// Copyright 2016 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_METRICS_FIELD_TRIAL_PARAM_ASSOCIATOR_H_ #define BASE_METRICS_FIELD_TRIAL_PARAM_ASSOCIATOR_H_ #include #include #include #include "base/base_export.h" #include "base/memory/singleton.h" #include "base/metrics/field_trial.h" #include "base/metrics/field_trial_params.h" #include "base/synchronization/lock.h" namespace base { // Keeps track of the parameters of all field trials and ensures access to them // is thread-safe. class BASE_EXPORT FieldTrialParamAssociator { public: FieldTrialParamAssociator(); FieldTrialParamAssociator(const FieldTrialParamAssociator&) = delete; FieldTrialParamAssociator& operator=(const FieldTrialParamAssociator&) = delete; ~FieldTrialParamAssociator(); // Retrieve the singleton. static FieldTrialParamAssociator* GetInstance(); // Sets parameters for the given field trial name and group. bool AssociateFieldTrialParams(const std::string& trial_name, const std::string& group_name, const FieldTrialParams& params); // Gets the parameters for a field trial and its chosen group. If not found in // field_trial_params_, then tries to looks it up in shared memory. Returns // false if no params are available or the passed |field_trial| is null. bool GetFieldTrialParams(FieldTrial* field_trial, FieldTrialParams* params); // Gets the parameters for a field trial and its chosen group. Does not // fallback to looking it up in shared memory. This should only be used if you // know for sure the params are in the mapping, like if you're in the browser // process, and even then you should probably just use GetFieldTrialParams(). bool GetFieldTrialParamsWithoutFallback(const std::string& trial_name, const std::string& group_name, FieldTrialParams* params); // Clears the internal field_trial_params_ mapping, plus removes all params in // shared memory. void ClearAllParamsForTesting(); // Clears a single field trial param. // Note: this does NOT remove the param in shared memory. void ClearParamsForTesting(const std::string& trial_name, const std::string& group_name); // Clears the internal field_trial_params_ mapping. void ClearAllCachedParamsForTesting(); private: friend struct DefaultSingletonTraits; // (field_trial_name, field_trial_group) typedef std::pair FieldTrialKey; // The following type can be used for lookups without needing to copy strings. typedef std::pair FieldTrialRefKey; Lock lock_; std::map field_trial_params_; }; } // namespace base #endif // BASE_METRICS_FIELD_TRIAL_PARAM_ASSOCIATOR_H_