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1c8103d4db
This new class implements the existing FieldTrialsView interface, extending it with the verification functionality. For now, the verification will only be performed if the rtc_strict_field_trials GN arg is set. Most classes extending FieldTrialsView today have been converted to extend from FieldTrialsRegistry instead to automatically perform verification. Bug: webrtc:14154 Change-Id: I4819724cd66a04507e62fcc2bb1019187b6ba8c7 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/276270 Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Commit-Queue: Emil Lundmark <lndmrk@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#38453}
107 lines
3.9 KiB
C++
107 lines
3.9 KiB
C++
/*
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* Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "api/field_trials.h"
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#include <atomic>
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#include "rtc_base/checks.h"
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#include "system_wrappers/include/field_trial.h"
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namespace {
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// This part is copied from system_wrappers/field_trial.cc.
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webrtc::flat_map<std::string, std::string> InsertIntoMap(const std::string& s) {
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std::string::size_type field_start = 0;
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webrtc::flat_map<std::string, std::string> key_value_map;
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while (field_start < s.size()) {
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std::string::size_type separator_pos = s.find('/', field_start);
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RTC_CHECK_NE(separator_pos, std::string::npos)
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<< "Missing separator '/' after field trial key.";
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RTC_CHECK_GT(separator_pos, field_start)
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<< "Field trial key cannot be empty.";
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std::string key = s.substr(field_start, separator_pos - field_start);
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field_start = separator_pos + 1;
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RTC_CHECK_LT(field_start, s.size())
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<< "Missing value after field trial key. String ended.";
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separator_pos = s.find('/', field_start);
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RTC_CHECK_NE(separator_pos, std::string::npos)
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<< "Missing terminating '/' in field trial string.";
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RTC_CHECK_GT(separator_pos, field_start)
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<< "Field trial value cannot be empty.";
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std::string value = s.substr(field_start, separator_pos - field_start);
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field_start = separator_pos + 1;
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// If a key is specified multiple times, only the value linked to the first
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// key is stored. note: This will crash in debug build when calling
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// InitFieldTrialsFromString().
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key_value_map.emplace(key, value);
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}
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// This check is technically redundant due to earlier checks.
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// We nevertheless keep the check to make it clear that the entire
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// string has been processed, and without indexing past the end.
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RTC_CHECK_EQ(field_start, s.size());
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return key_value_map;
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}
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// Makes sure that only one instance is created, since the usage
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// of global string makes behaviour unpredicatable otherwise.
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// TODO(bugs.webrtc.org/10335): Remove once global string is gone.
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std::atomic<bool> instance_created_{false};
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} // namespace
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namespace webrtc {
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FieldTrials::FieldTrials(const std::string& s)
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: uses_global_(true),
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field_trial_string_(s),
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previous_field_trial_string_(webrtc::field_trial::GetFieldTrialString()),
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key_value_map_(InsertIntoMap(s)) {
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// TODO(bugs.webrtc.org/10335): Remove the global string!
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field_trial::InitFieldTrialsFromString(field_trial_string_.c_str());
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RTC_CHECK(!instance_created_.exchange(true))
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<< "Only one instance may be instanciated at any given time!";
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}
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std::unique_ptr<FieldTrials> FieldTrials::CreateNoGlobal(const std::string& s) {
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return std::unique_ptr<FieldTrials>(new FieldTrials(s, true));
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}
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FieldTrials::FieldTrials(const std::string& s, bool)
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: uses_global_(false),
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previous_field_trial_string_(nullptr),
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key_value_map_(InsertIntoMap(s)) {}
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FieldTrials::~FieldTrials() {
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// TODO(bugs.webrtc.org/10335): Remove the global string!
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if (uses_global_) {
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field_trial::InitFieldTrialsFromString(previous_field_trial_string_);
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RTC_CHECK(instance_created_.exchange(false));
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}
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}
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std::string FieldTrials::GetValue(absl::string_view key) const {
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auto it = key_value_map_.find(std::string(key));
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if (it != key_value_map_.end())
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return it->second;
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// Check the global string so that programs using
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// a mix between FieldTrials and the global string continue to work
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// TODO(bugs.webrtc.org/10335): Remove the global string!
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if (uses_global_) {
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return field_trial::FindFullName(std::string(key));
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}
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return "";
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}
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} // namespace webrtc
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