X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FDSKQXS.pm;h=7bd7773e7225ae639c55e7d2f0811bc33c6a1dba;hb=HEAD;hp=1c3b970b7a332d3fd681fd885157005c70fea504;hpb=ecea327e3d4386a22652fc08f71ac7d65b8f9b70;p=public-inbox.git

diff --git a/lib/PublicInbox/DSKQXS.pm b/lib/PublicInbox/DSKQXS.pm
index 1c3b970b..7bd7773e 100644
--- a/lib/PublicInbox/DSKQXS.pm
+++ b/lib/PublicInbox/DSKQXS.pm
@@ -1,4 +1,4 @@
-# Copyright (C) 2019 all contributors <meta@public-inbox.org>
+# Copyright (C) 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>
@@ -8,18 +8,19 @@
 # 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".
 package PublicInbox::DSKQXS;
-use strict;
-use warnings;
-use parent qw(IO::KQueue);
+use v5.12;
 use parent qw(Exporter);
+use Symbol qw(gensym);
 use IO::KQueue;
+use Errno qw(EAGAIN);
 use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLLET
 	EPOLL_CTL_ADD EPOLL_CTL_MOD EPOLL_CTL_DEL);
 our @EXPORT_OK = qw(epoll_ctl epoll_wait);
-my $owner_pid = -1; # kqueue is close-on-fork (yes, fork, not exec)
+
+sub EV_DISPATCH () { 0x0080 }
 
 # map EPOLL* bits to kqueue EV_* flags for EV_SET
 sub kq_flag ($$) {
@@ -39,29 +40,92 @@ sub kq_flag ($$) {
 
 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, $nonblock) = @_;
+	my $sym = gensym;
+	tie *$sym, $class, $signo, $nonblock; # calls TIEHANDLE
+	$sym
+}
+
+sub TIEHANDLE { # similar to signalfd()
+	my ($class, $signo, $nonblock) = @_;
+	my $self = $class->new;
+	$self->{timeout} = $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;
+	$_[1] = '';
+	while (1) {
+		while ($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 { $self->{kq}->kevent($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;
+	}
+}
+
+# for fileno() calls in PublicInbox::DS
+sub FILENO { ${$_[0]->{kq}} }
+
 sub epoll_ctl {
 	my ($self, $op, $fd, $ev) = @_;
+	my $kq = $self->{kq};
 	if ($op == EPOLL_CTL_MOD) {
-		$self->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
-		$self->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev));
+		$kq->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
+		eval { $kq->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev)) };
 	} elsif ($op == EPOLL_CTL_DEL) {
-		$self->EV_SET($fd, EVFILT_READ, EV_DISABLE);
-		$self->EV_SET($fd, EVFILT_WRITE, EV_DISABLE);
-	} else {
-		$self->EV_SET($fd, EVFILT_READ, EV_ADD|kq_flag(EPOLLIN, $ev));
-		$self->EV_SET($fd, EVFILT_WRITE, EV_ADD|kq_flag(EPOLLOUT, $ev));
+		use Carp ();
+		$kq // Carp::confess("nokq $fd");
+		$kq->EV_SET($fd, EVFILT_READ, EV_DISABLE);
+		eval { $kq->EV_SET($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/) {
@@ -71,14 +135,16 @@ sub epoll_wait {
 		}
 	}
 	# caller only cares for $events[$i]->[0]
-	scalar(@$events);
+	$_ = $_->[0] for @$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);
 	}
 }