nntp: implement XROVER, speed up XHDR for some cases

Using Xapian allows us to implement XROVER without forking
new processes.

2 files changed, 76 insertions, 9 deletions

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 47b03e02..939fc3a6 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -528,17 +528,61 @@ sub xhdr_message_id ($$) { # optimize XHDR Message-ID [range] for slrnpull.
         }
 }
 
+sub header_obj_for {
+        my ($srch, $mid) = @_;
+        eval {
+                my $smsg = $srch->lookup_message($mid);
+                $smsg = PublicInbox::SearchMsg->load_doc($smsg->{doc});
+                $smsg->mini_mime->header_obj;
+        };
+};
+
+sub xhdr_searchmsg ($$$) {
+        my ($self, $sub, $range) = @_;
+        my $srch = $self->{ng}->search;
+        my $emit = ($sub eq 'date') ? sub {
+                my ($pfx, $m) = @_;
+                my @t = gmtime($m->header('X-PI-TS'));
+                more($self, "$pfx ". strftime('%a, %d %b %Y %T %z', @t));
+        } : sub {
+                my ($pfx, $m) = @_;
+                my $h = $m->header($sub);
+                more($self, "$pfx $h") if defined $h;
+        };
+
+        if (defined $range && $range =~ /\A<(.+)>\z/) { # Message-ID
+                more($self, '221 Header follows');
+                my $m = header_obj_for($srch, $1);
+                $emit->($range, $m) if defined $m;
+                '.';
+        } else { # numeric range
+                $range = $self->{article} unless defined $range;
+                my $mm = $self->{ng}->mm;
+                my $r = get_range($self, $range);
+                return $r unless ref $r;
+                my ($beg, $end) = @$r;
+                more($self, '221 Header follows');
+                $self->long_response($beg, $end, sub {
+                        my ($i) = @_;
+                        my $mid = $mm->mid_for($$i) or return;
+                        my $m = header_obj_for($srch, $mid) or return;
+                        $emit->($$i, $m);
+                });
+        }
+}
+
 sub cmd_xhdr ($$;$) {
         my ($self, $header, $range) = @_;
-        defined $self->{ng} or return '412 no news group currently selected';
-        my $sub = $header;
-        $sub =~ tr/A-Z-/a-z_/;
-        $sub = eval {
-                no strict 'refs';
-                $sub = *{'xhdr_'.$sub}{CODE};
-        };
-        return xhdr_slow($self, $header, $range) unless defined $sub;
-        $sub->($self, $range);
+        my $ng = $self->{ng};
+        defined $ng or return '412 no news group currently selected';
+        my $sub = lc $header;
+        if ($sub eq 'message-id') {
+                xhdr_message_id($self, $range);
+        } elsif ($sub =~ /\A(subject|references|date)\z/ && $ng->search) {
+                xhdr_searchmsg($self, $sub, $range);
+        } else {
+                xhdr_slow($self, $header, $range);
+        }
 }
 
 sub xhdr_slow ($$$) {
@@ -568,6 +612,28 @@ sub xhdr_slow ($$$) {
         }
 }
 
+sub cmd_xrover ($;$) {
+        my ($self, $range) = @_;
+        my $ng = $self->{ng} or return '412 no newsgroup selected';
+        (defined $range && $range =~ /[<>]/) and
+                return '420 No article(s) selected'; # no message IDs
+
+        $range = $self->{article} unless defined $range;
+        my $r = get_range($self, $range);
+        return $r unless ref $r;
+        my ($beg, $end) = @$r;
+        my $mm = $ng->mm;
+        my $srch = $ng->search;
+        more($self, '224 Overview information follows');
+        $self->long_response($beg, $end, sub {
+                my ($i) = @_;
+                my $mid = $mm->mid_for($$i) or return;
+                my $m = header_obj_for($srch, $mid) or return;
+                my $h = $m->header('references');
+                more($self, "$$i $h") if defined $h;
+        });
+}
+
 sub cmd_xover ($;$) {
         my ($self, $range) = @_;
         $range = $self->{article} unless defined $range;
diff --git a/lib/PublicInbox/SearchMsg.pm b/lib/PublicInbox/SearchMsg.pm
index e3a04605..8c55c929 100644
--- a/lib/PublicInbox/SearchMsg.pm
+++ b/lib/PublicInbox/SearchMsg.pm
@@ -141,6 +141,7 @@ sub mini_mime {
                 'X-PI-TS' => $self->ts,
         );
         if (my $refs = $self->{references_sorted}) {
+                $refs =~ s/></> </g;
                 push @h, References => $refs;
         }
         my $mime = Email::MIME->create(header_str => \@hs, header => \@h);