bench_support.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
#ifndef CA_BENCH_SUPPORT_H
#define CA_BENCH_SUPPORT_H
 
#include <algorithm>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <string>
#include <utility>
#include <vector>
 
namespace Aleph {
namespace CA {
namespace Bench {
 
struct Bench_Result
{
  std::string name;            
  std::uint64_t wall_ns = 0;   
  double cells_per_sec = 0.0;  
};
 
inline std::string compiler_string()
{
#if defined(__clang__)
  return std::string("clang ") + __clang_version__;
#elif defined(__GNUC__)
  return std::string("gcc ") + std::to_string(__GNUC__) + '.'
         + std::to_string(__GNUC_MINOR__) + '.' + std::to_string(__GNUC_PATCHLEVEL__);
#else
  return "unknown";
#endif
}
 
inline std::string cpu_string()
{
  std::string model = "unknown";
  std::ifstream cpuinfo("/proc/cpuinfo");
  std::string line;
  while (std::getline(cpuinfo, line))
    if (line.rfind("model name", 0) == 0)
      {
        const std::size_t colon = line.find(':');
        if (colon != std::string::npos and colon + 2 <= line.size())
          model = line.substr(colon + 2);
        break;
      }
  for (char &c : model)
    if (c == '"' or c == ',' or c == '\\')
      c = ' ';
  return model;
}
 
inline std::size_t resolve_repeats(const std::size_t fallback)
{
  if (const char *env = std::getenv("CA_BENCH_REPEATS"))
    {
      const long parsed = std::strtol(env, nullptr, 10);
      if (parsed > 0)
        return static_cast<std::size_t>(parsed);
    }
  return fallback == 0 ? 1 : fallback;
}
 
template <typename Work>
[[nodiscard]] Bench_Result measure(std::string name,
                                    const double processed_cells,
                                    std::size_t repeats,
                                    Work &&work)
{
  using clock = std::chrono::steady_clock;
  if (repeats == 0)
    repeats = 1;
 
  work();  // untimed warmup.
 
  std::vector<std::uint64_t> samples;
  samples.reserve(repeats);
  for (std::size_t i = 0; i < repeats; ++i)
    {
      const auto start = clock::now();
      work();
      const auto elapsed = clock::now() - start;
      samples.push_back(static_cast<std::uint64_t>(
        std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed).count()));
    }
 
  std::sort(samples.begin(), samples.end());
  const std::uint64_t median = samples[samples.size() / 2];
 
  Bench_Result result;
  result.name = std::move(name);
  result.wall_ns = median;
  result.cells_per_sec
    = median == 0 ? 0.0 : processed_cells / (static_cast<double>(median) * 1e-9);
  return result;
}
 
inline void emit_json(const Bench_Result &result, std::ostream &out = std::cout)
{
  char throughput[64];
  std::snprintf(throughput, sizeof throughput, "%.3f", result.cells_per_sec);
  out << "{\"name\":\"" << result.name << "\","
      << "\"wall_ns\":" << result.wall_ns << ','
      << "\"cells_per_sec\":" << throughput << ','
      << "\"compiler\":\"" << compiler_string() << "\","
      << "\"cpu\":\"" << cpu_string() << "\"}" << std::endl;
}
 
}  // namespace Bench
}  // namespace CA
}  // namespace Aleph
 
#endif  // CA_BENCH_SUPPORT_H