[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.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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