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.dataflow.worker;
  
  import java.io.Closeable;
  import java.io.IOException;
  
  /** ShuffleReader reads chunks of data from a shuffle dataset for a given position range. */
  interface ShuffleReader extends Closeable {
    /** Represents a chunk of data read from a shuffle dataset. */
    class ReadChunkResult {
      public final byte[] chunk;
      public final byte[] nextStartPosition;
  
      public ReadChunkResult(byte[] chunk, byte[] nextStartPosition) {
        this.chunk = chunk;
        this.nextStartPosition = nextStartPosition;
      }
    }
  
    /**
     * Reads a chunk of data for keys in the given position range. The chunk is a sequence of pairs
     * encoded as: {@code <position-size><position><key-size><key>
     * <secondary-key-size><secondary-key><value-size><value>} where the sizes are 4-byte big-endian
     * integers.
     *
     * @param startPosition the start of the requested range (inclusive)
     * @param endPosition the end of the requested range (exclusive)
     */
    ReadChunkResult readIncludingPosition(byte[] startPosition, byte[] endPosition)
        throws IOException;
  }
  