-# Copyright (C) 2019 all contributors <meta@public-inbox.org>
+# Copyright (C) 2019-2020 all contributors <meta@public-inbox.org>
# Licensed the same as Danga::Socket (and Perl5)
# License: GPL-1.0+ or Artistic-1.0-Perl
# <https://www.gnu.org/licenses/gpl-1.0.txt>
# 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.
-# A pure-Perl version using syscall() is planned, and it should be
-# faster due to the lack of syscall overhead.
+#
+# It also implements signalfd(2) emulation via "tie".
+#
+# A pure-Perl version using syscall() is planned.
package PublicInbox::DSKQXS;
use strict;
use warnings;
-use parent qw(IO::KQueue);
use parent qw(Exporter);
+use Symbol qw(gensym);
use IO::KQueue;
-use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLL_CTL_DEL);
-our @EXPORT = qw(epoll_ctl epoll_wait);
-my $owner_pid = -1; # kqueue is close-on-fork (yes, fork, not exec)
+use Errno qw(EAGAIN);
+use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLLET
+ EPOLL_CTL_ADD EPOLL_CTL_MOD EPOLL_CTL_DEL SFD_NONBLOCK);
+our @EXPORT_OK = qw(epoll_ctl epoll_wait);
+
+sub EV_DISPATCH () { 0x0080 }
# map EPOLL* bits to kqueue EV_* flags for EV_SET
sub kq_flag ($$) {
my ($bit, $ev) = @_;
if ($ev & $bit) {
- my $fl = EV_ADD | EV_ENABLE;
- ($ev & EPOLLONESHOT) ? ($fl | EV_ONESHOT) : $fl;
+ my $fl = EV_ENABLE;
+ $fl |= EV_CLEAR if $fl & EPOLLET;
+
+ # EV_DISPATCH matches EPOLLONESHOT semantics more closely
+ # than EV_ONESHOT, in that EV_ADD is not required to
+ # re-enable a disabled watch.
+ ($ev & EPOLLONESHOT) ? ($fl | EV_DISPATCH) : $fl;
} else {
- EV_ADD | EV_DISABLE;
+ EV_DISABLE;
}
}
sub new {
my ($class) = @_;
- die 'non-singleton use not supported' if $owner_pid == $$;
- $owner_pid = $$;
- $class->SUPER::new;
+ bless { kq => IO::KQueue->new, owner_pid => $$ }, $class;
}
+# returns a new instance which behaves like signalfd on Linux.
+# It's wasteful in that it uses another FD, but it simplifies
+# our epoll-oriented code.
+sub signalfd {
+ my ($class, $signo, $flags) = @_;
+ my $sym = gensym;
+ tie *$sym, $class, $signo, $flags; # calls TIEHANDLE
+ $sym
+}
+
+sub TIEHANDLE { # similar to signalfd()
+ my ($class, $signo, $flags) = @_;
+ my $self = $class->new;
+ $self->{timeout} = ($flags & SFD_NONBLOCK) ? 0 : -1;
+ 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 $timeout = $self->{timeout};
+ my $sigbuf = $self->{sigbuf} //= [];
+ my $nr = $len / 128;
+ my $r = 0;
+ $_[1] = '';
+ do {
+ while ($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 { $self->{kq}->kevent($timeout) };
+ # workaround https://rt.cpan.org/Ticket/Display.html?id=116615
+ if ($@) {
+ next if $@ =~ /Interrupted system call/;
+ die;
+ }
+ if (!scalar(@events) && $timeout == 0) {
+ $! = EAGAIN;
+ return;
+ }
+
+ # Grab the kevent.ident (signal number). The kevent.data
+ # field shows coalesced signals, and maybe we'll use it
+ # in the future...
+ @$sigbuf = map { $_->[0] } @events;
+ } while (1);
+}
+
+# for fileno() calls in PublicInbox::DS
+sub FILENO { ${$_[0]->{kq}} }
+
sub epoll_ctl {
my ($self, $op, $fd, $ev) = @_;
- if ($op != EPOLL_CTL_DEL) {
- $self->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
- $self->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev));
+ my $kq = $self->{kq};
+ if ($op == EPOLL_CTL_MOD) {
+ $kq->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
+ $kq->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev));
+ } elsif ($op == EPOLL_CTL_DEL) {
+ $kq->EV_SET($fd, EVFILT_READ, EV_DISABLE);
+ $kq->EV_SET($fd, EVFILT_WRITE, EV_DISABLE);
+ } else { # EPOLL_CTL_ADD
+ $kq->EV_SET($fd, EVFILT_READ, EV_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, EV_ADD |
+ kq_flag(EPOLLOUT, $ev));
+ };
}
0;
}
sub epoll_wait {
my ($self, $maxevents, $timeout_msec, $events) = @_;
- @$events = eval { $self->kevent($timeout_msec) };
+ @$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/) {
scalar(@$events);
}
+# kqueue is close-on-fork (not exec), so we must not close it
+# in forked processes:
sub DESTROY {
my ($self) = @_;
- if ($owner_pid == $$) {
- POSIX::close($$self);
- $owner_pid = -1;
+ my $kq = delete $self->{kq} or return;
+ if (delete($self->{owner_pid}) == $$) {
+ POSIX::close($$kq);
}
}