content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.runners.flink.translation.functions;
  
  import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
  import org.apache.beam.sdk.io.FileSystems;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.transforms.join.RawUnionValue;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.flink.api.common.functions.FlatMapFunction;
  import org.apache.flink.api.common.functions.RichFlatMapFunction;
  import org.apache.flink.configuration.Configuration;
  import org.apache.flink.util.Collector;
  
  /**
   * A {@link FlatMapFunction} function that filters out those elements that don't belong in this
   * output. We need this to implement MultiOutput ParDo functions in combination with {@link
   * FlinkDoFnFunction}.
   */
  public class FlinkMultiOutputPruningFunction<T>
      extends RichFlatMapFunction<WindowedValue<RawUnionValue>, WindowedValue<T>> {
  
    private final int ourOutputTag;
    private final SerializablePipelineOptions options;
  
    public FlinkMultiOutputPruningFunction(int ourOutputTag, PipelineOptions options) {
      this.ourOutputTag = ourOutputTag;
      this.options = new SerializablePipelineOptions(options);
    }
  
    @Override
    public void open(Configuration parameters) {
      // Initialize FileSystems for any coders which may want to use the FileSystem,
      // see https://issues.apache.org/jira/browse/BEAM-8303
      FileSystems.setDefaultPipelineOptions(options.get());
    }
  
    @Override
    @SuppressWarnings("unchecked")
    public void flatMap(
        WindowedValue<RawUnionValue> windowedValue, Collector<WindowedValue<T>> collector)
        throws Exception {
      int unionTag = windowedValue.getValue().getUnionTag();
      if (unionTag == ourOutputTag) {
        collector.collect(
            (WindowedValue<T>) windowedValue.withValue(windowedValue.getValue().getValue()));
      }
    }
  }
  