search: reopen and retry on updated databases

This seems like a nasty thing which breaks downloads of
large mailboxes.

1 files changed, 22 insertions, 13 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index d9fbc36c..856c8c14 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -97,7 +97,7 @@ sub query {
                 $opts->{relevance} = 1 unless exists $opts->{relevance};
         }
 
-        $self->do_enquire($query, $opts);
+        _do_enquire($self, $query, $opts);
 }
 
 sub get_thread {
@@ -111,10 +111,26 @@ sub get_thread {
         my $query = Search::Xapian::Query->new(OP_OR, $qtid, $qsub);
         $opts ||= {};
         $opts->{limit} ||= 1000;
-        $self->do_enquire($query, $opts);
+        _do_enquire($self, $query, $opts);
 }
 
-sub do_enquire {
+sub _do_enquire {
+        my ($self, $query, $opts) = @_;
+        my $ret;
+        for (1..10) {
+                eval { $ret = _enquire_once($self, $query, $opts) };
+                return $ret unless $@;
+                # Exception: The revision being read has been discarded -
+                # you should call Xapian::Database::reopen()
+                if (index($@, 'Xapian::Database::reopen') >= 0) {
+                        reopen($self);
+                } else {
+                        die $@;
+                }
+        }
+}
+
+sub _enquire_once {
         my ($self, $query, $opts) = @_;
         my $enquire = $self->enquire;
         if (defined $query) {
@@ -127,6 +143,8 @@ sub do_enquire {
         my $desc = !$opts->{asc};
         if ($opts->{relevance}) {
                 $enquire->set_sort_by_relevance_then_value(TS, $desc);
+        } elsif ($opts->{num}) {
+                $enquire->set_sort_by_value(NUM, 0);
         } else {
                 $enquire->set_sort_by_value_then_relevance(TS, $desc);
         }
@@ -186,21 +204,12 @@ sub num_range_processor {
 # only used for NNTP server
 sub query_xover {
         my ($self, $beg, $end, $offset) = @_;
-        my $enquire = $self->enquire;
         my $qp = Search::Xapian::QueryParser->new;
         $qp->set_database($self->{xdb});
         $qp->add_valuerangeprocessor($self->num_range_processor);
         my $query = $qp->parse_query("$beg..$end", QP_FLAGS);
-        $query = Search::Xapian::Query->new(OP_AND, $mail_query, $query);
-        $enquire->set_query($query);
-        $enquire->set_sort_by_value(NUM, 0);
-        my $limit = 200;
-        my $mset = $enquire->get_mset($offset, $limit);
-        my @msgs = map {
-                PublicInbox::SearchMsg->load_doc($_->get_document);
-        } $mset->items;
 
-        { total => $mset->get_matches_estimated, msgs => \@msgs }
+        _do_enquire($self, $query, {num => 1, limit => 200, offset => $offset});
 }
 
 sub lookup_message {