Replace random_shuffle with std::shuffle (#5463)

* Replace random_shuffle with std::shuffle
* Use default ctor in RandomGenerator and clean up

Author: nyllet

src/karts/kart_properties_manager.cpp

@@ -31,6 +31,7 @@
 #include "karts/kart_properties.hpp"
 #include "karts/xml_characteristic.hpp"
 #include "utils/log.hpp"
+#include "utils/random_generator.hpp"
 #include "utils/string_utils.hpp"
 
 #include <algorithm>
@@ -685,8 +686,9 @@ void KartPropertiesManager::getRandomKartList(int count,
 
             assert(random_kart_queue.size() > 0);
 
-            std::random_shuffle(random_kart_queue.begin(),
-                                random_kart_queue.end()   );
+            std::shuffle(random_kart_queue.begin(),
+                         random_kart_queue.end(),
+                         RandomGenerator::getGenerator());
         }
 
         while (count > 0 && random_kart_queue.size() > 0)

src/main.cpp

@@ -1030,6 +1030,7 @@ int handleCmdLinePreliminary()
     if (CommandLine::has("--seed", &n))
     {
         srand(n);
+        RandomGenerator::seed(n);
         Log::info("main", "STK using random seed (%d)", n);
     }
 

src/modes/free_for_all.cpp

@@ -239,7 +239,7 @@ std::pair<int, video::SColor> FreeForAll::getSpeedometerDigit(
 
     // Fade from green to red
     std::vector<int> sorted_scores;
-    for (int i = 0; i < m_scores.size(); i++)
+    for (unsigned int i = 0; i < m_scores.size(); i++)
     {
         if (!getKart(i)->isEliminated())
         {

src/modes/three_strikes_battle.cpp

@@ -708,8 +708,9 @@ void ThreeStrikesBattle::loadCustomModels()
             }
 
             // Find random nodes to pre-spawn spare tire karts
-            std::random_shuffle(sta_possible_nodes.begin(),
-                sta_possible_nodes.end());
+            std::shuffle(sta_possible_nodes.begin(),
+                         sta_possible_nodes.end(),
+                         RandomGenerator::getGenerator());
 
             // Compute a random kart list
             std::vector<std::string> sta_list;

src/states_screens/arenas_screen.cpp

@@ -351,7 +351,8 @@ void ArenasScreen::buildTrackList()
         w->addItem(_("Random Arena"), "random_track", "/gui/icons/track_random.png");
     w->updateItemDisplay();
 
-    std::random_shuffle( m_random_arena_list.begin(), m_random_arena_list.end() );
+    std::shuffle( m_random_arena_list.begin(), m_random_arena_list.end(),
+                  RandomGenerator::getGenerator());
 }
 
 // ------------------------------------------------------------------------------------------------------

src/states_screens/easter_egg_screen.cpp

@@ -258,7 +258,7 @@ void EasterEggScreen::buildTrackList()
     }
     tracks.insertionSort();
 
-    for (int n=0; n<tracks.size(); n++)
+    for (unsigned int n=0; n<tracks.size(); n++)
     {
         Track* curr = tracks.get(n);
 
@@ -288,7 +288,8 @@ void EasterEggScreen::buildTrackList()
                            0 /* no badge */, IconButtonWidget::ICON_PATH_TYPE_RELATIVE);
 
     tracks_widget->updateItemDisplay();
-    std::random_shuffle( m_random_track_list.begin(), m_random_track_list.end() );
+    std::shuffle( m_random_track_list.begin(), m_random_track_list.end(),
+                  RandomGenerator::getGenerator());
 }
 
 // -----------------------------------------------------------------------------

src/states_screens/online/tracks_screen.cpp

@@ -698,7 +698,8 @@ void TracksScreen::buildTrackList()
                            IconButtonWidget::ICON_PATH_TYPE_RELATIVE);
 
     tracks_widget->updateItemDisplay();
-    std::random_shuffle( m_random_track_list.begin(), m_random_track_list.end() );
+    std::shuffle( m_random_track_list.begin(), m_random_track_list.end(),
+                  RandomGenerator::getGenerator());
 }   // buildTrackList
 
 // -----------------------------------------------------------------------------

src/states_screens/tracks_and_gp_screen.cpp

@@ -371,7 +371,8 @@ void TracksAndGPScreen::buildTrackList()
     }
 
     tracks_widget->updateItemDisplay();
-    std::random_shuffle( m_random_track_list.begin(), m_random_track_list.end() );
+    std::shuffle( m_random_track_list.begin(), m_random_track_list.end(),
+                  RandomGenerator::getGenerator());
 }   // buildTrackList
 
 // -----------------------------------------------------------------------------

src/tracks/track.hpp

@@ -55,6 +55,7 @@ using namespace irr;
 
 #include "utils/aligned_array.hpp"
 #include "utils/log.hpp"
+#include "utils/random_generator.hpp"
 #include "utils/vec3.hpp"
 #include "utils/stk_process.hpp"
 
@@ -563,7 +564,8 @@ class Track
     */
     void shuffleStartTransforms()
     {
-        std::random_shuffle(m_start_transforms.begin(), m_start_transforms.end());
+       std::shuffle(m_start_transforms.begin(), m_start_transforms.end(),
+                    RandomGenerator::getGenerator());
     }
     // ------------------------------------------------------------------------
     /** Sets pointer to the aabb of this track. */

src/utils/random_generator.cpp

@@ -18,18 +18,19 @@
 
 #include "utils/random_generator.hpp"
 
-#include <stdlib.h>
-#include <ctime>
-
 //std::vector<RandomGenerator*> RandomGenerator::m_all_random_generators;
 
-RandomGenerator::RandomGenerator()
-{
-    m_a = 1103515245;
-    m_c = 12345;
-    //m_all_random_generators.push_back(this);
-    m_random_value = 3141591;
-}   // RandomGenerator
+unsigned int RandomGenerator::m_random_value = RandomGenerator::default_seed;
+
+std::mt19937& RandomGenerator::getGenerator() {
+   static thread_local std::mt19937 generator = [] {
+      if (m_random_value == default_seed)
+         return std::mt19937{std::random_device{}()};
+      else
+         return std::mt19937{m_random_value};
+   }();
+   return generator;
+}
 
 // ----------------------------------------------------------------------------
 #if 0