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// 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;
}
FieldTrialsAllowedInScopeForTesting::FieldTrialsAllowedInScopeForTesting(
flat_set<std::string> keys) {
TestKeys() = std::move(keys);
}
FieldTrialsAllowedInScopeForTesting::~FieldTrialsAllowedInScopeForTesting() {
TestKeys().clear();
}
} // namespace field_trial
} // namespace webrtc
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