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#include <c10/core/GeneratorImpl.h>
#include <chrono>
#include <random>
#ifndef _WIN32
#include <fcntl.h>
#include <unistd.h>
#endif
namespace c10 {
/**
* GeneratorImpl class implementation
*/
GeneratorImpl::GeneratorImpl(Device device_in, DispatchKeySet key_set)
: device_{device_in}, key_set_(key_set) {}
/**
* Clone this generator. Note that clone() is the only
* method for copying for Generators in ATen.
*/
c10::intrusive_ptr<GeneratorImpl> GeneratorImpl::clone() const {
auto res = this->clone_impl();
c10::raw::intrusive_ptr::incref(res);
return c10::intrusive_ptr<GeneratorImpl>::reclaim(res);
}
/**
* Gets the device of a generator.
*/
Device GeneratorImpl::device() const {
return device_;
}
namespace detail {
/**
* Gets a random number for /dev/urandom
* Note this is a legacy method (from THRandom.cpp)
* FIXME: use std::random_device with entropy information
*/
#ifndef _WIN32
static uint64_t readURandomLong()
{
int randDev = open("/dev/urandom", O_RDONLY);
uint64_t randValue;
TORCH_CHECK(randDev >= 0, "Unable to open /dev/urandom");
ssize_t readBytes = read(randDev, &randValue, sizeof(randValue));
TORCH_CHECK(readBytes >= (ssize_t) sizeof(randValue), "Unable to read from /dev/urandom");
close(randDev);
return randValue;
}
#endif // _WIN32
/**
* Gets a non deterministic random number number from either the
* /dev/urandom or the current time. For CUDA, gets random from
* std::random_device and adds a transformation on it.
*
* FIXME: The behavior in this function is from legacy code (THRandom_seed/THCRandom_seed)
* and is probably not the right thing to do, even though our tests pass.
* Figure out if tests get perturbed
* - when the same algorithm is used for all backends. Note that the current behavior is
* different for CPU, CUDA and Windows CPU.
* - when using C++11 std objects, such as std::random_device
* - when constructing a 64 bit seed properly, rather than static casting
* a 32 bit number to 64 bit.
*/
uint64_t getNonDeterministicRandom(bool is_cuda) {
uint64_t s;
if (!is_cuda) {
#ifdef _WIN32
s = (uint64_t)std::chrono::high_resolution_clock::now().time_since_epoch().count();
#else
s = readURandomLong();
#endif
} else {
std::random_device rd;
// limit to 53 bits to ensure unique representation in double
s = ((((uint64_t)rd()) << 32) + rd()) & 0x1FFFFFFFFFFFFF;
}
return s;
}
} // namespace detail
} // namespace c10
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