1 files changed, 31 insertions, 0 deletions
diff --git a/lib/PublicInbox/OnDestroy.pm b/lib/PublicInbox/OnDestroy.pm
new file mode 100644
index 00000000..4301edff
--- /dev/null
+++ b/lib/PublicInbox/OnDestroy.pm
@@ -0,0 +1,31 @@
+# Copyright (C) all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+package PublicInbox::OnDestroy;
+use v5.12;
+use parent qw(Exporter);
+use autodie qw(fork);
+our @EXPORT = qw(on_destroy);
+our $fork_gen = 0;
+
+# either parent or child is expected to exit or exec shortly after this:
+sub fork_tmp () {
+        my $pid = fork;
+        ++$fork_gen if $pid == 0;
+        $pid;
+}
+
+# all children
+sub all (@) { bless [ undef, @_ ], __PACKAGE__ }
+
+# same process
+sub on_destroy (@) { bless [ $fork_gen, @_ ], __PACKAGE__ }
+
+sub cancel { @{$_[0]} = () }
+
+sub DESTROY {
+        my ($fgen, $cb, @args) = @{$_[0]};
+        $cb->(@args) if ($cb && ($fgen // $fork_gen) == $fork_gen);
+}
+
+1;