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Code Issues 150 Wiki Activity

Improve random engine entropy and clean up random engine initialization

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This commit is contained in:
Hirek
2026-09-14 19:26:24 +02:00
parent 1c2f397fc5
commit 788135cc2d
4 changed files with 23 additions and 13 deletions
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19
utilities/utilities.cpp
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@@ -138,10 +138,20 @@ int Random(int min, int max)
return dist(Global.random_engine);
}
std::uint32_t clock_seed()
std::uint64_t true_random_seed()
{
static std::atomic<std::uint32_t> nth{0};
return static_cast<std::uint32_t>(std::time({})) + nth.fetch_add(1, std::memory_order_relaxed);
try
{
std::random_device rd;
if (rd.entropy() > 0.0)
{
std::uint32_t high = rd();
std::uint32_t low = rd();
return (high << 32) | low;
}
}
catch (...) {}
return static_cast<std::uint64_t>(std::chrono::high_resolution_clock::now().time_since_epoch().count());
}
std::uint32_t seed_of(std::string const &Text)
@@ -161,12 +171,11 @@ std::uint32_t seed_of(std::string const &Text)
std::string generate_uuid_v4()
{
static thread_local std::mt19937 generator{clock_seed()};
std::uniform_int_distribution<int> dist(0, 255);
std::array<uint8_t, 16> bytes;
for (auto &b : bytes)
b = static_cast<uint8_t>(dist(generator));
b = static_cast<uint8_t>(dist(Global.random_engine));
// UUID v4 (RFC 4122)
bytes[6] = bytes[6] & 0x0F | 0x40;

7
utilities/utilities.h
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@@ -63,9 +63,10 @@ inline long Round(double const f)
double Random(double a, double b);
int Random(int min, int max);
// Seed for the random engines: the clock, plus a counter so two engines seeded in
// the same second do not come out the same.
std::uint32_t clock_seed();
/// @author lxvia
/// @brief Returns a random seed from the system's entropy source, if available. Otherwise, falls back to a clock-based seed.
/// @return A random seed as 64 bit unsigned integer
std::uint64_t true_random_seed();
// The seed a word stands for. A number is taken as it is written; anything else is
// hashed the way Java's String.hashCode does it, so the same word gives the same

6
utilities/uuid.hpp
View File

@@ -7,6 +7,7 @@
#include <algorithm>
#include <cstdint>
#include "utilities/utilities.h"
#include "utilities/Globals.h"
class UID {
public:
@@ -14,10 +15,9 @@ public:
static UID random() {
static thread_local std::mt19937_64 gen{clock_seed()};
UID u;
uint64_t a = gen();
uint64_t b = gen();
uint64_t a = Global.random_engine();
uint64_t b = Global.random_engine();
for (int i = 0; i < 8; ++i) u.bytes[i] = uint8_t(a >> (i * 8) & 0xFF);
for (int i = 0; i < 8; ++i) u.bytes[8 + i] = uint8_t(b >> (i * 8) & 0xFF);