Use mt19937 random number generator instad of the default one

src/actions.cpp

@@ -2124,11 +2124,15 @@ void AddRandomItems::run()
 		Statusbar::put() << "Number of random " << tag_type_str << "s: ";
 		number = fromString<unsigned>(wFooter->prompt());
 	}
-	if (number && (rnd_type == 's' ? Mpd.AddRandomSongs(number) : Mpd.AddRandomTag(tag_type, number)))
+	if (number > 0)
 	{
-		Statusbar::printf("%1% random %2%%3% added to playlist",
-			number, tag_type_str, number == 1 ? "" : "s"
-		);
+		bool success;
+		if (rnd_type == 's')
+			success = Mpd.AddRandomSongs(number, Global::RNG);
+		else
+			success = Mpd.AddRandomTag(tag_type, number, Global::RNG);
+		if (success)
+			Statusbar::printf("%1% random %2%%3% added to playlist", number, tag_type_str, number == 1 ? "" : "s");
 	}
 }
 

src/global.cpp

@@ -38,4 +38,6 @@ bool SeekingInProgress = false;
 std::string VolumeState;
 boost::posix_time::ptime Timer;
 
+std::mt19937 RNG;
+
 }

src/global.h

@@ -22,6 +22,8 @@
 #define NCMPCPP_GLOBAL_H
 
 #include <boost/date_time/posix_time/posix_time_types.hpp>
+#include <random>
+
 #include "mpdpp.h"
 #include "screen.h"
 
@@ -58,6 +60,9 @@ extern std::string VolumeState;
 // global timer
 extern boost::posix_time::ptime Timer;
 
+// global RNG
+extern std::mt19937 RNG;
+
 }
 
 #endif // NCMPCPP_GLOBAL_H

src/mpdpp.cpp

@@ -561,7 +561,7 @@ void Connection::Add(const std::string &path)
 	}
 }
 
-bool Connection::AddRandomTag(mpd_tag_type tag, size_t number)
+bool Connection::AddRandomTag(mpd_tag_type tag, size_t number, std::mt19937 &rng)
 {
 	std::vector<std::string> tags(
 		std::make_move_iterator(GetList(tag)),
@@ -570,7 +570,7 @@ bool Connection::AddRandomTag(mpd_tag_type tag, size_t number)
 	if (number > tags.size())
 		return false;
 
-	std::random_shuffle(tags.begin(), tags.end());
+	std::shuffle(tags.begin(), tags.end(), rng);
 	auto it = tags.begin();
 	for (size_t i = 0; i < number && it != tags.end(); ++i)
 	{
@@ -588,7 +588,7 @@ bool Connection::AddRandomTag(mpd_tag_type tag, size_t number)
 	return true;
 }
 
-bool Connection::AddRandomSongs(size_t number)
+bool Connection::AddRandomSongs(size_t number, std::mt19937 &rng)
 {
 	prechecksNoCommandsList();
 	std::vector<std::string> files;
@@ -609,7 +609,7 @@ bool Connection::AddRandomSongs(size_t number)
 	}
 	else
 	{
-		std::random_shuffle(files.begin(), files.end());
+		std::shuffle(files.begin(), files.end(), rng);
 		StartCommandsList();
 		auto it = files.begin();
 		for (size_t i = 0; i < number && it != files.end(); ++i, ++it)

src/mpdpp.h

@@ -23,6 +23,7 @@
 
 #include <cassert>
 #include <exception>
+#include <random>
 #include <set>
 #include <vector>
 
@@ -524,8 +525,8 @@ struct Connection
 	
 	int AddSong(const std::string &, int = -1); // returns id of added song
 	int AddSong(const Song &, int = -1); // returns id of added song
-	bool AddRandomTag(mpd_tag_type, size_t);
-	bool AddRandomSongs(size_t);
+	bool AddRandomTag(mpd_tag_type, size_t, std::mt19937 &rng);
+	bool AddRandomSongs(size_t number, std::mt19937 &rng);
 	void Add(const std::string &path);
 	void Delete(unsigned int pos);
 	void PlaylistDelete(const std::string &playlist, unsigned int pos);

src/ncmpcpp.cpp

@@ -89,7 +89,6 @@ int main(int argc, char **argv)
 	using Global::VolumeState;
 	using Global::Timer;
 	
-	srand(time(nullptr));
 	std::setlocale(LC_ALL, "");
 	std::locale::global(Charset::internalLocale());
 	
@@ -131,6 +130,9 @@ int main(int argc, char **argv)
 	
 	// initialize global timer
 	Timer = boost::posix_time::microsec_clock::local_time();
+
+	// initialize global random number generator
+	Global::RNG.seed(std::random_device()());
 	
 	// initialize playlist
 	myPlaylist->switchTo();

src/sort_playlist.cpp

@@ -197,7 +197,7 @@ void SortPlaylistDialog::sort() const
 	quick_sort = [this, &song_cmp, &quick_sort, &iter_swap](Iterator first, Iterator last) {
 		if (last-first > 1)
 		{
-			Iterator pivot = first+rand()%(last-first);
+			Iterator pivot = first+Global::RNG()%(last-first);
 			iter_swap(pivot, last-1);
 			pivot = last-1;