# Copyright (C) all contributors
# Licensed the same as Danga::Socket (and Perl5)
# License: GPL-1.0+ or Artistic-1.0-Perl
#
#
#
# kqueue support via IO::KQueue XS module. This makes kqueue look
# like epoll to simplify the code in DS.pm. This is NOT meant to be
# an all encompassing emulation of epoll via IO::KQueue, but just to
# support cases public-inbox-nntpd/httpd care about.
#
# It also implements signalfd(2) emulation via "tie".
package PublicInbox::DSKQXS;
use v5.12;
use Symbol qw(gensym);
use IO::KQueue;
use Errno qw(EAGAIN);
use PublicInbox::OnDestroy;
use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLLET);
sub EV_DISPATCH () { 0x0080 }
# map EPOLL* bits to kqueue EV_* flags for EV_SET
sub kq_flag ($$) {
my ($bit, $ev) = @_;
if ($ev & $bit) {
my $fl = EV_ENABLE;
$fl |= EV_CLEAR if $fl & EPOLLET;
# EV_DISPATCH matches EPOLLONESHOT semantics more closely
# than EV_ONESHOT, in that EV_ADD is not required to
# re-enable a disabled watch.
($ev & EPOLLONESHOT) ? ($fl | EV_DISPATCH) : $fl;
} else {
EV_DISABLE;
}
}
sub new {
my ($class) = @_;
my $fgen = $PublicInbox::OnDestroy::fork_gen;
bless { kq => IO::KQueue->new, fgen => $fgen }, $class;
}
# returns a new instance which behaves like signalfd on Linux.
# It's wasteful in that it uses another FD, but it simplifies
# our epoll-oriented code.
sub signalfd {
my ($class, $signo) = @_;
my $sym = gensym;
tie *$sym, $class, $signo; # calls TIEHANDLE
$sym
}
sub TIEHANDLE { # similar to signalfd()
my ($class, $signo) = @_;
my $self = $class->new;
my $kq = $self->{kq};
$kq->EV_SET($_, EVFILT_SIGNAL, EV_ADD) for @$signo;
$self;
}
sub READ { # called by sysread() for signalfd compatibility
my ($self, undef, $len, $off) = @_; # $_[1] = buf
die "bad args for signalfd read" if ($len % 128) // defined($off);
my $sigbuf = $self->{sigbuf} //= [];
my $nr = $len / 128;
my $r = 0;
$_[1] = '';
while (1) {
while ($nr--) {
my $signo = shift(@$sigbuf) or last;
# caller only cares about signalfd_siginfo.ssi_signo:
$_[1] .= pack('L', $signo) . ("\0" x 124);
$r += 128;
}
return $r if $r;
my @events = eval { $self->{kq}->kevent(0) };
# workaround https://rt.cpan.org/Ticket/Display.html?id=116615
if ($@) {
next if $@ =~ /Interrupted system call/;
die;
}
if (!scalar(@events)) {
$! = EAGAIN;
return;
}
# Grab the kevent.ident (signal number). The kevent.data
# field shows coalesced signals, and maybe we'll use it
# in the future...
@$sigbuf = map { $_->[0] } @events;
}
}
# for fileno() calls in PublicInbox::DS
sub FILENO { ${$_[0]->{kq}} }
sub _ep_mod_add ($$$$) {
my ($kq, $fd, $ev, $add) = @_;
$kq->EV_SET($fd, EVFILT_READ, $add|kq_flag(EPOLLIN, $ev));
# we call this blindly for read-only FDs such as tied
# DSKQXS (signalfd emulation) and Listeners
eval { $kq->EV_SET($fd, EVFILT_WRITE, $add|kq_flag(EPOLLOUT, $ev)) };
0;
}
sub ep_add { _ep_mod_add($_[0]->{kq}, fileno($_[1]), $_[2], EV_ADD) };
sub ep_mod { _ep_mod_add($_[0]->{kq}, fileno($_[1]), $_[2], 0) };
sub ep_del {
my ($self, $io, $ev) = @_;
my $kq = $_[0]->{kq} // return; # called in cleanup
my $fd = fileno($io);
$kq->EV_SET($fd, EVFILT_READ, EV_DISABLE);
eval { $kq->EV_SET($fd, EVFILT_WRITE, EV_DISABLE) };
0;
}
sub ep_wait {
my ($self, $timeout_msec, $events) = @_;
# n.b.: IO::KQueue is hard-coded to return up to 1000 events
@$events = eval { $self->{kq}->kevent($timeout_msec) };
if (my $err = $@) {
# workaround https://rt.cpan.org/Ticket/Display.html?id=116615
if ($err =~ /Interrupted system call/) {
@$events = ();
} else {
die $err;
}
}
# caller only cares for $events[$i]->[0]
$_ = $_->[0] for @$events;
}
# kqueue is close-on-fork (not exec), so we must not close it
# in forked processes:
sub DESTROY {
my ($self) = @_;
my $kq = delete $self->{kq} or return;
delete($self->{fgen}) == $PublicInbox::OnDestroy::fork_gen and
POSIX::close($$kq);
}
1;