feat(routing): Expose restoration time limits

README.md

@@ -1473,6 +1473,20 @@ routing.solve(
 )
 ```
 
+Set a native time limit for route restoration after closing the model. The limit
+is in seconds and accepts fractional values:
+
+```ruby
+routing.close_model
+routing.update_time_limit(0.5)
+assignment = routing.read_assignment_from_routes(routes, true)
+```
+
+The limit is checked cooperatively, so the call can exceed it. Restoration can
+return a valid assignment found before the limit. A `nil` result does not
+distinguish an invalid route from a limit reached before finding a solution.
+A subsequent solve uses the time limit in its own search parameters.
+
 Native improvement-rate stopping is available through search parameters:
 
 ```ruby

ext/or-tools/routing.cpp

@@ -1,4 +1,5 @@
 #include <algorithm>
+#include <cmath>
 #include <memory>
 #include <mutex>
 #include <optional>
@@ -714,6 +715,14 @@ void init_routing(Rice::Module& m) {
           self.CloseModel();
         }
       })
+    .define_method(
+      "update_time_limit",
+      [](RoutingModel& self, double seconds) {
+        if (!std::isfinite(seconds) || seconds < 0) {
+          throw std::invalid_argument{"time limit must be finite and nonnegative"};
+        }
+        self.UpdateTimeLimit(absl::Seconds(seconds));
+      })
     .define_method(
       "_enable_solution_trace",
       [](RoutingModel& self, int64_t max_samples, int64_t sample_interval_ms) {

test/routing_time_limit_test.rb

@@ -0,0 +1,55 @@
+require_relative "test_helper"
+
+class RoutingTimeLimitTest < Minitest::Test
+  def test_restoration_limit_can_be_reset_after_timeout
+    routing = build_routing
+    routing.close_model
+    routing.update_time_limit(0)
+
+    assert_nil routing.read_assignment_from_routes([[1, 2]], true)
+    assert_equal :fail, routing.status
+
+    routing.update_time_limit(0.5)
+    assignment = routing.read_assignment_from_routes([[1, 2]], true)
+
+    refute_nil assignment
+    assert_equal 4, assignment.objective_value
+    assert_equal :success, routing.status
+  end
+
+  def test_solve_replaces_restoration_time_limit
+    routing = build_routing
+    routing.close_model
+    routing.update_time_limit(0.5)
+    assignment = routing.read_assignment_from_routes([[1, 2]], true)
+    refute_nil assignment
+
+    routing.update_time_limit(0)
+    parameters = ORTools.default_routing_search_parameters
+    parameters.time_limit = 1
+    parameters.solution_limit = 1
+    solution = routing.solve_from_assignment_with_parameters(assignment, parameters)
+
+    refute_nil solution
+    assert_equal 4, solution.objective_value
+  end
+
+  def test_rejects_invalid_time_limits
+    routing = build_routing
+
+    [-1, Float::INFINITY, -Float::INFINITY, Float::NAN].each do |seconds|
+      error = assert_raises(ArgumentError) { routing.update_time_limit(seconds) }
+      assert_equal "time limit must be finite and nonnegative", error.message
+    end
+  end
+
+  private
+
+  def build_routing
+    manager = ORTools::RoutingIndexManager.new(3, 1, 0)
+    routing = ORTools::RoutingModel.new(manager)
+    transit = routing.register_transit_matrix([[0, 1, 2], [1, 0, 1], [2, 1, 0]])
+    routing.set_arc_cost_evaluator_of_all_vehicles(transit)
+    routing
+  end
+end