[PATCH 1/5] nntp: xref_by_tc: simplify slightly

[Eric Wong <e@80x24.org>]

We can invalidate ibx->{newsgroup} at config load-time to avoid
having to check ibx->{newsgroup} validity in To/Cc: matching.
This saves us some hash lookups in all cases.
---
 lib/PublicInbox/NNTP.pm  | 3 +--
 lib/PublicInbox/NNTPD.pm | 9 +++++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index e0916011..6728f9c5 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -422,14 +422,13 @@ sub header_append ($$$) {
 sub xref_by_tc ($$$) {
 	my ($xref, $pi_cfg, $smsg) = @_;
 	my $by_addr = $pi_cfg->{-by_addr};
-	my $groups = $pi_cfg->{-by_newsgroup};
 	my $mid = $smsg->{mid};
 	for my $f (qw(to cc)) {
 		my @ibxs = map {
 			$by_addr->{lc($_)} // ()
 		} (PublicInbox::Address::emails($smsg->{$f} // ''));
 		for my $ibx (@ibxs) {
-			$groups->{my $ngname = $ibx->{newsgroup}} or next;
+			my $ngname = $ibx->{newsgroup} // next;
 			next if defined $xref->{$ngname};
 			$xref->{$ngname} = eval { $ibx->mm->num_for($mid) };
 		}
diff --git a/lib/PublicInbox/NNTPD.pm b/lib/PublicInbox/NNTPD.pm
index 967850e9..03c56db3 100644
--- a/lib/PublicInbox/NNTPD.pm
+++ b/lib/PublicInbox/NNTPD.pm
@@ -38,13 +38,18 @@ sub refresh_groups {
 	my $groups = $pi_config->{-by_newsgroup}; # filled during each_inbox
 	$pi_config->each_inbox(sub {
 		my ($ibx) = @_;
-		my $ngname = $ibx->{newsgroup} // return;
-		if ($ibx->nntp_usable) { # only valid if msgmap and over works
+		my $ngname = $ibx->{newsgroup};
+		if (defined($ngname) && $ibx->nntp_usable) {
+			# only valid if msgmap and over works
 			# preload to avoid fragmentation:
 			$ibx->description;
 			$ibx->base_url;
 		} else {
 			delete $groups->{$ngname};
+			delete $ibx->{newsgroup};
+			# Note: don't be tempted to delete more for memory
+			# savings just yet: NNTP, IMAP, and WWW may all
+			# run in the same process someday.
 		}
 	});
 	$self->{groupnames} = [ sort(keys %$groups) ];