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arangodb/lib/Random/RandomGenerator.cpp

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
////////////////////////////////////////////////////////////////////////////////
#include "RandomGenerator.h"
#include <chrono>
#include <random>
#ifdef TRI_HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <cstring>
#ifdef _WIN32
#include <Wincrypt.h>
#endif
#include "Basics/Exceptions.h"
#include "Basics/HybridLogicalClock.h"
#include "Basics/Thread.h"
#include "Basics/hashes.h"
#include "Logger/Logger.h"
using namespace arangodb;
using namespace arangodb::basics;
// -----------------------------------------------------------------------------
// RandomDevice
// -----------------------------------------------------------------------------
unsigned long RandomDevice::seed() {
// Random device ---
size_t dev = std::random_device()();
// Thread ID -------
auto tid = std::hash<std::thread::id>()(std::this_thread::get_id());
// Time now --------
for (unsigned short i = 0; i < 50; ++i) {
std::this_thread::yield();
std::this_thread::sleep_for(std::chrono::nanoseconds(100));
}
auto now = std::chrono::duration_cast<std::chrono::nanoseconds>(
std::chrono::high_resolution_clock::now().time_since_epoch())
.count();
return (unsigned long)(dev + tid + now);
}
int32_t RandomDevice::interval(int32_t left, int32_t right) {
return random(left, right);
}
uint32_t RandomDevice::interval(uint32_t left, uint32_t right) {
int32_t l = left + INT32_MIN;
int32_t r = right + INT32_MIN;
return static_cast<uint32_t>(static_cast<int64_t>(random(l, r)) - INT32_MIN);
}
int32_t RandomDevice::random(int32_t left, int32_t right) {
if (left >= right) {
return left;
}
if (left == INT32_MIN && right == INT32_MAX) {
return static_cast<int32_t>(random());
}
uint32_t range = static_cast<uint32_t>(right - left + 1);
switch (range) {
case 0x00000002:
return power2(left, 0x00000002 - 1);
case 0x00000004:
return power2(left, 0x00000004 - 1);
case 0x00000008:
return power2(left, 0x00000008 - 1);
case 0x00000010:
return power2(left, 0x00000010 - 1);
case 0x00000020:
return power2(left, 0x00000020 - 1);
case 0x00000040:
return power2(left, 0x00000040 - 1);
case 0x00000080:
return power2(left, 0x00000080 - 1);
case 0x00000100:
return power2(left, 0x00000100 - 1);
case 0x00000200:
return power2(left, 0x00000200 - 1);
case 0x00000400:
return power2(left, 0x00000400 - 1);
case 0x00000800:
return power2(left, 0x00000800 - 1);
case 0x00001000:
return power2(left, 0x00001000 - 1);
case 0x00002000:
return power2(left, 0x00002000 - 1);
case 0x00004000:
return power2(left, 0x00004000 - 1);
case 0x00008000:
return power2(left, 0x00008000 - 1);
case 0x00010000:
return power2(left, 0x00010000 - 1);
case 0x00020000:
return power2(left, 0x00020000 - 1);
case 0x00040000:
return power2(left, 0x00040000 - 1);
case 0x00080000:
return power2(left, 0x00080000 - 1);
case 0x00100000:
return power2(left, 0x00100000 - 1);
case 0x00200000:
return power2(left, 0x00200000 - 1);
case 0x00400000:
return power2(left, 0x00400000 - 1);
case 0x00800000:
return power2(left, 0x00800000 - 1);
case 0x01000000:
return power2(left, 0x01000000 - 1);
case 0x02000000:
return power2(left, 0x02000000 - 1);
case 0x04000000:
return power2(left, 0x04000000 - 1);
case 0x08000000:
return power2(left, 0x08000000 - 1);
case 0x10000000:
return power2(left, 0x10000000 - 1);
case 0x20000000:
return power2(left, 0x20000000 - 1);
case 0x40000000:
return power2(left, 0x40000000 - 1);
case 0x80000000:
return power2(left, 0x80000000 - 1);
}
return other(left, range);
}
int32_t RandomDevice::power2(int32_t left, uint32_t mask) {
return left + static_cast<int32_t>(random() & mask);
}
int32_t RandomDevice::other(int32_t left, uint32_t range) {
uint32_t g = UINT32_MAX - UINT32_MAX % range;
uint32_t r = random();
int count = 0;
static int const MAX_COUNT = 20;
TRI_ASSERT(g > 0);
while (r >= g) {
if (++count >= MAX_COUNT) {
LOG_TOPIC("3ca9f", ERR, arangodb::Logger::FIXME)
<< "cannot generate small random number after " << count << " tries";
r %= g;
continue;
}
LOG_TOPIC("47fbf", TRACE, arangodb::Logger::FIXME)
<< "random number too large, trying again";
r = random();
}
r %= range;
return left + static_cast<int32_t>(r);
}
// -----------------------------------------------------------------------------
// RandomDeviceDirect
// -----------------------------------------------------------------------------
#ifndef _WIN32
namespace {
template <int N>
class RandomDeviceDirect : public RandomDevice {
public:
explicit RandomDeviceDirect(std::string const& path) : fd(-1), pos(0) {
fd = TRI_OPEN(path.c_str(), O_RDONLY | TRI_O_CLOEXEC);
if (fd < 0) {
std::string message("cannot open random source '" + path + "'");
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL, message);
}
fillBuffer();
}
~RandomDeviceDirect() {
if (fd >= 0) {
TRI_CLOSE(fd);
}
}
uint32_t random() override {
if (pos >= N) {
fillBuffer();
}
return buffer[pos++];
}
private:
void fillBuffer() {
size_t n = sizeof(buffer);
char* ptr = reinterpret_cast<char*>(&buffer);
while (0 < n) {
ssize_t r = TRI_READ(fd, ptr, static_cast<TRI_read_t>(n));
if (r == 0) {
LOG_TOPIC("7153b", FATAL, arangodb::Logger::FIXME)
<< "read on random device failed: nothing read";
FATAL_ERROR_EXIT();
} else if (r < 0) {
LOG_TOPIC("f5ba9", FATAL, arangodb::Logger::FIXME)
<< "read on random device failed: " << strerror(errno);
FATAL_ERROR_EXIT();
}
ptr += r;
n -= r;
}
pos = 0;
}
private:
int fd;
uint32_t buffer[N];
size_t pos;
};
} // namespace
#endif
// -----------------------------------------------------------------------------
// RandomDeviceCombined
// -----------------------------------------------------------------------------
#ifndef _WIN32
namespace {
template <int N>
class RandomDeviceCombined : public RandomDevice {
public:
explicit RandomDeviceCombined(std::string const& path)
: fd(-1), pos(0), rseed(0) {
fd = TRI_OPEN(path.c_str(), O_RDONLY | TRI_O_CLOEXEC);
if (fd < 0) {
std::string message("cannot open random source '" + path + "'");
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL, message);
}
// Set the random number generator file to be non-blocking (not for windows)
{
long flags = fcntl(fd, F_GETFL, 0);
bool ok = (flags >= 0);
if (ok) {
flags = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
ok = (flags >= 0);
}
if (!ok) {
std::string message("cannot switch random source '" + path +
"' to non-blocking");
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL, message);
}
}
fillBuffer();
}
~RandomDeviceCombined() {
if (fd >= 0) {
TRI_CLOSE(fd);
}
}
uint32_t random() override {
if (pos >= N) {
fillBuffer();
}
return buffer[pos++];
}
private:
void fillBuffer() {
size_t n = sizeof(buffer);
char* ptr = reinterpret_cast<char*>(&buffer);
while (0 < n) {
ssize_t r = TRI_READ(fd, ptr, static_cast<TRI_read_t>(n));
if (r == 0) {
LOG_TOPIC("71bae", FATAL, arangodb::Logger::FIXME)
<< "read on random device failed: nothing read";
FATAL_ERROR_EXIT();
} else if (r < 0) {
if (errno == EWOULDBLOCK || errno == EAGAIN) {
LOG_TOPIC("15cf0", INFO, arangodb::Logger::FIXME)
<< "not enough entropy (got " << (sizeof(buffer) - n)
<< "), switching to pseudo-random";
break;
}
LOG_TOPIC("72c65", FATAL, arangodb::Logger::FIXME)
<< "read on random device failed: " << strerror(errno);
FATAL_ERROR_EXIT();
}
ptr += r;
n -= r;
rseed = buffer[0];
LOG_TOPIC("6a060", TRACE, arangodb::Logger::FIXME) << "using seed " << rseed;
}
if (0 < n) {
std::mt19937 engine;
unsigned long seed = RandomDevice::seed();
engine.seed((uint32_t)(rseed ^ (uint32_t)seed));
while (0 < n) {
*ptr++ = engine();
--n;
}
}
pos = 0;
}
private:
int fd;
uint32_t buffer[N];
size_t pos;
uint32_t rseed;
};
} // namespace
#endif
// -----------------------------------------------------------------------------
// RandomDeviceMersenne
// -----------------------------------------------------------------------------
class RandomDeviceMersenne : public RandomDevice {
public:
RandomDeviceMersenne() : engine((uint_fast32_t)RandomDevice::seed()) {}
uint32_t random() override { return engine(); }
void seed(uint64_t seed) {
engine.seed(static_cast<decltype(engine)::result_type>(seed));
}
std::mt19937 engine;
};
// -----------------------------------------------------------------------------
// RandomDeviceWin32
// -----------------------------------------------------------------------------
#ifdef _WIN32
namespace {
template <int N>
class RandomDeviceWin32 : public RandomDevice {
public:
RandomDeviceWin32() : cryptoHandle(0), pos(0) {
BOOL result;
result = CryptAcquireContext(&cryptoHandle, nullptr, nullptr, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT);
if (cryptoHandle == 0 || result == FALSE) {
std::string message("cannot create cryptographic windows handle");
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL, message);
}
fillBuffer();
}
~RandomDeviceWin32() {
if (cryptoHandle != 0) {
CryptReleaseContext(cryptoHandle, 0);
}
}
uint32_t random() override {
if (pos >= N) {
fillBuffer();
}
return buffer[pos++];
}
private:
void fillBuffer() {
DWORD n = sizeof(buffer);
BYTE* ptr = reinterpret_cast<BYTE*>(&buffer);
// fill the buffer with random characters
int result = CryptGenRandom(cryptoHandle, n, ptr);
if (result == 0) {
LOG_TOPIC("cec47", FATAL, arangodb::Logger::FIXME)
<< "read on random device failed: nothing read";
FATAL_ERROR_EXIT();
}
pos = 0;
}
private:
HCRYPTPROV cryptoHandle;
uint32_t buffer[N];
size_t pos;
};
} // namespace
#endif
// -----------------------------------------------------------------------------
// RandomGenerator
// -----------------------------------------------------------------------------
RandomGenerator::RandomType RandomGenerator::_type;
thread_local std::unique_ptr<RandomDevice> RandomGenerator::_device(nullptr);
void RandomGenerator::initialize(RandomType type) {
_type = type;
}
void RandomGenerator::ensureDeviceIsInitialized() {
if (_device) {
return;
}
switch (_type) {
case RandomType::MERSENNE: {
_device.reset(new RandomDeviceMersenne());
break;
}
#ifndef _WIN32
case RandomType::RANDOM: {
_device.reset(new RandomDeviceDirect<1024>("/dev/random"));
break;
}
case RandomType::URANDOM: {
_device.reset(new RandomDeviceDirect<1024>("/dev/urandom"));
break;
}
case RandomType::COMBINED: {
_device.reset(new RandomDeviceCombined<600>("/dev/random"));
break;
}
#endif
#ifdef _WIN32
case RandomType::WINDOWS_CRYPT: {
_device.reset(new RandomDeviceWin32<1024>());
break;
}
#endif
default: {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
"unknown random generator");
}
}
}
void RandomGenerator::shutdown() {
// nothing to do...
// thread-local devices will be released when their respective threads terminate.
}
int16_t RandomGenerator::interval(int16_t left, int16_t right) {
uint16_t value = static_cast<int16_t>(
interval(static_cast<int32_t>(left), static_cast<int32_t>(right)));
TRI_ASSERT(value >= left && value <= right);
return value;
}
int32_t RandomGenerator::interval(int32_t left, int32_t right) {
ensureDeviceIsInitialized();
int32_t value = _device->interval(left, right);
TRI_ASSERT(value >= left && value <= right);
return value;
}
int64_t RandomGenerator::interval(int64_t left, int64_t right) {
if (left >= right) {
return left;
}
int64_t value;
if (left == INT64_MIN && right == INT64_MAX) {
uint64_t r1 = interval(UINT32_MAX);
uint64_t r2 = interval(UINT32_MAX);
value = static_cast<int64_t>((r1 << 32) | r2);
TRI_ASSERT(value >= left && value <= right);
return value;
}
if (left < 0) {
if (right < 0) {
uint64_t high = static_cast<uint64_t>(-left);
uint64_t low = static_cast<uint64_t>(-right);
uint64_t d = high - low;
value = left + static_cast<int64_t>(interval(d));
TRI_ASSERT(value >= left && value <= right);
return value;
}
uint64_t low = static_cast<uint64_t>(-left);
uint64_t d = low + static_cast<uint64_t>(right);
uint64_t dRandom = interval(d);
if (dRandom < low) {
value = -1 - static_cast<int64_t>(dRandom);
} else {
value = static_cast<int64_t>(dRandom - low);
}
TRI_ASSERT(value >= left && value <= right);
return value;
} else {
uint64_t high = static_cast<uint64_t>(right);
uint64_t low = static_cast<uint64_t>(left);
uint64_t d = high - low;
value = left + static_cast<int64_t>(interval(d));
TRI_ASSERT(value >= left && value <= right);
return value;
}
}
uint16_t RandomGenerator::interval(uint16_t right) {
uint16_t value = static_cast<uint16_t>(interval(static_cast<uint32_t>(right)));
TRI_ASSERT(value <= right);
return value;
}
uint32_t RandomGenerator::interval(uint32_t right) {
ensureDeviceIsInitialized();
uint32_t value = _device->interval(static_cast<uint32_t>(0), right);
TRI_ASSERT(value <= right);
return value;
}
uint64_t RandomGenerator::interval(uint64_t right) {
if (right == 0) {
return 0;
}
uint64_t value;
if (right == UINT64_MAX) {
uint64_t r1 = interval(UINT32_MAX);
uint64_t r2 = interval(UINT32_MAX);
value = (r1 << 32) | r2;
} else {
uint32_t high = static_cast<uint32_t>(right >> 32);
uint64_t highMax = (static_cast<uint64_t>(high)) << 32;
uint64_t highRandom = (static_cast<uint64_t>(interval(high))) << 32;
if (highRandom == highMax) {
uint32_t low = static_cast<uint32_t>(right - highMax);
uint64_t lowRandom = static_cast<uint64_t>(interval(low));
value = highRandom | lowRandom;
} else {
uint64_t lowRandom = static_cast<uint64_t>(interval(UINT32_MAX));
value = highRandom | lowRandom;
}
}
TRI_ASSERT(value <= right);
return value;
}
void RandomGenerator::seed(uint64_t seed) {
ensureDeviceIsInitialized();
if (RandomDeviceMersenne* dev = dynamic_cast<RandomDeviceMersenne*>(_device.get())) {
dev->seed(seed);
return;
}
throw std::runtime_error(
"Random device is not mersenne and cannot be seeded!");
}
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