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- // Copyright 2020 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- // This program measures the time taken to decode the given JSON files (the
- // command line arguments). It is for manual benchmarking.
- //
- // Usage:
- // $ ninja -C out/foobar json_perftest_decodebench
- // $ out/foobar/json_perftest_decodebench -a -n=10 the/path/to/your/*.json
- //
- // The -n=10 switch controls the number of iterations. It defaults to 1.
- //
- // The -a switch means to print 1 non-comment line per input file (the average
- // iteration time). Without this switch (the default), it prints n non-comment
- // lines per input file (individual iteration times). For a single input file,
- // building and running this program before and after a particular commit can
- // work well with the 'ministat' tool: https://github.com/thorduri/ministat
- #include <inttypes.h>
- #include <iomanip>
- #include <iostream>
- #include "base/command_line.h"
- #include "base/files/file_util.h"
- #include "base/json/json_reader.h"
- #include "base/logging.h"
- #include "base/time/time.h"
- int main(int argc, char* argv[]) {
- if (!base::ThreadTicks::IsSupported()) {
- std::cout << "# base::ThreadTicks is not supported\n";
- return EXIT_FAILURE;
- }
- base::ThreadTicks::WaitUntilInitialized();
- base::CommandLine::Init(argc, argv);
- base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
- bool average = command_line->HasSwitch("a");
- int iterations = 1;
- std::string iterations_str = command_line->GetSwitchValueASCII("n");
- if (!iterations_str.empty()) {
- iterations = atoi(iterations_str.c_str());
- if (iterations < 1) {
- std::cout << "# invalid -n command line switch\n";
- return EXIT_FAILURE;
- }
- }
- if (average) {
- std::cout << "# Microseconds (μs), n=" << iterations << ", averaged"
- << std::endl;
- } else {
- std::cout << "# Microseconds (μs), n=" << iterations << std::endl;
- }
- for (const auto& filename : command_line->GetArgs()) {
- std::string src;
- if (!base::ReadFileToString(base::FilePath(filename), &src)) {
- std::cout << "# could not read " << filename << std::endl;
- return EXIT_FAILURE;
- }
- int64_t total_time = 0;
- std::string error_message;
- for (int i = 0; i < iterations; ++i) {
- auto start = base::ThreadTicks::Now();
- auto v = base::JSONReader::ReadAndReturnValueWithError(src);
- auto end = base::ThreadTicks::Now();
- int64_t iteration_time = (end - start).InMicroseconds();
- total_time += iteration_time;
- if (i == 0) {
- if (average) {
- error_message =
- !v.has_value() ? std::move(v.error().message) : std::string();
- } else {
- std::cout << "# " << filename;
- if (!v.has_value() && !v.error().message.empty()) {
- std::cout << ": " << v.error().message;
- }
- std::cout << std::endl;
- }
- }
- if (!average) {
- std::cout << iteration_time << std::endl;
- }
- }
- if (average) {
- int64_t average_time = total_time / iterations;
- std::cout << std::setw(12) << average_time << "\t# " << filename;
- if (!error_message.empty()) {
- std::cout << ": " << error_message;
- }
- std::cout << std::endl;
- }
- }
- return EXIT_SUCCESS;
- }
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