1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using System.Linq;
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24 | using System.Threading;
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25 | using HeuristicLab.Analysis;
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26 | using HeuristicLab.Common;
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27 | using HeuristicLab.Core;
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28 | using HeuristicLab.Data;
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29 | using HeuristicLab.Optimization;
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30 | using HeuristicLab.Parameters;
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31 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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32 |
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33 | namespace HeuristicLab.MathematicalOptimization.LinearProgramming {
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34 |
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35 | [StorableClass]
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36 | public class IncrementalLinearSolver : LinearSolver, IIncrementalLinearSolver {
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37 | [Storable] protected readonly IValueParameter<TimeSpanValue> qualityUpdateIntervalParam;
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38 |
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39 | private IndexedDataRow<double> bpcRow;
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40 |
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41 | private IndexedDataRow<double> qpcRow;
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42 |
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43 | [Storable] private IndexedDataTable<double> qualityPerClock;
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44 |
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45 | public IncrementalLinearSolver() {
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46 | Parameters.Add(qualityUpdateIntervalParam =
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47 | new ValueParameter<TimeSpanValue>(nameof(QualityUpdateInterval),
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48 | "Time interval before solver is paused, results are retrieved and solver is resumed. " +
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49 | "Set to zero for no intermediate results and faster solving.", new TimeSpanValue(new TimeSpan(0, 0, 10))));
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50 | problemTypeParam.Value.ValueChanged += (sender, args) => {
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51 | if (SupportsQualityUpdate) {
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52 | if (!Parameters.Contains(qualityUpdateIntervalParam)) {
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53 | Parameters.Add(qualityUpdateIntervalParam);
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54 | }
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55 | } else {
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56 | Parameters.Remove(qualityUpdateIntervalParam);
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57 | }
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58 | };
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59 | }
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60 |
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61 | [StorableConstructor]
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62 | protected IncrementalLinearSolver(bool deserializing)
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63 | : base(deserializing) {
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64 | }
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65 |
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66 | protected IncrementalLinearSolver(IncrementalLinearSolver original, Cloner cloner)
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67 | : base(original, cloner) {
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68 | problemTypeParam = cloner.Clone(original.problemTypeParam);
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69 | qualityUpdateIntervalParam = cloner.Clone(original.qualityUpdateIntervalParam);
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70 | if (original.qualityPerClock != null)
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71 | qualityPerClock = cloner.Clone(original.qualityPerClock);
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72 | }
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73 |
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74 | public TimeSpan QualityUpdateInterval {
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75 | get => qualityUpdateIntervalParam.Value.Value;
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76 | set => qualityUpdateIntervalParam.Value.Value = value;
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77 | }
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78 |
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79 | public virtual bool SupportsQualityUpdate => true;
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80 | protected virtual TimeSpan IntermediateTimeLimit => QualityUpdateInterval;
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81 |
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82 | public override void Solve(ILinearProgrammingProblemDefinition problemDefinition, ref TimeSpan executionTime,
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83 | ResultCollection results, CancellationToken cancellationToken) {
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84 | if (!SupportsQualityUpdate || QualityUpdateInterval == TimeSpan.Zero) {
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85 | base.Solve(problemDefinition, ref executionTime, results, cancellationToken);
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86 | return;
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87 | }
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88 |
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89 | var timeLimit = TimeLimit;
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90 | var unlimitedRuntime = timeLimit == TimeSpan.Zero;
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91 |
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92 | if (!unlimitedRuntime) {
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93 | timeLimit -= executionTime;
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94 | }
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95 |
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96 | var iterations = (long)timeLimit.TotalMilliseconds / (long)QualityUpdateInterval.TotalMilliseconds;
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97 | var remaining = timeLimit - TimeSpan.FromMilliseconds(iterations * QualityUpdateInterval.TotalMilliseconds);
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98 | var validResultStatuses = new[] { ResultStatus.NotSolved, ResultStatus.Feasible };
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99 |
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100 | while (unlimitedRuntime || iterations > 0) {
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101 | if (cancellationToken.IsCancellationRequested)
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102 | return;
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103 |
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104 | Solve(problemDefinition, results, IntermediateTimeLimit);
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105 | UpdateQuality(results, executionTime);
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106 |
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107 | var resultStatus = ((EnumValue<ResultStatus>)results["ResultStatus"].Value).Value;
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108 | if (!validResultStatuses.Contains(resultStatus))
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109 | return;
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110 |
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111 | if (!unlimitedRuntime)
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112 | iterations--;
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113 | }
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114 |
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115 | if (remaining > TimeSpan.Zero) {
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116 | Solve(problemDefinition, results, remaining);
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117 | UpdateQuality(results, executionTime);
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118 | }
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119 | }
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120 |
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121 | private void UpdateQuality(ResultCollection results, TimeSpan executionTime) {
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122 | if (!results.Exists(r => r.Name == "QualityPerClock")) {
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123 | qualityPerClock = new IndexedDataTable<double>("Quality per Clock");
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124 | qpcRow = new IndexedDataRow<double>("Objective Value");
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125 | bpcRow = new IndexedDataRow<double>("Bound");
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126 | results.AddOrUpdateResult("QualityPerClock", qualityPerClock);
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127 | }
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128 |
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129 | var resultStatus = ((EnumValue<ResultStatus>)results["ResultStatus"].Value).Value;
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130 |
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131 | if (new[] { ResultStatus.Abnormal, ResultStatus.NotSolved, ResultStatus.Unbounded }.Contains(resultStatus))
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132 | return;
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133 |
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134 | var objective = ((DoubleValue)results["BestObjectiveValue"].Value).Value;
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135 | var bound = solver.IsMIP() ? ((DoubleValue)results["BestObjectiveBound"].Value).Value : double.NaN;
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136 | var time = executionTime.TotalSeconds;
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137 |
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138 | if (!qpcRow.Values.Any()) {
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139 | if (!double.IsInfinity(objective) && !double.IsNaN(objective)) {
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140 | qpcRow.Values.Add(Tuple.Create(time, objective));
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141 | qpcRow.Values.Add(Tuple.Create(time, objective));
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142 | qualityPerClock.Rows.Add(qpcRow);
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143 | results.AddOrUpdateResult("BestObjectiveValueFoundAt", new TimeSpanValue(TimeSpan.FromSeconds(time)));
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144 | }
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145 | } else {
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146 | var previousBest = qpcRow.Values.Last().Item2;
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147 | qpcRow.Values[qpcRow.Values.Count - 1] = Tuple.Create(time, objective);
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148 | if (!objective.IsAlmost(previousBest)) {
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149 | qpcRow.Values.Add(Tuple.Create(time, objective));
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150 | results.AddOrUpdateResult("BestObjectiveValueFoundAt", new TimeSpanValue(TimeSpan.FromSeconds(time)));
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151 | }
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152 | }
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153 |
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154 | if (!solver.IsMIP())
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155 | return;
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156 |
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157 | if (!bpcRow.Values.Any()) {
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158 | if (!double.IsInfinity(bound) && !double.IsNaN(bound)) {
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159 | bpcRow.Values.Add(Tuple.Create(time, bound));
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160 | bpcRow.Values.Add(Tuple.Create(time, bound));
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161 | qualityPerClock.Rows.Add(bpcRow);
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162 | }
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163 | } else {
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164 | var previousBest = bpcRow.Values.Last().Item2;
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165 | bpcRow.Values[bpcRow.Values.Count - 1] = Tuple.Create(time, bound);
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166 | if (!bound.IsAlmost(previousBest)) {
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167 | bpcRow.Values.Add(Tuple.Create(time, bound));
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168 | }
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169 | }
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170 | }
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171 | }
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172 | }
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