extindex: guard against buggy unrefs

I noticed some unref messages which shouldn't have been
happening, but they were.  Which is troubling.  So add
a guard around an unref path until we can get to the bottom
of this.

diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index 750ced5c0f453bc8e0241a1ea2e6603a64c00104..3d7a6e7d76223a47904b62cb7bef1d9b42734d03 100644 (file)
--- a/lib/PublicInbox/ExtSearchIdx.pm
+++ b/lib/PublicInbox/ExtSearchIdx.pm
@@ -18,6 +18,7 @@ use strict;
 use v5.10.1;
 use parent qw(PublicInbox::ExtSearch PublicInbox::Lock);
 use Carp qw(croak carp);
+use Scalar::Util qw(blessed);
 use Sys::Hostname qw(hostname);
 use POSIX qw(strftime);
 use File::Glob qw(bsd_glob GLOB_NOSORT);
@@ -143,6 +144,14 @@ sub _unref_doc ($$$$$;$) {
                $smsg = $docid;
                $docid = $smsg->{num};
        }
+       if (defined($oidbin) && defined($xnum) && blessed($ibx) && $ibx->over) {
+               my $smsg = $ibx->over->get_art($xnum);
+               if ($smsg && pack('H*', $smsg->{blob}) eq $oidbin) {
+                       carp("BUG: (non-fatal) ".$ibx->eidx_key.
+                               " #$xnum $smsg->{blob} still valid");
+                       return;
+               }
+       }
        my $s = 'DELETE FROM xref3 WHERE oidbin = ?';
        $s .= ' AND ibx_id = ?' if defined($ibx);
        $s .= ' AND xnum = ?' if defined($xnum);