com.google.cloud.dataflow.sdk.runners.worker.ShuffleReader Maven / Gradle / Ivy

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/*******************************************************************************
 * Copyright (C) 2015 Google Inc.
 *
 * Licensed 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 com.google.cloud.dataflow.sdk.runners.worker;

import java.io.IOException;

/**
 * ShuffleReader reads chunks of data from a shuffle dataset for
 * a given position range.
 */
interface ShuffleReader {
  /** Represents a chunk of data read from a shuffle dataset. */
  public static 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 
      }
   * 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)
   */
  public ReadChunkResult readIncludingPosition(
      byte[] startPosition, byte[] endPosition) throws IOException;
}