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1#include <cstdlib>2#include <map>3 4#include "benchmark/benchmark.h"5 6namespace {7 8std::map<int, int> ConstructRandomMap(int size) {9 std::map<int, int> m;10 for (int i = 0; i < size; ++i) {11 m.insert(std::make_pair(std::rand() % size, std::rand() % size));12 }13 return m;14}15 16} // namespace17 18// Basic version.19static void BM_MapLookup(benchmark::State& state) {20 const int size = static_cast<int>(state.range(0));21 std::map<int, int> m;22 for (auto _ : state) {23 state.PauseTiming();24 m = ConstructRandomMap(size);25 state.ResumeTiming();26 for (int i = 0; i < size; ++i) {27 auto it = m.find(std::rand() % size);28 benchmark::DoNotOptimize(it);29 }30 }31 state.SetItemsProcessed(state.iterations() * size);32}33BENCHMARK(BM_MapLookup)->Range(1 << 3, 1 << 12);34 35// Using fixtures.36class MapFixture : public ::benchmark::Fixture {37 public:38 void SetUp(const ::benchmark::State& st) override {39 m = ConstructRandomMap(static_cast<int>(st.range(0)));40 }41 42 void TearDown(const ::benchmark::State&) override { m.clear(); }43 44 std::map<int, int> m;45};46 47BENCHMARK_DEFINE_F(MapFixture, Lookup)(benchmark::State& state) {48 const int size = static_cast<int>(state.range(0));49 for (auto _ : state) {50 for (int i = 0; i < size; ++i) {51 auto it = m.find(std::rand() % size);52 benchmark::DoNotOptimize(it);53 }54 }55 state.SetItemsProcessed(state.iterations() * size);56}57BENCHMARK_REGISTER_F(MapFixture, Lookup)->Range(1 << 3, 1 << 12);58 59BENCHMARK_MAIN();60