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.hdfs; |
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19 | |
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20 | import junit.framework.TestCase; |
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21 | import java.io.*; |
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22 | import java.util.Random; |
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23 | import org.apache.hadoop.conf.Configuration; |
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24 | import org.apache.hadoop.fs.FSDataInputStream; |
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25 | import org.apache.hadoop.fs.FileSystem; |
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26 | import org.apache.hadoop.fs.Path; |
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27 | import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset; |
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28 | |
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29 | /** |
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30 | * This class tests the DFS positional read functionality in a single node |
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31 | * mini-cluster. |
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32 | */ |
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33 | public class TestPread extends TestCase { |
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34 | static final long seed = 0xDEADBEEFL; |
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35 | static final int blockSize = 4096; |
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36 | boolean simulatedStorage = false; |
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37 | |
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38 | private void writeFile(FileSystem fileSys, Path name) throws IOException { |
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39 | // create and write a file that contains three blocks of data |
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40 | DataOutputStream stm = fileSys.create(name, true, 4096, (short)1, |
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41 | (long)blockSize); |
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42 | // test empty file open and read |
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43 | stm.close(); |
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44 | FSDataInputStream in = fileSys.open(name); |
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45 | byte[] buffer = new byte[(int)(12*blockSize)]; |
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46 | in.readFully(0, buffer, 0, 0); |
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47 | IOException res = null; |
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48 | try { // read beyond the end of the file |
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49 | in.readFully(0, buffer, 0, 1); |
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50 | } catch (IOException e) { |
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51 | // should throw an exception |
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52 | res = e; |
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53 | } |
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54 | assertTrue("Error reading beyond file boundary.", res != null); |
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55 | in.close(); |
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56 | if (!fileSys.delete(name, true)) |
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57 | assertTrue("Cannot delete file", false); |
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58 | |
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59 | // now create the real file |
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60 | stm = fileSys.create(name, true, 4096, (short)1, (long)blockSize); |
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61 | Random rand = new Random(seed); |
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62 | rand.nextBytes(buffer); |
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63 | stm.write(buffer); |
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64 | stm.close(); |
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65 | } |
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66 | |
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67 | private void checkAndEraseData(byte[] actual, int from, byte[] expected, String message) { |
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68 | for (int idx = 0; idx < actual.length; idx++) { |
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69 | assertEquals(message+" byte "+(from+idx)+" differs. expected "+ |
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70 | expected[from+idx]+" actual "+actual[idx], |
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71 | actual[idx], expected[from+idx]); |
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72 | actual[idx] = 0; |
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73 | } |
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74 | } |
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75 | |
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76 | private void doPread(FSDataInputStream stm, long position, byte[] buffer, |
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77 | int offset, int length) throws IOException { |
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78 | int nread = 0; |
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79 | while (nread < length) { |
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80 | int nbytes = stm.read(position+nread, buffer, offset+nread, length-nread); |
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81 | assertTrue("Error in pread", nbytes > 0); |
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82 | nread += nbytes; |
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83 | } |
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84 | } |
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85 | |
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86 | private void pReadFile(FileSystem fileSys, Path name) throws IOException { |
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87 | FSDataInputStream stm = fileSys.open(name); |
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88 | byte[] expected = new byte[(int)(12*blockSize)]; |
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89 | if (simulatedStorage) { |
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90 | for (int i= 0; i < expected.length; i++) { |
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91 | expected[i] = SimulatedFSDataset.DEFAULT_DATABYTE; |
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92 | } |
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93 | } else { |
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94 | Random rand = new Random(seed); |
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95 | rand.nextBytes(expected); |
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96 | } |
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97 | // do a sanity check. Read first 4K bytes |
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98 | byte[] actual = new byte[4096]; |
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99 | stm.readFully(actual); |
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100 | checkAndEraseData(actual, 0, expected, "Read Sanity Test"); |
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101 | // now do a pread for the first 8K bytes |
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102 | actual = new byte[8192]; |
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103 | doPread(stm, 0L, actual, 0, 8192); |
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104 | checkAndEraseData(actual, 0, expected, "Pread Test 1"); |
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105 | // Now check to see if the normal read returns 4K-8K byte range |
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106 | actual = new byte[4096]; |
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107 | stm.readFully(actual); |
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108 | checkAndEraseData(actual, 4096, expected, "Pread Test 2"); |
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109 | // Now see if we can cross a single block boundary successfully |
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110 | // read 4K bytes from blockSize - 2K offset |
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111 | stm.readFully(blockSize - 2048, actual, 0, 4096); |
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112 | checkAndEraseData(actual, (int)(blockSize-2048), expected, "Pread Test 3"); |
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113 | // now see if we can cross two block boundaries successfully |
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114 | // read blockSize + 4K bytes from blockSize - 2K offset |
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115 | actual = new byte[(int)(blockSize+4096)]; |
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116 | stm.readFully(blockSize - 2048, actual); |
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117 | checkAndEraseData(actual, (int)(blockSize-2048), expected, "Pread Test 4"); |
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118 | // now see if we can cross two block boundaries that are not cached |
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119 | // read blockSize + 4K bytes from 10*blockSize - 2K offset |
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120 | actual = new byte[(int)(blockSize+4096)]; |
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121 | stm.readFully(10*blockSize - 2048, actual); |
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122 | checkAndEraseData(actual, (int)(10*blockSize-2048), expected, "Pread Test 5"); |
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123 | // now check that even after all these preads, we can still read |
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124 | // bytes 8K-12K |
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125 | actual = new byte[4096]; |
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126 | stm.readFully(actual); |
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127 | checkAndEraseData(actual, 8192, expected, "Pread Test 6"); |
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128 | // done |
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129 | stm.close(); |
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130 | // check block location caching |
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131 | stm = fileSys.open(name); |
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132 | stm.readFully(1, actual, 0, 4096); |
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133 | stm.readFully(4*blockSize, actual, 0, 4096); |
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134 | stm.readFully(7*blockSize, actual, 0, 4096); |
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135 | actual = new byte[3*4096]; |
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136 | stm.readFully(0*blockSize, actual, 0, 3*4096); |
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137 | checkAndEraseData(actual, 0, expected, "Pread Test 7"); |
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138 | actual = new byte[8*4096]; |
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139 | stm.readFully(3*blockSize, actual, 0, 8*4096); |
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140 | checkAndEraseData(actual, 3*blockSize, expected, "Pread Test 8"); |
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141 | // read the tail |
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142 | stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize/2); |
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143 | IOException res = null; |
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144 | try { // read beyond the end of the file |
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145 | stm.readFully(11*blockSize+blockSize/2, actual, 0, blockSize); |
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146 | } catch (IOException e) { |
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147 | // should throw an exception |
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148 | res = e; |
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149 | } |
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150 | assertTrue("Error reading beyond file boundary.", res != null); |
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151 | |
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152 | stm.close(); |
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153 | } |
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154 | |
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155 | private void cleanupFile(FileSystem fileSys, Path name) throws IOException { |
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156 | assertTrue(fileSys.exists(name)); |
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157 | assertTrue(fileSys.delete(name, true)); |
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158 | assertTrue(!fileSys.exists(name)); |
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159 | } |
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160 | |
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161 | /** |
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162 | * Tests positional read in DFS. |
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163 | */ |
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164 | public void testPreadDFS() throws IOException { |
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165 | dfsPreadTest(false); //normal pread |
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166 | dfsPreadTest(true); //trigger read code path without transferTo. |
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167 | } |
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168 | |
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169 | private void dfsPreadTest(boolean disableTransferTo) throws IOException { |
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170 | Configuration conf = new Configuration(); |
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171 | conf.setLong("dfs.block.size", 4096); |
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172 | conf.setLong("dfs.read.prefetch.size", 4096); |
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173 | if (simulatedStorage) { |
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174 | conf.setBoolean("dfs.datanode.simulateddatastorage", true); |
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175 | } |
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176 | if (disableTransferTo) { |
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177 | conf.setBoolean("dfs.datanode.transferTo.allowed", false); |
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178 | } |
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179 | MiniDFSCluster cluster = new MiniDFSCluster(conf, 3, true, null); |
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180 | FileSystem fileSys = cluster.getFileSystem(); |
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181 | try { |
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182 | Path file1 = new Path("preadtest.dat"); |
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183 | writeFile(fileSys, file1); |
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184 | pReadFile(fileSys, file1); |
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185 | cleanupFile(fileSys, file1); |
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186 | } finally { |
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187 | fileSys.close(); |
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188 | cluster.shutdown(); |
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189 | } |
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190 | } |
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191 | |
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192 | public void testPreadDFSSimulated() throws IOException { |
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193 | simulatedStorage = true; |
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194 | testPreadDFS(); |
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195 | simulatedStorage = true; |
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196 | } |
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197 | |
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198 | /** |
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199 | * Tests positional read in LocalFS. |
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200 | */ |
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201 | public void testPreadLocalFS() throws IOException { |
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202 | Configuration conf = new Configuration(); |
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203 | FileSystem fileSys = FileSystem.getLocal(conf); |
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204 | try { |
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205 | Path file1 = new Path("build/test/data", "preadtest.dat"); |
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206 | writeFile(fileSys, file1); |
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207 | pReadFile(fileSys, file1); |
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208 | cleanupFile(fileSys, file1); |
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209 | } finally { |
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210 | fileSys.close(); |
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211 | } |
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212 | } |
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213 | |
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214 | public static void main(String[] args) throws Exception { |
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215 | new TestPread().testPreadDFS(); |
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216 | } |
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217 | } |
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