* limitations under the License.
*/
-#include "folly/Random.h"
+#include <folly/Random.h>
#include <atomic>
#include <unistd.h>
#include <random>
#include <array>
-#if __GNUC_PREREQ(4, 8)
-#include <ext/random>
-#define USE_SIMD_PRNG
-#endif
+#include <glog/logging.h>
+#include <folly/File.h>
+#include <folly/FileUtil.h>
namespace folly {
namespace {
-std::atomic<uint32_t> seedInput(0);
+
+// Keep it open for the duration of the program
+File randomDevice("/dev/urandom");
+
+void readRandomDevice(void* data, size_t size) {
+ PCHECK(readFull(randomDevice.fd(), data, size) == size);
}
-uint32_t randomNumberSeed() {
- struct timeval tv;
- gettimeofday(&tv, nullptr);
- const uint32_t kPrime0 = 51551;
- const uint32_t kPrime1 = 61631;
- const uint32_t kPrime2 = 64997;
- const uint32_t kPrime3 = 111857;
- return kPrime0 * (seedInput++)
- + kPrime1 * static_cast<uint32_t>(getpid())
- + kPrime2 * static_cast<uint32_t>(tv.tv_sec)
- + kPrime3 * static_cast<uint32_t>(tv.tv_usec);
+class BufferedRandomDevice {
+ public:
+ static constexpr size_t kDefaultBufferSize = 128;
+
+ explicit BufferedRandomDevice(size_t bufferSize = kDefaultBufferSize);
+
+ void get(void* data, size_t size) {
+ if (LIKELY(size <= remaining())) {
+ memcpy(data, ptr_, size);
+ ptr_ += size;
+ } else {
+ getSlow(static_cast<unsigned char*>(data), size);
+ }
+ }
+
+ private:
+ void getSlow(unsigned char* data, size_t size);
+
+ inline size_t remaining() const {
+ return buffer_.get() + bufferSize_ - ptr_;
+ }
+
+ const size_t bufferSize_;
+ std::unique_ptr<unsigned char[]> buffer_;
+ unsigned char* ptr_;
+};
+
+BufferedRandomDevice::BufferedRandomDevice(size_t bufferSize)
+ : bufferSize_(bufferSize),
+ buffer_(new unsigned char[bufferSize]),
+ ptr_(buffer_.get() + bufferSize) { // refill on first use
}
+void BufferedRandomDevice::getSlow(unsigned char* data, size_t size) {
+ DCHECK_GT(size, remaining());
+ if (size >= bufferSize_) {
+ // Just read directly.
+ readRandomDevice(data, size);
+ return;
+ }
+
+ size_t copied = remaining();
+ memcpy(data, ptr_, copied);
+ data += copied;
+ size -= copied;
+
+ // refill
+ readRandomDevice(buffer_.get(), bufferSize_);
+ ptr_ = buffer_.get();
+
+ memcpy(data, ptr_, size);
+ ptr_ += size;
+}
+
+ThreadLocal<BufferedRandomDevice> bufferedRandomDevice;
+
+} // namespace
+
+void Random::secureRandom(void* data, size_t size) {
+ bufferedRandomDevice->get(data, size);
+}
folly::ThreadLocalPtr<ThreadLocalPRNG::LocalInstancePRNG>
ThreadLocalPRNG::localInstance;
class ThreadLocalPRNG::LocalInstancePRNG {
-#ifdef USE_SIMD_PRNG
- typedef __gnu_cxx::sfmt19937 RNG;
-#else
- typedef std::mt19937 RNG;
-#endif
-
- static RNG makeRng() {
- std::array<int, RNG::state_size> seed_data;
- std::random_device r;
- std::generate_n(seed_data.data(), seed_data.size(), std::ref(r));
- std::seed_seq seq(std::begin(seed_data), std::end(seed_data));
- return RNG(seq);
- }
-
public:
- LocalInstancePRNG() : rng(std::move(makeRng())) {}
+ LocalInstancePRNG() : rng(Random::create()) { }
- RNG rng;
+ Random::DefaultGenerator rng;
};
ThreadLocalPRNG::LocalInstancePRNG* ThreadLocalPRNG::initLocal() {