transport8.cpp
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3 * GAMS - General Algebraic Modeling System C++ API
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26#include "gams.h"
27#include <vector>
28#include <mutex>
29#include <thread>
30#include <iostream>
31
32using namespace gams;
33using namespace std;
34
36void scenSolve(GAMSWorkspace* ws, GAMSCheckpoint* cp, vector<double>* bmultVector, std::mutex* vectorMutex, std::mutex* ioMutex)
37{
38 unique_lock<mutex> vectorLock(*vectorMutex);
40 vectorLock.unlock();
41
42 GAMSParameter bmult = mi.syncDb().addParameter("bmult", "demand multiplier");
43 GAMSOptions opt = ws->addOptions();
44 opt.setAllModelTypes("cplexd");
45 // instantiate the GAMSModelInstance and pass a model definition and GAMSModifier to declare bmult mutable
46 mi.instantiate("transport use lp min z", opt, GAMSModifier(bmult));
47
48 bmult.addRecord().setValue(1.0);
49
50 while (true)
51 {
52 double b;
53
54 // dynamically get a bmult value from the vector instead of passing it to the different threads at creation time
55 vectorLock.lock();
56 if (bmultVector->empty())
57 return;
58 b = bmultVector->back();
59 bmultVector->pop_back();
60 vectorLock.unlock();
61 bmult.firstRecord().setValue(b);
62 mi.solve();
63
64 // we need to make the output a critical section to avoid messed up report informations
65 unique_lock<mutex> ioLock(*ioMutex);
66 cout << "Scenario bmult=" << b << ":" << endl;
67 cout << " Modelstatus: " << mi.modelStatus() << endl;
68 cout << " Solvestatus: " << mi.solveStatus() << endl;
69 cout << " Obj: " << mi.syncDb().getVariable("z").findRecord().level() << endl;
70 ioLock.unlock();
71 }
72}
73
76{
77 return "Sets \n"
78 " i canning plants / seattle, san-diego / \n"
79 " j markets / new-york, chicago, topeka / ; \n"
80 " \n"
81 "Parameters \n"
82 " \n"
83 " a(i) capacity of plant i in cases \n"
84 " / seattle 350 \n"
85 " san-diego 600 / \n"
86 " \n"
87 " b(j) demand at market j in cases \n"
88 " / new-york 325 \n"
89 " chicago 300 \n"
90 " topeka 275 / ; \n"
91 " \n"
92 "Table d(i, j) distance in thousands of miles \n"
93 " new-york chicago topeka \n"
94 " seattle 2.5 1.7 1.8 \n"
95 " san-diego 2.5 1.8 1.4; \n"
96 " \n"
97 "Scalar f freight in dollars per case per thousand miles / 90 / ; \n"
98 "Scalar bmult demand multiplier / 1 / ; \n"
99 " \n"
100 "Parameter c(i, j) transport cost in thousands of dollars per case; \n"
101 " \n"
102 "c(i, j) = f * d(i, j) / 1000; \n"
103 " \n"
104 "Variables \n"
105 " x(i, j) shipment quantities in cases \n"
106 " z total transportation costs in thousands of dollars; \n"
107 " \n"
108 "Positive Variable x; \n"
109 " \n"
110 "Equations \n"
111 " cost define objective function \n"
112 " supply(i) observe supply limit at plant i \n"
113 " demand(j) satisfy demand at market j; \n"
114 " \n"
115 "cost.. z =e= sum((i, j), c(i, j)*x(i, j)); \n"
116 " \n"
117 "supply(i).. sum(j, x(i, j)) =l= a(i); \n"
118 " \n"
119 "demand(j).. sum(i, x(i, j)) =g= bmult*b(j); \n"
120 " \n"
121 "Model transport / all / ; \n";
122}
123
129int main(int argc, char* argv[])
130{
131 cout << "---------- Transport 8 --------------" << endl;
132
133 try {
134 GAMSWorkspaceInfo wsInfo;
135 if (argc > 1)
136 wsInfo.setSystemDirectory(argv[1]);
137 GAMSWorkspace ws(wsInfo);
139
140 // initialize a GAMSCheckpoint by running a GAMSJob
142
143 vector<double> bmultVector = { 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6 };
144 int nrThreads = 2;
145 // solve multiple model instances in parallel
146 std::mutex vectorMutex;
147 std::mutex ioMutex;
148 vector<thread> v;
149 for (int i = 0; i < nrThreads; i++)
150 v.emplace_back([&ws, &cp, &bmultVector, &vectorMutex, &ioMutex] {scenSolve(&ws, &cp, &bmultVector, &vectorMutex, &ioMutex);});
151 for (auto& t : v)
152 t.join();
153
154 } catch (GAMSException &ex) {
155 cout << "GAMSException occured: " << ex.what() << endl;
156 } catch (exception &ex) {
157 cout << ex.what() << endl;
158 }
159
160 return 0;
161}
162
void setValue(const double val)
GAMSCheckpoint addCheckpoint(const std::string &checkpointName="")
void setAllModelTypes(const std::string &solver)
string getModelText()
Get model as string.
Definition: transport8.cpp:75
void solve(GAMSEnum::SymbolUpdateType updateType, std::ostream &output, GAMSModelInstanceOpt miOpt)
GAMSEnum::SolveStat solveStatus()
GAMSDatabase syncDb()
GAMSParameter addParameter(const std::string &name, const int dimension, const std::string &explanatoryText="")
void setSystemDirectory(std::string systemDir)
void instantiate(const std::string &modelDefinition, const gams::GAMSOptions &options, const std::vector< gams::GAMSModifier > &modifiers={ })
GAMSEnum::ModelStat modelStatus()
GAMSParameterRecord firstRecord(const std::vector< std::string > &slice)
GAMSOptions addOptions()
GAMSVariable getVariable(const std::string &name)
GAMSModelInstance addModelInstance(const std::string &modelInstanceName="")
GAMSVariableRecord findRecord(const std::vector< std::string > &keys)
GAMSJob addJobFromString(const std::string &gamsSource, const std::string &jobName="")
void scenSolve(GAMSWorkspace *ws, GAMSCheckpoint *cp, vector< double > *bmultVector, std::mutex *vectorMutex, std::mutex *ioMutex)
Solve the model in different scenarios.
Definition: transport8.cpp:36
GAMSParameterRecord addRecord(const std::vector< std::string > &keys)