflight);
 		return $self->close unless $self->{sock};
-		# more to do? requeue for fairness:
-		$self->requeue if @$inflight || exists($self->{rbuf});
+		# don't loop here to keep things fair, but we must requeue
+		# if there's already-read data in rbuf
+		$self->requeue if exists($self->{rbuf});
 	}
 }
 
 # idempotently registers with DS epoll/kqueue/select/poll
 sub watch_async ($) {
 	$_[0]->{epwatch} //= do {
-		$_[0]->SUPER::new($_[0]->{sock}, EPOLLIN|EPOLLET);
+		$_[0]->SUPER::new($_[0]->{sock}, EPOLLIN);
 		\undef;
 	}
 }