[WIP] searchidx: support incremental indexing on indexlevel=basic

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

I wrote:
> While testing this, it looks like I introduced a bug to
> indexlevel=basic which broke incremental indexing when I made it
> possible to upgrade to (medium|full).  Patch coming for that in
> a bit...

Eep, I think there's deeper problems with indexlevel=basic and
incremental updates, since it's still doing lookups against
Xapian for deletes...

This is my work-in-progress to stop full-reindexing, at least.

----8<-----
Subject: [PATCH] searchidx: support incremental indexing on indexlevel=basic

---
 lib/PublicInbox/SearchIdx.pm | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
index 54f82aa..5cac08f 100644
--- a/lib/PublicInbox/SearchIdx.pm
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -668,6 +668,15 @@ sub need_update ($$$) {
 	($n eq '' || $n > 0);
 }
 
+sub _last_x_commit {
+	my ($self) = @_;
+	if ($self->{indexlevel} =~ $xapianlevels) {
+		$self->{xdb}->get_metadata('last_commit');
+	} else {
+		$self->{mm}->last_commit || '';
+	}
+}
+
 # indexes all unindexed messages (v1 only)
 sub _index_sync {
 	my ($self, $opts) = @_;
@@ -682,7 +691,7 @@ sub _index_sync {
 	do {
 		$xlog = undef;
 		$mkey = 'last_commit';
-		$last_commit = $xdb->get_metadata('last_commit');
+		$last_commit = $self->_last_x_commit;
 		$lx = $last_commit;
 		if ($reindex) {
 			$lx = '';
@@ -707,7 +716,7 @@ sub _index_sync {
 		$xlog = _git_log($self, $range);
 
 		$xdb = $self->begin_txn_lazy;
-	} while ($xdb->get_metadata('last_commit') ne $last_commit);
+	} while ($self->_last_x_commit ne $last_commit);
 
 	my $dbh = $mm->{dbh} if $mm;
 	my $cb = sub {
-- 
EW