1// 2// Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. 3// 4// Use of this source code is governed by a BSD-style license 5// that can be found in the LICENSE file in the root of the source 6// tree. An additional intellectual property rights grant can be found 7// in the file PATENTS. All contributing project authors may 8// be found in the AUTHORS file in the root of the source tree. 9// 10 11#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_ 12#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_ 13 14#include <string> 15 16#include "webrtc/common_types.h" 17 18// Field trials allow webrtc clients (such as Chrome) to turn on feature code 19// in binaries out in the field and gather information with that. 20// 21// WebRTC clients MUST provide an implementation of: 22// 23// std::string webrtc::field_trial::FindFullName(const std::string& trial). 24// 25// Or link with a default one provided in: 26// 27// system_wrappers/source/system_wrappers.gyp:field_trial_default 28// 29// 30// They are designed to wire up directly to chrome field trials and to speed up 31// developers by reducing the need to wire APIs to control whether a feature is 32// on/off. E.g. to experiment with a new method that could lead to a different 33// trade-off between CPU/bandwidth: 34// 35// 1 - Develop the feature with default behaviour off: 36// 37// if (FieldTrial::FindFullName("WebRTCExperimenMethod2") == "Enabled") 38// method2(); 39// else 40// method1(); 41// 42// 2 - Once the changes are rolled to chrome, the new code path can be 43// controlled as normal chrome field trials. 44// 45// 3 - Evaluate the new feature and clean the code paths. 46// 47// Notes: 48// - NOT every feature is a candidate to be controlled by this mechanism as 49// it may require negotation between involved parties (e.g. SDP). 50// 51// TODO(andresp): since chrome --force-fieldtrials does not marks the trial 52// as active it does not gets propaged to renderer process. For now one 53// needs to push a config with start_active:true or run a local finch 54// server. 55// 56// TODO(andresp): find out how to get bots to run tests with trials enabled. 57 58namespace webrtc { 59namespace field_trial { 60 61// Returns the group name chosen for the named trial, or the empty string 62// if the trial does not exists. 63// 64// Note: To keep things tidy append all the trial names with WebRTC. 65std::string FindFullName(const std::string& name); 66 67} // namespace field_trial 68} // namespace webrtc 69 70#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_FIELD_TRIAL_H_ 71