1 # Copyright (C) all contributors <meta@public-inbox.org>
2 # Licensed the same as Danga::Socket (and Perl5)
3 # License: GPL-1.0+ or Artistic-1.0-Perl
4 # <https://www.gnu.org/licenses/gpl-1.0.txt>
5 # <https://dev.perl.org/licenses/artistic.html>
7 # kqueue support via IO::KQueue XS module. This makes kqueue look
8 # like epoll to simplify the code in DS.pm. This is NOT meant to be
9 # an all encompassing emulation of epoll via IO::KQueue, but just to
10 # support cases public-inbox-nntpd/httpd care about.
12 # It also implements signalfd(2) emulation via "tie".
13 package PublicInbox::DSKQXS;
15 use parent qw(Exporter);
16 use Symbol qw(gensym);
19 use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLLET
20 EPOLL_CTL_ADD EPOLL_CTL_MOD EPOLL_CTL_DEL);
21 our @EXPORT_OK = qw(epoll_ctl epoll_wait);
23 sub EV_DISPATCH () { 0x0080 }
25 # map EPOLL* bits to kqueue EV_* flags for EV_SET
30 $fl |= EV_CLEAR if $fl & EPOLLET;
32 # EV_DISPATCH matches EPOLLONESHOT semantics more closely
33 # than EV_ONESHOT, in that EV_ADD is not required to
34 # re-enable a disabled watch.
35 ($ev & EPOLLONESHOT) ? ($fl | EV_DISPATCH) : $fl;
43 bless { kq => IO::KQueue->new, owner_pid => $$ }, $class;
46 # returns a new instance which behaves like signalfd on Linux.
47 # It's wasteful in that it uses another FD, but it simplifies
48 # our epoll-oriented code.
50 my ($class, $signo, $nonblock) = @_;
52 tie *$sym, $class, $signo, $nonblock; # calls TIEHANDLE
56 sub TIEHANDLE { # similar to signalfd()
57 my ($class, $signo, $nonblock) = @_;
58 my $self = $class->new;
59 $self->{timeout} = $nonblock ? 0 : -1;
61 $kq->EV_SET($_, EVFILT_SIGNAL, EV_ADD) for @$signo;
65 sub READ { # called by sysread() for signalfd compatibility
66 my ($self, undef, $len, $off) = @_; # $_[1] = buf
67 die "bad args for signalfd read" if ($len % 128) // defined($off);
68 my $timeout = $self->{timeout};
69 my $sigbuf = $self->{sigbuf} //= [];
75 my $signo = shift(@$sigbuf) or last;
76 # caller only cares about signalfd_siginfo.ssi_signo:
77 $_[1] .= pack('L', $signo) . ("\0" x 124);
81 my @events = eval { $self->{kq}->kevent($timeout) };
82 # workaround https://rt.cpan.org/Ticket/Display.html?id=116615
84 next if $@ =~ /Interrupted system call/;
87 if (!scalar(@events) && $timeout == 0) {
92 # Grab the kevent.ident (signal number). The kevent.data
93 # field shows coalesced signals, and maybe we'll use it
95 @$sigbuf = map { $_->[0] } @events;
99 # for fileno() calls in PublicInbox::DS
100 sub FILENO { ${$_[0]->{kq}} }
103 my ($self, $op, $fd, $ev) = @_;
104 my $kq = $self->{kq};
105 if ($op == EPOLL_CTL_MOD) {
106 $kq->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
107 eval { $kq->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev)) };
108 } elsif ($op == EPOLL_CTL_DEL) {
110 $kq // Carp::confess("nokq $fd");
111 $kq->EV_SET($fd, EVFILT_READ, EV_DISABLE);
112 eval { $kq->EV_SET($fd, EVFILT_WRITE, EV_DISABLE) };
113 } else { # EPOLL_CTL_ADD
114 $kq->EV_SET($fd, EVFILT_READ, EV_ADD|kq_flag(EPOLLIN, $ev));
116 # we call this blindly for read-only FDs such as tied
117 # DSKQXS (signalfd emulation) and Listeners
119 $kq->EV_SET($fd, EVFILT_WRITE, EV_ADD |
120 kq_flag(EPOLLOUT, $ev));
127 my ($self, $maxevents, $timeout_msec, $events) = @_;
128 @$events = eval { $self->{kq}->kevent($timeout_msec) };
130 # workaround https://rt.cpan.org/Ticket/Display.html?id=116615
131 if ($err =~ /Interrupted system call/) {
137 # caller only cares for $events[$i]->[0]
138 $_ = $_->[0] for @$events;
141 # kqueue is close-on-fork (not exec), so we must not close it
142 # in forked processes:
145 my $kq = delete $self->{kq} or return;
146 if (delete($self->{owner_pid}) == $$) {