root/components/variations/variations_associated_data.cc

DEFINITIONS

1. GetInstance
2. AssociateID
3. GetID
4. ClearAllMapsForTesting
5. GetGroupToIDMap
6. GetInstance
7. AssociateVariationParams
8. GetVariationParams
9. ClearAllParamsForTesting
10. IsFieldTrialActive
11. MakeActiveGroupId
12. AssociateGoogleVariationID
13. AssociateGoogleVariationIDForce
14. GetGoogleVariationID
15. AssociateVariationParams
16. GetVariationParams
17. GetVariationParamValue
18. ClearAllVariationIDs
19. ClearAllVariationParams

// Copyright 2013 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 "components/variations/variations_associated_data.h"

#include <map>
#include <utility>
#include <vector>

#include "base/memory/singleton.h"
#include "components/variations/metrics_util.h"

namespace chrome_variations {

namespace {

// The internal singleton accessor for the map, used to keep it thread-safe.
class GroupMapAccessor {
 public:
  typedef std::map<ActiveGroupId, VariationID, ActiveGroupIdCompare>
      GroupToIDMap;

  // Retrieve the singleton.
  static GroupMapAccessor* GetInstance() {
    return Singleton<GroupMapAccessor>::get();
  }

  // Note that this normally only sets the ID for a group the first time, unless
  // |force| is set to true, in which case it will always override it.
  void AssociateID(IDCollectionKey key,
                   const ActiveGroupId& group_identifier,
                   const VariationID id,
                   const bool force) {
#if !defined(NDEBUG)
    // Validate that all collections with this |group_identifier| have the same
    // associated ID.
    DCHECK_EQ(2, ID_COLLECTION_COUNT);
    IDCollectionKey other_key = GOOGLE_WEB_PROPERTIES;
    if (key == GOOGLE_WEB_PROPERTIES)
      other_key = GOOGLE_UPDATE_SERVICE;
    VariationID other_id = GetID(other_key, group_identifier);
    DCHECK(other_id == EMPTY_ID || other_id == id);
#endif

    base::AutoLock scoped_lock(lock_);

    GroupToIDMap* group_to_id_map = GetGroupToIDMap(key);
    if (force ||
        group_to_id_map->find(group_identifier) == group_to_id_map->end())
      (*group_to_id_map)[group_identifier] = id;
  }

  VariationID GetID(IDCollectionKey key,
                    const ActiveGroupId& group_identifier) {
    base::AutoLock scoped_lock(lock_);
    GroupToIDMap* group_to_id_map = GetGroupToIDMap(key);
    GroupToIDMap::const_iterator it = group_to_id_map->find(group_identifier);
    if (it == group_to_id_map->end())
      return EMPTY_ID;
    return it->second;
  }

  void ClearAllMapsForTesting() {
    base::AutoLock scoped_lock(lock_);

    for (int i = 0; i < ID_COLLECTION_COUNT; ++i) {
      GroupToIDMap* map = GetGroupToIDMap(static_cast<IDCollectionKey>(i));
      DCHECK(map);
      map->clear();
    }
  }

 private:
  friend struct DefaultSingletonTraits<GroupMapAccessor>;

  // Retrieves the GroupToIDMap for |key|.
  GroupToIDMap* GetGroupToIDMap(IDCollectionKey key) {
    return &group_to_id_maps_[key];
  }

  GroupMapAccessor() {
    group_to_id_maps_.resize(ID_COLLECTION_COUNT);
  }
  ~GroupMapAccessor() {}

  base::Lock lock_;
  std::vector<GroupToIDMap> group_to_id_maps_;

  DISALLOW_COPY_AND_ASSIGN(GroupMapAccessor);
};

// Singleton helper class that keeps track of the parameters of all variations
// and ensures access to these is thread-safe.
class VariationsParamAssociator {
 public:
  typedef std::pair<std::string, std::string> VariationKey;
  typedef std::map<std::string, std::string> VariationParams;

  // Retrieve the singleton.
  static VariationsParamAssociator* GetInstance() {
    return Singleton<VariationsParamAssociator>::get();
  }

  bool AssociateVariationParams(const std::string& trial_name,
                                const std::string& group_name,
                                const VariationParams& params) {
    base::AutoLock scoped_lock(lock_);

    if (IsFieldTrialActive(trial_name))
      return false;

    const VariationKey key(trial_name, group_name);
    if (ContainsKey(variation_params_, key))
      return false;

    variation_params_[key] = params;
    return true;
  }

  bool GetVariationParams(const std::string& trial_name,
                          VariationParams* params) {
    base::AutoLock scoped_lock(lock_);

    const std::string group_name =
        base::FieldTrialList::FindFullName(trial_name);
    const VariationKey key(trial_name, group_name);
    if (!ContainsKey(variation_params_, key))
      return false;

    *params = variation_params_[key];
    return true;
  }

  void ClearAllParamsForTesting() {
    base::AutoLock scoped_lock(lock_);
    variation_params_.clear();
  }

 private:
  friend struct DefaultSingletonTraits<VariationsParamAssociator>;

  VariationsParamAssociator() {}
  ~VariationsParamAssociator() {}

  // Tests whether a field trial is active (i.e. group() has been called on it).
  // TODO(asvitkine): Expose this as an API on base::FieldTrial.
  bool IsFieldTrialActive(const std::string& trial_name) {
    base::FieldTrial::ActiveGroups active_groups;
    base::FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    for (size_t i = 0; i < active_groups.size(); ++i) {
      if (active_groups[i].trial_name == trial_name)
        return true;
    }
    return false;
  }

  base::Lock lock_;
  std::map<VariationKey, VariationParams> variation_params_;

  DISALLOW_COPY_AND_ASSIGN(VariationsParamAssociator);
};

}  // namespace

ActiveGroupId MakeActiveGroupId(const std::string& trial_name,
                                const std::string& group_name) {
  ActiveGroupId id;
  id.name = metrics::HashName(trial_name);
  id.group = metrics::HashName(group_name);
  return id;
}

void AssociateGoogleVariationID(IDCollectionKey key,
                                const std::string& trial_name,
                                const std::string& group_name,
                                VariationID id) {
  GroupMapAccessor::GetInstance()->AssociateID(
      key, MakeActiveGroupId(trial_name, group_name), id, false);
}

void AssociateGoogleVariationIDForce(IDCollectionKey key,
                                     const std::string& trial_name,
                                     const std::string& group_name,
                                     VariationID id) {
  GroupMapAccessor::GetInstance()->AssociateID(
      key, MakeActiveGroupId(trial_name, group_name), id, true);
}

VariationID GetGoogleVariationID(IDCollectionKey key,
                                 const std::string& trial_name,
                                 const std::string& group_name) {
  return GroupMapAccessor::GetInstance()->GetID(
      key, MakeActiveGroupId(trial_name, group_name));
}

bool AssociateVariationParams(
    const std::string& trial_name,
    const std::string& group_name,
    const std::map<std::string, std::string>& params) {
  return VariationsParamAssociator::GetInstance()->AssociateVariationParams(
      trial_name, group_name, params);
}

bool GetVariationParams(const std::string& trial_name,
                        std::map<std::string, std::string>* params) {
  return VariationsParamAssociator::GetInstance()->GetVariationParams(
      trial_name, params);
}

std::string GetVariationParamValue(const std::string& trial_name,
                                   const std::string& param_name) {
  std::map<std::string, std::string> params;
  if (GetVariationParams(trial_name, &params)) {
    std::map<std::string, std::string>::iterator it = params.find(param_name);
    if (it != params.end())
      return it->second;
  }
  return std::string();
}

// Functions below are exposed for testing explicitly behind this namespace.
// They simply wrap existing functions in this file.
namespace testing {

void ClearAllVariationIDs() {
  GroupMapAccessor::GetInstance()->ClearAllMapsForTesting();
}

void ClearAllVariationParams() {
  VariationsParamAssociator::GetInstance()->ClearAllParamsForTesting();
}

}  // namespace testing

}  // namespace chrome_variations