| // Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the LICENSE file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| // |
| |
| #include "system_wrappers/include/field_trial.h" |
| |
| #include <stddef.h> |
| |
| #include <map> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/algorithm/container.h" |
| #include "absl/strings/string_view.h" |
| #include "experiments/registered_field_trials.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/containers/flat_set.h" |
| #include "rtc_base/logging.h" |
| #include "rtc_base/string_encode.h" |
| |
| // Simple field trial implementation, which allows client to |
| // specify desired flags in InitFieldTrialsFromString. |
| namespace webrtc { |
| namespace field_trial { |
| |
| static const char* trials_init_string = NULL; |
| |
| namespace { |
| |
| constexpr char kPersistentStringSeparator = '/'; |
| |
| flat_set<std::string>& TestKeys() { |
| static auto* test_keys = new flat_set<std::string>(); |
| return *test_keys; |
| } |
| |
| // Validates the given field trial string. |
| // E.g.: |
| // "WebRTC-experimentFoo/Enabled/WebRTC-experimentBar/Enabled100kbps/" |
| // Assigns the process to group "Enabled" on WebRTCExperimentFoo trial |
| // and to group "Enabled100kbps" on WebRTCExperimentBar. |
| // |
| // E.g. invalid config: |
| // "WebRTC-experiment1/Enabled" (note missing / separator at the end). |
| bool FieldTrialsStringIsValidInternal(const absl::string_view trials) { |
| if (trials.empty()) |
| return true; |
| |
| size_t next_item = 0; |
| std::map<absl::string_view, absl::string_view> field_trials; |
| while (next_item < trials.length()) { |
| size_t name_end = trials.find(kPersistentStringSeparator, next_item); |
| if (name_end == trials.npos || next_item == name_end) |
| return false; |
| size_t group_name_end = |
| trials.find(kPersistentStringSeparator, name_end + 1); |
| if (group_name_end == trials.npos || name_end + 1 == group_name_end) |
| return false; |
| absl::string_view name = trials.substr(next_item, name_end - next_item); |
| absl::string_view group_name = |
| trials.substr(name_end + 1, group_name_end - name_end - 1); |
| |
| next_item = group_name_end + 1; |
| |
| // Fail if duplicate with different group name. |
| if (field_trials.find(name) != field_trials.end() && |
| field_trials.find(name)->second != group_name) { |
| return false; |
| } |
| |
| field_trials[name] = group_name; |
| } |
| |
| return true; |
| } |
| |
| } // namespace |
| |
| bool FieldTrialsStringIsValid(absl::string_view trials_string) { |
| return FieldTrialsStringIsValidInternal(trials_string); |
| } |
| |
| void InsertOrReplaceFieldTrialStringsInMap( |
| std::map<std::string, std::string>* fieldtrial_map, |
| const absl::string_view trials_string) { |
| if (FieldTrialsStringIsValidInternal(trials_string)) { |
| std::vector<absl::string_view> tokens = rtc::split(trials_string, '/'); |
| // Skip last token which is empty due to trailing '/'. |
| for (size_t idx = 0; idx < tokens.size() - 1; idx += 2) { |
| (*fieldtrial_map)[std::string(tokens[idx])] = |
| std::string(tokens[idx + 1]); |
| } |
| } else { |
| RTC_DCHECK_NOTREACHED() << "Invalid field trials string:" << trials_string; |
| } |
| } |
| |
| std::string MergeFieldTrialsStrings(absl::string_view first, |
| absl::string_view second) { |
| std::map<std::string, std::string> fieldtrial_map; |
| InsertOrReplaceFieldTrialStringsInMap(&fieldtrial_map, first); |
| InsertOrReplaceFieldTrialStringsInMap(&fieldtrial_map, second); |
| |
| // Merge into fieldtrial string. |
| std::string merged = ""; |
| for (auto const& fieldtrial : fieldtrial_map) { |
| merged += fieldtrial.first + '/' + fieldtrial.second + '/'; |
| } |
| return merged; |
| } |
| |
| #ifndef WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT |
| std::string FindFullName(absl::string_view name) { |
| #if WEBRTC_STRICT_FIELD_TRIALS |
| RTC_DCHECK(absl::c_linear_search(kRegisteredFieldTrials, name) || |
| TestKeys().contains(name)) |
| << name << " is not registered."; |
| #endif |
| |
| if (trials_init_string == NULL) |
| return std::string(); |
| |
| absl::string_view trials_string(trials_init_string); |
| if (trials_string.empty()) |
| return std::string(); |
| |
| size_t next_item = 0; |
| while (next_item < trials_string.length()) { |
| // Find next name/value pair in field trial configuration string. |
| size_t field_name_end = |
| trials_string.find(kPersistentStringSeparator, next_item); |
| if (field_name_end == trials_string.npos || field_name_end == next_item) |
| break; |
| size_t field_value_end = |
| trials_string.find(kPersistentStringSeparator, field_name_end + 1); |
| if (field_value_end == trials_string.npos || |
| field_value_end == field_name_end + 1) |
| break; |
| absl::string_view field_name = |
| trials_string.substr(next_item, field_name_end - next_item); |
| absl::string_view field_value = trials_string.substr( |
| field_name_end + 1, field_value_end - field_name_end - 1); |
| next_item = field_value_end + 1; |
| |
| if (name == field_name) |
| return std::string(field_value); |
| } |
| return std::string(); |
| } |
| #endif // WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT |
| |
| // Optionally initialize field trial from a string. |
| void InitFieldTrialsFromString(const char* trials_string) { |
| RTC_LOG(LS_INFO) << "Setting field trial string:" << trials_string; |
| if (trials_string) { |
| RTC_DCHECK(FieldTrialsStringIsValidInternal(trials_string)) |
| << "Invalid field trials string:" << trials_string; |
| }; |
| trials_init_string = trials_string; |
| } |
| |
| const char* GetFieldTrialString() { |
| return trials_init_string; |
| } |
| |
| ScopedGlobalFieldTrialsForTesting::ScopedGlobalFieldTrialsForTesting( |
| flat_set<std::string> keys) { |
| TestKeys() = std::move(keys); |
| } |
| |
| ScopedGlobalFieldTrialsForTesting::~ScopedGlobalFieldTrialsForTesting() { |
| TestKeys().clear(); |
| } |
| |
| } // namespace field_trial |
| } // namespace webrtc |