message: SQL: add a few comments explaining how to deal with connection issues
diff: @@ -125,6 +125,11 @@ bool SQL::Reconnect(int32_t attempts)
  GetServices()->m_log->Error("Reconnect attempt %d out of %d failed: %s",
  i+1, attempts, e.what());
  + // NOTE: We are on the main thread and cannot sleep for to long, as
  + // it will stall the entire server. If a reconnect fails here, the
  + // user requested operation will fail as well. It is then up to the
  + // user to retry later (e.g. Use DelayCommand()), and another
  + // reconnect attempt will be triggered automatically.
  if (i != attempts - 1)
  std::this_thread::sleep_for(std::chrono::milliseconds(1 << i));
  }
  @@ -162,6 +167,10 @@ Events::ArgumentStack SQL::OnExecutePreparedQuery(Events::ArgumentStack&&)
  return stack;
  }
  + // NOTE: There is a time-of-check-to-time-of-use race condition here.
  + // The target may be there at the check, but will go away afterwards.
  + // In these cases the reconnect will not be attempted, and the call will fail.
  + // It is up to the user to check the return value, and repeat the query if needed.
  if (!m_target->IsConnected())
  {
  if (!Reconnect())
  