1 | package de.ugoe.cs.quest.testgeneration; |
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2 | |
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3 | import java.security.InvalidParameterException; |
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4 | import java.util.Collection; |
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5 | import java.util.HashSet; |
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6 | import java.util.List; |
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7 | import java.util.Set; |
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8 | |
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9 | import de.ugoe.cs.quest.eventcore.Event; |
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10 | import de.ugoe.cs.quest.usageprofiles.IStochasticProcess; |
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11 | |
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12 | /** |
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13 | * <p> |
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14 | * Generates a test suite by randomly walking an {@link IStochasticProcess}. |
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15 | * </p> |
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16 | * |
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17 | * @author Steffen Herbold |
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18 | * @version 1.0 |
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19 | */ |
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20 | public class RandomWalkGenerator { |
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21 | |
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22 | /** |
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23 | * <p> |
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24 | * Number of sequences in the test suite. |
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25 | * </p> |
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26 | */ |
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27 | private final int numSequences; |
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28 | |
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29 | /** |
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30 | * <p> |
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31 | * Minimal length of a test sequence. |
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32 | * </p> |
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33 | */ |
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34 | private final int minLength; |
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35 | |
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36 | /** |
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37 | * <p> |
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38 | * Maximal length of a test sequence. |
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39 | * </p> |
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40 | */ |
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41 | private final int maxLength; |
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42 | |
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43 | /** |
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44 | * <p> |
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45 | * In case this member is true, only test cases that end in the global end event |
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46 | * {@link Event#ENDEVENT} are generated. If it is false, the end event can be any event. |
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47 | * </p> |
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48 | */ |
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49 | private final boolean validEnd; |
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50 | |
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51 | /** |
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52 | * <p> |
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53 | * Maximal number of random walks performed before aborting the test case generation and |
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54 | * returning a test suite with less than {@link #numSequences} test cases. This can happen if |
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55 | * too many generated random walks have to be discarded because their length is not between |
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56 | * {@link #minLength} and {@link #maxLength}. |
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57 | * </p> |
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58 | */ |
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59 | private final long maxIter; |
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60 | |
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61 | /** |
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62 | * <p> |
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63 | * Actual number of random walks performed to generate the test suite. |
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64 | * </p> |
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65 | */ |
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66 | private long actualIter = -1; |
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67 | |
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68 | /** |
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69 | * <p> |
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70 | * Constructor. Creates a new RandomWalkGenerator and ensures the validity of the parameters: |
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71 | * <ul> |
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72 | * <li>numSequences must at least be 1 |
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73 | * <li>maxLength must at least be 1 |
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74 | * <li>minLength must be less than or equal to maxLength |
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75 | * <li>maxIter must be greater than or equal to numSequences |
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76 | * </ul> |
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77 | * If one of these conditions is violated an {@link InvalidParameterException} is thrown. |
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78 | * </p> |
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79 | * |
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80 | * @param numSequences |
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81 | * number of sequences desired for the test suite |
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82 | * @param minLength |
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83 | * minimal length of a test sequence |
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84 | * @param maxLength |
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85 | * maximal length of a test sequence |
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86 | * @param validEnd |
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87 | * defines if test cases have to end with the global end event {@link Event#ENDEVENT} |
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88 | * (see {@link #validEnd}) |
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89 | * @param maxIter |
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90 | * maximal number of random walks before aborting the test case generation (see |
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91 | * {@link #maxIter}) |
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92 | */ |
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93 | public RandomWalkGenerator(int numSequences, |
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94 | int minLength, |
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95 | int maxLength, |
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96 | boolean validEnd, |
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97 | long maxIter) |
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98 | { |
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99 | // check validity of the parameters |
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100 | if (numSequences < 1) { |
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101 | throw new InvalidParameterException("number of sequences must be at least 1 but is " + |
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102 | numSequences); |
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103 | } |
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104 | if (maxLength < 1) { |
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105 | throw new InvalidParameterException( |
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106 | "maximal allowed length of test cases must be at least 1 but is " + |
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107 | maxLength); |
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108 | } |
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109 | if (minLength > maxLength) { |
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110 | throw new InvalidParameterException( |
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111 | "minimal allowed length of test cases must be less than or equal to the maximal allowed length (min length: " + |
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112 | minLength + " ; max length: " + maxLength + ")"); |
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113 | } |
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114 | if (maxIter < numSequences) { |
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115 | throw new InvalidParameterException( |
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116 | "maximal number of iterations must greater than or equal to the number of sequences (number of sequences: " + |
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117 | numSequences + |
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118 | " ; max iterations: " + |
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119 | maxIter + |
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120 | ")"); |
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121 | } |
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122 | this.numSequences = numSequences; |
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123 | this.minLength = minLength; |
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124 | this.maxLength = maxLength; |
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125 | this.validEnd = validEnd; |
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126 | this.maxIter = maxIter; |
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127 | } |
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128 | |
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129 | /** |
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130 | * <p> |
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131 | * Generates a test suite by repeatedly randomly walking a stochastic process. |
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132 | * </p> |
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133 | * |
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134 | * @param model |
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135 | * stochastic process which performs the random walks |
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136 | * @return the test suite |
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137 | */ |
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138 | public Collection<List<Event>> generateTestSuite(IStochasticProcess model) { |
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139 | if (model == null) { |
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140 | throw new InvalidParameterException("model must not be null!"); |
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141 | } |
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142 | |
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143 | Set<List<Event>> sequences = new HashSet<List<Event>>(numSequences); |
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144 | actualIter = 0; |
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145 | while (sequences.size() < numSequences && actualIter < maxIter) { |
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146 | List<Event> generatedSequence = model.randomSequence(maxLength, validEnd); |
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147 | if (generatedSequence.size() >= minLength && generatedSequence.size() <= maxLength) { |
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148 | ((List<Event>) generatedSequence).add(0, Event.STARTEVENT); |
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149 | if (validEnd) { |
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150 | ((List<Event>) generatedSequence).add(Event.ENDEVENT); |
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151 | } |
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152 | sequences.add(generatedSequence); |
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153 | } |
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154 | actualIter++; |
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155 | } |
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156 | |
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157 | return sequences; |
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158 | } |
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159 | |
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160 | /** |
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161 | * <p> |
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162 | * Returns the actual number of random walks performed during the last call of |
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163 | * {@link #generateTestSuite(IStochasticProcess)} or -1 if |
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164 | * {@link #generateTestSuite(IStochasticProcess)} has not been called yet. |
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165 | * </p> |
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166 | * |
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167 | * @return actual number of random walks or -1 if {@link #generateTestSuite(IStochasticProcess)} |
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168 | * has not been called |
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169 | */ |
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170 | public long getActualIter() { |
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171 | return actualIter; |
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172 | } |
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173 | } |
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