1 files changed, 60 insertions, 0 deletions
diff --git a/lib/PublicInbox/KQNotify.pm b/lib/PublicInbox/KQNotify.pm
new file mode 100644
index 00000000..3cf9c0f5
--- /dev/null
+++ b/lib/PublicInbox/KQNotify.pm
@@ -0,0 +1,60 @@
+# Copyright (C) 2020 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# implements the small subset of Linux::Inotify2 functionality we use
+# using IO::KQueue on *BSD systems.
+package PublicInbox::KQNotify;
+use strict;
+use IO::KQueue;
+use PublicInbox::DSKQXS; # wraps IO::KQueue for fork-safe DESTROY
+
+# only true as far as public-inbox is concerned with .lock files:
+sub IN_CLOSE () { NOTE_WRITE }
+#sub IN_CLOSE () { 0x200 } # NOTE_CLOSE_WRITE (FreeBSD 11+ only)
+
+sub new {
+        my ($class) = @_;
+        bless { dskq => PublicInbox::DSKQXS->new, watch => {} }, $class;
+}
+
+sub watch {
+        my ($self, $path, $mask, $cb) = @_;
+        open(my $fh, '<', $path) or return;
+        my $ident = fileno($fh);
+        $self->{dskq}->{kq}->EV_SET($ident, # ident
+                EVFILT_VNODE, # filter
+                EV_ADD | EV_CLEAR, # flags
+                $mask, # fflags
+                0, 0); # data, udata
+        if ($mask == IN_CLOSE) {
+                $self->{watch}->{$ident} = [ $fh, $cb ];
+        } else {
+                die "TODO Not implemented: $mask";
+        }
+}
+
+# emulate Linux::Inotify::fileno
+sub fileno { ${$_[0]->{dskq}->{kq}} }
+
+# noop for Linux::Inotify2 compatibility.  Unlike inotify,
+# kqueue doesn't seem to overflow since it's limited by the number of
+# open FDs the process has
+sub on_overflow {}
+
+# noop for Linux::Inotify2 compatibility, we use `0' timeout for ->kevent
+sub blocking {}
+
+# behave like Linux::Inotify2::poll
+sub poll {
+        my ($self) = @_;
+        my @kevents = $self->{dskq}->{kq}->kevent(0);
+        for my $kev (@kevents) {
+                my $ident = $kev->[KQ_IDENT];
+                my $mask = $kev->[KQ_FFLAGS];
+                if (($mask & IN_CLOSE) == IN_CLOSE) {
+                        eval { $self->{watch}->{$ident}->[1]->() };
+                }
+        }
+}
+
+1;