nntp: speed up XHDR Xref for rtin

We could also start displaying Xref in XOVER as rtin seems to
prefer it.  Anyways this is nearly 100 times faster now and
requires no DB changes.

1 files changed, 32 insertions, 1 deletions

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 79f2c2f8..d5eb4971 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -371,7 +371,7 @@ found:
         if ($set_headers) {
                 $s->header_set('Newsgroups', $ng->{name});
                 $s->header_set('Lines', $s->body =~ tr!\n!\n!);
-                $s->header_set('Xref', "$ng->{domain} $ng->{name}:$n");
+                $s->header_set('Xref', xref($ng, $n));
 
                 # must be last
                 if ($set_headers == 2) {
@@ -562,6 +562,35 @@ sub xhdr_message_id ($$) { # optimize XHDR Message-ID [range] for slrnpull.
         }
 }
 
+sub xref ($$) {
+        my ($ng, $n) = @_;
+        "$ng->{domain} $ng->{name}:$n"
+}
+
+sub xhdr_xref ($$) { # optimize XHDR Xref [range] for rtin
+        my ($self, $range) = @_;
+
+        my $ng = $self->{ng};
+        my $mm = $ng->mm;
+        if (defined $range && $range =~ /\A<(.+)>\z/) { # Message-ID
+                my $n = $mm->num_for($range);
+                more($self, '221 Header follows');
+                more($self, "<$range> ".xref($ng, $n)) if defined $n;
+                '.';
+        } else { # numeric range
+                $range = $self->{article} unless defined $range;
+                my $r = get_range($self, $range);
+                return $r unless ref $r;
+                my ($beg, $end) = @$r;
+                more($self, '221 Header follows');
+                $self->long_response($beg, $end, sub {
+                        my ($i) = @_;
+                        my $mid = $mm->mid_for($$i);
+                        more($self, "$$i ".xref($ng, $$i)) if defined $mid;
+                });
+        }
+}
+
 sub header_obj_for {
         my ($srch, $mid) = @_;
         eval {
@@ -612,6 +641,8 @@ sub cmd_xhdr ($$;$) {
         my $sub = lc $header;
         if ($sub eq 'message-id') {
                 xhdr_message_id($self, $range);
+        } elsif ($sub eq 'xref') {
+                xhdr_xref($self, $range);
         } elsif ($sub =~ /\A(subject|references|date)\z/ && $ng->search) {
                 xhdr_searchmsg($self, $sub, $range);
         } else {