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.util; |
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19 | |
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20 | import java.io.BufferedReader; |
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21 | import java.io.File; |
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22 | import java.io.IOException; |
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23 | import java.io.InputStreamReader; |
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24 | import java.util.Map; |
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25 | |
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26 | import org.apache.commons.logging.Log; |
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27 | import org.apache.commons.logging.LogFactory; |
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28 | import org.apache.hadoop.conf.Configuration; |
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29 | |
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30 | /** |
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31 | * A base class for running a Unix command. |
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32 | * |
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33 | * <code>Shell</code> can be used to run unix commands like <code>du</code> or |
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34 | * <code>df</code>. It also offers facilities to gate commands by |
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35 | * time-intervals. |
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36 | */ |
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37 | abstract public class Shell { |
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38 | |
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39 | public static final Log LOG = LogFactory.getLog(Shell.class); |
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40 | |
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41 | /** a Unix command to get the current user's name */ |
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42 | public final static String USER_NAME_COMMAND = "whoami"; |
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43 | /** a Unix command to get the current user's groups list */ |
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44 | public static String[] getGROUPS_COMMAND() { |
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45 | return new String[]{"bash", "-c", "groups"}; |
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46 | } |
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47 | /** a Unix command to set permission */ |
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48 | public static final String SET_PERMISSION_COMMAND = "chmod"; |
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49 | /** a Unix command to set owner */ |
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50 | public static final String SET_OWNER_COMMAND = "chown"; |
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51 | public static final String SET_GROUP_COMMAND = "chgrp"; |
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52 | /** Return a Unix command to get permission information. */ |
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53 | public static String[] getGET_PERMISSION_COMMAND() { |
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54 | //force /bin/ls, except on windows. |
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55 | return new String[] {(WINDOWS ? "ls" : "/bin/ls"), "-ld"}; |
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56 | } |
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57 | |
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58 | /** |
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59 | * Get the Unix command for setting the maximum virtual memory available |
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60 | * to a given child process. This is only relevant when we are forking a |
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61 | * process from within the {@link org.apache.hadoop.mapred.Mapper} or the |
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62 | * {@link org.apache.hadoop.mapred.Reducer} implementations |
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63 | * e.g. <a href="{@docRoot}/org/apache/hadoop/mapred/pipes/package-summary.html">Hadoop Pipes</a> |
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64 | * or <a href="{@docRoot}/org/apache/hadoop/streaming/package-summary.html">Hadoop Streaming</a>. |
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65 | * |
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66 | * It also checks to ensure that we are running on a *nix platform else |
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67 | * (e.g. in Cygwin/Windows) it returns <code>null</code>. |
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68 | * @param conf configuration |
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69 | * @return a <code>String[]</code> with the ulimit command arguments or |
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70 | * <code>null</code> if we are running on a non *nix platform or |
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71 | * if the limit is unspecified. |
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72 | */ |
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73 | public static String[] getUlimitMemoryCommand(Configuration conf) { |
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74 | // ulimit isn't supported on Windows |
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75 | if (WINDOWS) { |
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76 | return null; |
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77 | } |
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78 | |
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79 | // get the memory limit from the configuration |
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80 | String ulimit = conf.get("mapred.child.ulimit"); |
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81 | if (ulimit == null) { |
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82 | return null; |
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83 | } |
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84 | |
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85 | // Parse it to ensure it is legal/sane |
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86 | int memoryLimit = Integer.valueOf(ulimit); |
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87 | |
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88 | return new String[] {"ulimit", "-v", String.valueOf(memoryLimit)}; |
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89 | } |
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90 | |
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91 | /** Set to true on Windows platforms */ |
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92 | public static final boolean WINDOWS /* borrowed from Path.WINDOWS */ |
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93 | = System.getProperty("os.name").startsWith("Windows"); |
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94 | |
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95 | private long interval; // refresh interval in msec |
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96 | private long lastTime; // last time the command was performed |
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97 | private Map<String, String> environment; // env for the command execution |
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98 | private File dir; |
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99 | private Process process; // sub process used to execute the command |
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100 | private int exitCode; |
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101 | |
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102 | public Shell() { |
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103 | this(0L); |
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104 | } |
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105 | |
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106 | /** |
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107 | * @param interval the minimum duration to wait before re-executing the |
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108 | * command. |
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109 | */ |
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110 | public Shell( long interval ) { |
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111 | this.interval = interval; |
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112 | this.lastTime = (interval<0) ? 0 : -interval; |
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113 | } |
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114 | |
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115 | /** set the environment for the command |
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116 | * @param env Mapping of environment variables |
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117 | */ |
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118 | protected void setEnvironment(Map<String, String> env) { |
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119 | this.environment = env; |
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120 | } |
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121 | |
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122 | /** set the working directory |
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123 | * @param dir The directory where the command would be executed |
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124 | */ |
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125 | protected void setWorkingDirectory(File dir) { |
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126 | this.dir = dir; |
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127 | } |
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128 | |
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129 | /** check to see if a command needs to be executed and execute if needed */ |
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130 | protected void run() throws IOException { |
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131 | if (lastTime + interval > System.currentTimeMillis()) |
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132 | return; |
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133 | exitCode = 0; // reset for next run |
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134 | runCommand(); |
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135 | } |
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136 | |
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137 | /** Run a command */ |
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138 | private void runCommand() throws IOException { |
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139 | ProcessBuilder builder = new ProcessBuilder(getExecString()); |
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140 | boolean completed = false; |
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141 | |
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142 | if (environment != null) { |
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143 | builder.environment().putAll(this.environment); |
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144 | } |
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145 | if (dir != null) { |
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146 | builder.directory(this.dir); |
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147 | } |
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148 | |
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149 | process = builder.start(); |
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150 | final BufferedReader errReader = |
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151 | new BufferedReader(new InputStreamReader(process |
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152 | .getErrorStream())); |
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153 | BufferedReader inReader = |
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154 | new BufferedReader(new InputStreamReader(process |
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155 | .getInputStream())); |
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156 | final StringBuffer errMsg = new StringBuffer(); |
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157 | |
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158 | // read error and input streams as this would free up the buffers |
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159 | // free the error stream buffer |
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160 | Thread errThread = new Thread() { |
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161 | @Override |
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162 | public void run() { |
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163 | try { |
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164 | String line = errReader.readLine(); |
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165 | while((line != null) && !isInterrupted()) { |
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166 | errMsg.append(line); |
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167 | errMsg.append(System.getProperty("line.separator")); |
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168 | line = errReader.readLine(); |
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169 | } |
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170 | } catch(IOException ioe) { |
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171 | LOG.warn("Error reading the error stream", ioe); |
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172 | } |
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173 | } |
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174 | }; |
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175 | try { |
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176 | errThread.start(); |
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177 | } catch (IllegalStateException ise) { } |
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178 | try { |
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179 | parseExecResult(inReader); // parse the output |
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180 | // clear the input stream buffer |
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181 | String line = inReader.readLine(); |
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182 | while(line != null) { |
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183 | line = inReader.readLine(); |
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184 | } |
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185 | // wait for the process to finish and check the exit code |
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186 | exitCode = process.waitFor(); |
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187 | try { |
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188 | // make sure that the error thread exits |
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189 | errThread.join(); |
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190 | } catch (InterruptedException ie) { |
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191 | LOG.warn("Interrupted while reading the error stream", ie); |
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192 | } |
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193 | completed = true; |
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194 | if (exitCode != 0) { |
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195 | throw new ExitCodeException(exitCode, errMsg.toString()); |
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196 | } |
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197 | } catch (InterruptedException ie) { |
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198 | throw new IOException(ie.toString()); |
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199 | } finally { |
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200 | // close the input stream |
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201 | try { |
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202 | inReader.close(); |
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203 | } catch (IOException ioe) { |
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204 | LOG.warn("Error while closing the input stream", ioe); |
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205 | } |
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206 | if (!completed) { |
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207 | errThread.interrupt(); |
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208 | } |
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209 | try { |
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210 | errReader.close(); |
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211 | } catch (IOException ioe) { |
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212 | LOG.warn("Error while closing the error stream", ioe); |
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213 | } |
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214 | process.destroy(); |
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215 | lastTime = System.currentTimeMillis(); |
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216 | } |
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217 | } |
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218 | |
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219 | /** return an array containing the command name & its parameters */ |
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220 | protected abstract String[] getExecString(); |
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221 | |
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222 | /** Parse the execution result */ |
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223 | protected abstract void parseExecResult(BufferedReader lines) |
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224 | throws IOException; |
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225 | |
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226 | /** get the current sub-process executing the given command |
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227 | * @return process executing the command |
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228 | */ |
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229 | public Process getProcess() { |
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230 | return process; |
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231 | } |
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232 | |
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233 | /** get the exit code |
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234 | * @return the exit code of the process |
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235 | */ |
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236 | public int getExitCode() { |
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237 | return exitCode; |
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238 | } |
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239 | |
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240 | /** |
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241 | * This is an IOException with exit code added. |
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242 | */ |
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243 | public static class ExitCodeException extends IOException { |
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244 | int exitCode; |
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245 | |
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246 | public ExitCodeException(int exitCode, String message) { |
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247 | super(message); |
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248 | this.exitCode = exitCode; |
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249 | } |
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250 | |
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251 | public int getExitCode() { |
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252 | return exitCode; |
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253 | } |
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254 | } |
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255 | |
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256 | /** |
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257 | * A simple shell command executor. |
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258 | * |
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259 | * <code>ShellCommandExecutor</code>should be used in cases where the output |
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260 | * of the command needs no explicit parsing and where the command, working |
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261 | * directory and the environment remains unchanged. The output of the command |
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262 | * is stored as-is and is expected to be small. |
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263 | */ |
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264 | public static class ShellCommandExecutor extends Shell { |
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265 | |
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266 | private String[] command; |
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267 | private StringBuffer output; |
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268 | |
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269 | public ShellCommandExecutor(String[] execString) { |
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270 | command = execString.clone(); |
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271 | } |
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272 | |
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273 | public ShellCommandExecutor(String[] execString, File dir) { |
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274 | this(execString); |
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275 | this.setWorkingDirectory(dir); |
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276 | } |
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277 | |
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278 | public ShellCommandExecutor(String[] execString, File dir, |
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279 | Map<String, String> env) { |
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280 | this(execString, dir); |
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281 | this.setEnvironment(env); |
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282 | } |
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283 | |
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284 | /** Execute the shell command. */ |
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285 | public void execute() throws IOException { |
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286 | this.run(); |
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287 | } |
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288 | |
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289 | protected String[] getExecString() { |
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290 | return command; |
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291 | } |
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292 | |
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293 | protected void parseExecResult(BufferedReader lines) throws IOException { |
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294 | output = new StringBuffer(); |
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295 | char[] buf = new char[512]; |
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296 | int nRead; |
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297 | while ( (nRead = lines.read(buf, 0, buf.length)) > 0 ) { |
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298 | output.append(buf, 0, nRead); |
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299 | } |
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300 | } |
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301 | |
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302 | /** Get the output of the shell command.*/ |
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303 | public String getOutput() { |
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304 | return (output == null) ? "" : output.toString(); |
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305 | } |
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306 | |
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307 | /** |
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308 | * Returns the commands of this instance. |
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309 | * Arguments with spaces in are presented with quotes round; other |
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310 | * arguments are presented raw |
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311 | * |
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312 | * @return a string representation of the object. |
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313 | */ |
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314 | public String toString() { |
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315 | StringBuilder builder = new StringBuilder(); |
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316 | String[] args = getExecString(); |
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317 | for (String s : args) { |
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318 | if (s.indexOf(' ') >= 0) { |
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319 | builder.append('"').append(s).append('"'); |
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320 | } else { |
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321 | builder.append(s); |
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322 | } |
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323 | builder.append(' '); |
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324 | } |
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325 | return builder.toString(); |
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326 | } |
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327 | } |
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328 | |
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329 | /** |
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330 | * Static method to execute a shell command. |
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331 | * Covers most of the simple cases without requiring the user to implement |
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332 | * the <code>Shell</code> interface. |
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333 | * @param cmd shell command to execute. |
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334 | * @return the output of the executed command. |
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335 | */ |
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336 | public static String execCommand(String ... cmd) throws IOException { |
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337 | return execCommand(null, cmd); |
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338 | } |
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339 | |
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340 | /** |
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341 | * Static method to execute a shell command. |
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342 | * Covers most of the simple cases without requiring the user to implement |
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343 | * the <code>Shell</code> interface. |
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344 | * @param env the map of environment key=value |
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345 | * @param cmd shell command to execute. |
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346 | * @return the output of the executed command. |
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347 | */ |
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348 | public static String execCommand(Map<String,String> env, String ... cmd) |
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349 | throws IOException { |
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350 | ShellCommandExecutor exec = new ShellCommandExecutor(cmd); |
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351 | if (env != null) { |
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352 | exec.setEnvironment(env); |
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353 | } |
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354 | exec.execute(); |
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355 | return exec.getOutput(); |
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356 | } |
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357 | } |
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