GurobiApi.h

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#ifndef LIMBO_SOLVERS_API_GUROBIAPI_H
#define LIMBO_SOLVERS_API_GUROBIAPI_H

#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <boost/lexical_cast.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/assert.hpp> 
#include <limbo/solvers/Solvers.h>
// make sure gurobi is configured properly 
extern "C" 
{
#include "gurobi_c.h"
}

namespace limbo 
{ 
namespace solvers 
{

class GurobiParameters
{
    public:
        GurobiParameters() 
            : m_outputFlag(0)
            , m_numThreads(std::numeric_limits<int>::max())
        {
        }
        virtual ~GurobiParameters() {}
        virtual void operator()(GRBenv* env) const 
        {
            // mute the log from the LP solver
            GRBsetintparam(env, GRB_INT_PAR_OUTPUTFLAG, m_outputFlag); 
            if (m_numThreads > 0 && m_numThreads != std::numeric_limits<int>::max())
                GRBsetintparam(env, GRB_INT_PAR_THREADS, m_numThreads);
        }
        virtual void operator()(GRBmodel* /*model*/) const 
        {
        }

        void setOutputFlag(int v) {m_outputFlag = v;}
        void setNumThreads(int v) {m_numThreads = v;}

    protected:
        int m_outputFlag; 
        int m_numThreads; 
};

template <typename T, typename V>
class GurobiLinearApi 
{
    public:
        typedef LinearModel<T, V> model_type; 
        typedef typename model_type::coefficient_value_type coefficient_value_type; 
        typedef typename model_type::variable_value_type variable_value_type; 
        typedef typename model_type::variable_type variable_type;
        typedef typename model_type::constraint_type constraint_type; 
        typedef typename model_type::expression_type expression_type; 
        typedef typename model_type::term_type term_type; 
        typedef typename model_type::property_type property_type;
        typedef GurobiParameters parameter_type; 
        
        GurobiLinearApi(model_type* model)
            : m_model(model)
              , m_grbModel(NULL)
        {
        }
        ~GurobiLinearApi()
        {
        }
        
        SolverProperty operator()(parameter_type* param = NULL)
        {
            bool defaultParam = false; 
            if (param == NULL)
            {
                param = new GurobiParameters;
                defaultParam = true; 
            }

            // ILP environment
            GRBenv* env = NULL; 
            m_grbModel = NULL; 
            // Create environment
            int error = GRBloadenv(&env, NULL);
            errorHandler(env, error);
            param->operator()(env); 
            // Create an empty model 
            error = GRBnewmodel(env, &m_grbModel, "GurobiLinearApi", m_model->numVariables(), NULL, NULL, NULL, NULL, NULL);
            errorHandler(env, error);

            // create variables 
            error = GRBupdatemodel(m_grbModel);
            errorHandler(env, error);
            for (unsigned int i = 0, ie = m_model->numVariables(); i < ie; ++i)
            {
                variable_type var (i);
                error = GRBsetdblattrelement(m_grbModel, GRB_DBL_ATTR_LB, var.id(), m_model->variableLowerBound(var));
                errorHandler(env, error);
                error = GRBsetdblattrelement(m_grbModel, GRB_DBL_ATTR_UB, var.id(), m_model->variableUpperBound(var));
                errorHandler(env, error);
                error = GRBsetdblattrelement(m_grbModel, GRB_DBL_ATTR_START, var.id(), m_model->variableSolution(var));
                errorHandler(env, error);
                error = GRBsetcharattrelement(m_grbModel, GRB_CHAR_ATTR_VTYPE, var.id(), m_model->variableNumericType(var) == CONTINUOUS? GRB_CONTINUOUS : GRB_INTEGER);
                errorHandler(env, error);
                error = GRBsetstrattrelement(m_grbModel, GRB_STR_ATTR_VARNAME, var.id(), m_model->variableName(var).c_str());
                errorHandler(env, error);
            }

            // create constraints 
            std::vector<int> vIdx; 
            std::vector<double> vValue; 
            for (unsigned int i = 0, ie = m_model->constraints().size(); i < ie; ++i)
            {
                constraint_type const& constr = m_model->constraints().at(i);

                vIdx.clear(); 
                vValue.clear();
                for (typename std::vector<term_type>::const_iterator it = constr.expression().terms().begin(), ite = constr.expression().terms().end(); it != ite; ++it)
                {
                    vIdx.push_back(it->variable().id()); 
                    vValue.push_back(it->coefficient());
                }

                error = GRBaddconstr(m_grbModel, constr.expression().terms().size(), &vIdx[0], &vValue[0], constr.sense(), constr.rightHandSide(), m_model->constraintName(constr).c_str());
                errorHandler(env, error);
            }

            // create objective 
            for (typename std::vector<term_type>::const_iterator it = m_model->objective().terms().begin(), ite = m_model->objective().terms().end(); it != ite; ++it)
            {
                error = GRBsetdblattrelement(m_grbModel, GRB_DBL_ATTR_OBJ, it->variable().id(), it->coefficient());
                errorHandler(env, error);
            }
            error = GRBsetintattr(m_grbModel, GRB_INT_ATTR_MODELSENSE, m_model->optimizeType() == MIN? GRB_MINIMIZE : GRB_MAXIMIZE);
            errorHandler(env, error);

            // call parameter setting before optimization 
            param->operator()(m_grbModel); 
            error = GRBupdatemodel(m_grbModel);
            errorHandler(env, error);

#ifdef DEBUG_GUROBIAPI
            GRBwrite(m_grbModel, "problem.lp");
#endif 
            error = GRBoptimize(m_grbModel);

            int status = 0; 
            error = GRBgetintattr(m_grbModel, GRB_INT_ATTR_STATUS, &status);
            errorHandler(env, error);

            if (status == GRB_INFEASIBLE)
            {
                error = GRBcomputeIIS(m_grbModel);
                errorHandler(env, error); 
                GRBwrite(m_grbModel, "problem.ilp");
                limboPrint(kERROR, "Model is infeasible, compute IIS and write to problem.ilp\n");
            }
#ifdef DEBUG_GUROBIAPI
            GRBwrite(m_grbModel, "problem.sol");
#endif 

            for (unsigned int i = 0; i < m_model->numVariables(); ++i)
            {
                variable_type var = m_model->variable(i); 
                double value = 0; 
                error = GRBgetdblattrelement(m_grbModel, GRB_DBL_ATTR_X, var.id(), &value);
                errorHandler(env, error);
                m_model->setVariableSolution(m_model->variable(i), value);
            }

            if (defaultParam)
                delete param; 
            // Free model 
            GRBfreemodel(m_grbModel);
            // Free environment 
            GRBfreeenv(env);

            switch (status)
            {
                case GRB_OPTIMAL:
                    return OPTIMAL;
                case GRB_INFEASIBLE:
                    return INFEASIBLE;
                case GRB_INF_OR_UNBD:
                case GRB_UNBOUNDED:
                    return UNBOUNDED;
                default:
                    limboAssertMsg(0, "unknown status %d", status);
            }
        }

        void errorHandler(GRBenv* env, int error) const; 
    protected:
        GurobiLinearApi(GurobiLinearApi const& rhs);
        GurobiLinearApi& operator=(GurobiLinearApi const& rhs);

        model_type* m_model; 
        GRBmodel* m_grbModel; 
};

template <typename T, typename V>
void GurobiLinearApi<T, V>::errorHandler(GRBenv* env, int error) const 
{
    // Error reporting 
    if (error) 
        limboAssertMsg(0, "%s", GRBgeterrormsg(env)); 
}

#if GUROBIFILEAPI == 1
#include "gurobi_c++.h"
template <typename T>
struct GurobiFileApi 
{
    typedef T value_type;

    struct solution_type 
    {
        value_type obj; 
        std::list<std::pair<std::string, value_type> > vVariable; 
    };
    virtual boost::shared_ptr<solution_type> operator()(std::string const& fileName, bool = true) const 
    {
        // better to use full path for file name 
        boost::shared_ptr<solution_type> pSol (new solution_type);
        // remove previous solution file 
        std::cout << "rm -rf "+fileName+".sol" << std::endl;
        std::cout << system(("rm -rf "+fileName+".sol").c_str()) << std::endl;;

        std::cout << "solve linear program "+fileName << std::endl;
        this->solve_lp(fileName);

        // read rpt 
        {
            std::ifstream solFile ((fileName+".sol").c_str(), std::ifstream::in);
            if (!solFile.good()) BOOST_ASSERT_MSG(false, ("failed to open " + fileName + ".sol").c_str());

            std::string var;
            double value;

            // read objective value 
            solFile >> var >> var >> var >> var >> value;
            pSol->obj = value;

            while (!solFile.eof())
            {
                solFile >> var >> value;
                pSol->vVariable.push_back(make_pair(var, value));
            }
            solFile.close();
        }

        return pSol;
    }
    virtual void solve_lp(std::string fileName) const 
    {
        try 
        {
            GRBEnv env = GRBEnv();
            GRBModel model = GRBModel(env, fileName+".lp");

            model.optimize();

            int optimstatus = model.get(GRB_IntAttr_Status);

            if (optimstatus == GRB_INF_OR_UNBD) 
            {
                model.getEnv().set(GRB_IntParam_Presolve, 0);
                model.optimize();
                optimstatus = model.get(GRB_IntAttr_Status);
            }

            if (optimstatus == GRB_OPTIMAL) 
            {
                double objval = model.get(GRB_DoubleAttr_ObjVal);
                std::cout << "Optimal objective: " << objval << std::endl;
                // write result 
                model.write(fileName+".sol");
            } 
            else if (optimstatus == GRB_INFEASIBLE) 
            {
                std::cout << "Model is infeasible" << std::endl;

                // compute and write out IIS

                model.computeIIS();
                model.write(fileName+".ilp");
            } 
            else if (optimstatus == GRB_UNBOUNDED) 
            {
                std::cout << "Model is unbounded" << std::endl;
            } 
            else 
            {
                std::cout << "Optimization was stopped with status = "
                    << optimstatus << std::endl;
            }
        } 
        catch(GRBException e) 
        {
            std::cout << "Error code = " << e.getErrorCode() << std::endl;
            std::cout << e.getMessage() << std::endl;
        } 
        catch (...) 
        {
            std::cout << "Error during optimization" << std::endl;
        }
    }

};
#endif

} // namespace solvers
} // namespace limbo

#endif