src/json_reporter.cc

// Copyright 2015 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "benchmark/reporter.h"

#include <cstdint>
#include <iostream>
#include <string>
#include <vector>

#include "string_util.h"
#include "walltime.h"

namespace benchmark {

namespace {

std::string FormatKV(std::string const& key, std::string const& value) {
  return StringPrintF("\"%s\": \"%s\"", key.c_str(), value.c_str());
}

std::string FormatKV(std::string const& key, const char* value) {
  return StringPrintF("\"%s\": \"%s\"", key.c_str(), value);
}

std::string FormatKV(std::string const& key, bool value) {
  return StringPrintF("\"%s\": %s", key.c_str(), value ? "true" : "false");
}

std::string FormatKV(std::string const& key, int64_t value) {
  std::stringstream ss;
  ss << '"' << key << "\": " << value;
  return ss.str();
}

std::string FormatKV(std::string const& key, std::size_t value) {
  std::stringstream ss;
  ss << '"' << key << "\": " << value;
  return ss.str();
}

int64_t RoundDouble(double v) {
    return static_cast<int64_t>(v + 0.5);
}

} // end namespace

bool JSONReporter::ReportContext(const Context& context) {
  std::ostream& out = std::cout;

  out << "{\n";
  std::string inner_indent(2, ' ');

  // Open context block and print context information.
  out << inner_indent << "\"context\": {\n";
  std::string indent(4, ' ');
  int remainder_us;
  std::string walltime_value = walltime::Print(
                                    walltime::Now(), "%Y/%m/%d-%H:%M:%S",
                                    true,  // use local timezone
                                    &remainder_us);
  out << indent << FormatKV("date", walltime_value) << ",\n";

  out << indent
      << FormatKV("num_cpus", static_cast<int64_t>(context.num_cpus))
      << ",\n";
  out << indent
      << FormatKV("mhz_per_cpu", RoundDouble(context.mhz_per_cpu))
      << ",\n";
  out << indent
      << FormatKV("cpu_scaling_enabled", context.cpu_scaling_enabled)
      << ",\n";

#if defined(NDEBUG)
  const char build_type[] = "release";
#else
  const char build_type[] = "debug";
#endif
  out << indent << FormatKV("build_type", build_type) << "\n";
  // Close context block and open the list of benchmarks.
  out << inner_indent << "},\n";
  out << inner_indent << "\"benchmarks\": [\n";
  return true;
}

void JSONReporter::ReportRuns(std::vector<Run> const& reports) {
  if (reports.empty()) {
    return;
  }
  std::string indent(4, ' ');
  std::ostream& out = std::cout;
  if (!first_report_) {
    out << ",\n";
  }
  first_report_ = false;
  std::vector<Run> reports_cp = reports;
  if (reports.size() >= 2) {
    Run mean_data;
    Run stddev_data;
    BenchmarkReporter::ComputeStats(reports, &mean_data, &stddev_data);
    reports_cp.push_back(mean_data);
    reports_cp.push_back(stddev_data);
  }
  for (auto it = reports_cp.begin(); it != reports_cp.end(); ++it) {
     out << indent << "{\n";
     PrintRunData(*it);
     out << indent << '}';
     auto it_cp = it;
     if (++it_cp != reports_cp.end()) {
         out << ',';
     }
  }
}

void JSONReporter::Finalize() {
    // Close the list of benchmarks and the top level object.
    std::cout << "\n  ]\n}\n";
}

void JSONReporter::PrintRunData(Run const& run) {
    double const multiplier = 1e9; // nano second multiplier
    double cpu_time = run.cpu_accumulated_time * multiplier;
    double real_time = run.real_accumulated_time * multiplier;
    if (run.iterations != 0) {
        real_time = real_time / static_cast<double>(run.iterations);
        cpu_time = cpu_time / static_cast<double>(run.iterations);
    }

    std::string indent(6, ' ');
    std::ostream& out = std::cout;
    out << indent
        << FormatKV("name", run.benchmark_name)
        << ",\n";
    out << indent
        << FormatKV("iterations", run.iterations)
        << ",\n";
    out << indent
        << FormatKV("real_time", RoundDouble(real_time))
        << ",\n";
    out << indent
        << FormatKV("cpu_time", RoundDouble(cpu_time));
    if (run.bytes_per_second > 0.0) {
        out << ",\n" << indent
            << FormatKV("bytes_per_second", RoundDouble(run.bytes_per_second));
    }
    if (run.items_per_second > 0.0) {
        out << ",\n" << indent
            << FormatKV("items_per_second", RoundDouble(run.items_per_second));
    }
    if (!run.report_label.empty()) {
        out << ",\n" << indent
            << FormatKV("label", run.report_label);
    }
    out << '\n';
}

} // end namespace benchmark