imapd: use nntpd_cache to speed up startup/reload time

ConfigIter was still too slow despite being fair.  The addition of
ART_MIN in ALL->misc means it can be used as a startup/reload cache
for -imapd, too.

This results in a ~3x faster startup for -imapd with 50K inboxes.

1 files changed, 9 insertions, 8 deletions

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 19ead70c..9955984b 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -350,12 +350,12 @@ sub idle_done ($$) {
         "$idle_tag OK Idle done\r\n";
 }
 
-sub ensure_slices_exist ($$$) {
-        my ($imapd, $ibx, $max) = @_;
-        defined(my $mb_top = $ibx->{newsgroup}) or return;
+sub ensure_slices_exist ($$) {
+        my ($imapd, $ibx) = @_;
+        my $mb_top = $ibx->{newsgroup} // return;
         my $mailboxes = $imapd->{mailboxes};
         my @created;
-        for (my $i = int($max/UID_SLICE); $i >= 0; --$i) {
+        for (my $i = int($ibx->art_max/UID_SLICE); $i >= 0; --$i) {
                 my $sub_mailbox = "$mb_top.$i";
                 last if exists $mailboxes->{$sub_mailbox};
                 $mailboxes->{$sub_mailbox} = $ibx;
@@ -387,7 +387,8 @@ sub inbox_lookup ($$;$) {
                         my $uid_end = $uid_base + UID_SLICE;
                         $exists = $over->imap_exists($uid_base, $uid_end);
                 }
-                ensure_slices_exist($self->{imapd}, $ibx, $over->max);
+                delete $ibx->{-art_max};
+                ensure_slices_exist($self->{imapd}, $ibx);
         } else {
                 if ($examine) {
                         $self->{uid_base} = $uid_base;
@@ -396,9 +397,9 @@ sub inbox_lookup ($$;$) {
                 }
                 # if "INBOX.foo.bar" is selected and "INBOX.foo.bar.0",
                 # check for new UID ranges (e.g. "INBOX.foo.bar.1")
-                if (my $z = $self->{imapd}->{mailboxes}->{"$mailbox.0"}) {
-                        ensure_slices_exist($self->{imapd}, $z,
-                                                $z->over(1)->max);
+                if (my $ibx = $self->{imapd}->{mailboxes}->{"$mailbox.0"}) {
+                        delete $ibx->{-art_max};
+                        ensure_slices_exist($self->{imapd}, $ibx);
                 }
         }
         ($ibx, $exists, $uidmax + 1, $uid_base);