chromium/v8/src/base/utils/random-number-generator.h

// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_UTILS_RANDOM_NUMBER_GENERATOR_H_
#define V8_BASE_UTILS_RANDOM_NUMBER_GENERATOR_H_

#include <unordered_set>
#include <vector>

#include "src/base/base-export.h"
#include "src/base/macros.h"

namespace v8 {
namespace base {

// -----------------------------------------------------------------------------
// RandomNumberGenerator

// This class is used to generate a stream of pseudo-random numbers. The class
// uses a 64-bit seed, which is passed through MurmurHash3 to create two 64-bit
// state values. This pair of state values is then used in xorshift128+.
// The resulting stream of pseudo-random numbers has a period length of 2^128-1.
// See Marsaglia: http://www.jstatsoft.org/v08/i14/paper
// And Vigna: http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf
// NOTE: Any changes to the algorithm must be tested against TestU01.
//       Please find instructions for this in the internal repository.

// If two instances of RandomNumberGenerator are created with the same seed, and
// the same sequence of method calls is made for each, they will generate and
// return identical sequences of numbers.
// This class uses (probably) weak entropy by default, but it's sufficient,
// because it is the responsibility of the embedder to install an entropy source
// using v8::V8::SetEntropySource(), which provides reasonable entropy, see:
// https://code.google.com/p/v8/issues/detail?id=2905
// This class is neither reentrant nor threadsafe.

class V8_BASE_EXPORT RandomNumberGenerator final { … };

}  // namespace base
}  // namespace v8

#endif  // V8_BASE_UTILS_RANDOM_NUMBER_GENERATOR_H_