ds: @post_loop_do replaces SetPostLoopCallback

This allows us to avoid repeatedly using memory-intensive
anonymous subs in CodeSearchIdx where the callback is assigned
frequently.  Anonymous subs are known to leak memory in old
Perls (e.g. 5.16.3 in enterprise distros) and still expensive in
newer Perls.  So favor the (\&subroutine, @args) form which
allows us to eliminate anonymous subs going forward.

Only CodeSearchIdx takes advantage of the new API at the moment,
since it's the biggest repeat user of post-loop callback
changes.

Getting rid of the subroutine and relying on a global `our'
variable also has two advantages:

1) Perl warnings can detect typos at compile-time, whereas the
   (now gone) method could only detect errors at run-time.

2) `our' variable assignment can be `local'-ized to a scope

6 files changed, 19 insertions, 18 deletions

diff --git a/t/dir_idle.t b/t/dir_idle.t
index 19e54967..50e1dd27 100644
--- a/t/dir_idle.t
+++ b/t/dir_idle.t
@@ -1,7 +1,7 @@
 #!perl -w
-# Copyright (C) 2020-2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
-use v5.10.1; use strict; use PublicInbox::TestCommon;
+use v5.12; use strict; use PublicInbox::TestCommon;
 use PublicInbox::DS qw(now);
 use File::Path qw(make_path);
 use_ok 'PublicInbox::DirIdle';
@@ -13,7 +13,7 @@ my $di = PublicInbox::DirIdle->new($cb);
 $di->add_watches(["$tmpdir/a", "$tmpdir/c"], 1);
 PublicInbox::DS->SetLoopTimeout(1000);
 my $end = 3 + now;
-PublicInbox::DS->SetPostLoopCallback(sub { scalar(@x) == 0 && now < $end });
+local @PublicInbox::DS::post_loop_do = (sub { scalar(@x) == 0 && now < $end });
 tick(0.011);
 rmdir("$tmpdir/a/b") or xbail "rmdir $!";
 PublicInbox::DS::event_loop();
diff --git a/t/ds-leak.t b/t/ds-leak.t
index 4e8d76cd..eaca05b8 100644
--- a/t/ds-leak.t
+++ b/t/ds-leak.t
@@ -1,9 +1,9 @@
-# Copyright (C) 2019-2021 all contributors <meta@public-inbox.org>
+# Copyright (C) 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>
-use strict; use v5.10.1; use PublicInbox::TestCommon;
+use v5.12; use PublicInbox::TestCommon;
 use_ok 'PublicInbox::DS';
 
 if ('close-on-exec for epoll and kqueue') {
@@ -12,7 +12,7 @@ if ('close-on-exec for epoll and kqueue') {
         my $evfd_re = qr/(?:kqueue|eventpoll)/i;
 
         PublicInbox::DS->SetLoopTimeout(0);
-        PublicInbox::DS->SetPostLoopCallback(sub { 0 });
+        local @PublicInbox::DS::post_loop_do = (sub { 0 });
 
         # make sure execve closes if we're using fork()
         my ($r, $w);
@@ -55,7 +55,7 @@ SKIP: {
         my $cb = sub {};
         for my $i (0..$n) {
                 PublicInbox::DS->SetLoopTimeout(0);
-                PublicInbox::DS->SetPostLoopCallback($cb);
+                local @PublicInbox::DS::post_loop_do = ($cb);
                 PublicInbox::DS::event_loop();
                 PublicInbox::DS->Reset;
         }
diff --git a/t/imapd.t b/t/imapd.t
index c7dc01a5..0443c7cb 100644
--- a/t/imapd.t
+++ b/t/imapd.t
@@ -457,7 +457,7 @@ SKIP: {
         my $cfg = PublicInbox::Config->new;
         PublicInbox::DS->Reset;
         my $ii = PublicInbox::InboxIdle->new($cfg);
-        my $cb = sub { PublicInbox::DS->SetPostLoopCallback(sub {}) };
+        my $cb = sub { @PublicInbox::DS::post_loop_do = (sub {}) };
         my $obj = bless \$cb, 'PublicInbox::TestCommon::InboxWakeup';
         $cfg->each_inbox(sub { $_[0]->subscribe_unlock('ident', $obj) });
         my $watcherr = "$tmpdir/watcherr";
@@ -476,7 +476,7 @@ SKIP: {
                 'delivered a message for IDLE to kick -watch') or
                 diag "mda error \$?=$?";
         diag 'waiting for IMAP IDLE wakeup';
-        PublicInbox::DS->SetPostLoopCallback(undef);
+        @PublicInbox::DS::post_loop_do = ();
         PublicInbox::DS::event_loop();
         diag 'inbox unlocked on IDLE wakeup';
 
@@ -493,7 +493,7 @@ SKIP: {
                 'delivered a message for -watch PollInterval');
 
         diag 'waiting for PollInterval wakeup';
-        PublicInbox::DS->SetPostLoopCallback(undef);
+        @PublicInbox::DS::post_loop_do = ();
         PublicInbox::DS::event_loop();
         diag 'inbox unlocked (poll)';
         $w->kill;
diff --git a/t/nntpd.t b/t/nntpd.t
index dbbc37b8..ab6876bb 100644
--- a/t/nntpd.t
+++ b/t/nntpd.t
@@ -436,7 +436,7 @@ sub test_watch {
         my $cfg = PublicInbox::Config->new;
         PublicInbox::DS->Reset;
         my $ii = PublicInbox::InboxIdle->new($cfg);
-        my $cb = sub { PublicInbox::DS->SetPostLoopCallback(sub {}) };
+        my $cb = sub { @PublicInbox::DS::post_loop_do = (sub {}) };
         my $obj = bless \$cb, 'PublicInbox::TestCommon::InboxWakeup';
         $cfg->each_inbox(sub { $_[0]->subscribe_unlock('ident', $obj) });
         my $watcherr = "$tmpdir/watcherr";
diff --git a/t/sigfd.t b/t/sigfd.t
index 7eb6b222..8fc8206c 100644
--- a/t/sigfd.t
+++ b/t/sigfd.t
@@ -1,5 +1,6 @@
-# Copyright (C) 2019-2021 all contributors <meta@public-inbox.org>
-use strict;
+#!perl -w
+# Copyright (C) all contributors <meta@public-inbox.org>
+use v5.12;
 use Test::More;
 use IO::Handle;
 use POSIX qw(:signal_h);
@@ -46,7 +47,7 @@ SKIP: {
                 is($nbsig->wait_once, undef, 'nonblocking ->wait_once');
                 ok($! == Errno::EAGAIN, 'got EAGAIN');
                 kill('HUP', $$) or die "kill $!";
-                PublicInbox::DS->SetPostLoopCallback(sub {}); # loop once
+                local @PublicInbox::DS::post_loop_do = (sub {}); # loop once
                 PublicInbox::DS::event_loop();
                 is($hit->{HUP}->{sigfd}, 2, 'HUP sigfd fired in event loop') or
                         diag explain($hit); # sometimes fails on FreeBSD 11.x
diff --git a/t/watch_maildir.t b/t/watch_maildir.t
index e0719f54..04a1c959 100644
--- a/t/watch_maildir.t
+++ b/t/watch_maildir.t
@@ -1,7 +1,7 @@
-# Copyright (C) 2016-2021 all contributors <meta@public-inbox.org>
+#!perl -w
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
-use strict;
-use Test::More;
+use v5.12;
 use PublicInbox::Eml;
 use Cwd;
 use PublicInbox::Config;
@@ -170,7 +170,7 @@ More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
         my $ii = PublicInbox::InboxIdle->new($cfg);
         my $obj = bless \$cb, 'PublicInbox::TestCommon::InboxWakeup';
         $cfg->each_inbox(sub { $_[0]->subscribe_unlock('ident', $obj) });
-        PublicInbox::DS->SetPostLoopCallback(sub { $delivered == 0 });
+        local @PublicInbox::DS::post_loop_do = (sub { $delivered == 0 });
 
         # wait for -watch to setup inotify watches
         my $sleep = 1;