1 // Copyright 2014 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/variations/experiment_labels.h"
6
7 #include <vector>
8
9 #include "base/logging.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/utf_string_conversions.h"
14 #include "chrome/installer/util/google_update_experiment_util.h"
15 #include "components/variations/variations_associated_data.h"
16
17 namespace chrome_variations {
18
19 namespace {
20
21 const char kVariationPrefix[] = "CrVar";
22
23 // This method builds a single experiment label for a Chrome Variation,
24 // including a timestamp that is a year in the future from |current_time|. Since
25 // multiple headers can be transmitted, |count| is a number that is appended
26 // after the label key to differentiate the labels.
CreateSingleExperimentLabel(int count,VariationID id,const base::Time & current_time)27 base::string16 CreateSingleExperimentLabel(int count, VariationID id,
28 const base::Time& current_time) {
29 // Build the parts separately so they can be validated.
30 const base::string16 key =
31 base::ASCIIToUTF16(kVariationPrefix) + base::IntToString16(count);
32 DCHECK_LE(key.size(), 8U);
33 const base::string16 value = base::IntToString16(id);
34 DCHECK_LE(value.size(), 8U);
35 base::string16 label(key);
36 label += base::ASCIIToUTF16("=");
37 label += value;
38 label += base::ASCIIToUTF16("|");
39 label += installer::BuildExperimentDateString(current_time);
40 return label;
41 }
42
43 } // namespace
44
BuildGoogleUpdateExperimentLabel(const base::FieldTrial::ActiveGroups & active_groups)45 base::string16 BuildGoogleUpdateExperimentLabel(
46 const base::FieldTrial::ActiveGroups& active_groups) {
47 base::string16 experiment_labels;
48 int counter = 0;
49
50 const base::Time current_time(base::Time::Now());
51
52 // Find all currently active VariationIDs associated with Google Update.
53 for (base::FieldTrial::ActiveGroups::const_iterator it =
54 active_groups.begin(); it != active_groups.end(); ++it) {
55 const VariationID id = GetGoogleVariationID(GOOGLE_UPDATE_SERVICE,
56 it->trial_name, it->group_name);
57
58 if (id == EMPTY_ID)
59 continue;
60
61 if (!experiment_labels.empty())
62 experiment_labels += google_update::kExperimentLabelSeparator;
63 experiment_labels += CreateSingleExperimentLabel(++counter, id,
64 current_time);
65 }
66
67 return experiment_labels;
68 }
69
ExtractNonVariationLabels(const base::string16 & labels)70 base::string16 ExtractNonVariationLabels(const base::string16& labels) {
71 // First, split everything by the label separator.
72 std::vector<base::string16> entries;
73 base::SplitString(labels, google_update::kExperimentLabelSeparator, &entries);
74
75 // For each label, keep the ones that do not look like a Variations label.
76 base::string16 non_variation_labels;
77 for (std::vector<base::string16>::const_iterator it = entries.begin();
78 it != entries.end(); ++it) {
79 if (it->empty() ||
80 StartsWith(*it, base::ASCIIToUTF16(kVariationPrefix), false)) {
81 continue;
82 }
83
84 // Dump the whole thing, including the timestamp.
85 if (!non_variation_labels.empty())
86 non_variation_labels += google_update::kExperimentLabelSeparator;
87 non_variation_labels += *it;
88 }
89
90 return non_variation_labels;
91 }
92
CombineExperimentLabels(const base::string16 & variation_labels,const base::string16 & other_labels)93 base::string16 CombineExperimentLabels(const base::string16& variation_labels,
94 const base::string16& other_labels) {
95 const base::string16 separator(1, google_update::kExperimentLabelSeparator);
96 DCHECK(!StartsWith(variation_labels, separator, false));
97 DCHECK(!EndsWith(variation_labels, separator, false));
98 DCHECK(!StartsWith(other_labels, separator, false));
99 DCHECK(!EndsWith(other_labels, separator, false));
100 // Note that if either label is empty, a separator is not necessary.
101 base::string16 combined_labels = other_labels;
102 if (!other_labels.empty() && !variation_labels.empty())
103 combined_labels += google_update::kExperimentLabelSeparator;
104 combined_labels += variation_labels;
105 return combined_labels;
106 }
107
108 } // namespace chrome_variations
109