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; |
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20 | |
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21 | import java.io.DataInput; |
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22 | import java.io.DataOutput; |
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23 | import java.io.IOException; |
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24 | import java.text.NumberFormat; |
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25 | |
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26 | /** |
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27 | * TaskID represents the immutable and unique identifier for |
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28 | * a Map or Reduce Task. Each TaskID encompasses multiple attempts made to |
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29 | * execute the Map or Reduce Task, each of which are uniquely indentified by |
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30 | * their TaskAttemptID. |
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31 | * |
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32 | * TaskID consists of 3 parts. First part is the {@link JobID}, that this |
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33 | * TaskInProgress belongs to. Second part of the TaskID is either 'm' or 'r' |
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34 | * representing whether the task is a map task or a reduce task. |
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35 | * And the third part is the task number. <br> |
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36 | * An example TaskID is : |
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37 | * <code>task_200707121733_0003_m_000005</code> , which represents the |
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38 | * fifth map task in the third job running at the jobtracker |
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39 | * started at <code>200707121733</code>. |
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40 | * <p> |
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41 | * Applications should never construct or parse TaskID strings |
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42 | * , but rather use appropriate constructors or {@link #forName(String)} |
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43 | * method. |
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44 | * |
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45 | * @see JobID |
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46 | * @see TaskAttemptID |
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47 | */ |
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48 | public class TaskID extends org.apache.hadoop.mapred.ID { |
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49 | protected static final String TASK = "task"; |
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50 | protected static final NumberFormat idFormat = NumberFormat.getInstance(); |
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51 | static { |
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52 | idFormat.setGroupingUsed(false); |
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53 | idFormat.setMinimumIntegerDigits(6); |
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54 | } |
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55 | |
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56 | private JobID jobId; |
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57 | private boolean isMap; |
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58 | |
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59 | /** |
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60 | * Constructs a TaskID object from given {@link JobID}. |
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61 | * @param jobId JobID that this tip belongs to |
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62 | * @param isMap whether the tip is a map |
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63 | * @param id the tip number |
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64 | */ |
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65 | public TaskID(JobID jobId, boolean isMap, int id) { |
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66 | super(id); |
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67 | if(jobId == null) { |
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68 | throw new IllegalArgumentException("jobId cannot be null"); |
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69 | } |
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70 | this.jobId = jobId; |
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71 | this.isMap = isMap; |
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72 | } |
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73 | |
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74 | /** |
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75 | * Constructs a TaskInProgressId object from given parts. |
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76 | * @param jtIdentifier jobTracker identifier |
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77 | * @param jobId job number |
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78 | * @param isMap whether the tip is a map |
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79 | * @param id the tip number |
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80 | */ |
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81 | public TaskID(String jtIdentifier, int jobId, boolean isMap, int id) { |
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82 | this(new JobID(jtIdentifier, jobId), isMap, id); |
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83 | } |
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84 | |
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85 | public TaskID() { |
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86 | jobId = new JobID(); |
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87 | } |
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88 | |
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89 | /** Returns the {@link JobID} object that this tip belongs to */ |
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90 | public JobID getJobID() { |
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91 | return jobId; |
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92 | } |
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93 | |
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94 | /**Returns whether this TaskID is a map ID */ |
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95 | public boolean isMap() { |
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96 | return isMap; |
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97 | } |
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98 | |
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99 | @Override |
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100 | public boolean equals(Object o) { |
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101 | if (!super.equals(o)) |
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102 | return false; |
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103 | |
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104 | TaskID that = (TaskID)o; |
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105 | return this.isMap == that.isMap && this.jobId.equals(that.jobId); |
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106 | } |
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107 | |
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108 | /**Compare TaskInProgressIds by first jobIds, then by tip numbers. Reduces are |
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109 | * defined as greater then maps.*/ |
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110 | @Override |
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111 | public int compareTo(ID o) { |
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112 | TaskID that = (TaskID)o; |
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113 | int jobComp = this.jobId.compareTo(that.jobId); |
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114 | if(jobComp == 0) { |
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115 | if(this.isMap == that.isMap) { |
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116 | return this.id - that.id; |
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117 | } |
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118 | else return this.isMap ? -1 : 1; |
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119 | } |
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120 | else return jobComp; |
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121 | } |
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122 | @Override |
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123 | public String toString() { |
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124 | return appendTo(new StringBuilder(TASK)).toString(); |
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125 | } |
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126 | |
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127 | /** |
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128 | * Add the unique string to the given builder. |
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129 | * @param builder the builder to append to |
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130 | * @return the builder that was passed in |
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131 | */ |
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132 | protected StringBuilder appendTo(StringBuilder builder) { |
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133 | return jobId.appendTo(builder). |
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134 | append(SEPARATOR). |
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135 | append(isMap ? 'm' : 'r'). |
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136 | append(SEPARATOR). |
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137 | append(idFormat.format(id)); |
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138 | } |
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139 | |
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140 | @Override |
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141 | public int hashCode() { |
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142 | return jobId.hashCode() * 524287 + id; |
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143 | } |
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144 | |
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145 | @Override |
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146 | public void readFields(DataInput in) throws IOException { |
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147 | super.readFields(in); |
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148 | jobId.readFields(in); |
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149 | isMap = in.readBoolean(); |
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150 | } |
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151 | |
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152 | @Override |
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153 | public void write(DataOutput out) throws IOException { |
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154 | super.write(out); |
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155 | jobId.write(out); |
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156 | out.writeBoolean(isMap); |
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157 | } |
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158 | |
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159 | /** Construct a TaskID object from given string |
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160 | * @return constructed TaskID object or null if the given String is null |
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161 | * @throws IllegalArgumentException if the given string is malformed |
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162 | */ |
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163 | public static TaskID forName(String str) |
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164 | throws IllegalArgumentException { |
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165 | if(str == null) |
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166 | return null; |
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167 | try { |
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168 | String[] parts = str.split("_"); |
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169 | if(parts.length == 5) { |
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170 | if(parts[0].equals(TASK)) { |
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171 | boolean isMap = false; |
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172 | if(parts[3].equals("m")) isMap = true; |
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173 | else if(parts[3].equals("r")) isMap = false; |
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174 | else throw new Exception(); |
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175 | return new org.apache.hadoop.mapred.TaskID(parts[1], |
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176 | Integer.parseInt(parts[2]), |
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177 | isMap, |
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178 | Integer.parseInt(parts[4])); |
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179 | } |
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180 | } |
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181 | }catch (Exception ex) {//fall below |
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182 | } |
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183 | throw new IllegalArgumentException("TaskId string : " + str |
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184 | + " is not properly formed"); |
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185 | } |
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186 | |
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187 | } |
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