Abseil Common Libraries (C++) (grcp 依赖)
https://abseil.io/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
182 lines
6.3 KiB
182 lines
6.3 KiB
// Copyright 2017 The Abseil Authors. |
|
// |
|
// Licensed under the Apache License, Version 2.0 (the "License"); |
|
// you may not use this file except in compliance with the License. |
|
// You may obtain a copy of the License at |
|
// |
|
// https://www.apache.org/licenses/LICENSE-2.0 |
|
// |
|
// Unless required by applicable law or agreed to in writing, software |
|
// distributed under the License is distributed on an "AS IS" BASIS, |
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
|
// See the License for the specific language governing permissions and |
|
// limitations under the License. |
|
|
|
#include "absl/random/internal/pool_urbg.h" |
|
|
|
#include <algorithm> |
|
#include <bitset> |
|
#include <cmath> |
|
#include <cstdint> |
|
#include <iterator> |
|
|
|
#include "gtest/gtest.h" |
|
#include "absl/meta/type_traits.h" |
|
#include "absl/types/span.h" |
|
|
|
using absl::random_internal::PoolURBG; |
|
using absl::random_internal::RandenPool; |
|
|
|
namespace { |
|
|
|
// is_randen_pool trait is true when parameterized by an RandenPool |
|
template <typename T> |
|
using is_randen_pool = typename absl::disjunction< // |
|
std::is_same<T, RandenPool<uint8_t>>, // |
|
std::is_same<T, RandenPool<uint16_t>>, // |
|
std::is_same<T, RandenPool<uint32_t>>, // |
|
std::is_same<T, RandenPool<uint64_t>>>; // |
|
|
|
// MyFill either calls RandenPool::Fill() or std::generate(..., rng) |
|
template <typename T, typename V> |
|
typename absl::enable_if_t<absl::negation<is_randen_pool<T>>::value, void> // |
|
MyFill(T& rng, absl::Span<V> data) { // NOLINT(runtime/references) |
|
std::generate(std::begin(data), std::end(data), rng); |
|
} |
|
|
|
template <typename T, typename V> |
|
typename absl::enable_if_t<is_randen_pool<T>::value, void> // |
|
MyFill(T& rng, absl::Span<V> data) { // NOLINT(runtime/references) |
|
rng.Fill(data); |
|
} |
|
|
|
template <typename EngineType> |
|
class PoolURBGTypedTest : public ::testing::Test {}; |
|
|
|
using EngineTypes = ::testing::Types< // |
|
RandenPool<uint8_t>, // |
|
RandenPool<uint16_t>, // |
|
RandenPool<uint32_t>, // |
|
RandenPool<uint64_t>, // |
|
PoolURBG<uint8_t, 2>, // |
|
PoolURBG<uint16_t, 2>, // |
|
PoolURBG<uint32_t, 2>, // |
|
PoolURBG<uint64_t, 2>, // |
|
PoolURBG<unsigned int, 8>, // NOLINT(runtime/int) |
|
PoolURBG<unsigned long, 8>, // NOLINT(runtime/int) |
|
PoolURBG<unsigned long int, 4>, // NOLINT(runtime/int) |
|
PoolURBG<unsigned long long, 4>>; // NOLINT(runtime/int) |
|
|
|
TYPED_TEST_SUITE(PoolURBGTypedTest, EngineTypes); |
|
|
|
// This test is checks that the engines meet the URBG interface requirements |
|
// defined in [rand.req.urbg]. |
|
TYPED_TEST(PoolURBGTypedTest, URBGInterface) { |
|
using E = TypeParam; |
|
using T = typename E::result_type; |
|
|
|
static_assert(std::is_copy_constructible<E>::value, |
|
"engine must be copy constructible"); |
|
|
|
static_assert(absl::is_copy_assignable<E>::value, |
|
"engine must be copy assignable"); |
|
|
|
E e; |
|
const E x; |
|
|
|
e(); |
|
|
|
static_assert(std::is_same<decltype(e()), T>::value, |
|
"return type of operator() must be result_type"); |
|
|
|
E u0(x); |
|
u0(); |
|
|
|
E u1 = e; |
|
u1(); |
|
} |
|
|
|
// This validates that sequences are independent. |
|
TYPED_TEST(PoolURBGTypedTest, VerifySequences) { |
|
using E = TypeParam; |
|
using result_type = typename E::result_type; |
|
|
|
E rng; |
|
(void)rng(); // Discard one value. |
|
|
|
constexpr int kNumOutputs = 64; |
|
result_type a[kNumOutputs]; |
|
result_type b[kNumOutputs]; |
|
std::fill(std::begin(b), std::end(b), 0); |
|
|
|
// Fill a using Fill or generate, depending on the engine type. |
|
{ |
|
E x = rng; |
|
MyFill(x, absl::MakeSpan(a)); |
|
} |
|
|
|
// Fill b using std::generate(). |
|
{ |
|
E x = rng; |
|
std::generate(std::begin(b), std::end(b), x); |
|
} |
|
|
|
// Test that generated sequence changed as sequence of bits, i.e. if about |
|
// half of the bites were flipped between two non-correlated values. |
|
size_t changed_bits = 0; |
|
size_t unchanged_bits = 0; |
|
size_t total_set = 0; |
|
size_t total_bits = 0; |
|
size_t equal_count = 0; |
|
for (size_t i = 0; i < kNumOutputs; ++i) { |
|
equal_count += (a[i] == b[i]) ? 1 : 0; |
|
std::bitset<sizeof(result_type) * 8> bitset(a[i] ^ b[i]); |
|
changed_bits += bitset.count(); |
|
unchanged_bits += bitset.size() - bitset.count(); |
|
|
|
std::bitset<sizeof(result_type) * 8> a_set(a[i]); |
|
std::bitset<sizeof(result_type) * 8> b_set(b[i]); |
|
total_set += a_set.count() + b_set.count(); |
|
total_bits += 2 * 8 * sizeof(result_type); |
|
} |
|
// On average, half the bits are changed between two calls. |
|
EXPECT_LE(changed_bits, 0.60 * (changed_bits + unchanged_bits)); |
|
EXPECT_GE(changed_bits, 0.40 * (changed_bits + unchanged_bits)); |
|
|
|
// verify using a quick normal-approximation to the binomial. |
|
EXPECT_NEAR(total_set, total_bits * 0.5, 4 * std::sqrt(total_bits)) |
|
<< "@" << total_set / static_cast<double>(total_bits); |
|
|
|
// Also, A[i] == B[i] with probability (1/range) * N. |
|
// Give this a pretty wide latitude, though. |
|
const double kExpected = kNumOutputs / (1.0 * sizeof(result_type) * 8); |
|
EXPECT_LE(equal_count, 1.0 + kExpected); |
|
} |
|
|
|
} // namespace |
|
|
|
/* |
|
$ nanobenchmarks 1 RandenPool construct |
|
$ nanobenchmarks 1 PoolURBG construct |
|
|
|
RandenPool<uint32_t> | 1 | 1000 | 48482.00 ticks | 48.48 ticks | 13.9 ns |
|
RandenPool<uint32_t> | 10 | 2000 | 1028795.00 ticks | 51.44 ticks | 14.7 ns |
|
RandenPool<uint32_t> | 100 | 1000 | 5119968.00 ticks | 51.20 ticks | 14.6 ns |
|
RandenPool<uint32_t> | 1000 | 500 | 25867936.00 ticks | 51.74 ticks | 14.8 ns |
|
|
|
RandenPool<uint64_t> | 1 | 1000 | 49921.00 ticks | 49.92 ticks | 14.3 ns |
|
RandenPool<uint64_t> | 10 | 2000 | 1208269.00 ticks | 60.41 ticks | 17.3 ns |
|
RandenPool<uint64_t> | 100 | 1000 | 5844955.00 ticks | 58.45 ticks | 16.7 ns |
|
RandenPool<uint64_t> | 1000 | 500 | 28767404.00 ticks | 57.53 ticks | 16.4 ns |
|
|
|
PoolURBG<uint32_t,8> | 1 | 1000 | 86431.00 ticks | 86.43 ticks | 24.7 ns |
|
PoolURBG<uint32_t,8> | 10 | 1000 | 206191.00 ticks | 20.62 ticks | 5.9 ns |
|
PoolURBG<uint32_t,8> | 100 | 1000 | 1516049.00 ticks | 15.16 ticks | 4.3 ns |
|
PoolURBG<uint32_t,8> | 1000 | 500 | 7613936.00 ticks | 15.23 ticks | 4.4 ns |
|
|
|
PoolURBG<uint64_t,4> | 1 | 1000 | 96668.00 ticks | 96.67 ticks | 27.6 ns |
|
PoolURBG<uint64_t,4> | 10 | 1000 | 282423.00 ticks | 28.24 ticks | 8.1 ns |
|
PoolURBG<uint64_t,4> | 100 | 1000 | 2609587.00 ticks | 26.10 ticks | 7.5 ns |
|
PoolURBG<uint64_t,4> | 1000 | 500 | 12408757.00 ticks | 24.82 ticks | 7.1 ns |
|
|
|
*/
|
|
|