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.spark.network.shuffle;
  
  import java.io.DataInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.LongBuffer;
  
  /**
   * Keeps the index information for a particular map output
   * as an in-memory LongBuffer.
   */
  public class ShuffleIndexInformation {
    /** offsets as long buffer */
    private final LongBuffer offsets;
  
    public ShuffleIndexInformation(File indexFile) throws IOException {
      int size = (int)indexFile.length();
      ByteBuffer buffer = ByteBuffer.allocate(size);
      offsets = buffer.asLongBuffer();
      DataInputStream dis = null;
      try {
        dis = new DataInputStream(new FileInputStream(indexFile));
        dis.readFully(buffer.array());
      } finally {
        if (dis != null) {
          dis.close();
        }
      }
    }
  
    /**
     * Get index offset for a particular reducer.
     */
    public ShuffleIndexRecord getIndex(int reduceId) {
      long offset = offsets.get(reduceId);
      long nextOffset = offsets.get(reduceId + 1);
      return new ShuffleIndexRecord(offset, nextOffset - offset);
    }
  }
  