// Copyright 2014 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.

// Tests manifest parser performance.  Expects to be run in ninja's root
// directory.

#include <numeric>

#include <errno.h>
#include <stdio.h>
#include <string.h>

#ifdef _WIN32
#include "getopt.h"
#include <direct.h>
#else
#include <getopt.h>
#include <unistd.h>
#endif

#include "disk_interface.h"
#include "graph.h"
#include "manifest_parser.h"
#include "metrics.h"
#include "state.h"
#include "util.h"

struct RealFileReader : public ManifestParser::FileReader {
  virtual bool ReadFile(const string& path, string* content, string* err) {
    return ::ReadFile(path, content, err) == 0;
  }
};

bool WriteFakeManifests(const string& dir, string* err) {
  RealDiskInterface disk_interface;
  TimeStamp mtime = disk_interface.Stat(dir + "/build.ninja", err);
  if (mtime != 0)  // 0 means that the file doesn't exist yet.
    return mtime != -1;

  string command = "python misc/write_fake_manifests.py " + dir;
  printf("Creating manifest data..."); fflush(stdout);
  int exit_code = system(command.c_str());
  printf("done.\n");
  if (exit_code != 0)
    *err = "Failed to run " + command;
  return exit_code == 0;
}

int LoadManifests(bool measure_command_evaluation) {
  string err;
  RealFileReader file_reader;
  State state;
  ManifestParser parser(&state, &file_reader);
  if (!parser.Load("build.ninja", &err)) {
    fprintf(stderr, "Failed to read test data: %s\n", err.c_str());
    exit(1);
  }
  // Doing an empty build involves reading the manifest and evaluating all
  // commands required for the requested targets. So include command
  // evaluation in the perftest by default.
  int optimization_guard = 0;
  if (measure_command_evaluation)
    for (size_t i = 0; i < state.edges_.size(); ++i)
      optimization_guard += state.edges_[i]->EvaluateCommand().size();
  return optimization_guard;
}

int main(int argc, char* argv[]) {
  bool measure_command_evaluation = true;
  int opt;
  while ((opt = getopt(argc, argv, const_cast<char*>("fh"))) != -1) {
    switch (opt) {
    case 'f':
      measure_command_evaluation = false;
      break;
    case 'h':
    default:
      printf("usage: manifest_parser_perftest\n"
"\n"
"options:\n"
"  -f     only measure manifest load time, not command evaluation time\n"
             );
    return 1;
    }
  }

  const char kManifestDir[] = "build/manifest_perftest";

  string err;
  if (!WriteFakeManifests(kManifestDir, &err)) {
    fprintf(stderr, "Failed to write test data: %s\n", err.c_str());
    return 1;
  }

  if (chdir(kManifestDir) < 0)
    Fatal("chdir: %s", strerror(errno));

  const int kNumRepetitions = 5;
  vector<int> times;
  for (int i = 0; i < kNumRepetitions; ++i) {
    int64_t start = GetTimeMillis();
    int optimization_guard = LoadManifests(measure_command_evaluation);
    int delta = (int)(GetTimeMillis() - start);
    printf("%dms (hash: %x)\n", delta, optimization_guard);
    times.push_back(delta);
  }

  int min = *min_element(times.begin(), times.end());
  int max = *max_element(times.begin(), times.end());
  float total = accumulate(times.begin(), times.end(), 0.0f);
  printf("min %dms  max %dms  avg %.1fms\n", min, max, total / times.size());
}