search: v2: ensure shards are numerically sorted

This seems required to correctly get the NNTP article number
from Xapian docid on combined Xapian DBs.  The default
(ASCII-betical) sorting was only acceptable for -imapd users
until somebody hit 11 (or more) shards, which is a rare case.

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index 4e08aed7acbf0697ccdd9593325080b63e8e637d..4d02a7c169c202ebd150ccd1e0158ab21939c56a 100644 (file)
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -177,19 +177,24 @@ sub _xdb ($) {
        my ($xdb, $slow_phrase);
        my $qpf = \($self->{qp_flags} ||= $QP_FLAGS);
        if ($self->{ibx_ver} >= 2) {
-               my $n = 0;
-               foreach my $shard (<$dir/*>) {
-                       -d $shard && $shard =~ m!/[0-9]+\z! or next;
-                       my $sub = $X{Database}->new($shard);
-                       if ($xdb) {
-                               $xdb->add_database($sub);
-                       } else {
-                               $xdb = $sub;
+               my @xdb;
+               opendir(my $dh, $dir) or return; # not initialized yet
+
+               # We need numeric sorting so shard[0] is first for reading
+               # Xapian metadata, if needed
+               for (sort { $a <=> $b } grep(/\A[0-9]+\z/, readdir($dh))) {
+                       my $shard_dir = "$dir/$_";
+                       if (-d $shard_dir && -r _) {
+                               push @xdb, $X{Database}->new($shard_dir);
+                               $slow_phrase ||= -f "$shard_dir/iamchert";
+                       } else { # gaps from missing epochs throw off mdocid()
+                               warn "E: $shard_dir missing or unreadable\n";
+                               return;
                        }
-                       $slow_phrase ||= -f "$shard/iamchert";
-                       ++$n;
                }
-               $self->{nshard} = $n;
+               $self->{nshard} = scalar(@xdb);
+               $xdb = shift @xdb;
+               $xdb->add_database($_) for @xdb;
        } else {
                $slow_phrase = -f "$dir/iamchert";
                $xdb = $X{Database}->new($dir);