Rename all of experiments_helper to variations_helper, including files, namespaces, and various fun…

chrome/common/metrics/experiments_helper.cc

-// Copyright (c) 2012 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 "chrome/common/metrics/experiments_helper.h"
-
-#include <map>
-#include <vector>
-
-#include "base/memory/singleton.h"
-#include "base/sha1.h"
-#include "base/string16.h"
-#include "base/stringprintf.h"
-#include "base/sys_byteorder.h"
-#include "base/utf_string_conversions.h"
-#include "chrome/common/child_process_logging.h"
-#include "chrome/common/metrics/variation_ids.h"
-
-namespace {
-
-// The internal singleton accessor for the map, used to keep it thread-safe.
-class GroupMapAccessor {
- public:
-  // Retrieve the singleton.
-  static GroupMapAccessor* GetInstance() {
-    return Singleton<GroupMapAccessor>::get();
-  }
-
-  GroupMapAccessor() {}
-  ~GroupMapAccessor() {}
-
-  // 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(const experiments_helper::SelectedGroupId& group_identifier,
-                   chrome_variations::VariationID id,
-                   const bool force) {
-    base::AutoLock scoped_lock(lock_);
-    if (force ||
-        group_to_id_map_.find(group_identifier) == group_to_id_map_.end())
-      group_to_id_map_[group_identifier] = id;
-  }
-
-  chrome_variations::VariationID GetID(
-      const experiments_helper::SelectedGroupId& group_identifier) {
-    base::AutoLock scoped_lock(lock_);
-    GroupToIDMap::const_iterator it = group_to_id_map_.find(group_identifier);
-    if (it == group_to_id_map_.end())
-      return chrome_variations::kEmptyID;
-    return it->second;
-  }
-
- private:
-  typedef std::map<experiments_helper::SelectedGroupId,
-      chrome_variations::VariationID,
-      experiments_helper::SelectedGroupIdCompare> GroupToIDMap;
-
-  base::Lock lock_;
-  GroupToIDMap group_to_id_map_;
-};
-
-// Creates unique identifier for the trial by hashing a name string, whether
-// it's for the field trial or the group name.
-uint32 HashName(const std::string& name) {
-  // SHA-1 is designed to produce a uniformly random spread in its output space,
-  // even for nearly-identical inputs.
-  unsigned char sha1_hash[base::kSHA1Length];
-  base::SHA1HashBytes(reinterpret_cast<const unsigned char*>(name.c_str()),
-                      name.size(),
-                      sha1_hash);
-
-  COMPILE_ASSERT(sizeof(uint32) < sizeof(sha1_hash), need_more_data);
-  uint32 bits;
-  memcpy(&bits, sha1_hash, sizeof(bits));
-
-  return base::ByteSwapToLE32(bits);
-}
-
-experiments_helper::SelectedGroupId MakeSelectedGroupId(
-    const std::string& trial_name,
-    const std::string& group_name) {
-  experiments_helper::SelectedGroupId id;
-  id.name = HashName(trial_name);
-  id.group = HashName(group_name);
-  return id;
-}
-
-// Populates |name_group_ids| based on |selected_groups|.
-void GetFieldTrialSelectedGroupIdsForSelectedGroups(
-    const base::FieldTrial::SelectedGroups& selected_groups,
-    std::vector<experiments_helper::SelectedGroupId>* name_group_ids) {
-  DCHECK(name_group_ids->empty());
-  for (base::FieldTrial::SelectedGroups::const_iterator it =
-       selected_groups.begin(); it != selected_groups.end(); ++it) {
-    name_group_ids->push_back(MakeSelectedGroupId(it->trial, it->group));
-  }
-}
-
-}  // namespace
-
-namespace experiments_helper {
-
-void GetFieldTrialSelectedGroupIds(
-    std::vector<SelectedGroupId>* name_group_ids) {
-  DCHECK(name_group_ids->empty());
-  // A note on thread safety: Since GetFieldTrialSelectedGroups is thread
-  // safe, and we operate on a separate list of that data, this function is
-  // technically thread safe as well, with respect to the FieldTriaList data.
-  base::FieldTrial::SelectedGroups selected_groups;
-  base::FieldTrialList::GetFieldTrialSelectedGroups(&selected_groups);
-  GetFieldTrialSelectedGroupIdsForSelectedGroups(selected_groups,
-                                                 name_group_ids);
-}
-
-void AssociateGoogleVariationID(const std::string& trial_name,
-                                const std::string& group_name,
-                                chrome_variations::VariationID id) {
-  GroupMapAccessor::GetInstance()->AssociateID(
-      MakeSelectedGroupId(trial_name, group_name), id, false);
-}
-
-void AssociateGoogleVariationIDForce(const std::string& trial_name,
-                                     const std::string& group_name,
-                                     chrome_variations::VariationID id) {
-  GroupMapAccessor::GetInstance()->AssociateID(
-      MakeSelectedGroupId(trial_name, group_name), id, true);
-}
-
-chrome_variations::VariationID GetGoogleVariationID(
-    const std::string& trial_name,
-    const std::string& group_name) {
-  return GroupMapAccessor::GetInstance()->GetID(
-      MakeSelectedGroupId(trial_name, group_name));
-}
-
-void GenerateExperimentChunks(const std::vector<string16>& experiments,
-                              std::vector<string16>* chunks) {
-  string16 current_chunk;
-  for (size_t i = 0; i < experiments.size(); ++i) {
-    const size_t needed_length =
-        (current_chunk.empty() ? 1 : 0) + experiments[i].length();
-    if (current_chunk.length() + needed_length > kMaxExperimentChunkSize) {
-      chunks->push_back(current_chunk);
-      current_chunk = experiments[i];
-    } else {
-      if (!current_chunk.empty())
-        current_chunk.push_back(',');
-      current_chunk += experiments[i];
-    }
-  }
-  if (!current_chunk.empty())
-    chunks->push_back(current_chunk);
-}
-
-void SetChildProcessLoggingExperimentList() {
-  std::vector<SelectedGroupId> name_group_ids;
-  GetFieldTrialSelectedGroupIds(&name_group_ids);
-  std::vector<string16> experiment_strings(name_group_ids.size());
-  for (size_t i = 0; i < name_group_ids.size(); ++i) {
-    experiment_strings[i] = UTF8ToUTF16(base::StringPrintf(
-        "%x-%x", name_group_ids[i].name, name_group_ids[i].group));
-  }
-  child_process_logging::SetExperimentList(experiment_strings);
-}
-
-}  // namespace experiments_helper
-
-// Functions below are exposed for testing explicitly behind this namespace.
-// They simply wrap existing functions in this file.
-namespace testing {
-
-void TestGetFieldTrialSelectedGroupIdsForSelectedGroups(
-    const base::FieldTrial::SelectedGroups& selected_groups,
-    std::vector<experiments_helper::SelectedGroupId>* name_group_ids) {
-  ::GetFieldTrialSelectedGroupIdsForSelectedGroups(selected_groups,
-                                                   name_group_ids);
-}
-
-uint32 TestHashName(const std::string& name) {
-  return ::HashName(name);
-}
-
-}  // namespace testing