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/*******************************************************/
/* CUDF solver: gurobi_solver.c */
/* Interface to the Gurobi solver */
/* (c) Claude Michel I3S (UNSA-CNRS) 2009,2010,2011 */
/*******************************************************/
#include <gurobi_solver.h>
#include <math.h>
#define OUTPUT_MODEL 1
// solver creation
abstract_solver *new_gurobi_solver() { return new gurobi_solver(); }
// solver initialisation
// requires the list of versioned packages and the total amount of variables (including additional ones)
int gurobi_solver::init_solver(CUDFVersionedPackageList *all_versioned_packages, int other_vars) {
int status;
nb_packages = all_versioned_packages->size();
this->all_versioned_packages = all_versioned_packages;
// Coefficient initialization
initialize_coeffs(nb_packages + other_vars);
/* Initialize the gurobi environment */
status = GRBloadenv(&env, NULL); // NULL => no file log
if (status || (env == (GRBenv *)NULL)) {
fprintf (stderr, "Could not create Gurobi environment.\n");
exit(-1);
}
// Limit display according to verbosity
if (verbosity < 2) status = GRBsetintparam(env, "OutputFlag", 0);
/* Set MIP gap to zero */
status = GRBsetdblparam(env, "MIPGap", 0.0);
/* Create Gurobi model */
status = GRBnewmodel(env, &model, "mip1", 0, NULL, NULL, NULL, NULL, NULL);
if (status || (model == (GRBmodel *)NULL)) {
fprintf (stderr, "Could not create Gurobi model.\n");
exit(-1);
}
/* Other data initialization */
first_objective = 0;
lb = (double *)malloc(nb_vars*sizeof(double));
ub = (double *)malloc(nb_vars*sizeof(double));
vartype = (char *)malloc(nb_vars*sizeof(char));
varname = (char **)malloc(nb_vars*sizeof(char *));
if ((lb == (double *)NULL) ||
(ub == (double *)NULL) ||
(vartype == (char *)NULL) ||
(varname == (char **)NULL)) {
fprintf(stderr, "gurobi_solver: initialization: not enough memory.\n");
exit(-1);
}
// Set package variable names
int i = 0;
for (CUDFVersionedPackageListIterator ipkg = all_versioned_packages->begin(); ipkg != all_versioned_packages->end(); ipkg++) {
lb[i] = 0;
ub[i] = 1;
vartype[i] = GRB_BINARY;
varname[(*ipkg)->rank] = (*ipkg)->versioned_name;
i++;
}
// Set additional variable names
for (i = nb_packages; i < nb_vars; i++) {
char *name;
char buffer[20];
sprintf(buffer, "x%d", i);
if ((name = (char *)malloc(strlen(buffer)+1)) == (char *)NULL) {
fprintf(stderr, "CUDF error: can not alloc memory for variable name in glpk_solver::end_objective.\n");
exit(-1);
}
strcpy(name, buffer);
lb[i] = 0;
ub[i] = 1;
vartype[i] = GRB_BINARY;
varname[i] = name;
}
return 0;
}
// cplex can handle integer variables
bool gurobi_solver::has_intvars() { return true; }
// set integer variable range (must be used before end_objective)
int gurobi_solver::set_intvar_range(int rank, CUDFcoefficient lower, CUDFcoefficient upper) {
lb[rank] = lower;
ub[rank] = upper;
vartype[rank] = GRB_INTEGER;
return 0;
};
// Just write the lp problem in a file
int gurobi_solver::writelp(char *filename) {
return 0;
}
// solve the current problem
int gurobi_solver::solve() {
int nb_objectives = objectives.size();
int mipstat, status;
// Solve the objectives in a lexical order
for (int i = first_objective; i < nb_objectives; i++) {
// Solve the mip problem
if (GRBoptimize(model)) return 0;
// Get solution status
status = GRBgetintattr(model, GRB_INT_ATTR_STATUS, &mipstat);
if (status) { exit(-1); }
if (mipstat == GRB_OPTIMAL) {
if (i < nb_objectives - 1) {
// Get next non empty objective
// (must be done here to avoid conflicting method calls
int previ = i, nexti, nexti_nb_coeffs = 0;
for (; i < nb_objectives - 1; i++) {
nexti = i + 1;
nexti_nb_coeffs = objectives[nexti]->nb_coeffs;
if (nexti_nb_coeffs > 0) break;
}
if (nexti_nb_coeffs > 0) { // there is one more objective to solve
// Set objective constraint value to objval
double objval = objective_value();
if (verbosity > 0) printf(">>>> Objective value %d = %f\n", previ, objval);
if (GRBaddconstr(model, objectives[previ]->nb_coeffs, objectives[previ]->sindex, objectives[previ]->coefficients, GRB_EQUAL, objval, NULL)) {
fprintf(stderr, "gurobi_solver: end_objective: cannot add %d objective as constraint.\n", i);
exit(-1);
}
// Set the new objective value
reset_coeffs();
// Set previous objective coefficients to zero
for (int k = 0; k < objectives[previ]->nb_coeffs; k++) GRBsetdblattrelement(model, "Obj", objectives[previ]->sindex[k], 0);
// Set next objective coefficients to their actual values
for (int k = 0; k < nexti_nb_coeffs; k++) GRBsetdblattrelement(model, "Obj", objectives[nexti]->sindex[k], objectives[nexti]->coefficients[k]);
// Output model to file (when requested)
if (OUTPUT_MODEL) {
}
} else
return 1;
} else
return 1;
} else {
fprintf(stderr, "CPLEX solution status = %d\n", mipstat);
return 0;
}
}
return 0;
}
// return the objective value
CUDFcoefficient gurobi_solver::objective_value() {
double objval;
int status = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, &objval);
if (status) {
fprintf (stderr,"No MIP objective value available. Exiting...\n");
exit(-1);
}
// printf("Objective value = % 24.24e\n", objval);
return (CUDFcoefficient)nearbyint(objval);
}
// solution initialisation
int gurobi_solver::init_solutions() {
int status;
if (solution != (double *)NULL) free(solution);
if ((solution = (double *)malloc(nb_vars*sizeof(double))) == (double *)NULL) {
fprintf (stderr, "gurobi_solver: init_solutions: cannot get enough memory to store solutions.\n");
exit(-1);
}
status = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, nb_vars, solution);
if ( status ) {
fprintf (stderr, "gurobi_solver: init_solutions: failed to get solutions.\n");
exit(-1);
}
return 0;
}
// get the computed status of a package (0 = uninstalled, 1 = installed)
CUDFcoefficient gurobi_solver::get_solution(CUDFVersionedPackage *package) { return (CUDFcoefficient)nearbyint(solution[package->rank]); }
CUDFcoefficient gurobi_solver::get_solution(int k) { return (CUDFcoefficient)nearbyint(solution[k]); }
// initialize the objective function
int gurobi_solver::begin_objectives(void) {
return 0;
}
// return the objective function coefficient of a package
CUDFcoefficient gurobi_solver::get_obj_coeff(CUDFVersionedPackage *package) { return (CUDFcoefficient)get_coeff(package); }
// return the objective function coefficient of a rank
CUDFcoefficient gurobi_solver::get_obj_coeff(int rank) { return (CUDFcoefficient)get_coeff(rank); }
// set the objective function coefficient of a package
int gurobi_solver::set_obj_coeff(CUDFVersionedPackage *package, CUDFcoefficient value) { set_coeff(package, value); return 0; }
// set the objective function coefficient of a ranked variable
int gurobi_solver::set_obj_coeff(int rank, CUDFcoefficient value) { set_coeff(rank, value); return 0; };
// initialize an additional objective function
int gurobi_solver::new_objective(void) {
reset_coeffs();
return 0;
}
// add an additional objective function
int gurobi_solver::add_objective(void) {
push_obj();
return 0;
}
// ends up objective function construction
int gurobi_solver::end_objectives(void) {
if (objectives.size() > 0) {
int status = 0, nb_coeffs = 0;
// Set the first objective as the actual objective
for (int k = 0; k < nb_vars; k++) coefficients[k] = 0;
for (; first_objective < (int)objectives.size(); first_objective++)
if ((nb_coeffs = objectives[first_objective]->nb_coeffs) > 0) break;
if (nb_coeffs > 0)
for (int k = 0; k < nb_coeffs; k++)
coefficients[objectives[first_objective]->sindex[k]] = objectives[first_objective]->coefficients[k];
else
if (first_objective == (int)objectives.size()) first_objective--; // So that we solve at least one pbs
status = GRBaddvars(model, nb_vars, 0, NULL, NULL, NULL, coefficients, lb, ub, vartype, varname);
if (status) {
fprintf(stderr, "gurobi_solver: end_objective: cannot create objective function.\n");
exit(-1);
}
status = GRBupdatemodel(model);
if (status) {
fprintf(stderr, "gurobi_solver: end_objective: cannot update model with variables.\n");
exit(-1);
}
}
return 0;
}
// initialize constraint declaration
int gurobi_solver::begin_add_constraints(void) { return 0; }
// begin the declaration of a new constraint
int gurobi_solver::new_constraint(void) { reset_coeffs(); return 0; }
// return the coefficient value of a package
CUDFcoefficient gurobi_solver::get_constraint_coeff(CUDFVersionedPackage *package) { return (CUDFcoefficient)get_coeff(package); }
// return the coefficient value of a package
CUDFcoefficient gurobi_solver::get_constraint_coeff(int rank) { return (CUDFcoefficient)get_coeff(rank); }
// set the coeffcient value of a package
int gurobi_solver::set_constraint_coeff(CUDFVersionedPackage *package, CUDFcoefficient value) { set_coeff(package, value); return 0; }
// set the coefficient value of a ranked variable
int gurobi_solver::set_constraint_coeff(int rank, CUDFcoefficient value) { set_coeff(rank, value); return 0; }
// add constraint under construction as a greater or equal constraint
int gurobi_solver::add_constraint_geq(CUDFcoefficient bound) {
if (nb_coeffs > 0) {
if (GRBaddconstr(model, nb_coeffs, sindex, coefficients, GRB_GREATER_EQUAL, bound, NULL)) {
fprintf(stderr, "gurobi_solver: add_constraint_geq: cannot create geq constraint.\n");
exit(-1);
}
}
return 0;
}
// add constraint under construction as a less or equal constraint
int gurobi_solver::add_constraint_leq(CUDFcoefficient bound) {
if (nb_coeffs > 0) {
if (GRBaddconstr(model, nb_coeffs, sindex, coefficients, GRB_LESS_EQUAL, bound, NULL)) {
fprintf(stderr, "gurobi_solver: add_constraint_geq: cannot create geq constraint.\n");
exit(-1);
}
}
return 0;
}
// add constraint under construction as an equal constraint
int gurobi_solver::add_constraint_eq(CUDFcoefficient bound) {
if (nb_coeffs > 0) {
if (GRBaddconstr(model, nb_coeffs, sindex, coefficients, GRB_EQUAL, bound, NULL)) {
fprintf(stderr, "gurobi_solver: add_constraint_geq: cannot create geq constraint.\n");
exit(-1);
}
}
return 0;
}
// ends up constraint declaration
int gurobi_solver::end_add_constraints(void) {
return 0;
}
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