2 * Copyright 2016 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #include <folly/Random.h>
19 #include <glog/logging.h>
20 #include <gtest/gtest.h>
27 using namespace folly;
29 TEST(Random, StateSize) {
30 using namespace folly::detail;
32 // uint_fast32_t is uint64_t on x86_64, w00t
33 EXPECT_EQ(sizeof(uint_fast32_t) / 4 + 3,
34 StateSize<std::minstd_rand0>::value);
35 EXPECT_EQ(624, StateSize<std::mt19937>::value);
36 #if FOLLY_HAVE_EXTRANDOM_SFMT19937
37 EXPECT_EQ(624, StateSize<__gnu_cxx::sfmt19937>::value);
39 EXPECT_EQ(24, StateSize<std::ranlux24_base>::value);
42 TEST(Random, Simple) {
43 uint32_t prev = 0, seed = 0;
44 for (int i = 0; i < 1024; ++i) {
45 EXPECT_NE(seed = randomNumberSeed(), prev);
50 TEST(Random, FixedSeed) {
53 typedef uint32_t result_type;
54 result_type operator()() {
55 return 4; // chosen by fair dice roll.
56 // guaranteed to be random.
58 static constexpr result_type min() {
59 return std::numeric_limits<result_type>::min();
61 static constexpr result_type max() {
62 return std::numeric_limits<result_type>::max();
69 // Pick a constant random number...
70 auto value = Random::rand32(10, gen);
72 // Loop to make sure it really is constant.
73 for (int i = 0; i < 1024; ++i) {
74 auto result = Random::rand32(10, gen);
75 EXPECT_EQ(value, result);
79 TEST(Random, MultiThreaded) {
81 std::vector<uint32_t> seeds(n);
82 std::vector<std::thread> threads;
83 for (int i = 0; i < n; ++i) {
84 threads.push_back(std::thread([i, &seeds] {
85 seeds[i] = randomNumberSeed();
88 for (auto& t : threads) {
91 std::sort(seeds.begin(), seeds.end());
92 for (int i = 0; i < n-1; ++i) {
93 EXPECT_LT(seeds[i], seeds[i+1]);