Function BenchmarkMemoize

cpp/src/arrow/util/cache_benchmark.cc:109–124

template <typename Memoized>
static void BenchmarkMemoize(benchmark::State& state, Memoized&& mem,
                             const std::vector<std::string>& keys) {
  // Prime memoization cache
  for (const auto& key : keys) {
    mem(key);
  }

  for (auto _ : state) {
    int64_t nbytes = 0;
    for (const auto& key : keys) {
      nbytes += static_cast<int64_t>(mem(key).length());
    }
    benchmark::DoNotOptimize(nbytes);
  }
  state.SetItemsProcessed(state.iterations() * keys.size());
}

static void MemoizeLruCached(benchmark::State& state) {
  const auto keys = MakeStrings(kCacheSize, state.range(0));