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#include "benchmark/benchmark.h"
#include <cstdlib>
#include <map>
namespace {
std::map<int, int> ConstructRandomMap(int size) {
std::map<int, int> m;
for (int i = 0; i < size; ++i) {
m.insert(std::make_pair(std::rand() % size, std::rand() % size));
}
return m;
}
} // namespace
// Basic version.
static void BM_MapLookup(benchmark::State& state) {
const int size = static_cast<int>(state.range(0));
std::map<int, int> m;
for (auto _ : state) {
state.PauseTiming();
m = ConstructRandomMap(size);
state.ResumeTiming();
for (int i = 0; i < size; ++i) {
benchmark::DoNotOptimize(m.find(std::rand() % size));
}
}
state.SetItemsProcessed(state.iterations() * size);
}
BENCHMARK(BM_MapLookup)->Range(1 << 3, 1 << 12);
// Using fixtures.
class MapFixture : public ::benchmark::Fixture {
public:
void SetUp(const ::benchmark::State& st) {
m = ConstructRandomMap(static_cast<int>(st.range(0)));
}
void TearDown(const ::benchmark::State&) { m.clear(); }
std::map<int, int> m;
};
BENCHMARK_DEFINE_F(MapFixture, Lookup)(benchmark::State& state) {
const int size = static_cast<int>(state.range(0));
for (auto _ : state) {
for (int i = 0; i < size; ++i) {
benchmark::DoNotOptimize(m.find(std::rand() % size));
}
}
state.SetItemsProcessed(state.iterations() * size);
}
BENCHMARK_REGISTER_F(MapFixture, Lookup)->Range(1 << 3, 1 << 12);
BENCHMARK_MAIN();
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