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 */
018 package org.apache.hadoop.hdfs.client;
019
020 import java.io.InputStream;
021 import java.io.IOException;
022 import java.util.List;
023
024 import org.apache.hadoop.classification.InterfaceAudience;
025 import org.apache.hadoop.classification.InterfaceStability;
026 import org.apache.hadoop.fs.FSDataInputStream;
027 import org.apache.hadoop.crypto.CryptoInputStream;
028 import org.apache.hadoop.hdfs.DFSInputStream;
029 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
030 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
031 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
032
033 import com.google.common.base.Preconditions;
034
035 /**
036 * The Hdfs implementation of {@link FSDataInputStream}.
037 */
038 @InterfaceAudience.Public
039 @InterfaceStability.Evolving
040 public 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 synchronized 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 synchronized DFSInputStream.ReadStatistics getReadStatistics() {
107 return getDFSInputStream().getReadStatistics();
108 }
109 }