xap_helper: drop DB handles on EMFILE/ENFILE/etc...

This allows the process to recover in case we get the SHARD_COST
calculation wrong in case Xapian uses more FDs than expected in
new versions.  We'll no longer attempt to recover from ENOMEM
and similar errors during Xapian DB initialization and instead
just tear down the process (as we do in other places).

1 files changed, 20 insertions, 7 deletions

diff --git a/lib/PublicInbox/XapHelper.pm b/lib/PublicInbox/XapHelper.pm
index db9e99ae..ba41b5d2 100644
--- a/lib/PublicInbox/XapHelper.pm
+++ b/lib/PublicInbox/XapHelper.pm
@@ -202,14 +202,27 @@ sub dispatch {
                         %SRCH = ();
                 }
                 my $first = shift @$dirs;
-                my $slow_phrase = -f "$first/iamchert";
-                $new->{xdb} = $X->{Database}->new($first);
-                for (@$dirs) {
-                        $slow_phrase ||= -f "$_/iamchert";
-                        $new->{xdb}->add_database($X->{Database}->new($_));
+                for my $retried (0, 1) {
+                        my $slow_phrase = -f "$first/iamchert";
+                        eval {
+                                $new->{xdb} = $X->{Database}->new($first);
+                                for (@$dirs) {
+                                        $slow_phrase ||= -f "$_/iamchert";
+                                        $new->{xdb}->add_database(
+                                                        $X->{Database}->new($_))
+                                }
+                        };
+                        last unless $@;
+                        if ($retried) {
+                                die "E: $@\n";
+                        } else { # may be EMFILE/ENFILE/ENOMEM....
+                                warn "W: $@, retrying...\n";
+                                %SRCH = ();
+                                $SHARD_NFD = $nfd;
+                        }
+                        $slow_phrase or $new->{qp_flags}
+                                |= PublicInbox::Search::FLAG_PHRASE();
                 }
-                $slow_phrase or
-                        $new->{qp_flags} |= PublicInbox::Search::FLAG_PHRASE();
                 bless $new, $req->{c} ? 'PublicInbox::CodeSearch' :
                                         'PublicInbox::Search';
                 $new->{qp} = $new->qparse_new;