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FastRandom rewrite (#3754)

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This commit is contained in:
peterbell10
2017-06-13 20:35:30 +01:00
committed by Lukas Pioch
parent 9b0eb118b3
commit 360d8eade0
63 changed files with 467 additions and 417 deletions
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131
src/FastRandom.cpp
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@@ -1,11 +1,11 @@
// FastRandom.cpp
// Implements the cFastRandom class representing a fast random number generator
#include "Globals.h"
#include "FastRandom.h"
#include <mutex>
#include <random>
#if defined (__GNUC__)
@@ -13,109 +13,50 @@
#elif defined (_MSC_VER)
#define ATTRIBUTE_TLS static __declspec(thread)
#else
#error "Unknown thread local storage qualifier"
#define ATTRIBUTE_TLS thread_local
#endif
static unsigned int GetRandomSeed()
MTRand & GetRandomProvider()
{
ATTRIBUTE_TLS bool SeedCounterInitialized = 0;
ATTRIBUTE_TLS unsigned int SeedCounter = 0;
// Some compilers don't support thread_local for non-POD types, this is purely a work around for that restriction.
// There should be minimal overhead for the non-initializing case and all thread's instances are deleted properly.
ATTRIBUTE_TLS MTRand * LocalPtr = nullptr;
if (LocalPtr == nullptr)
{
// This list allows deletion of elements as if they had static storage duration
static std::mutex CSDeleteList;
static std::list<std::unique_ptr<MTRand>> DeleteList;
cRandomDeviceSeeder seeder;
auto NewInstance = cpp14::make_unique<MTRand>(seeder);
auto TempPtr = NewInstance.get();
std::lock_guard<std::mutex> Lock(CSDeleteList);
DeleteList.push_front(std::move(NewInstance));
LocalPtr = TempPtr; // Set after push_back so LocalPtr won't dangle if it throws
}
return *LocalPtr;
}
UInt32 Detail::GetRandomSeed()
{
ATTRIBUTE_TLS bool SeedCounterInitialized = false;
ATTRIBUTE_TLS UInt32 SeedCounter = 0;
if (!SeedCounterInitialized)
{
std::random_device rd;
std::uniform_int_distribution<unsigned int> dist;
std::uniform_int_distribution<UInt32> dist;
SeedCounter = dist(rd);
SeedCounterInitialized = true;
}
return ++SeedCounter;
}
////////////////////////////////////////////////////////////////////////////////
// cFastRandom:
cFastRandom::cFastRandom(void) :
m_LinearRand(GetRandomSeed())
{
}
int cFastRandom::NextInt(int a_Range)
{
std::uniform_int_distribution<> distribution(0, a_Range - 1);
return distribution(m_LinearRand);
}
float cFastRandom::NextFloat(float a_Range)
{
std::uniform_real_distribution<float> distribution(0, a_Range);
return distribution(m_LinearRand);
}
int cFastRandom::GenerateRandomInteger(int a_Begin, int a_End)
{
std::uniform_int_distribution<> distribution(a_Begin, a_End);
return distribution(m_LinearRand);
}
////////////////////////////////////////////////////////////////////////////////
// MTRand:
MTRand::MTRand() :
m_MersenneRand(GetRandomSeed())
{
}
int MTRand::randInt(int a_Range)
{
std::uniform_int_distribution<> distribution(0, a_Range);
return distribution(m_MersenneRand);
}
int MTRand::randInt()
{
std::uniform_int_distribution<> distribution(0, std::numeric_limits<int>::max());
return distribution(m_MersenneRand);
}
double MTRand::rand(double a_Range)
{
std::uniform_real_distribution<> distribution(0, a_Range);
return distribution(m_MersenneRand);
}