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.wrappers;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState;
  
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.flink.api.common.io.DefaultInputSplitAssigner;
  import org.apache.flink.api.common.io.RichInputFormat;
  import org.apache.flink.api.common.io.statistics.BaseStatistics;
  import org.apache.flink.configuration.Configuration;
  import org.apache.flink.core.io.GenericInputSplit;
  import org.apache.flink.core.io.InputSplitAssigner;
  
  /** Flink input format that implements impulses. */
  public class ImpulseInputFormat extends RichInputFormat<WindowedValue<byte[]>, GenericInputSplit> {
  
    // Whether the input format has remaining output that has not yet been read.
    private boolean availableOutput = false;
  
    public ImpulseInputFormat() {}
  
    @Override
    public void configure(Configuration configuration) {
      // Do nothing.
    }
  
    @Override
    public BaseStatistics getStatistics(BaseStatistics baseStatistics) {
      return new BaseStatistics() {
        @Override
        public long getTotalInputSize() {
          return 1;
        }
  
        @Override
        public long getNumberOfRecords() {
          return 1;
        }
  
        @Override
        public float getAverageRecordWidth() {
          return 1;
        }
      };
    }
  
    @Override
    public GenericInputSplit[] createInputSplits(int numSplits) {
      // Always return a single split because only one global "impulse" will ever be sent.
      return new GenericInputSplit[] {new GenericInputSplit(1, 1)};
    }
  
    @Override
    public InputSplitAssigner getInputSplitAssigner(GenericInputSplit[] genericInputSplits) {
      return new DefaultInputSplitAssigner(genericInputSplits);
    }
  
    @Override
    public void open(GenericInputSplit genericInputSplit) {
      availableOutput = true;
    }
  
    @Override
    public boolean reachedEnd() {
      return !availableOutput;
    }
  
    @Override
    public WindowedValue<byte[]> nextRecord(WindowedValue<byte[]> windowedValue) {
      checkState(availableOutput);
      availableOutput = false;
      if (windowedValue != null) {
        return windowedValue;
      }
      return WindowedValues.valueInGlobalWindow(new byte[0]);
    }
  
    @Override
    public void close() {
      // Do nothing.
    }
  }
  