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      1 // Copyright 2016 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/metrics/field_trial_param_associator.h"
      6 
      7 #include "base/metrics/field_trial.h"
      8 
      9 namespace base {
     10 
     11 FieldTrialParamAssociator::FieldTrialParamAssociator() {}
     12 FieldTrialParamAssociator::~FieldTrialParamAssociator() {}
     13 
     14 // static
     15 FieldTrialParamAssociator* FieldTrialParamAssociator::GetInstance() {
     16   return Singleton<FieldTrialParamAssociator,
     17                    LeakySingletonTraits<FieldTrialParamAssociator>>::get();
     18 }
     19 
     20 bool FieldTrialParamAssociator::AssociateFieldTrialParams(
     21     const std::string& trial_name,
     22     const std::string& group_name,
     23     const FieldTrialParams& params) {
     24   if (FieldTrialList::IsTrialActive(trial_name))
     25     return false;
     26 
     27   AutoLock scoped_lock(lock_);
     28   const FieldTrialKey key(trial_name, group_name);
     29   if (ContainsKey(field_trial_params_, key))
     30     return false;
     31 
     32   field_trial_params_[key] = params;
     33   return true;
     34 }
     35 
     36 bool FieldTrialParamAssociator::GetFieldTrialParams(
     37     const std::string& trial_name,
     38     FieldTrialParams* params) {
     39   FieldTrial* field_trial = FieldTrialList::Find(trial_name);
     40   if (!field_trial)
     41     return false;
     42 
     43   // First try the local map, falling back to getting it from shared memory.
     44   if (GetFieldTrialParamsWithoutFallback(trial_name, field_trial->group_name(),
     45                                          params)) {
     46     return true;
     47   }
     48 
     49   // TODO(lawrencewu): add the params to field_trial_params_ for next time.
     50   return FieldTrialList::GetParamsFromSharedMemory(field_trial, params);
     51 }
     52 
     53 bool FieldTrialParamAssociator::GetFieldTrialParamsWithoutFallback(
     54     const std::string& trial_name,
     55     const std::string& group_name,
     56     FieldTrialParams* params) {
     57   AutoLock scoped_lock(lock_);
     58 
     59   const FieldTrialKey key(trial_name, group_name);
     60   if (!ContainsKey(field_trial_params_, key))
     61     return false;
     62 
     63   *params = field_trial_params_[key];
     64   return true;
     65 }
     66 
     67 void FieldTrialParamAssociator::ClearAllParamsForTesting() {
     68   {
     69     AutoLock scoped_lock(lock_);
     70     field_trial_params_.clear();
     71   }
     72   FieldTrialList::ClearParamsFromSharedMemoryForTesting();
     73 }
     74 
     75 void FieldTrialParamAssociator::ClearAllCachedParamsForTesting() {
     76   AutoLock scoped_lock(lock_);
     77   field_trial_params_.clear();
     78 }
     79 
     80 }  // namespace base
     81