Store field trial parameters in shared memory

base/metrics/field_trial_param_associator.cc

 // 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.
 
 #include "base/metrics/field_trial_param_associator.h"
 
 #include "base/metrics/field_trial.h"
 
 namespace base {
 
 FieldTrialParamAssociator::FieldTrialParamAssociator() {}
 FieldTrialParamAssociator::~FieldTrialParamAssociator() {}
 
 // static
 FieldTrialParamAssociator* FieldTrialParamAssociator::GetInstance() {
   return Singleton<FieldTrialParamAssociator,
                    LeakySingletonTraits<FieldTrialParamAssociator>>::get();
 }
 
 bool FieldTrialParamAssociator::AssociateFieldTrialParams(
     const std::string& trial_name,
     const std::string& group_name,
     const FieldTrialParams& params) {
   AutoLock scoped_lock(lock_);
 
-  if (FieldTrialList::IsTrialActive(trial_name))
-    return false;
-
-  const FieldTrialKey key(trial_name, group_name);
-  if (ContainsKey(field_trial_params_, key))
-    return false;
-
-  field_trial_params_[key] = params;
-  return true;
+  return AssociateParamsWhileLocked(trial_name, group_name, params);
 }
 
 bool FieldTrialParamAssociator::GetFieldTrialParams(
     const std::string& trial_name,
     FieldTrialParams* params) {
   AutoLock scoped_lock(lock_);
 
   const std::string group_name = FieldTrialList::FindFullName(trial_name);
+  return GetFieldTrialParamsWithGroupName(trial_name, group_name, params);
+}
+
+bool FieldTrialParamAssociator::GetFieldTrialParamsWithGroupName(
+    const std::string& trial_name,
+    const std::string& group_name,
+    FieldTrialParams* params) {
+  AutoLock scoped_lock(lock_);
+
   const FieldTrialKey key(trial_name, group_name);
   if (!ContainsKey(field_trial_params_, key))
-    return false;
+    return GetParamsFromSharedMemory(trial_name, group_name, params);
 
   *params = field_trial_params_[key];
   return true;
 }
 
 void FieldTrialParamAssociator::ClearAllParamsForTesting() {
   AutoLock scoped_lock(lock_);
   field_trial_params_.clear();
 }
 
+bool FieldTrialParamAssociator::GetParamsFromSharedMemory(
+    const std::string& trial_name,
+    const std::string& group_name,
+    FieldTrialParams* params) {
+  bool result = FieldTrialList::FindParams(trial_name, params);
+  if (result)
+    AssociateParamsWhileLocked(trial_name, group_name, *params);
+  return result;
+}
+
+bool FieldTrialParamAssociator::AssociateParamsWhileLocked(
+    const std::string& trial_name,
+    const std::string& group_name,
+    const FieldTrialParams& params) {
+  if (FieldTrialList::IsTrialActive(trial_name))
+    return false;
+
+  const FieldTrialKey key(trial_name, group_name);
+  if (ContainsKey(field_trial_params_, key))
+    return false;
+
+  field_trial_params_[key] = params;
+  return true;
+}
+
 }  // namespace base