From ce8cdcd68fd899d28b5d7c0354883b0cb33fc4d6 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 24 Jun 2019 02:52:52 +0000
Subject: nntp: send greeting immediately for plain sockets

A tiny write() for the greeting on a just accept()-ed TCP socket
won't fail with EAGAIN, so we can avoid the extra epoll syscall
traffic with plain sockets.
---
 lib/PublicInbox/NNTP.pm | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 10a2e158..53e18281 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -24,7 +24,7 @@ use constant {
 	r225 =>	'225 Headers follow (multi-line)',
 	r430 => '430 No article with that message-id',
 };
-use PublicInbox::Syscall qw(EPOLLOUT EPOLLONESHOT);
+use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT);
 use Errno qw(EAGAIN);
 
 my @OVERVIEW = qw(Subject From Date Message-ID References Xref);
@@ -96,17 +96,19 @@ sub greet ($) { $_[0]->write($_[0]->{nntpd}->{greet}) };
 sub new ($$$) {
 	my ($class, $sock, $nntpd) = @_;
 	my $self = fields::new($class);
-	my $ev = EPOLLOUT | EPOLLONESHOT;
-	my $wbuf = [];
+	my $ev = EPOLLIN;
+	my $wbuf;
 	if (ref($sock) eq 'IO::Socket::SSL' && !$sock->accept_SSL) {
 		$ev = PublicInbox::TLS::epollbit() or return CORE::close($sock);
-		$ev |= EPOLLONESHOT;
-		$wbuf->[0] = \&PublicInbox::DS::accept_tls_step;
+		$wbuf = [ \&PublicInbox::DS::accept_tls_step, \&greet ];
 	}
-	$self->SUPER::new($sock, $ev);
+	$self->SUPER::new($sock, $ev | EPOLLONESHOT);
 	$self->{nntpd} = $nntpd;
-	push @$wbuf, \&greet;
-	$self->{wbuf} = $wbuf;
+	if ($wbuf) {
+		$self->{wbuf} = $wbuf;
+	} else {
+		greet($self);
+	}
 	update_idle_time($self);
 	$expt ||= PublicInbox::EvCleanup::later(*expire_old);
 	$self;
-- 
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