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>
26 #include <folly/portability/GTest.h>
28 using namespace folly;
30 TEST(Random, StateSize) {
31 using namespace folly::detail;
33 // uint_fast32_t is uint64_t on x86_64, w00t
34 EXPECT_EQ(sizeof(uint_fast32_t) / 4 + 3,
35 StateSize<std::minstd_rand0>::value);
36 EXPECT_EQ(624, StateSize<std::mt19937>::value);
37 #if FOLLY_HAVE_EXTRANDOM_SFMT19937
38 EXPECT_EQ(624, StateSize<__gnu_cxx::sfmt19937>::value);
40 EXPECT_EQ(24, StateSize<std::ranlux24_base>::value);
43 TEST(Random, Simple) {
44 uint32_t prev = 0, seed = 0;
45 for (int i = 0; i < 1024; ++i) {
46 EXPECT_NE(seed = randomNumberSeed(), prev);
51 TEST(Random, FixedSeed) {
54 typedef uint32_t result_type;
55 result_type operator()() {
56 return 4; // chosen by fair dice roll.
57 // guaranteed to be random.
59 static constexpr result_type min() {
60 return std::numeric_limits<result_type>::min();
62 static constexpr result_type max() {
63 return std::numeric_limits<result_type>::max();
70 // Pick a constant random number...
71 auto value = Random::rand32(10, gen);
73 // Loop to make sure it really is constant.
74 for (int i = 0; i < 1024; ++i) {
75 auto result = Random::rand32(10, gen);
76 EXPECT_EQ(value, result);
80 TEST(Random, MultiThreaded) {
82 std::vector<uint32_t> seeds(n);
83 std::vector<std::thread> threads;
84 for (int i = 0; i < n; ++i) {
85 threads.push_back(std::thread([i, &seeds] {
86 seeds[i] = randomNumberSeed();
89 for (auto& t : threads) {
92 std::sort(seeds.begin(), seeds.end());
93 for (int i = 0; i < n-1; ++i) {
94 EXPECT_LT(seeds[i], seeds[i+1]);