fast_io benchmark

#include <benchmark/benchmark.h>
#include <fmt/compile.h>
#include <fmt/os.h>

#include <cstdio>
#include <fstream>

#if 1 //__cpp_lib_concepts>=201907L
#include "../fast_io/include/fast_io.h"
#include "../fast_io/include/fast_io_device.h"
#endif

const char* test_str ="Hello, world!";
int num_iters = 1'000'000;

void fprintf(benchmark::State& state) {
  std::unique_ptr<FILE,decltype(std::fclose)*> fp(std::fopen("fprintf.txt","wb"),std::fclose);
  for (auto s : state) {
    for (int i = 0; i < num_iters; ++i) {
      std::fprintf(fp.get(), "%s\n", test_str);
    }
  }
}
BENCHMARK(fprintf);

void std_ofstream(benchmark::State& state) {
  std::ofstream os("ofstream.txt",std::ofstream::binary);
  for (auto s : state) {
    for (int i = 0; i < num_iters; ++i) {
      os << std::string_view(test_str) <<'\n';
    }
  }
}
BENCHMARK(std_ofstream);

void fmt_print(benchmark::State& state) {
  fmt::direct_buffered_file f("fmt_print.txt", fmt::file::WRONLY | fmt::file::CREATE);
  for (auto s : state) {
    for (int i = 0; i < num_iters; ++i) {
      fmt::print(f, FMT_COMPILE("{}\n"), std::string_view(test_str));
    }
  }
}
BENCHMARK(fmt_print);

void fast_io_println(benchmark::State& state) {
  fast_io::obuf_file obf("fast_io_println.txt");
  for (auto s : state) {
    for (int i = 0; i < num_iters; ++i) {
      println(obf, std::string_view(test_str));
    }
  }
}
BENCHMARK(fast_io_println);

BENCHMARK_MAIN();

/*
2020-07-11 08:44:11
Running ./file-benchmark
Run on (16 X 5000 MHz CPU s)
CPU Caches:
  L1 Data 32K (x8)
  L1 Instruction 32K (x8)
  L2 Unified 256K (x8)
  L3 Unified 16384K (x1)
Load Average: 0.56, 0.54, 0.30
----------------------------------------------------------
Benchmark                Time             CPU   Iterations
----------------------------------------------------------
fprintf           48174360 ns     48171386 ns           14
std_ofstream      31823293 ns     31821828 ns           21
fmt_print          7883662 ns      7883940 ns           81
fast_io_println    8555129 ns      8555077 ns           81
*/

Switched to string_view because fast_io prints C strings as pointers.

As you can see {fmt} is ~8% faster than fast_io.