[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 | package org.apache.hadoop.fs; |
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| 19 | |
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| 20 | import java.io.IOException; |
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| 21 | import java.net.InetAddress; |
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| 22 | import org.apache.hadoop.conf.Configuration; |
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| 23 | import org.apache.hadoop.conf.Configured; |
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| 24 | import org.apache.hadoop.io.LongWritable; |
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| 25 | import org.apache.hadoop.io.UTF8; |
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| 26 | import org.apache.hadoop.io.Writable; |
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| 27 | import org.apache.hadoop.io.WritableComparable; |
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| 28 | import org.apache.hadoop.mapred.JobConf; |
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| 29 | import org.apache.hadoop.mapred.Mapper; |
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| 30 | import org.apache.hadoop.mapred.OutputCollector; |
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| 31 | import org.apache.hadoop.mapred.Reporter; |
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| 32 | |
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| 33 | /** |
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| 34 | * Base mapper class for IO operations. |
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| 35 | * <p> |
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| 36 | * Two abstract method {@link #doIO(Reporter, String, long)} and |
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| 37 | * {@link #collectStats(OutputCollector,String,long,Object)} should be |
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| 38 | * overloaded in derived classes to define the IO operation and the |
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| 39 | * statistics data to be collected by subsequent reducers. |
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| 40 | * |
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| 41 | */ |
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| 42 | public abstract class IOMapperBase extends Configured |
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| 43 | implements Mapper<UTF8, LongWritable, UTF8, UTF8> { |
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| 44 | |
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| 45 | protected byte[] buffer; |
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| 46 | protected int bufferSize; |
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| 47 | protected FileSystem fs; |
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| 48 | protected String hostName; |
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| 49 | |
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| 50 | public IOMapperBase(Configuration conf) { |
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| 51 | super(conf); |
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| 52 | try { |
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| 53 | fs = FileSystem.get(conf); |
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| 54 | } catch (Exception e) { |
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| 55 | throw new RuntimeException("Cannot create file system.", e); |
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| 56 | } |
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| 57 | bufferSize = conf.getInt("test.io.file.buffer.size", 4096); |
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| 58 | buffer = new byte[bufferSize]; |
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| 59 | try { |
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| 60 | hostName = InetAddress.getLocalHost().getHostName(); |
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| 61 | } catch(Exception e) { |
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| 62 | hostName = "localhost"; |
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| 63 | } |
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| 64 | } |
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| 65 | |
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| 66 | public void configure(JobConf job) { |
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| 67 | setConf(job); |
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| 68 | } |
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| 69 | |
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| 70 | public void close() throws IOException { |
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| 71 | } |
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| 72 | |
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| 73 | /** |
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| 74 | * Perform io operation, usually read or write. |
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| 75 | * |
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| 76 | * @param reporter |
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| 77 | * @param name file name |
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| 78 | * @param value offset within the file |
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| 79 | * @return object that is passed as a parameter to |
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| 80 | * {@link #collectStats(OutputCollector,String,long,Object)} |
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| 81 | * @throws IOException |
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| 82 | */ |
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| 83 | abstract Object doIO(Reporter reporter, |
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| 84 | String name, |
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| 85 | long value) throws IOException; |
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| 86 | |
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| 87 | /** |
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| 88 | * Collect stat data to be combined by a subsequent reducer. |
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| 89 | * |
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| 90 | * @param output |
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| 91 | * @param name file name |
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| 92 | * @param execTime IO execution time |
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| 93 | * @param doIOReturnValue value returned by {@link #doIO(Reporter,String,long)} |
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| 94 | * @throws IOException |
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| 95 | */ |
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| 96 | abstract void collectStats(OutputCollector<UTF8, UTF8> output, |
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| 97 | String name, |
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| 98 | long execTime, |
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| 99 | Object doIOReturnValue) throws IOException; |
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| 100 | |
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| 101 | /** |
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| 102 | * Map file name and offset into statistical data. |
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| 103 | * <p> |
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| 104 | * The map task is to get the |
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| 105 | * <tt>key</tt>, which contains the file name, and the |
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| 106 | * <tt>value</tt>, which is the offset within the file. |
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| 107 | * |
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| 108 | * The parameters are passed to the abstract method |
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| 109 | * {@link #doIO(Reporter,String,long)}, which performs the io operation, |
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| 110 | * usually read or write data, and then |
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| 111 | * {@link #collectStats(OutputCollector,String,long,Object)} |
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| 112 | * is called to prepare stat data for a subsequent reducer. |
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| 113 | */ |
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| 114 | public void map(UTF8 key, |
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| 115 | LongWritable value, |
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| 116 | OutputCollector<UTF8, UTF8> output, |
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| 117 | Reporter reporter) throws IOException { |
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| 118 | String name = key.toString(); |
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| 119 | long longValue = value.get(); |
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| 120 | |
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| 121 | reporter.setStatus("starting " + name + " ::host = " + hostName); |
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| 122 | |
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| 123 | long tStart = System.currentTimeMillis(); |
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| 124 | Object statValue = doIO(reporter, name, longValue); |
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| 125 | long tEnd = System.currentTimeMillis(); |
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| 126 | long execTime = tEnd - tStart; |
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| 127 | collectStats(output, name, execTime, statValue); |
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| 128 | |
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| 129 | reporter.setStatus("finished " + name + " ::host = " + hostName); |
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| 130 | } |
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| 131 | } |
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