1//
2// Copyright (C) 2014 The Android Open Source Project
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8//      http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15//
16
17#ifndef UPDATE_ENGINE_UPDATE_MANAGER_PRNG_H_
18#define UPDATE_ENGINE_UPDATE_MANAGER_PRNG_H_
19
20#include <random>
21
22#include <base/logging.h>
23
24namespace chromeos_update_manager {
25
26// A thread-safe, unsecure, 32-bit pseudo-random number generator based on
27// std::mt19937.
28class PRNG {
29 public:
30  // Initializes the generator with the passed |seed| value.
31  explicit PRNG(uint32_t seed) : gen_(seed) {}
32
33  // Returns a random unsigned 32-bit integer.
34  uint32_t Rand() { return gen_(); }
35
36  // Returns a random integer uniformly distributed in the range [min, max].
37  int RandMinMax(int min, int max) {
38    DCHECK_LE(min, max);
39    return std::uniform_int_distribution<>(min, max)(gen_);
40  }
41
42 private:
43  // A pseudo-random number generator.
44  std::mt19937 gen_;
45
46  DISALLOW_COPY_AND_ASSIGN(PRNG);
47};
48
49}  // namespace chromeos_update_manager
50
51#endif  // UPDATE_ENGINE_UPDATE_MANAGER_PRNG_H_
52