[neighorch] Remove pending DEL operation after SET operation for the …

…same key (#1485)

* Remove del operation if set is successfully done in neighorch

* using reverse iterator to travel backwards

orchagent/neighorch.cpp

@@ -354,13 +354,31 @@ void NeighOrch::doTask(Consumer &consumer)
  if (m_syncdNeighbors.find(neighbor_entry) == m_syncdNeighbors.end() || m_syncdNeighbors[neighbor_entry] != mac_address)
  {
  if (addNeighbor(neighbor_entry, mac_address))
+ {
  it = consumer.m_toSync.erase(it);
+ }
  else
+ {
  it++;
+ continue;
+ }
  }
  else
+ {
  /* Duplicate entry */
  it = consumer.m_toSync.erase(it);
+ }
+
+ /* Remove remaining DEL operation in m_toSync for the same neighbor.
+ * Since DEL operation is supposed to be executed before SET for the same neighbor
+ * A remaining DEL after the SET operation means the DEL operation failed previously and should not be executed anymore
+ */
+ auto rit = make_reverse_iterator(it);
+ while (rit != consumer.m_toSync.rend() && rit->first == key && kfvOp(rit->second) == DEL_COMMAND)
+ {
+ consumer.m_toSync.erase(next(rit).base());
+ SWSS_LOG_NOTICE("Removed pending neighbor DEL operation for %s after SET operation", key.c_str());
+ }
  }
  else if (op == DEL_COMMAND)
  {