src/chrome/common/metrics/variations/variations_util.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/common/metrics/variations/variations_util.h"
   6
   7 #include <vector>
   8
   9 #include "base/strings/string16.h"
  10 #include "base/strings/string_number_conversions.h"
  11 #include "base/strings/string_split.h"
  12 #include "base/strings/string_util.h"
  13 #include "base/strings/stringprintf.h"
  14 #include "base/strings/utf_string_conversions.h"
  15 #include "chrome/common/child_process_logging.h"
  16 #include "chrome/common/crash_keys.h"
  17 #include "chrome/installer/util/google_update_experiment_util.h"
  18
  19 namespace chrome_variations {
  20
  21 namespace {
  22
  23 const char kVariationPrefix[] = "CrVar";
  24 const char kExperimentLabelSep[] = ";";
  25
  26 // Populates |name_group_ids| based on |active_groups|.
  27 void GetFieldTrialActiveGroupIdsForActiveGroups(
  28     const base::FieldTrial::ActiveGroups& active_groups,
  29     std::vector<ActiveGroupId>* name_group_ids) {
  30   DCHECK(name_group_ids->empty());
  31   for (base::FieldTrial::ActiveGroups::const_iterator it =
  32        active_groups.begin(); it != active_groups.end(); ++it) {
  33     name_group_ids->push_back(MakeActiveGroupId(it->trial_name,
  34                                                 it->group_name));
  35   }
  36 }
  37
  38 // This method builds a single experiment label for a Chrome Variation,
  39 // including a timestamp that is a year in the future from now. Since multiple
  40 // headers can be transmitted, |count| is a number that is appended after the
  41 // label key to differentiate the labels.
  42 string16 CreateSingleExperimentLabel(int count, VariationID id) {
  43   // Build the parts separately so they can be validated.
  44   const string16 key =
  45       ASCIIToUTF16(kVariationPrefix) + base::IntToString16(count);
  46   DCHECK_LE(key.size(), 8U);
  47   const string16 value = base::IntToString16(id);
  48   DCHECK_LE(value.size(), 8U);
  49   string16 label(key);
  50   label += ASCIIToUTF16("=");
  51   label += value;
  52   label += ASCIIToUTF16("|");
  53   label += installer::BuildExperimentDateString();
  54   return label;
  55 }
  56
  57 }  // namespace
  58
  59 void GetFieldTrialActiveGroupIds(
  60     std::vector<ActiveGroupId>* name_group_ids) {
  61   DCHECK(name_group_ids->empty());
  62   // A note on thread safety: Since GetActiveFieldTrialGroups() is thread
  63   // safe, and we operate on a separate list of that data, this function is
  64   // technically thread safe as well, with respect to the FieldTrialList data.
  65   base::FieldTrial::ActiveGroups active_groups;
  66   base::FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
  67   GetFieldTrialActiveGroupIdsForActiveGroups(active_groups,
  68                                              name_group_ids);
  69 }
  70
  71 void GetFieldTrialActiveGroupIdsAsStrings(
  72     std::vector<std::string>* output) {
  73   DCHECK(output->empty());
  74   std::vector<ActiveGroupId> name_group_ids;
  75   GetFieldTrialActiveGroupIds(&name_group_ids);
  76   for (size_t i = 0; i < name_group_ids.size(); ++i) {
  77     output->push_back(base::StringPrintf(
  78         "%x-%x", name_group_ids[i].name, name_group_ids[i].group));
  79   }
  80 }
  81
  82 void SetChildProcessLoggingVariationList() {
  83   std::vector<std::string> experiment_strings;
  84   GetFieldTrialActiveGroupIdsAsStrings(&experiment_strings);
  85   crash_keys::SetVariationsList(experiment_strings);
  86 }
  87
  88 string16 BuildGoogleUpdateExperimentLabel(
  89     const base::FieldTrial::ActiveGroups& active_groups) {
  90   string16 experiment_labels;
  91   int counter = 0;
  92
  93   // Find all currently active VariationIDs associated with Google Update.
  94   for (base::FieldTrial::ActiveGroups::const_iterator it =
  95        active_groups.begin(); it != active_groups.end(); ++it) {
  96     const VariationID id = GetGoogleVariationID(GOOGLE_UPDATE_SERVICE,
  97                                                 it->trial_name, it->group_name);
  98
  99     if (id == EMPTY_ID)
 100       continue;
 101
 102     if (!experiment_labels.empty())
 103       experiment_labels += ASCIIToUTF16(kExperimentLabelSep);
 104     experiment_labels += CreateSingleExperimentLabel(++counter, id);
 105   }
 106
 107   return experiment_labels;
 108 }
 109
 110 string16 ExtractNonVariationLabels(const string16& labels) {
 111   const string16 separator = ASCIIToUTF16(kExperimentLabelSep);
 112   string16 non_variation_labels;
 113
 114   // First, split everything by the label separator.
 115   std::vector<string16> entries;
 116   base::SplitStringUsingSubstr(labels, separator, &entries);
 117
 118   // For each label, keep the ones that do not look like a Variations label.
 119   for (std::vector<string16>::const_iterator it = entries.begin();
 120        it != entries.end(); ++it) {
 121     if (it->empty() || StartsWith(*it, ASCIIToUTF16(kVariationPrefix), false))
 122       continue;
 123
 124     // Dump the whole thing, including the timestamp.
 125     if (!non_variation_labels.empty())
 126       non_variation_labels += separator;
 127     non_variation_labels += *it;
 128   }
 129
 130   return non_variation_labels;
 131 }
 132
 133 string16 CombineExperimentLabels(const string16& variation_labels,
 134                                  const string16& other_labels) {
 135   const string16 separator = ASCIIToUTF16(kExperimentLabelSep);
 136   DCHECK(!StartsWith(variation_labels, separator, false));
 137   DCHECK(!EndsWith(variation_labels, separator, false));
 138   DCHECK(!StartsWith(other_labels, separator, false));
 139   DCHECK(!EndsWith(other_labels, separator, false));
 140   // Note that if either label is empty, a separator is not necessary.
 141   string16 combined_labels = other_labels;
 142   if (!other_labels.empty() && !variation_labels.empty())
 143     combined_labels += separator;
 144   combined_labels += variation_labels;
 145   return combined_labels;
 146 }
 147
 148 // Functions below are exposed for testing explicitly behind this namespace.
 149 // They simply wrap existing functions in this file.
 150 namespace testing {
 151
 152 void TestGetFieldTrialActiveGroupIds(
 153     const base::FieldTrial::ActiveGroups& active_groups,
 154     std::vector<ActiveGroupId>* name_group_ids) {
 155   GetFieldTrialActiveGroupIdsForActiveGroups(active_groups,
 156                                              name_group_ids);
 157 }
 158
 159 }  // namespace testing
 160
 161 }  // namespace chrome_variations