Provide notification callbacks for progress and new solutions

app/services/vns/engine.rb

@@ -5,6 +5,7 @@
 module VNS
   class Engine
     PERTURBATION_SIZES = [1, 1, 1, 2, 2, 3].freeze
+    ITERATIONS = 50
     class << self
       def sequence(elements)
         elements = elements.to_a
@@ -26,6 +27,14 @@ module VNS
       @perturbations << klass
     end
 
+    def notify_progress(&block)
+      @progress_notifier = block
+    end
+
+    def on_better_solution(&block)
+      @better_solution_notifier = block
+    end
+
     attr_writer :initial_solution
 
     def run
@@ -40,18 +49,24 @@ module VNS
 
       run_all_optimizations
 
+      @progress_notifier&.call(Rational(1, ITERATIONS + 1))
+
       best_solution = @current_solution
 
-      50.times do
+      ITERATIONS.times do |iteration|
         @current_solution = Tables::WheelSwap.new(best_solution).call(PERTURBATION_SIZES.sample)
         @best_score = @target_function.call(@current_solution)
         Rails.logger.debug { "After perturbation: #{@best_score}" }
 
         run_all_optimizations
 
+        @progress_notifier&.call(Rational(iteration + 1, ITERATIONS + 1))
+
         next unless best_solution.discomfort > @current_solution.discomfort
 
         best_solution = @current_solution
+        @better_solution_notifier&.call(best_solution)
+
         Rails.logger.debug do
           "Found better solution after perturbation optimization: #{@current_solution.discomfort}"
         end

lib/tasks/vns.rake

@@ -21,6 +21,14 @@ namespace :vns do
 
       engine.target_function(&:discomfort)
 
+      engine.notify_progress do |current_progress|
+        Rails.logger.info "Progress: #{(current_progress * 100.0).round(2)}%"
+      end
+
+      engine.on_better_solution do |better_solution|
+        Rails.logger.info "New best solution found with discomfort: #{better_solution.discomfort}"
+      end
+
       solution = Rails.benchmark('VNS Benchmarking') { engine.run }
 
       Rails.logger.info "Best solution found with discomfort: #{solution.discomfort}"