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