001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.client;
019
020import java.io.InputStream;
021import java.io.IOException;
022import java.util.List;
023
024import org.apache.hadoop.classification.InterfaceAudience;
025import org.apache.hadoop.classification.InterfaceStability;
026import org.apache.hadoop.fs.FSDataInputStream;
027import org.apache.hadoop.crypto.CryptoInputStream;
028import org.apache.hadoop.hdfs.DFSInputStream;
029import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
030import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
031import org.apache.hadoop.hdfs.protocol.LocatedBlock;
032
033import com.google.common.base.Preconditions;
034
035/**
036 * The Hdfs implementation of {@link FSDataInputStream}.
037 */
038@InterfaceAudience.Public
039@InterfaceStability.Evolving
040public class HdfsDataInputStream extends FSDataInputStream {
041  public HdfsDataInputStream(DFSInputStream in) throws IOException {
042    super(in);
043  }
044
045  public HdfsDataInputStream(CryptoInputStream in) throws IOException {
046    super(in);
047    Preconditions.checkArgument(in.getWrappedStream() instanceof DFSInputStream,
048        "CryptoInputStream should wrap a DFSInputStream");
049  }
050
051  private DFSInputStream getDFSInputStream() {
052    if (in instanceof CryptoInputStream) {
053      return (DFSInputStream) ((CryptoInputStream) in).getWrappedStream();
054    }
055    return (DFSInputStream) in;
056  }
057
058  /**
059   * Get a reference to the wrapped output stream. We always want to return the
060   * actual underlying InputStream, even when we're using a CryptoStream. e.g.
061   * in the delegated methods below.
062   *
063   * @return the underlying output stream
064   */
065  public InputStream getWrappedStream() {
066      return in;
067  }
068
069  /**
070   * Get the datanode from which the stream is currently reading.
071   */
072  public DatanodeInfo getCurrentDatanode() {
073    return getDFSInputStream().getCurrentDatanode();
074  }
075
076  /**
077   * Get the block containing the target position.
078   */
079  public ExtendedBlock getCurrentBlock() {
080    return getDFSInputStream().getCurrentBlock();
081  }
082
083  /**
084   * Get the collection of blocks that has already been located.
085   */
086  public List<LocatedBlock> getAllBlocks() throws IOException {
087    return getDFSInputStream().getAllBlocks();
088  }
089
090  /**
091   * Get the visible length of the file. It will include the length of the last
092   * block even if that is in UnderConstruction state.
093   * 
094   * @return The visible length of the file.
095   */
096  public long getVisibleLength() throws IOException {
097    return getDFSInputStream().getFileLength();
098  }
099
100  /**
101   * Get statistics about the reads which this DFSInputStream has done.
102   * Note that because HdfsDataInputStream is buffered, these stats may
103   * be higher than you would expect just by adding up the number of
104   * bytes read through HdfsDataInputStream.
105   */
106  public DFSInputStream.ReadStatistics getReadStatistics() {
107    return getDFSInputStream().getReadStatistics();
108  }
109
110  public void clearReadStatistics() {
111    getDFSInputStream().clearReadStatistics();
112  }
113}