anchor.diff:           }).
   
   -record(state, {
  +          status :: init_in_progress | {init_failed, Reason::term()} | ready,
             qbufs = [] :: [{qbuf_ref(), #qbuf{}}],
             total_size = 0 :: non_neg_integer(),
             %% no new queries; accumulation allowed
  
positive.code: 
  
  -spec handle_cast(term(), #state{}) -> {noreply, #state{}}.
  handle_cast(tick, State) ->
      do_reap_expired_qbufs(State);
  handle_cast(_Msg, State) ->
  
negative.code: init([RootPath, MaxRetSize,
        SoftWatermark, HardWatermark,
        QBufExpireMsec, IncompleteQBufReleaseMsec]) ->
      spawn(fun() -> prepare_qbuf_dir(RootPath) end),
      State =
          #state{status                       = init_in_progress,
                 root_path                    = RootPath,
                 max_query_data_size          = MaxRetSize,
                 soft_watermark               = SoftWatermark,
                 hard_watermark               = HardWatermark,
  