[CP-SAT] fix dtime reporting for lns

ortools/sat/cp_model_lns.cc

@@ -1247,7 +1247,7 @@ double NeighborhoodGenerator::GetUCBScore(int64_t total_num_calls) const {
   return current_average_ + sqrt((2 * log(total_num_calls)) / num_calls_);
 }
 
-double NeighborhoodGenerator::Synchronize() {
+absl::Span<const double> NeighborhoodGenerator::Synchronize() {
   absl::MutexLock mutex_lock(&generator_mutex_);
 
   // To make the whole update process deterministic, we currently sort the
@@ -1258,7 +1258,7 @@ double NeighborhoodGenerator::Synchronize() {
   int num_fully_solved_in_batch = 0;
   int num_not_fully_solved_in_batch = 0;
 
-  double total_dtime = 0.0;
+  tmp_dtimes_.clear();
   for (const SolveData& data : solve_data_) {
     ++num_calls_;
 
@@ -1304,7 +1304,7 @@ double NeighborhoodGenerator::Synchronize() {
       current_average_ = 0.9 * current_average_ + 0.1 * gain_per_time_unit;
     }
 
-    total_dtime += data.deterministic_time;
+    tmp_dtimes_.push_back(data.deterministic_time);
   }
 
   // Update the difficulty.
@@ -1327,7 +1327,7 @@ double NeighborhoodGenerator::Synchronize() {
   }
 
   solve_data_.clear();
-  return total_dtime;
+  return tmp_dtimes_;
 }
 
 std::vector<int>

ortools/sat/cp_model_lns.h

@@ -475,9 +475,9 @@ class NeighborhoodGenerator {
   }
 
   // Process all the recently added solve data and update this generator
-  // score and difficulty. This returns the sum of the deterministic time of
+  // score and difficulty. This returns list of the deterministic time of
   // each SolveData.
-  double Synchronize();
+  absl::Span<const double> Synchronize();
 
   // Returns a short description of the generator.
   std::string name() const { return name_; }
@@ -528,6 +528,7 @@ class NeighborhoodGenerator {
 
  private:
   std::vector<SolveData> solve_data_;
+  std::vector<double> tmp_dtimes_;
 
   // Current parameters to be used when generating/solving a neighborhood with
   // this generator. Only updated on Synchronize().

ortools/sat/cp_model_solver.cc

@@ -1721,9 +1721,13 @@ class LnsSolver : public SubSolver {
   }
 
   void Synchronize() override {
-    const double dtime = generator_->Synchronize();
-    AddTaskDeterministicDuration(dtime);
-    shared_->time_limit->AdvanceDeterministicTime(dtime);
+    double sum = 0.0;
+    const absl::Span<const double> dtimes = generator_->Synchronize();
+    for (const double dtime : dtimes) {
+      sum += dtime;
+      AddTaskDeterministicDuration(dtime);
+    }
+    shared_->time_limit->AdvanceDeterministicTime(sum);
   }
 
  private: