X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FDSKQXS.pm;h=acc31d9baa2242c75487510b87111574e1c98078;hb=af0b0fb7a454470a32c452119d0392e0dedb3fe1;hp=38e13446888ea893ec88f8091e6d1a156c460604;hpb=df5755b40b4ba1d6048042e18d8ea501755b9a02;p=public-inbox.git

diff --git a/lib/PublicInbox/DSKQXS.pm b/lib/PublicInbox/DSKQXS.pm
index 38e13446..acc31d9b 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) 2019-2021 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>
@@ -8,48 +8,123 @@
 # 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 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));
+		eval { $kq->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev)) };
+	} elsif ($op == EPOLL_CTL_DEL) {
+		$kq->EV_SET($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/) {
@@ -59,14 +134,16 @@ 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);
 	}
 }