comment_count updates happening in core

Entry.pm

MT::Comment->add_callback( 'post_save', 0, MT->component('core'),
    sub {
        my ($cb, $comment) = @_;
        my $entry   = MT::Entry->load( $comment->entry_id )
            or return;
        $entry->clear_cache('comment_latest');
        my $count   = MT::Comment->count(
            {
                entry_id => $comment->entry_id,
                visible  => 1,
            }
        );
        return unless ( $entry->comment_count != $count );
        $entry->comment_count($count);
        $entry->save;
    },
);

MT::Comment->add_callback( 'post_remove', 0, MT->component('core'),
    sub {
        my ($cb, $comment) = @_;
        my $entry   = MT::Entry->load( $comment->entry_id )
            or return;
        $entry->clear_cache('comment_latest');
        if ( $comment->visible ) {
            my $count = $entry->comment_count > 0 ? $entry->comment_count - 1 : 0;
            $entry->comment_count($count);
            $entry->save;
        }
    },
);