listener: switch to level-triggered epoll

On second thought, the ->requeue + accept retry code path isn't
worth the userspace complexity and overhead.  Level-triggered
epoll has always annoyed me since it takes an inefficient code
path in the kernel; but taking our less-efficient code path in
Perl seems even worse.  We also need to take load distribution
into account for multi-worker systems.

diff --git a/lib/PublicInbox/Listener.pm b/lib/PublicInbox/Listener.pm
index 64bba5b0fd7c491e7e1d5641116c83581c3e85e4..09f1f2e5fabde020d464995552e896729981d4c6 100644 (file)
--- a/lib/PublicInbox/Listener.pm
+++ b/lib/PublicInbox/Listener.pm
@@ -7,7 +7,7 @@ use strict;
 use parent 'PublicInbox::DS';
 use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY);
 use IO::Handle;
-use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE EPOLLET);
+use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE);
 use Errno qw(EAGAIN ECONNABORTED EPERM);
 
 # Warn on transient errors, mostly resource limitations.
@@ -22,7 +22,7 @@ sub new ($$$) {
        setsockopt($s, IPPROTO_TCP, TCP_NODELAY, 1); # ignore errors on non-TCP
        listen($s, 2**31 - 1); # kernel will clamp
        my $self = bless { post_accept => $cb }, $class;
-       $self->SUPER::new($s, EPOLLIN|EPOLLET|EPOLLEXCLUSIVE);
+       $self->SUPER::new($s, EPOLLIN|EPOLLEXCLUSIVE);
 }
 
 sub event_step {
@@ -38,7 +38,6 @@ sub event_step {
                IO::Handle::blocking($c, 0); # no accept4 :<
                eval { $self->{post_accept}->($c, $addr, $sock) };
                warn "E: $@\n" if $@;
-               $self->requeue;
        } elsif ($! == EAGAIN || $! == ECONNABORTED || $! == EPERM) {
                # EAGAIN is common and likely
                # ECONNABORTED is common with bad connections