[PATCH] msgmap: do not cache num_highwater

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

Caching the value doesn't seem necessary from a performance
perspective, and it adds a caveat for read-only users which
may lead to bugs in future code.
---
 lib/PublicInbox/IMAP.pm   | 3 +--
 lib/PublicInbox/Msgmap.pm | 7 +++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 41bcf9af..4a7ff2f4 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -393,8 +393,7 @@ sub inbox_lookup ($$;$) {
 				die "BUG: unexpected dummy mailbox: $mailbox\n";
 		$uid_base = $1 * UID_SLICE;
 
-		# ->num_highwater caches for writers, so use ->meta_accessor
-		$uidmax = $ibx->mm->meta_accessor('num_highwater') // 0;
+		$uidmax = $ibx->mm->num_highwater // 0;
 		if ($examine) {
 			$self->{uid_base} = $uid_base;
 			$self->{ibx} = $ibx;
diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index e71f16f8..699a8bf0 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -100,13 +100,12 @@ sub created_at {
 
 sub num_highwater {
 	my ($self, $num) = @_;
-	my $high = $self->{num_highwater} ||=
-	    $self->meta_accessor('num_highwater');
+	my $high = $self->meta_accessor('num_highwater');
 	if (defined($num) && (!defined($high) || ($num > $high))) {
-		$self->{num_highwater} = $num;
+		$high = $num;
 		$self->meta_accessor('num_highwater', $num);
 	}
-	$self->{num_highwater};
+	$high
 }
 
 sub mid_insert {