content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.client.block.stream;
  
  import alluxio.network.protocol.databuffer.DataBuffer;
  
  import java.io.Closeable;
  import java.io.IOException;
  
  /**
   * The interface to read data chunks.
   */
  public interface DataReader extends Closeable {
  
    /**
     * Reads a chunk. The caller needs to release the chunk.
     *
     * @return the data buffer or null if EOF is reached
     */
    DataBuffer readChunk() throws IOException;
  
    /**
     * @return the current stream position
     */
    long pos();
  
    /**
     * The factory interface to create {@link DataReader}s.
     */
    interface Factory extends Closeable {
      /**
       * Creates an instance of {@link DataReader}.
       *
       * @param offset the stream offset
       * @param len the length of the stream
       * @return the created object
       */
      DataReader create(long offset, long len) throws IOException;
    }
  }
  