[PATCH] git_async_cat: remove circular reference

[Eric Wong]

While this circular reference was carefully managed to not leak
memory; it was still triggering a warning at -imapd/-nntpd
shutdown due to the EPOLL_CTL_DEL op failing after the $Epoll FD
gets closed.

So remove the circular reference by providing a ref to `undef',
instead.
---
 lib/PublicInbox/Git.pm         |  4 +---
 lib/PublicInbox/GitAsyncCat.pm | 10 +++++-----
 lib/PublicInbox/IMAP.pm        |  2 +-
 lib/PublicInbox/NNTP.pm        |  9 +++------
 4 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index a55c48d5..776e4832 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -295,9 +295,7 @@ sub qx {
 sub cleanup {
        my ($self) = @_;
        local $in_cleanup = 1;
-       if (my $ac = $self->{async_cat}) {
-               $ac->close; # PublicInbox::GitAsyncCat::close -> EPOLL_CTL_DEL
-       }
+       delete $self->{async_cat};
        cat_async_wait($self);
        _destroy($self, qw(cat_rbuf in out pid));
        _destroy($self, qw(chk_rbuf in_c out_c pid_c err_c));
diff --git a/lib/PublicInbox/GitAsyncCat.pm b/lib/PublicInbox/GitAsyncCat.pm
index 8701e4cf..098101ae 100644
--- a/lib/PublicInbox/GitAsyncCat.pm
+++ b/lib/PublicInbox/GitAsyncCat.pm
@@ -15,20 +15,20 @@ use fields qw(git);
 use PublicInbox::Syscall qw(EPOLLIN EPOLLET);
 our @EXPORT = qw(git_async_cat);
 
-sub new {
+sub _add {
        my ($class, $git) = @_;
        my $self = fields::new($class);
        $git->batch_prepare;
        $self->SUPER::new($git->{in}, EPOLLIN|EPOLLET);
        $self->{git} = $git;
-       $self;
+       \undef; # this is a true ref()
 }
 
 sub event_step {
        my ($self) = @_;
        my $git = $self->{git} or return; # ->close-ed
        my $inflight = $git->{inflight};
-       if (@$inflight) {
+       if ($inflight && @$inflight) {
                $git->cat_async_step($inflight);
                $self->requeue if @$inflight || exists $git->{cat_rbuf};
        }
@@ -37,7 +37,7 @@ sub event_step {
 sub close {
        my ($self) = @_;
        if (my $git = delete $self->{git}) {
-               delete $git->{async_cat}; # drop circular reference
+               delete $git->{async_cat};
        }
        $self->SUPER::close; # PublicInbox::DS::close
 }
@@ -45,7 +45,7 @@ sub close {
 sub git_async_cat ($$$$) {
        my ($git, $oid, $cb, $arg) = @_;
        $git->cat_async($oid, $cb, $arg);
-       $git->{async_cat} //= new(__PACKAGE__, $git); # circular reference
+       $git->{async_cat} //= _add(__PACKAGE__, $git);
 }
 
 1;
diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index dec10d61..0a6993c6 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -1294,7 +1294,7 @@ sub long_step {
        } elsif ($more) { # $self->{wbuf}:
                $self->update_idle_time;
 
-               # control passed to $more may be a GitAsyncCat object
+               # control passed to git_async_cat if $more == \undef
                requeue_once($self) if !ref($more);
        } else { # all done!
                delete $self->{long_cb};
diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 6df19f32..76f14bbd 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -553,8 +553,7 @@ sub cmd_article ($;$) {
        return $smsg unless ref $smsg;
        set_art($self, $art);
        $smsg->{nntp} = $self;
-       git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg);
-       undef;
+       ${git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg)};
 }
 
 sub cmd_head ($;$) {
@@ -564,8 +563,7 @@ sub cmd_head ($;$) {
        set_art($self, $art);
        $smsg->{nntp} = $self;
        $smsg->{nntp_code} = 221;
-       git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg);
-       undef;
+       ${git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg)};
 }
 
 sub cmd_body ($;$) {
@@ -575,8 +573,7 @@ sub cmd_body ($;$) {
        set_art($self, $art);
        $smsg->{nntp} = $self;
        $smsg->{nntp_code} = 222;
-       git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg);
-       undef;
+       ${git_async_cat($self->{ng}->git, $smsg->{blob}, \&blob_cb, $smsg)};
 }
 
 sub cmd_stat ($;$) {
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