field_trials.h - mozsearch

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/*

 *  Copyright (c) 2022 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.

*/

#ifndef API_FIELD_TRIALS_H_

#define API_FIELD_TRIALS_H_

#include <memory>

#include <string>

#include "absl/strings/string_view.h"

#include "api/field_trials_registry.h"

#include "rtc_base/containers/flat_map.h"

namespace webrtc {

// The FieldTrials class is used to inject field trials into webrtc.

//

// Field trials allow webrtc clients (such as Chromium) to turn on feature code

// in binaries out in the field and gather information with that.

//

// They are designed to be easy to use with Chromium field trials and to speed

// up developers by reducing the need to wire up APIs to control whether a

// feature is on/off.

//

// The field trials are injected into objects that use them at creation time.

//

// NOTE: Creating multiple FieldTrials-object is currently prohibited

// until we remove the global string (TODO(bugs.webrtc.org/10335))

// (unless using CreateNoGlobal):

class FieldTrials : public FieldTrialsRegistry {

 public:

  explicit FieldTrials(const std::string& s);

  ~FieldTrials();

  // Create a FieldTrials object that is not reading/writing from

  // global variable (i.e can not be used for all parts of webrtc).

  static std::unique_ptr<FieldTrials> CreateNoGlobal(const std::string& s);

 private:

  explicit FieldTrials(const std::string& s, bool);

  std::string GetValue(absl::string_view key) const override;

  const bool uses_global_;

  const std::string field_trial_string_;

  const char* const previous_field_trial_string_;

  const flat_map<std::string, std::string> key_value_map_;

};

}  // namespace webrtc

#endif  // API_FIELD_TRIALS_H_