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.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index 750ced5c..3d7a6e7d 100644
--- 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);