How to use

empty

method

in

org.apache.beam.sdk.transforms.Requirements

/** Watches the growth of the given poll function. See class documentation for more details. */
public static <InputT, OutputT> Growth<InputT, OutputT, OutputT> growthOf(
  Growth.PollFn<InputT, OutputT> pollFn) {
 return growthOf(pollFn, Requirements.empty());
}

/**
 * Wraps a {@link SerializableFunction} as a {@link Contextful} of {@link Fn} with empty {@link
 * Requirements}.
 */
public static <InputT, OutputT> Contextful<Fn<InputT, OutputT>> fn(
  final SerializableFunction<InputT, OutputT> fn) {
 return new Contextful<>((element, c) -> fn.apply(element), Requirements.empty());
}

@Override
public PCollection<MatchResult.Metadata> expand(PCollection<String> input) {
 PCollection<MatchResult.Metadata> res;
 if (getConfiguration().getWatchInterval() == null) {
  res =
    input.apply(
      "Match filepatterns",
      ParDo.of(new MatchFn(getConfiguration().getEmptyMatchTreatment())));
 } else {
  res =
    input
      .apply(
        "Continuously match filepatterns",
        Watch.growthOf(
            Contextful.of(new MatchPollFn(), Requirements.empty()),
            new ExtractFilenameFn())
          .withPollInterval(getConfiguration().getWatchInterval())
          .withTerminationPerInput(getConfiguration().getWatchTerminationCondition()))
      .apply(Values.create());
 }
 return res.apply(Reshuffle.viaRandomKey());
}

      standardSeconds(3) /* timeToDeclareOutputFinal */,
      standardSeconds(30) /* timeToFail */),
    Requirements.empty()),
  KV::getKey)
.withTerminationPerInput(Growth.afterTotalOf(standardSeconds(5)))