use the mersenne twister rng for random faction, side shuffling

This is because players were able to notice problems when the
rand rng was used for random map pools, so it cannot hurt to use
the good rng for these things also.

src/game_initialization/connect_engine.cpp

@@ -21,6 +21,7 @@
 #include "map.hpp"
 #include "multiplayer_ui.hpp"
 #include "mp_game_utils.hpp"
+#include "mt_rng.hpp"
 #include "tod_manager.hpp"
 
 #include <boost/foreach.hpp>
@@ -391,8 +392,9 @@ void connect_engine::start_game(LOAD_USERS load_users)
 {
 	DBG_MP << "starting a new game" << std::endl;
 
-    // Resolves the "random faction", "random gender" and "random message"
-    // Must be done before shuffle sides, or some cases will cause errors
+	// Resolves the "random faction", "random gender" and "random message"
+	// Must be done before shuffle sides, or some cases will cause errors
+	rand_rng::mt_rng rng; // Make an RNG for all the shuffling and random faction operations
 	BOOST_FOREACH(side_engine_ptr side, side_engines_) {
 		std::vector<std::string> avoid_faction_ids;
 
@@ -415,7 +417,7 @@ void connect_engine::start_game(LOAD_USERS load_users)
 				}
 			}
 		}
-		side->resolve_random(avoid_faction_ids);
+		side->resolve_random(rng, avoid_faction_ids);
 	}
 
 	// Shuffle sides (check settings and if it is a re-loaded game).
@@ -434,7 +436,7 @@ void connect_engine::start_game(LOAD_USERS load_users)
 		// Fisher-Yates shuffle.
 		for (int i = playable_sides.size(); i > 1; i--)
 		{
-			int j_side = playable_sides[rand() % i];
+			int j_side = playable_sides[rng.get_next_random() % i];
 			int i_side = playable_sides[i - 1];
 
 			if (i_side == j_side) continue; //nothing to swap
@@ -485,6 +487,8 @@ void connect_engine::start_game_commandline(
 
 	typedef boost::tuple<unsigned int, std::string> mp_option;
 
+	rand_rng::mt_rng rng;
+
 	unsigned num = 0;
 	BOOST_FOREACH(side_engine_ptr side, side_engines_) {
 		num++;
@@ -535,7 +539,7 @@ void connect_engine::start_game_commandline(
 
 		// Finally, resolve "random faction",
 		// "random gender" and "random message", if any remains unresolved.
-		side->resolve_random();
+		side->resolve_random(rng);
 	} // end top-level loop
 
 	update_and_send_diff(true);
@@ -1189,15 +1193,15 @@ bool side_engine::swap_sides_on_drop_target(const unsigned drop_target) {
 	return true;
 }
 
-void side_engine::resolve_random(const std::vector<std::string> & avoid_faction_ids)
+void side_engine::resolve_random(rand_rng::mt_rng & rng, const std::vector<std::string> & avoid_faction_ids)
 {
 	if (parent_.params_.saved_game) {
 		return;
 	}
 
 	chose_random_ = flg_.is_random_faction();
 
-	flg_.resolve_random(avoid_faction_ids);
+	flg_.resolve_random(rng, avoid_faction_ids);
 
 	LOG_MP << "side " << (index_ + 1) << ": faction=" <<
 		(flg_.current_faction())["name"] << ", leader=" <<

src/game_initialization/connect_engine.hpp

@@ -22,6 +22,8 @@
 #include "saved_game.hpp"
 #include <boost/scoped_ptr.hpp>
 
+namespace rand_rng { class mt_rng; }
+
 namespace ng {
 
 enum controller {
@@ -157,7 +159,7 @@ class side_engine
 
 	bool swap_sides_on_drop_target(const unsigned drop_target);
 
-	void resolve_random(const std::vector<std::string> & avoid_faction_ids = std::vector<std::string>());
+	void resolve_random( rand_rng::mt_rng & rng, const std::vector<std::string> & avoid_faction_ids = std::vector<std::string>());
 
 	// Resets this side to its default state.
 	void reset();

src/game_initialization/flg_manager.cpp

@@ -16,6 +16,7 @@
 #include "config.hpp"
 #include "formula_string_utils.hpp"
 #include "gettext.hpp"
+#include "mt_rng.hpp"
 #include "unit_types.hpp"
 #include "wml_separators.hpp"
 
@@ -215,7 +216,7 @@ bool flg_manager::is_random_faction()
 // assigning as we would have if it were off.
 // If there is still no options we throw a config error because it means the
 // era is misconfigured.
-void flg_manager::resolve_random(const std::vector<std::string> & avoid) {
+void flg_manager::resolve_random(rand_rng::mt_rng & rng, const std::vector<std::string> & avoid) {
 	if (is_random_faction()) {
 		std::vector<std::string> faction_choices, faction_excepts;
 
@@ -272,7 +273,7 @@ void flg_manager::resolve_random(const std::vector<std::string> & avoid) {
 		}
 
 		const int faction_index =
-			nonrandom_sides[rand() % nonrandom_sides.size()];
+			nonrandom_sides[rng.get_next_random() % nonrandom_sides.size()];
 		current_faction_ = available_factions_[faction_index];
 
 		update_available_leaders();
@@ -297,7 +298,7 @@ void flg_manager::resolve_random(const std::vector<std::string> & avoid) {
 				"Unable to find a leader type for faction $faction",
 				i18n_symbols));
 		} else {
-			const int lchoice = rand() % nonrandom_leaders.size();
+			const int lchoice = rng.get_next_random() % nonrandom_leaders.size();
 			current_leader_ = nonrandom_leaders[lchoice];
 
 			update_available_genders();
@@ -316,7 +317,7 @@ void flg_manager::resolve_random(const std::vector<std::string> & avoid) {
 				}
 			}
 
-			const int gchoice = rand() % nonrandom_genders.size();
+			const int gchoice = rng.get_next_random() % nonrandom_genders.size();
 			current_gender_ = nonrandom_genders[gchoice];
 		} else {
 			utils::string_map i18n_symbols;

src/game_initialization/flg_manager.hpp

@@ -20,6 +20,7 @@
 #include <vector>
 
 class config;
+namespace rand_rng { class mt_rng; }
 
 namespace ng {
 
@@ -55,7 +56,7 @@ class flg_manager
 	void reset_gender_combo(gui::combo& combo_gender) const;
 
 	bool is_random_faction();
-	void resolve_random(const std::vector<std::string> & avoid); //Argument is a list of faction ids we don't want to match, used to implement random faction modes. If it is not possible to resolve then we just proceed anyways rather than give an error.
+	void resolve_random(rand_rng::mt_rng & rng, const std::vector<std::string> & avoid); //Second Argument is a list of faction ids we don't want to match, used to implement random faction modes. If it is not possible to resolve then we just proceed anyways rather than give an error.
 
 	// Picks the first faction with the greater amount of data
 	// matching the criteria.

src/tests/test_mp_connect.cpp

@@ -21,6 +21,7 @@
 #include "game_initialization/multiplayer_connect.hpp"
 #include "game_initialization/multiplayer_ui.hpp"
 #include "hotkey/hotkey_manager.hpp"
+#include "mt_rng.hpp"
 #include "saved_game.hpp"
 
 #include <boost/foreach.hpp>
@@ -53,6 +54,7 @@ namespace {
 
 boost::scoped_ptr<game_display> disp;
 boost::scoped_ptr<saved_game> state;
+boost::scoped_ptr<rand_rng::mt_rng> rng;
 
 }
 
@@ -87,6 +89,8 @@ struct mp_connect_fixture {
 			game_config().find_child(lexical_cast<std::string>(game_classification::MULTIPLAYER), "id", state->mp_settings().name));
 
 		state->mp_settings().num_turns = state->get_starting_pos()["turns"];
+
+		rng.reset(new rand_rng::mt_rng());
 	}
 	~mp_connect_fixture()
 	{
@@ -299,7 +303,7 @@ BOOST_AUTO_TEST_CASE( flg_map_settings )
 	side.clear();
 	side["faction"] = "Random";
 	side_engine.reset(create_side_engine(side, connect_engine.get()));
-	side_engine->resolve_random();
+	side_engine->resolve_random(*rng);
 	BOOST_CHECK( side_engine->flg().current_faction()["id"] != "Random" );
 	BOOST_CHECK( side_engine->flg().current_leader() != "random" &&
 		side_engine->flg().current_leader() != "null");
@@ -311,7 +315,7 @@ BOOST_AUTO_TEST_CASE( flg_map_settings )
 	side["faction"] = "Random";
 	side["type"] = "Troll";
 	side_engine.reset(create_side_engine(side, connect_engine.get()));
-	side_engine->resolve_random();
+	side_engine->resolve_random(*rng);
 	BOOST_CHECK( side_engine->flg().current_faction()["id"] != "Random" );
 	BOOST_CHECK_EQUAL( side_engine->flg().current_leader(), "Troll" );
 	BOOST_CHECK( side_engine->flg().current_gender() != "random" &&
@@ -323,7 +327,7 @@ BOOST_AUTO_TEST_CASE( flg_map_settings )
 	side["type"] = "White Mage";
 	side["gender"] = "male";
 	side_engine.reset(create_side_engine(side, connect_engine.get()));
-	side_engine->resolve_random();
+	side_engine->resolve_random(*rng);
 	BOOST_CHECK( side_engine->flg().current_faction()["id"] != "Random" );
 	BOOST_CHECK_EQUAL( side_engine->flg().current_leader(), "White Mage" );
 	BOOST_CHECK_EQUAL( side_engine->flg().current_gender(), "male" );
@@ -332,7 +336,7 @@ BOOST_AUTO_TEST_CASE( flg_map_settings )
 	side.clear();
 	side["type"] = "random";
 	side_engine.reset(create_side_engine(side, connect_engine.get()));
-	side_engine->resolve_random();
+	side_engine->resolve_random(*rng);
 	BOOST_CHECK( side_engine->flg().current_leader() != "random" );
 }