treewide: "require" + "use" cleanup and docs

[public-inbox.git] / lib / PublicInbox / Listener.pm

diff --git a/lib/PublicInbox/Listener.pm b/lib/PublicInbox/Listener.pm
index a3a2015b04d16dc5bd8904140bf14d63e7c6ccd6..928d9301902fdb059ddbd4a2603af92cb6848736 100644 (file)
--- a/lib/PublicInbox/Listener.pm
+++ b/lib/PublicInbox/Listener.pm
@@ -1,31 +1,37 @@
-# Copyright (C) 2015 all contributors <meta@public-inbox.org>
-# License: AGPLv3 or later (https://www.gnu.org/licenses/agpl-3.0.txt)
+# Copyright (C) 2015-2019 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 #
 # Used by -nntpd for listen sockets
 package PublicInbox::Listener;
 use strict;
 use warnings;
-use base 'Danga::Socket';
+use base 'PublicInbox::DS';
 use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY);
 use fields qw(post_accept);
-require IO::Handle;
+use IO::Handle;
+use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE EPOLLET);
+use Errno qw(EAGAIN ECONNABORTED EPERM);
+
+# Warn on transient errors, mostly resource limitations.
+# EINTR would indicate the failure to set NonBlocking in systemd or similar
+my %ERR_WARN = map {;
+       eval("Errno::$_()") => $_
+} qw(EMFILE ENFILE ENOBUFS ENOMEM EINTR);
 
 sub new ($$$) {
        my ($class, $s, $cb) = @_;
        setsockopt($s, SOL_SOCKET, SO_KEEPALIVE, 1);
        setsockopt($s, IPPROTO_TCP, TCP_NODELAY, 1); # ignore errors on non-TCP
        listen($s, 1024);
-       IO::Handle::blocking($s, 0);
        my $self = fields::new($class);
-       $self->SUPER::new($s); # calls epoll_create for the first socket
-       $self->watch_read(1);
+       $self->SUPER::new($s, EPOLLIN|EPOLLET|EPOLLEXCLUSIVE);
        $self->{post_accept} = $cb;
        $self
 }
 
-sub event_read {
+sub event_step {
        my ($self) = @_;
-       my $sock = $self->{sock};
+       my $sock = $self->{sock} or return;
 
        # no loop here, we want to fairly distribute clients
        # between multiple processes sharing the same socket
@@ -35,6 +41,19 @@ sub event_read {
        if (my $addr = accept(my $c, $sock)) {
                IO::Handle::blocking($c, 0); # no accept4 :<
                $self->{post_accept}->($c, $addr, $sock);
+               $self->requeue;
+       } elsif ($! == EAGAIN || $! == ECONNABORTED || $! == EPERM) {
+               # EAGAIN is common and likely
+               # ECONNABORTED is common with bad connections
+               # EPERM happens if firewall rules prevent a connection
+               # on Linux (and everything that emulates Linux).
+               # Firewall rules are sometimes intentional, so we don't
+               # warn on EPERM to avoid being too noisy...
+               return;
+       } elsif (my $sym = $ERR_WARN{int($!)}) {
+               warn "W: accept(): $! ($sym)\n";
+       } else {
+               warn "BUG?: accept(): $!\n";
        }
 }