Add caching of updated paths

src/dsm/dsm.hpp

@@ -6,7 +6,7 @@
 
 static constexpr uint8_t DSM_VERSION_MAJOR = 2;
 static constexpr uint8_t DSM_VERSION_MINOR = 3;
-static constexpr uint8_t DSM_VERSION_PATCH = 16;
+static constexpr uint8_t DSM_VERSION_PATCH = 17;
 
 static auto const DSM_VERSION =
     std::format("{}.{}.{}", DSM_VERSION_MAJOR, DSM_VERSION_MINOR, DSM_VERSION_PATCH);

src/dsm/headers/Dynamics.hpp

@@ -21,6 +21,8 @@
 #include <format>
 #include <thread>
 #include <exception>
+#include <fstream>
+#include <filesystem>
 
 #include "DijkstraWeights.hpp"
 #include "Itinerary.hpp"
@@ -31,6 +33,8 @@
 #include "../utility/Logger.hpp"
 #include "../utility/Typedef.hpp"
 
+static auto constexpr g_cacheFolder = "./.dsmcache/";
+
 namespace dsm {
   /// @brief The Measurement struct represents the mean of a quantity and its standard deviation
   /// @tparam T The type of the quantity
@@ -81,6 +85,13 @@
     /// @brief Update the path of a single itinerary using Dijsktra's algorithm
     /// @param pItinerary An std::unique_prt to the itinerary
     void m_updatePath(const std::unique_ptr<Itinerary>& pItinerary) {
+      auto const& file = std::format("{}it{}.dsmcache", g_cacheFolder, pItinerary->id());
+      if (std::filesystem::exists(file)) {
+        auto path = SparseMatrix<bool>{};
+        path.load(file);
+        pItinerary->setPath(std::move(path));
+        return;
+      }
       Size const dimension = m_graph.adjMatrix().getRowDim();
       auto const destinationID = pItinerary->destination();
       SparseMatrix<bool> path{dimension, dimension};
@@ -125,6 +136,8 @@
                         pItinerary->destination()));
       }
       pItinerary->setPath(path);
+      pItinerary->path().cache(
+          std::format("{}it{}.dsmcache", g_cacheFolder, pItinerary->id()));
     }
 
   public:
@@ -288,6 +301,9 @@
 
   template <typename agent_t>
   void Dynamics<agent_t>::updatePaths() {
+    if (!std::filesystem::exists(g_cacheFolder)) {
+      std::filesystem::create_directory(g_cacheFolder);
+    }
     std::vector<std::thread> threads;
     threads.reserve(m_itineraries.size());
     std::exception_ptr pThreadException;
@@ -492,7 +508,7 @@
       auto meanDensity{std::accumulate(densities.begin(), densities.end(), 0.) / sum};
       return Measurement(meanDensity, 0.);
     }
     return Measurement<double>(densities);
   }
 
   template <typename agent_t>