extindex: retry sync_inbox before reindex

Ensure the num highwater mark of the target inbox is stable
before using it.  Otherwise we may end up repeating work
done to index a message.

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index 67d72036..daff656d 100644
--- a/lib/PublicInbox/ExtSearchIdx.pm
+++ b/lib/PublicInbox/ExtSearchIdx.pm
@@ -859,14 +859,20 @@ sub _reindex_check_ibx ($$$) {
         my $slice = 10000;
         my $opt = { limit => $slice };
         my ($beg, $end) = (1, $slice);
-        my $err = sync_inbox($self, $sync, $ibx) and return;
-        my $max = $ibx->mm->num_highwater;
+        my $ekey = $ibx->eidx_key;
+        my ($max, $max0);
+        do {
+                $max0 = $ibx->mm->num_highwater;
+                sync_inbox($self, $sync, $ibx) and return; # warned
+                $max = $ibx->mm->num_highwater;
+                return if $sync->{quit};
+        } while ($max > $max0 &&
+                warn("# $ekey moved $max0..$max, resyncing..\n"));
         $end = $max if $end > $max;
 
         # first, check if we missed any messages in target $ibx
         my $msgs;
         my $pr = $sync->{-opt}->{-progress};
-        my $ekey = $ibx->eidx_key;
         local $sync->{-regen_fmt} = "$ekey checking %u/$max\n";
         ${$sync->{nr}} = 0;
         my $fast = $sync->{-opt}->{fast};