Use of std::random_device for GUId generation.

src/guid.cpp

@@ -21,14 +21,31 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <sstream>
 
 #include "serverenvironment.h"
+#include "util/base64.h"
+
+GUIdGenerator::GUIdGenerator()
+{
+	m_rand_usable = m_rand.entropy() > 0.01;
+}
 
 GUId GUIdGenerator::next(const std::string &prefix)
 {
 	std::stringstream s_guid;
 
-	s_guid << prefix << std::hex << m_next << '-' << std::hex << m_env->getGameTime();
-
-	m_next++;
+	std::mt19937_64 gen(m_rand());
+	std::uniform_int_distribution<unsigned long long> m_uniform(0, UINT64_MAX);
+
+	u64 a[2];
+	if (m_rand_usable) {
+		a[0] = m_uniform(m_rand);
+		a[1] = m_uniform(m_rand);
+	}
+	else {
+		a[0] = (static_cast<u64>(m_env->getGameTime()) << 32) + m_next;
+		a[1] = m_uniform(m_rand);
+		m_next++;
+	}
+	s_guid << prefix << base64_encode(reinterpret_cast<unsigned char *>(a), 16);
 
 	return s_guid.str();
 }

src/guid.h

@@ -21,7 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "irrlichttypes.h"
 #include "util/basic_macros.h"
-#include <vector>
+#include <random>
 #include <string>
 
 class ServerEnvironment;
@@ -44,7 +44,7 @@ class GUIdGenerator {
 	 * @param prefix Prefix of generated GUId
 	 * @param next next value getted from loadMeta
 	 */
-	GUIdGenerator() = default;
+	GUIdGenerator();
 
 	~GUIdGenerator() = default;
 	DISABLE_CLASS_COPY(GUIdGenerator)
@@ -56,25 +56,13 @@ class GUIdGenerator {
 	GUId next(const std::string &prefix);
 
 private:
-	/**
-	 * Set ServerEnvironment,
-	 * @param env ServerEnvironment.
-	 */
-	void setServerEnvironment(ServerEnvironment *env, u64 state) { m_env = env; m_next = state; };
-	/**
-	 * Set state to defined/known state,
-	 * @param next New state value.
-	 */
-	void setState(u64 state) { m_next = state; };
-	/**
-	 * Get state,
-	 * @return Return aactual state value.
-	 */
-	u64 getState() const { return m_next; };
-
-private:
+	void setServerEnvironment(ServerEnvironment *env) { m_env = env; }
+
 	ServerEnvironment *m_env;
-	u64 m_next;
-
+	std::random_device m_rand;
+	//std::uniform_int_distribution<> m_uniform(0, UINT64_MAX);
+	bool m_rand_usable;
+	u32 m_next;
+
 	friend class ServerEnvironment;
 };

src/serverenvironment.cpp

@@ -457,7 +457,7 @@ ServerEnvironment::ServerEnvironment(ServerMap *map,
 	m_active_object_gauge = mb->addGauge(
 		"minetest_env_active_objects", "Number of active objects");
 
-	m_guid_generator.setServerEnvironment(this, porting::getTimeS());
+	m_guid_generator.setServerEnvironment(this);
 }
 
 void ServerEnvironment::init()