search: retry document loading from Xapian

In addition to needing to retry enquire queries, we also need
to protect document loading from the Xapian DB and retry on
modification, as it seems to throw the same errors.

Checking the $@ ref for Search::Xapian::DatabaseModifiedError
is actually in the test suite for both the XS and SWIG Xapian
bindings, so we should be good as far as forward/backwards
compatibility.

1 files changed, 10 insertions, 5 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index 5e6bfc68..24cb2667 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -166,22 +166,27 @@ sub get_thread {
         _do_enquire($self, $qtid, $opts);
 }
 
-sub _do_enquire {
-        my ($self, $query, $opts) = @_;
+sub retry_reopen {
+        my ($self, $cb) = @_;
         my $ret;
         for (1..10) {
-                eval { $ret = _enquire_once($self, $query, $opts) };
+                eval { $ret = $cb->() };
                 return $ret unless $@;
                 # Exception: The revision being read has been discarded -
                 # you should call Xapian::Database::reopen()
-                if (index($@, 'Xapian::Database::reopen') >= 0) {
+                if (ref($@) eq 'Search::Xapian::DatabaseModifiedError') {
                         reopen($self);
                 } else {
-                        die $@;
+                        die;
                 }
         }
 }
 
+sub _do_enquire {
+        my ($self, $query, $opts) = @_;
+        retry_reopen($self, sub { _enquire_once($self, $query, $opts) });
+}
+
 sub _enquire_once {
         my ($self, $query, $opts) = @_;
         my $enquire = $self->enquire;