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    
019    package org.apache.hadoop.fs;
020    
021    import java.io.Closeable;
022    import java.io.IOException;
023    
024    import org.apache.avro.file.SeekableInput;
025    import org.apache.hadoop.classification.InterfaceAudience;
026    import org.apache.hadoop.classification.InterfaceStability;
027    
028    /** Adapts an {@link FSDataInputStream} to Avro's SeekableInput interface. */
029    @InterfaceAudience.Public
030    @InterfaceStability.Stable
031    public class AvroFSInput implements Closeable, SeekableInput {
032      private final FSDataInputStream stream;
033      private final long len;
034    
035      /** Construct given an {@link FSDataInputStream} and its length. */
036      public AvroFSInput(final FSDataInputStream in, final long len) {
037        this.stream = in;
038        this.len = len;
039      }
040    
041      /** Construct given a {@link FileContext} and a {@link Path}. */
042      public AvroFSInput(final FileContext fc, final Path p) throws IOException {
043        FileStatus status = fc.getFileStatus(p);
044        this.len = status.getLen();
045        this.stream = fc.open(p);
046      }
047    
048      @Override
049      public long length() {
050        return len;
051      }
052    
053      @Override
054      public int read(byte[] b, int off, int len) throws IOException {
055        return stream.read(b, off, len);
056      }
057    
058      @Override
059      public void seek(long p) throws IOException {
060        stream.seek(p);
061      }
062    
063      @Override
064      public long tell() throws IOException {
065        return stream.getPos();
066      }
067    
068      @Override
069      public void close() throws IOException {
070        stream.close();
071      }
072    }