1/*
2 *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include "webrtc/test/field_trial.h"
12
13#include <algorithm>
14#include <cassert>
15#include <cstdio>
16#include <cstdlib>
17#include <map>
18#include <string>
19
20#include "webrtc/system_wrappers/include/field_trial.h"
21#include "webrtc/system_wrappers/include/field_trial_default.h"
22
23namespace webrtc {
24namespace {
25bool field_trials_initiated_ = false;
26}  // namespace
27
28namespace test {
29// Note: this code is copied from src/base/metrics/field_trial.cc since the aim
30// is to mimic chromium --force-fieldtrials.
31void InitFieldTrialsFromString(const std::string& trials_string) {
32  static const char kPersistentStringSeparator = '/';
33
34  // Catch an error if this is called more than once.
35  assert(!field_trials_initiated_);
36  field_trials_initiated_ = true;
37
38  if (trials_string.empty())
39    return;
40
41  size_t next_item = 0;
42  std::map<std::string, std::string> field_trials;
43  while (next_item < trials_string.length()) {
44    size_t name_end = trials_string.find(kPersistentStringSeparator, next_item);
45    if (name_end == trials_string.npos || next_item == name_end)
46      break;
47    size_t group_name_end = trials_string.find(kPersistentStringSeparator,
48                                               name_end + 1);
49    if (group_name_end == trials_string.npos || name_end + 1 == group_name_end)
50      break;
51    std::string name(trials_string, next_item, name_end - next_item);
52    std::string group_name(trials_string, name_end + 1,
53                           group_name_end - name_end - 1);
54    next_item = group_name_end + 1;
55
56    // Fail if duplicate with different group name.
57    if (field_trials.find(name) != field_trials.end() &&
58        field_trials.find(name)->second != group_name) {
59      break;
60    }
61
62    field_trials[name] = group_name;
63
64    // Successfully parsed all field trials from the string.
65    if (next_item == trials_string.length()) {
66      webrtc::field_trial::InitFieldTrialsFromString(trials_string.c_str());
67      return;
68    }
69  }
70  // Using fprintf as LOG does not print when this is called early in main.
71  fprintf(stderr, "Invalid field trials string.\n");
72
73  // Using abort so it crashes in both debug and release mode.
74  abort();
75}
76
77ScopedFieldTrials::ScopedFieldTrials(const std::string& config)
78  : previous_field_trials_(webrtc::field_trial::GetFieldTrialString()) {
79  assert(field_trials_initiated_);
80  field_trials_initiated_ = false;
81  current_field_trials_ = config;
82  InitFieldTrialsFromString(current_field_trials_);
83}
84
85ScopedFieldTrials::~ScopedFieldTrials() {
86  // Should still be initialized, since InitFieldTrials is called from ctor.
87  // That's why we don't restore the flag.
88  assert(field_trials_initiated_);
89  webrtc::field_trial::InitFieldTrialsFromString(previous_field_trials_);
90}
91
92}  // namespace test
93}  // namespace webrtc
94