Merge pull request #6437 from vespa-engine/balder/ensure-that-there-is-at-least-1-valid-stopsign-visible-at-all-times

There must always be a stopsign visible to any concurrent reader no m…

1 files changed, 5 insertions, 2 deletions

diff --git a/searchlib/src/vespa/searchlib/common/bitvector.h b/searchlib/src/vespa/searchlib/common/bitvector.h
index fa8ec5b5cdd..298528d0846 100644
--- a/searchlib/src/vespa/searchlib/common/bitvector.h
+++ b/searchlib/src/vespa/searchlib/common/bitvector.h
@@ -120,9 +120,12 @@ public:
     }
 
     void setSize(Index sz) {
-        clearBit(size());
+        setBit(sz);  // Need to place the new stop sign first
+        if (sz > _sz) {
+            // Can only remove the old stopsign if it is ahead of the new.
+            clearBit(_sz);
+        }
         _sz = sz;
-        setBit(size());
     }
     void setBit(Index idx) {
         _words[wordNum(idx)] |= mask(idx);