treewide: avoid getpid() for OnDestroy checks

getpid() isn't cached by glibc nowadays and system calls are
more expensive due to CPU vulnerability mitigations.  To
ensure we switch to the new semantics properly, introduce
a new `on_destroy' function to simplify callers.
Furthermore, most OnDestroy correctness is often tied to the
process which creates it, so make the new API default to
guarded against running in subprocesses.

For cases which require running in all children, a new
PublicInbox::OnDestroy::all call is provided.

1 files changed, 11 insertions, 14 deletions

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index 4e3e1d1c..08e61e4b 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -293,7 +293,7 @@ sub start_update_ref {
         pipe(my $r, my $w);
         my $cmd = [ 'git', "--git-dir=$fgrp->{cur_dst}",
                 qw(update-ref --stdin -z) ];
-        my $pack = PublicInbox::OnDestroy->new($$, \&satellite_done, $fgrp);
+        my $pack = on_destroy \&satellite_done, $fgrp;
         start_cmd($fgrp, $cmd, { 0 => $r, 2 => $fgrp->{lei}->{2} }, $pack);
         close $r;
         $fgrp->{dry_run} ? undef : $w;
@@ -373,10 +373,7 @@ sub fgrpv_done {
         for my $fgrp (@$fgrpv) {
                 my $rn = $fgrp->{-remote};
                 my %opt = ( 2 => $fgrp->{lei}->{2} );
-
-                my $update_ref = PublicInbox::OnDestroy->new($$,
-                                                        \&fgrp_update, $fgrp);
-
+                my $update_ref = on_destroy \&fgrp_update, $fgrp;
                 my $src = [ 'git', "--git-dir=$fgrp->{-osdir}", 'for-each-ref',
                         "--format=refs/%(refname:lstrip=3)%00%(objectname)",
                         "refs/remotes/$rn/" ];
@@ -467,7 +464,7 @@ sub fgrp_fetch_all {
                 }
                 $cmd  = [ @git, "--git-dir=$osdir", @fetch, $grp ];
                 push @$old, @$new;
-                my $end = PublicInbox::OnDestroy->new($$, \&fgrpv_done, $old);
+                my $end = on_destroy \&fgrpv_done, $old;
                 start_cmd($self, $cmd, $opt, $end);
         }
 }
@@ -567,7 +564,7 @@ sub resume_fetch {
         my $cmd = [ @{$self->{-torsocks}}, @git,
                         fetch_args($self->{lei}, $opt), $rn ];
         push @$cmd, '-P' if $self->{lei}->{prune}; # --prune-tags implied
-        my $run_puh = PublicInbox::OnDestroy->new($$, \&run_puh, $self, $fini);
+        my $run_puh = on_destroy \&run_puh, $self, $fini;
         ++$self->{chg}->{nr_chg};
         start_cmd($self, $cmd, $opt, $run_puh);
 }
@@ -599,7 +596,7 @@ sub clone_v1 {
                         return;
                 }
         }
-        my $fini = PublicInbox::OnDestroy->new($$, \&v1_done, $self);
+        my $fini = on_destroy \&v1_done, $self;
         if (my $fgrp = forkgroup_prep($self, $uri)) {
                 $fgrp->{-fini} = $fini;
                 if ($resume) {
@@ -621,8 +618,8 @@ sub clone_v1 {
                         }
                 }
                 ++$self->{chg}->{nr_chg};
-                start_cmd($self, $cmd, $opt, PublicInbox::OnDestroy->new($$,
-                                                \&run_puh, $self, $fini));
+                start_cmd($self, $cmd, $opt,
+                        on_destroy(\&run_puh, $self, $fini));
         }
         if (!$self->{-is_epoch} && $lei->{opt}->{'inbox-config'} =~
                                 /\A(?:always|v1)\z/s &&
@@ -737,7 +734,7 @@ sub atomic_write ($$$) {
 sub run_next_puh {
         my ($self) = @_;
         my $puh = shift @{$self->{-puh_todo}} // return delete($self->{-fini});
-        my $fini = PublicInbox::OnDestroy->new($$, \&run_next_puh, $self);
+        my $fini = on_destroy \&run_next_puh, $self;
         my $cmd = [ @$puh, ($self->{cur_dst} // $self->{dst}) ];
         my $opt = +{ map { $_ => $self->{lei}->{$_} } (0..2) };
         start_cmd($self, $cmd, undef, $opt, $fini);
@@ -762,7 +759,7 @@ sub update_ent {
                 my $opt = { 2 => $self->{lei}->{2} };
                 open($opt->{1}, '+>', undef);
                 $self->{-show_ref_up} = $opt->{1};
-                my $done = PublicInbox::OnDestroy->new($$, \&up_fp_done, $self);
+                my $done = on_destroy \&up_fp_done, $self;
                 start_cmd($self, $cmd, $opt, $done);
         }
         $new = $self->{-ent}->{head};
@@ -883,7 +880,7 @@ sub clone_v2_prep ($$;$) {
         my $want = parse_epochs($lei->{opt}->{epoch}, $v2_epochs);
         my $task = $m ? bless { %$self }, __PACKAGE__ : $self;
         my (@skip, $desc);
-        my $fini = PublicInbox::OnDestroy->new($$, \&v2_done, $task);
+        my $fini = on_destroy \&v2_done, $task;
         for my $nr (sort { $a <=> $b } keys %$v2_epochs) {
                 my ($uri, $key) = @{$v2_epochs->{$nr}};
                 my $src = $uri->as_string;
@@ -1018,7 +1015,7 @@ sub clone_all {
         my ($self, $m) = @_;
         my $todo = $TODO;
         $TODO = \'BUG on further use';
-        my $end = PublicInbox::OnDestroy->new($$, \&fgrp_fetch_all, $self);
+        my $end = on_destroy \&fgrp_fetch_all, $self;
         {
                 my $nodep = delete $todo->{''};