docstr: Returns whether the caching phase is done.
docstr_tok: ["Returns","whether","the","caching","phase","is","done","."]
code: def filled(self) -> bool:
      """Returns whether the caching phase is done."""
      if self._is_done:
          return True
      files = os.listdir(self._cache_dir)
      index_files = [f for f in files if f.endswith(_INDEX_FILENAME)]
      worker_end = _WorkerEnv.detect()
      data_optimiser_num_workers = os.getenv(
          "DATA_OPTIMIZER_NUM_WORKERS", None
      )
      if data_optimiser_num_workers is not None:
          self._is_done = len(index_files) == int(
              data_optimiser_num_workers
          )
      else:
          self._is_done = (
              len(index_files)
              == self._distributed_env.world_size
              * worker_end.world_size
          )
      return self._is_done
  
imports: import json
  import os
  import warnings
  from dataclasses import dataclass
  from time import sleep
  from typing import Any, Dict, List, Optional, Tuple, Union
  import numpy
  import torch
  from lightning.data.streaming.compression import _COMPRESSORS, Compressor
  from lightning.data.streaming.constants import _INDEX_FILENAME, _TORCH_GREATER_EQUAL_2_1_0
  from lightning.data.streaming.serializers import Serializer, _get_serializers
  from lightning.data.utilities.env import _DistributedEnv, _WorkerEnv
  from lightning.data.utilities.format import _convert_bytes_to_int, _human_readable_bytes
label_desc: Use image node_id 2 for calling the BinaryWriter obj's underlying member method code with example usage: obj.filled() and returns: self, True