在BoundedSource中的Apache Beam python如何调用estimate_size和splits方法？

Question

python beam.io.Read无法调用方法Estimate_size（）和split（）。如何使用apache管道调用该方法？

我在CountingSource示例之后添加了该文档，在Apache Beam网站上也没有任何示例。

`     CountingSource（iobase.BoundedSource）类：

  def __init__(self, count):
    self.records_read = Metrics.counter(self.__class__, 'recordsRead')
    self._count = count

  def estimate_size(self):
    print('estimate_size')
    return self._count

  def get_range_tracker(self, start_position, stop_position):
    print('get_range_tracker')
    if start_position is None:
      start_position = 0
    if stop_position is None:
      stop_position = self._count

    print(start_position, start_position)
    return OffsetRangeTracker(start_position, stop_position)

  def read(self, range_tracker):
    print('read')
    for i in range(self._count):
      if not range_tracker.try_claim(i):
        return
      self.records_read.inc()
      yield i

  def split(self, desired_bundle_size, start_position=None,
            stop_position=None):
    print('split')
    if start_position is None:
      start_position = 0
    if stop_position is None:
      stop_position = self._count

    bundle_start = start_position
    while bundle_start < self._count:
      print(bundle_start)
      bundle_stop = max(self._count, bundle_start + desired_bundle_size)
      yield iobase.SourceBundle(weight=(bundle_stop - bundle_start),
                                source=self,
                                start_position=bundle_start,
                                stop_position=bundle_stop)
      bundle_start = bundle_stop


with beam.Pipeline(options=PipelineOptions()) as p:
  (p | 'Read Rows' >> beam.io.Read(CountingSource(100)))

`