view: improve grouping for topic view

This reduces the amount of mbox/Atom links while keeping
better track of overall thread count.  We no longer loop
to fill up slots to simplify the code a bit and hopefully
get better grouping.

1 files changed, 59 insertions, 64 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 275fed43..5a312d84 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -839,84 +839,82 @@ sub _tryload_ghost ($$) {
 }
 
 # accumulate recent topics if search is supported
-# returns 1 if done, undef if not
-sub add_topic {
+# returns 200 if done, 404 if not
+sub acc_topic {
         my ($ctx, $level, $node) = @_;
         my $srch = $ctx->{srch};
         my $mid = $node->messageid;
         my $x = $node->message || _tryload_ghost($srch, $mid);
         my ($subj, $ts);
+        my $topic;
         if ($x) {
                 $x = $x->header_obj;
-                $subj = $x->header('Subject');
+                $subj = $x->header('Subject') || '';
                 $subj = $srch->subject_normalized($subj);
                 $ts = $x->header('X-PI-TS');
-        } else { # ghost message, do not bump level
-                $ts = -666;
-                $subj = "<$mid>";
-        }
-        if (++$ctx->{subjs}->{$subj} == 1) {
-                push @{$ctx->{order}}, [ $level, $subj ];
-        }
-        my $exist = $ctx->{latest}->{$subj};
-        if (!$exist || $exist->[1] < $ts) {
-                $ctx->{latest}->{$subj} = [ $mid, $ts ];
+                if ($level == 0) {
+                        $topic = [ $ts, 1, { $subj => $mid }, $subj ];
+                        $ctx->{-cur_topic} = $topic;
+                        push @{$ctx->{order}}, $topic;
+                        return;
+                }
+
+                $topic = $ctx->{-cur_topic}; # should never be undef
+                $topic->[0] = $ts if $ts > $topic->[0];
+                $topic->[1]++;
+                my $seen = $topic->[2];
+                if (scalar(@$topic) == 3) { # parent was a ghost
+                        push @$topic, $subj;
+                } elsif (!$seen->{$subj}) {
+                        push @$topic, $level, $subj;
+                }
+                $seen->{$subj} = $mid; # latest for subject
+        } else { # ghost message
+                return if $level != 0; # ignore child ghosts
+                $topic = [ -666, 0, {} ];
+                $ctx->{-cur_topic} = $topic;
+                push @{$ctx->{order}}, $topic;
         }
 }
 
-sub topics {
+sub dump_topics {
         my ($ctx) = @_;
-        my $order = $ctx->{order};
-        my $subjs = $ctx->{subjs};
-        my $latest = $ctx->{latest};
+        my $order = $ctx->{order}; # [ ts, subj1, subj2, subj3, ... ]
         if (!@$order) {
                 $ctx->{-html_tip} = '<pre>[No topics in range]</pre>';
                 return 404;
         }
-        my $pfx;
-        my $prev = 0;
-        my $prev_attr = '';
-        my $cur;
-        my @recent;
-        while (defined(my $info = shift @$order)) {
-                my ($level, $subj) = @$info;
-                my $n = delete $subjs->{$subj};
-                my ($mid, $ts) = @{delete $latest->{$subj}};
-                my $href = PublicInbox::Hval->new_msgid($mid)->as_href;
-                $pfx = indent_for($level);
-                my $nl = $level == $prev ? "\n" : '';
-                if ($nl && $cur) {
-                        push @recent, $cur;
-                        $cur = undef;
-                }
-                $cur ||= [ $ts, '' ];
-                $cur->[0] = $ts if $ts > $cur->[0];
-                $cur->[1] .= $nl . $pfx . th_pfx($level);
-                if ($ts == -666) { # ghost
-                        $cur->[1] .= ghost_parent('', $mid) . "\n";
-                        next; # child will have mbox / atom link
-                }
 
-                $subj = PublicInbox::Hval->new($subj)->as_html;
-                $cur->[1] .= "<a\nhref=\"$href/T/#u\"><b>$subj</b></a>\n";
+        my @out;
+        foreach my $topic (@$order) {
+                my ($ts, $n, $seen, $top, @ex) = @$topic;
+                @$topic = ();
+                next unless defined $top;  # ghost topic
+                my $mid = delete $seen->{$top};
+                my $href = PublicInbox::Hval->new_msgid($mid)->as_href;
+                $top = PublicInbox::Hval->new($top)->as_html;
                 $ts = fmt_ts($ts);
-                my $attr = " $ts UTC";
 
                 # $n isn't the total number of posts on the topic,
                 # just the number of posts in the current results window
                 $n = $n == 1 ? '' : " ($n+ messages)";
 
-                if ($level == 0 || $attr ne $prev_attr) {
-                        my $mbox = qq(<a\nhref="$href/t.mbox.gz">mbox.gz</a>);
-                        my $atom = qq(<a\nhref="$href/t.atom">Atom</a>);
-                        $pfx .= INDENT if $level > 0;
-                        $cur->[1] .= $pfx . $attr . $n . " - $mbox / $atom\n";
-                        $prev_attr = $attr;
+                my $mbox = qq(<a\nhref="$href/t.mbox.gz">mbox.gz</a>);
+                my $atom = qq(<a\nhref="$href/t.atom">Atom</a>);
+                my $s = "<a\nhref=\"$href/T/#t\"><b>$top</b></a>\n" .
+                        " $ts UTC $n - $mbox / $atom\n";
+                for (my $i = 0; $i < scalar(@ex); $i += 2) {
+                        my $level = $ex[$i];
+                        my $sub = $ex[$i + 1];
+                        $mid = delete $seen->{$sub};
+                        $sub = PublicInbox::Hval->new($sub)->as_html;
+                        $href = PublicInbox::Hval->new_msgid($mid)->as_href;
+                        $s .= indent_for($level) . TCHILD;
+                        $s .= "<a\nhref=\"$href/T/#u\">$sub</a>\n";
                 }
+                push @out, $s;
         }
-        push @recent, $cur if $cur;
-        @recent = map { $_->[1] } sort { $b->[0] <=> $a->[0] } @recent;
-        $ctx->{-html_tip} = join('', '<pre>', @recent, '</pre>');
+        $ctx->{-html_tip} = '<pre>' . join("\n", @out) . '</pre>';
         200;
 }
 
@@ -947,21 +945,18 @@ sub index_nav { # callback for WwwStream
 sub index_topics {
         my ($ctx) = @_;
         my ($off) = (($ctx->{qp}->{o} || '0') =~ /(\d+)/);
-        my $order = $ctx->{order} = [];
-        $ctx->{subjs} = {};
-        $ctx->{latest} = {};
-        my $max = 25;
-        my %opts = ( offset => $off, limit => $max * 4 );
-        while (scalar @{$ctx->{order}} < $max) {
-                my $sres = $ctx->{srch}->query('', \%opts);
-                my $nr = scalar @{$sres->{msgs}} or last;
+        my $opts = { offset => $off, limit => 200 };
+
+        $ctx->{order} = [];
+        my $sres = $ctx->{srch}->query('', $opts);
+        my $nr = scalar @{$sres->{msgs}};
+        if ($nr) {
                 $sres = load_results($sres);
-                walk_thread(thread_results($sres), $ctx, *add_topic);
-                $opts{offset} += $nr;
+                walk_thread(thread_results($sres), $ctx, *acc_topic);
         }
-        $ctx->{-next_o} = $opts{offset};
+        $ctx->{-next_o} = $off+ $nr;
         $ctx->{-cur_o} = $off;
-        PublicInbox::WwwStream->response($ctx, topics($ctx), *index_nav);
+        PublicInbox::WwwStream->response($ctx, dump_topics($ctx), *index_nav);
 }
 
 sub thread_adj_level {