enable setting random generator on glop

ortools/glop/entering_variable.h

@@ -74,12 +74,14 @@ class EnteringVariable {
   // Sets the parameters.
   void SetParameters(const GlopParameters& parameters);
 
+  void SetRandom(absl::BitGenRef random) { random_ = random; }
+
   // Stats related functions.
   std::string StatString() const { return stats_.StatString(); }
 
   // Deterministic time used by some of the functions of this class.
   //
-  // TODO(user): Be exhausitive and more precise.
+  // TODO(user): Be exhaustive and more precise.
   double DeterministicTime() const {
     return DeterministicTimeForFpOperations(num_operations_);
   }

ortools/glop/parameters.proto

@@ -24,7 +24,7 @@ package operations_research.glop;
 option java_package = "com.google.ortools.glop";
 option java_multiple_files = true;
 option csharp_namespace = "Google.OrTools.Glop";
-// next id = 72
+// next id = 73
 message GlopParameters {
   // Supported algorithms for scaling:
   // EQUILIBRATION - progressive scaling by row and column norms until the
@@ -404,6 +404,12 @@ message GlopParameters {
   // advanced farther than the other.
   optional int32 random_seed = 43 [default = 1];
 
+  // Whether to use absl::BitGen instead of MTRandom.
+  // MOE:begin_strip
+  // Note that in unit tests if this field is not explicitly set it will be
+  // default to true. MOE:end_strip
+  optional bool use_absl_random = 72 [default = false];
+
   // Number of threads in the OMP parallel sections. If left to 1, the code will
   // not create any OMP threads and will remain single-threaded.
   optional int32 num_omp_threads = 44 [default = 1];

ortools/glop/pricing.h

@@ -76,6 +76,8 @@ class DynamicMaximum {
   // Removes the given index from the set of candidates.
   void Remove(Index position);
 
+  void SetRandom(absl::BitGenRef random) { random_ = random; }
+
   // Adds an element to the set of candidate and sets its value. If the element
   // is already present, this updates its value. The value must be finite.
   void AddOrUpdate(Index position, Fractional value);

ortools/glop/reduced_costs.h

@@ -67,6 +67,8 @@ class ReducedCosts {
   // next call to GetReducedCosts().
   bool NeedsBasisRefactorization() const;
 
+  void SetRandom(absl::BitGenRef random) { random_ = random; }
+
   // Checks the precision of the entering variable choice now that the direction
   // is computed. Returns its precise version. This will also trigger a
   // reduced cost recomputation if it was deemed too imprecise.
@@ -307,6 +309,8 @@ class PrimalPrices {
   // the basis during a primal simplex iterations.
   ColIndex GetBestEnteringColumn();
 
+  void SetRandom(absl::BitGenRef random) { prices_.SetRandom(random); }
+
   // Similar to the other UpdateBeforeBasisPivot() functions.
   //
   // Important: Both the primal norms and reduced costs must have been updated

ortools/glop/revised_simplex.cc

@@ -97,7 +97,9 @@ constexpr const uint64_t kDeterministicSeed = 42;
 
 namespace {
 
-bool UseAbslRandom() { return false; }
+bool UseAbslRandom(const GlopParameters& parameters) {
+  return parameters.use_absl_random();
+}
 
 }  // namespace
 
@@ -108,8 +110,7 @@ RevisedSimplex::RevisedSimplex()
       variable_name_(),
       direction_(),
       error_(),
-      random_(UseAbslRandom() ? absl::BitGenRef(absl_random_)
-                              : absl::BitGenRef(deterministic_random_)),
+      random_(absl::BitGenRef(deterministic_random_)),
       basis_factorization_(&compact_matrix_, &basis_),
       variables_info_(compact_matrix_),
       primal_edge_norms_(compact_matrix_, variables_info_,
@@ -876,7 +877,7 @@ void RevisedSimplex::UpdateBasis(ColIndex entering_col, RowIndex basis_row,
   DCHECK(variables_info_.GetIsBasicBitRow().IsSet(leaving_col));
 
   // Make leaving_col leave the basis and update relevant data.
-  // Note thate the leaving variable value is not necessarily at its exact
+  // Note that the leaving variable value is not necessarily at its exact
   // bound, which is like a bound shift.
   variables_info_.UpdateToNonBasicStatus(leaving_col, leaving_variable_status);
   DCHECK(leaving_variable_status == VariableStatus::AT_UPPER_BOUND ||
@@ -3678,10 +3679,21 @@ Fractional RevisedSimplex::ComputeInitialProblemObjectiveValue() const {
   return objective_scaling_factor_ * (sum + objective_offset_);
 }
 
+void RevisedSimplex::SetRandom(absl::BitGenRef random) {
+  random_ = random;
+  dual_prices_.SetRandom(random_);
+  entering_variable_.SetRandom(random_);
+  reduced_costs_.SetRandom(random_);
+  primal_prices_.SetRandom(random_);
+}
+
 void RevisedSimplex::SetParameters(const GlopParameters& parameters) {
   SCOPED_TIME_STAT(&function_stats_);
   deterministic_random_.seed(parameters.random_seed());
   absl_random_ = absl::BitGen(absl::SeedSeq({parameters.random_seed()}));
+  SetRandom((UseAbslRandom(parameters)
+                 ? absl::BitGenRef(absl_random_)
+                 : absl::BitGenRef(deterministic_random_)));
   initial_parameters_ = parameters;
   parameters_ = parameters;
   PropagateParameters();
@@ -3911,7 +3923,7 @@ void RevisedSimplex::ComputeBasicVariablesForState(
 
 void RevisedSimplex::DisplayRevisedSimplexDebugInfo() {
   if (VLOG_IS_ON(3)) {
-    // This function has a complexity in O(num_non_zeros_in_matrix).
+    variable_name_.resize(num_cols_, "");
     DisplayInfoOnVariables();
 
     std::string output = "z = " + StringifyWithFlags(ComputeObjectiveValue());
@@ -3944,10 +3956,11 @@ void RevisedSimplex::DisplayRevisedSimplexDebugInfo() {
   }
 }
 
-void RevisedSimplex::DisplayProblem() const {
+void RevisedSimplex::DisplayProblem() {
   // This function has a complexity in O(num_rows * num_cols *
   // num_non_zeros_in_row).
   if (VLOG_IS_ON(3)) {
+    variable_name_.resize(num_cols_, "");
     DisplayInfoOnVariables();
     std::string output = "min: ";
     bool has_objective = false;

ortools/glop/revised_simplex.h

@@ -248,6 +248,11 @@ class RevisedSimplex {
 
   void SetLogger(SolverLogger* logger) { logger_ = logger; }
 
+  // Note: SetParameters() calls SetRandom() on its implementation, so if you
+  // want to set the parameters and then set the random generator, you should
+  // call SetRandom() after SetParameters().
+  void SetRandom(absl::BitGenRef random);
+
   // Advanced usage. For fast incremental call to the solver, it is better not
   // to use LinearProgram at all. This api allows to directly modify the
   // internal data of glop and then call solve.
@@ -376,7 +381,7 @@ class RevisedSimplex {
   void DisplayRevisedSimplexDebugInfo();
 
   // Displays the Linear Programming problem as it was input.
-  void DisplayProblem() const;
+  void DisplayProblem();
 
   // Returns the current objective value. This is just the sum of the current
   // variable values times their current cost.