[120] | 1 | /** |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one |
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| 3 | * or more contributor license agreements. See the NOTICE file |
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| 4 | * distributed with this work for additional information |
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| 5 | * regarding copyright ownership. The ASF licenses this file |
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| 6 | * to you under the Apache License, Version 2.0 (the |
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| 7 | * "License"); you may not use this file except in compliance |
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| 8 | * with the License. You may obtain a copy of the License at |
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| 9 | * |
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| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 11 | * |
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| 12 | * Unless required by applicable law or agreed to in writing, software |
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| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 15 | * See the License for the specific language governing permissions and |
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| 16 | * limitations under the License. |
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| 17 | */ |
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| 18 | |
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| 19 | package org.apache.hadoop.mapreduce.lib.input; |
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| 20 | |
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| 21 | import java.io.IOException; |
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| 22 | import java.io.DataInput; |
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| 23 | import java.io.DataOutput; |
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| 24 | |
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| 25 | import org.apache.hadoop.mapreduce.InputFormat; |
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| 26 | import org.apache.hadoop.mapreduce.InputSplit; |
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| 27 | import org.apache.hadoop.mapreduce.TaskAttemptContext; |
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| 28 | import org.apache.hadoop.fs.Path; |
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| 29 | import org.apache.hadoop.io.Text; |
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| 30 | import org.apache.hadoop.io.Writable; |
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| 31 | |
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| 32 | /** A section of an input file. Returned by {@link |
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| 33 | * InputFormat#getSplits(JobContext)} and passed to |
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| 34 | * {@link InputFormat#createRecordReader(InputSplit,TaskAttemptContext)}. */ |
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| 35 | public class FileSplit extends InputSplit implements Writable { |
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| 36 | private Path file; |
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| 37 | private long start; |
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| 38 | private long length; |
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| 39 | private String[] hosts; |
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| 40 | |
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| 41 | FileSplit() {} |
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| 42 | |
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| 43 | /** Constructs a split with host information |
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| 44 | * |
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| 45 | * @param file the file name |
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| 46 | * @param start the position of the first byte in the file to process |
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| 47 | * @param length the number of bytes in the file to process |
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| 48 | * @param hosts the list of hosts containing the block, possibly null |
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| 49 | */ |
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| 50 | public FileSplit(Path file, long start, long length, String[] hosts) { |
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| 51 | this.file = file; |
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| 52 | this.start = start; |
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| 53 | this.length = length; |
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| 54 | this.hosts = hosts; |
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| 55 | } |
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| 56 | |
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| 57 | /** The file containing this split's data. */ |
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| 58 | public Path getPath() { return file; } |
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| 59 | |
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| 60 | /** The position of the first byte in the file to process. */ |
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| 61 | public long getStart() { return start; } |
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| 62 | |
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| 63 | /** The number of bytes in the file to process. */ |
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| 64 | @Override |
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| 65 | public long getLength() { return length; } |
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| 66 | |
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| 67 | @Override |
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| 68 | public String toString() { return file + ":" + start + "+" + length; } |
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| 69 | |
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| 70 | //////////////////////////////////////////// |
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| 71 | // Writable methods |
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| 72 | //////////////////////////////////////////// |
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| 73 | |
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| 74 | @Override |
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| 75 | public void write(DataOutput out) throws IOException { |
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| 76 | Text.writeString(out, file.toString()); |
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| 77 | out.writeLong(start); |
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| 78 | out.writeLong(length); |
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| 79 | } |
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| 80 | |
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| 81 | @Override |
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| 82 | public void readFields(DataInput in) throws IOException { |
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| 83 | file = new Path(Text.readString(in)); |
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| 84 | start = in.readLong(); |
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| 85 | length = in.readLong(); |
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| 86 | hosts = null; |
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| 87 | } |
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| 88 | |
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| 89 | @Override |
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| 90 | public String[] getLocations() throws IOException { |
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| 91 | if (this.hosts == null) { |
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| 92 | return new String[]{}; |
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| 93 | } else { |
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| 94 | return this.hosts; |
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| 95 | } |
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| 96 | } |
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| 97 | } |
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