ds: split out IO::KQueue-specific code

We don't need to code multiple event loops or have branches in
watch() if we can easily make the IO::KQueue-based interface
look like our lower-level epoll_* API.

1 files changed, 73 insertions, 0 deletions

diff --git a/lib/PublicInbox/DSKQXS.pm b/lib/PublicInbox/DSKQXS.pm
new file mode 100644
index 00000000..38e13446
--- /dev/null
+++ b/lib/PublicInbox/DSKQXS.pm
@@ -0,0 +1,73 @@
+# Copyright (C) 2019 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>
+#  <https://dev.perl.org/licenses/artistic.html>
+#
+# 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.
+# A pure-Perl version using syscall() is planned, and it should be
+# faster due to the lack of syscall overhead.
+package PublicInbox::DSKQXS;
+use strict;
+use warnings;
+use parent qw(IO::KQueue);
+use parent qw(Exporter);
+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)
+
+# map EPOLL* bits to kqueue EV_* flags for EV_SET
+sub kq_flag ($$) {
+        my ($bit, $ev) = @_;
+        if ($ev & $bit) {
+                my $fl = EV_ADD | EV_ENABLE;
+                ($ev & EPOLLONESHOT) ? ($fl | EV_ONESHOT) : $fl;
+        } else {
+                EV_ADD | EV_DISABLE;
+        }
+}
+
+sub new {
+        my ($class) = @_;
+        die 'non-singleton use not supported' if $owner_pid == $$;
+        $owner_pid = $$;
+        $class->SUPER::new;
+}
+
+sub epoll_ctl {
+        my ($self, $op, $fd, $ev) = @_;
+        if ($op != EPOLL_CTL_DEL) {
+                $self->EV_SET($fd, EVFILT_READ, kq_flag(EPOLLIN, $ev));
+                $self->EV_SET($fd, EVFILT_WRITE, kq_flag(EPOLLOUT, $ev));
+        }
+        0;
+}
+
+sub epoll_wait {
+        my ($self, $maxevents, $timeout_msec, $events) = @_;
+        @$events = eval { $self->kevent($timeout_msec) };
+        if (my $err = $@) {
+                # workaround https://rt.cpan.org/Ticket/Display.html?id=116615
+                if ($err =~ /Interrupted system call/) {
+                        @$events = ();
+                } else {
+                        die $err;
+                }
+        }
+        # caller only cares for $events[$i]->[0]
+        scalar(@$events);
+}
+
+sub DESTROY {
+        my ($self) = @_;
+        if ($owner_pid == $$) {
+                POSIX::close($$self);
+                $owner_pid = -1;
+        }
+}
+
+1;