view: avoid recursion in topic index

Recursion can cause problems, so do our best to avoid it
even in the topic index.

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index bc4a44323d2aa6a801a3988f4e93199debe3c8f3..8075e4ae93259568cb9669e5e7eea37464fa4d23 100644 (file)
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -757,8 +757,7 @@ sub _tryload_ghost ($$) {
 # accumulate recent topics if search is supported
 # returns 1 if done, undef if not
 sub add_topic {
-       my ($state, $node, $level) = @_;
-       return unless $node;
+       my ($state, $level, $node) = @_;
        my $child_adjust = 1;
        my $srch = $state->{srch};
        my $x = $node->message || _tryload_ghost($srch, $node);
@@ -784,9 +783,6 @@ sub add_topic {
                # ghost message, do not bump level
                $child_adjust = 0;
        }
-
-       add_topic($state, $node->child, $level + $child_adjust);
-       add_topic($state, $node->next, $level);
 }
 
 sub emit_topics {
@@ -850,9 +846,13 @@ sub emit_index_topics {
        while (scalar @{$state->{order}} < $max) {
                my $sres = $state->{srch}->query('', \%opts);
                my $nr = scalar @{$sres->{msgs}} or last;
-
-               for (thread_results(load_results($sres))->rootset) {
-                       add_topic($state, $_, 0);
+               $sres = load_results($sres);
+               my @q = map { (0, $_) } thread_results($sres)->rootset;
+               while (@q) {
+                       my $level = shift @q;
+                       my $node = shift @q or next;
+                       add_topic($state, $level, $node);
+                       unshift @q, $level+1, $node->child, $level, $node->next;
                }
                $opts{offset} += $nr;
        }