[PATCH 2/2] thread: fix parent/child relationships

[Eric Wong]

The ordering change in add_child is critical if $self == $parent
as the {children} hash was lost before this change.

has_descendent can be simplified by walking upwards from the child
instead of downwards from the parent.

This fixes threading regressions introduced in
commit 30100c46326e2eac275e0af13116636701d2537e
("thread: use hash + array instead of hand-rolled linked list")
---
 lib/PublicInbox/SearchThread.pm | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/lib/PublicInbox/SearchThread.pm b/lib/PublicInbox/SearchThread.pm
index c6bd999..24a56d2 100644
--- a/lib/PublicInbox/SearchThread.pm
+++ b/lib/PublicInbox/SearchThread.pm
@@ -104,27 +104,21 @@ sub add_child {
          if $self == $child;
 
        my $cid = $child->{id};
-       $self->{children}->{$cid} = $child;
 
        # reparenting:
        if (defined(my $parent = $child->{parent})) {
                delete $parent->{children}->{$cid};
        }
 
+       $self->{children}->{$cid} = $child;
        $child->{parent} = $self;
 }
 
 sub has_descendent {
-       my ($cur, $child) = @_;
-       my %seen;
-       my @q = ($cur->{parent} || $cur);
-
-       while (defined($cur = shift @q)) {
-               return 1 if $cur == $child;
-
-               if (!$seen{$cur}++) {
-                       push @q, values %{$cur->{children}};
-               }
+       my ($self, $child) = @_;
+       while ($child) {
+               return 1 if $self == $child;
+               $child = $child->{parent};
        }
        0;
 }
-- 
EW