Abseil Common Libraries (C++) (grcp 依赖) https://abseil.io/
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Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
// Copyright 2018 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/strings/string_view.h"
#include <algorithm>
#include <cstdint>
#include <map>
#include <random>
#include <string>
#include <unordered_set>
#include <vector>
#include "benchmark/benchmark.h"
#include "absl/base/attributes.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/macros.h"
#include "absl/strings/str_cat.h"
namespace {
void BM_StringViewFromString(benchmark::State& state) {
std::string s(state.range(0), 'x');
std::string* ps = &s;
struct SV {
SV() = default;
explicit SV(const std::string& s) : sv(s) {}
absl::string_view sv;
} sv;
SV* psv = &sv;
benchmark::DoNotOptimize(ps);
benchmark::DoNotOptimize(psv);
for (auto _ : state) {
new (psv) SV(*ps);
benchmark::DoNotOptimize(sv);
}
}
BENCHMARK(BM_StringViewFromString)->Arg(12)->Arg(128);
// Provide a forcibly out-of-line wrapper for operator== that can be used in
// benchmarks to measure the impact of inlining.
ABSL_ATTRIBUTE_NOINLINE
bool NonInlinedEq(absl::string_view a, absl::string_view b) { return a == b; }
// We use functions that cannot be inlined to perform the comparison loops so
// that inlining of the operator== can't optimize away *everything*.
ABSL_ATTRIBUTE_NOINLINE
void DoEqualityComparisons(benchmark::State& state, absl::string_view a,
absl::string_view b) {
for (auto _ : state) {
benchmark::DoNotOptimize(a == b);
}
}
void BM_EqualIdentical(benchmark::State& state) {
std::string x(state.range(0), 'a');
DoEqualityComparisons(state, x, x);
}
BENCHMARK(BM_EqualIdentical)->DenseRange(0, 3)->Range(4, 1 << 10);
void BM_EqualSame(benchmark::State& state) {
std::string x(state.range(0), 'a');
std::string y = x;
DoEqualityComparisons(state, x, y);
}
BENCHMARK(BM_EqualSame)
->DenseRange(0, 10)
->Arg(20)
->Arg(40)
->Arg(70)
->Arg(110)
->Range(160, 4096);
void BM_EqualDifferent(benchmark::State& state) {
const int len = state.range(0);
std::string x(len, 'a');
std::string y = x;
if (len > 0) {
y[len - 1] = 'b';
}
DoEqualityComparisons(state, x, y);
}
BENCHMARK(BM_EqualDifferent)->DenseRange(0, 3)->Range(4, 1 << 10);
// This benchmark is intended to check that important simplifications can be
// made with absl::string_view comparisons against constant strings. The idea is
// that if constant strings cause redundant components of the comparison, the
// compiler should detect and eliminate them. Here we use 8 different strings,
// each with the same size. Provided our comparison makes the implementation
// inline-able by the compiler, it should fold all of these away into a single
// size check once per loop iteration.
ABSL_ATTRIBUTE_NOINLINE
void DoConstantSizeInlinedEqualityComparisons(benchmark::State& state,
absl::string_view a) {
for (auto _ : state) {
benchmark::DoNotOptimize(a == "aaa");
benchmark::DoNotOptimize(a == "bbb");
benchmark::DoNotOptimize(a == "ccc");
benchmark::DoNotOptimize(a == "ddd");
benchmark::DoNotOptimize(a == "eee");
benchmark::DoNotOptimize(a == "fff");
benchmark::DoNotOptimize(a == "ggg");
benchmark::DoNotOptimize(a == "hhh");
}
}
void BM_EqualConstantSizeInlined(benchmark::State& state) {
std::string x(state.range(0), 'a');
DoConstantSizeInlinedEqualityComparisons(state, x);
}
// We only need to check for size of 3, and <> 3 as this benchmark only has to
// do with size differences.
BENCHMARK(BM_EqualConstantSizeInlined)->DenseRange(2, 4);
// This benchmark exists purely to give context to the above timings: this is
// what they would look like if the compiler is completely unable to simplify
// between two comparisons when they are comparing against constant strings.
ABSL_ATTRIBUTE_NOINLINE
void DoConstantSizeNonInlinedEqualityComparisons(benchmark::State& state,
absl::string_view a) {
for (auto _ : state) {
// Force these out-of-line to compare with the above function.
benchmark::DoNotOptimize(NonInlinedEq(a, "aaa"));
benchmark::DoNotOptimize(NonInlinedEq(a, "bbb"));
benchmark::DoNotOptimize(NonInlinedEq(a, "ccc"));
benchmark::DoNotOptimize(NonInlinedEq(a, "ddd"));
benchmark::DoNotOptimize(NonInlinedEq(a, "eee"));
benchmark::DoNotOptimize(NonInlinedEq(a, "fff"));
benchmark::DoNotOptimize(NonInlinedEq(a, "ggg"));
benchmark::DoNotOptimize(NonInlinedEq(a, "hhh"));
}
}
void BM_EqualConstantSizeNonInlined(benchmark::State& state) {
std::string x(state.range(0), 'a');
DoConstantSizeNonInlinedEqualityComparisons(state, x);
}
// We only need to check for size of 3, and <> 3 as this benchmark only has to
// do with size differences.
BENCHMARK(BM_EqualConstantSizeNonInlined)->DenseRange(2, 4);
void BM_CompareSame(benchmark::State& state) {
const int len = state.range(0);
std::string x;
for (int i = 0; i < len; i++) {
x += 'a';
}
std::string y = x;
absl::string_view a = x;
absl::string_view b = y;
for (auto _ : state) {
benchmark::DoNotOptimize(a);
benchmark::DoNotOptimize(b);
benchmark::DoNotOptimize(a.compare(b));
}
}
BENCHMARK(BM_CompareSame)->DenseRange(0, 3)->Range(4, 1 << 10);
void BM_CompareFirstOneLess(benchmark::State& state) {
const int len = state.range(0);
std::string x(len, 'a');
std::string y = x;
y.back() = 'b';
absl::string_view a = x;
absl::string_view b = y;
for (auto _ : state) {
benchmark::DoNotOptimize(a);
benchmark::DoNotOptimize(b);
benchmark::DoNotOptimize(a.compare(b));
}
}
BENCHMARK(BM_CompareFirstOneLess)->DenseRange(1, 3)->Range(4, 1 << 10);
void BM_CompareSecondOneLess(benchmark::State& state) {
const int len = state.range(0);
std::string x(len, 'a');
std::string y = x;
x.back() = 'b';
absl::string_view a = x;
absl::string_view b = y;
for (auto _ : state) {
benchmark::DoNotOptimize(a);
benchmark::DoNotOptimize(b);
benchmark::DoNotOptimize(a.compare(b));
}
}
BENCHMARK(BM_CompareSecondOneLess)->DenseRange(1, 3)->Range(4, 1 << 10);
void BM_find_string_view_len_one(benchmark::State& state) {
std::string haystack(state.range(0), '0');
absl::string_view s(haystack);
for (auto _ : state) {
benchmark::DoNotOptimize(s.find("x")); // not present; length 1
}
}
BENCHMARK(BM_find_string_view_len_one)->Range(1, 1 << 20);
void BM_find_string_view_len_two(benchmark::State& state) {
std::string haystack(state.range(0), '0');
absl::string_view s(haystack);
for (auto _ : state) {
benchmark::DoNotOptimize(s.find("xx")); // not present; length 2
}
}
BENCHMARK(BM_find_string_view_len_two)->Range(1, 1 << 20);
void BM_find_one_char(benchmark::State& state) {
std::string haystack(state.range(0), '0');
absl::string_view s(haystack);
for (auto _ : state) {
benchmark::DoNotOptimize(s.find('x')); // not present
}
}
BENCHMARK(BM_find_one_char)->Range(1, 1 << 20);
void BM_rfind_one_char(benchmark::State& state) {
std::string haystack(state.range(0), '0');
absl::string_view s(haystack);
for (auto _ : state) {
benchmark::DoNotOptimize(s.rfind('x')); // not present
}
}
BENCHMARK(BM_rfind_one_char)->Range(1, 1 << 20);
void BM_worst_case_find_first_of(benchmark::State& state, int haystack_len) {
const int needle_len = state.range(0);
std::string needle;
for (int i = 0; i < needle_len; ++i) {
needle += 'a' + i;
}
std::string haystack(haystack_len, '0'); // 1000 zeros.
absl::string_view s(haystack);
for (auto _ : state) {
benchmark::DoNotOptimize(s.find_first_of(needle));
}
}
void BM_find_first_of_short(benchmark::State& state) {
BM_worst_case_find_first_of(state, 10);
}
void BM_find_first_of_medium(benchmark::State& state) {
BM_worst_case_find_first_of(state, 100);
}
void BM_find_first_of_long(benchmark::State& state) {
BM_worst_case_find_first_of(state, 1000);
}
BENCHMARK(BM_find_first_of_short)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32);
BENCHMARK(BM_find_first_of_medium)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32);
BENCHMARK(BM_find_first_of_long)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32);
struct EasyMap : public std::map<absl::string_view, uint64_t> {
explicit EasyMap(size_t) {}
};
// This templated benchmark helper function is intended to stress operator== or
// operator< in a realistic test. It surely isn't entirely realistic, but it's
// a start. The test creates a map of type Map, a template arg, and populates
// it with table_size key/value pairs. Each key has WordsPerKey words. After
// creating the map, a number of lookups are done in random order. Some keys
// are used much more frequently than others in this phase of the test.
template <typename Map, int WordsPerKey>
void StringViewMapBenchmark(benchmark::State& state) {
const int table_size = state.range(0);
const double kFractionOfKeysThatAreHot = 0.2;
const int kNumLookupsOfHotKeys = 20;
const int kNumLookupsOfColdKeys = 1;
const char* words[] = {"the", "quick", "brown", "fox", "jumped",
"over", "the", "lazy", "dog", "and",
"found", "a", "large", "mushroom", "and",
"a", "couple", "crickets", "eating", "pie"};
// Create some keys that consist of words in random order.
std::random_device r;
std::seed_seq seed({r(), r(), r(), r(), r(), r(), r(), r()});
std::mt19937 rng(seed);
std::vector<std::string> keys(table_size);
std::vector<int> all_indices;
const int kBlockSize = 1 << 12;
std::unordered_set<std::string> t(kBlockSize);
std::uniform_int_distribution<int> uniform(0, ABSL_ARRAYSIZE(words) - 1);
for (int i = 0; i < table_size; i++) {
all_indices.push_back(i);
do {
keys[i].clear();
for (int j = 0; j < WordsPerKey; j++) {
absl::StrAppend(&keys[i], j > 0 ? " " : "", words[uniform(rng)]);
}
} while (!t.insert(keys[i]).second);
}
// Create a list of strings to lookup: a permutation of the array of
// keys we just created, with repeats. "Hot" keys get repeated more.
std::shuffle(all_indices.begin(), all_indices.end(), rng);
const int num_hot = table_size * kFractionOfKeysThatAreHot;
const int num_cold = table_size - num_hot;
std::vector<int> hot_indices(all_indices.begin(),
all_indices.begin() + num_hot);
std::vector<int> indices;
for (int i = 0; i < kNumLookupsOfColdKeys; i++) {
indices.insert(indices.end(), all_indices.begin(), all_indices.end());
}
for (int i = 0; i < kNumLookupsOfHotKeys - kNumLookupsOfColdKeys; i++) {
indices.insert(indices.end(), hot_indices.begin(), hot_indices.end());
}
std::shuffle(indices.begin(), indices.end(), rng);
ABSL_RAW_CHECK(
num_cold * kNumLookupsOfColdKeys + num_hot * kNumLookupsOfHotKeys ==
indices.size(),
"");
// After constructing the array we probe it with absl::string_views built from
// test_strings. This means operator== won't see equal pointers, so
// it'll have to check for equal lengths and equal characters.
std::vector<std::string> test_strings(indices.size());
for (int i = 0; i < indices.size(); i++) {
test_strings[i] = keys[indices[i]];
}
// Run the benchmark. It includes map construction but is mostly
// map lookups.
for (auto _ : state) {
Map h(table_size);
for (int i = 0; i < table_size; i++) {
h[keys[i]] = i * 2;
}
ABSL_RAW_CHECK(h.size() == table_size, "");
uint64_t sum = 0;
for (int i = 0; i < indices.size(); i++) {
sum += h[test_strings[i]];
}
benchmark::DoNotOptimize(sum);
}
}
void BM_StdMap_4(benchmark::State& state) {
StringViewMapBenchmark<EasyMap, 4>(state);
}
BENCHMARK(BM_StdMap_4)->Range(1 << 10, 1 << 16);
void BM_StdMap_8(benchmark::State& state) {
StringViewMapBenchmark<EasyMap, 8>(state);
}
BENCHMARK(BM_StdMap_8)->Range(1 << 10, 1 << 16);
void BM_CopyToStringNative(benchmark::State& state) {
std::string src(state.range(0), 'x');
absl::string_view sv(src);
std::string dst;
for (auto _ : state) {
dst.assign(sv.begin(), sv.end());
}
}
BENCHMARK(BM_CopyToStringNative)->Range(1 << 3, 1 << 12);
void BM_AppendToStringNative(benchmark::State& state) {
std::string src(state.range(0), 'x');
absl::string_view sv(src);
std::string dst;
for (auto _ : state) {
dst.clear();
dst.insert(dst.end(), sv.begin(), sv.end());
}
}
BENCHMARK(BM_AppendToStringNative)->Range(1 << 3, 1 << 12);
} // namespace