// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ash/app_list/search/ranking/ranker_manager.h"
#include "chrome/browser/ash/app_list/search/ranking/answer_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/best_match_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/continue_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/filtering_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/ftrl_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/keyword_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/mrfu_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/query_highlighter.h"
#include "chrome/browser/ash/app_list/search/ranking/removed_results.pb.h"
#include "chrome/browser/ash/app_list/search/ranking/removed_results_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/score_normalizing_ranker.h"
#include "chrome/browser/ash/app_list/search/ranking/util.h"
#include "chrome/browser/ash/app_list/search/search_features.h"
#include "chrome/browser/ash/app_list/search/util/score_normalizer.h"
#include "chrome/browser/ash/app_list/search/util/score_normalizer.pb.h"
#include "chrome/browser/profiles/profile.h"
namespace app_list {
namespace {
// A standard write delay used for protos without time-sensitive writes. This is
// intended to be slightly longer than the longest conceivable latency for a
// search.
constexpr base::TimeDelta kStandardWriteDelay = base::Seconds(3);
} // namespace
RankerManager::RankerManager(Profile* profile) {
// Score normalization parameters:
ScoreNormalizer::Params score_normalizer_params;
// Change this version number when changing the number of bins below.
score_normalizer_params.version = 1;
// The maximum number of buckets the score normalizer discretizes result
// scores into.
score_normalizer_params.max_bins = 5;
// Result ranking parameters.
FtrlOptimizer::Params ftrl_result_params;
ftrl_result_params.alpha = 0.1;
ftrl_result_params.gamma = 0.1;
ftrl_result_params.num_experts = 2u;
MrfuCache::Params mrfu_result_params;
mrfu_result_params.half_life = 30.0f;
mrfu_result_params.boost_factor = 2.5f;
mrfu_result_params.max_items = 200u;
// Category ranking parameters.
FtrlOptimizer::Params ftrl_category_params;
ftrl_category_params.alpha = 0.1;
ftrl_category_params.gamma = 0.1;
ftrl_category_params.num_experts = 2u;
MrfuCache::Params mrfu_category_params;
mrfu_category_params.half_life = 20.0f;
mrfu_category_params.boost_factor = 7.0f;
mrfu_category_params.max_items = 20u;
const auto state_dir = RankerStateDirectory(profile);
// 1. Result pre-processing. These filter or modify search results but don't
// change their scores.
AddRanker(std::make_unique<QueryHighlighter>());
AddRanker(std::make_unique<ContinueRanker>());
AddRanker(std::make_unique<FilteringRanker>());
AddRanker(std::make_unique<RemovedResultsRanker>(profile));
// 2. Score normalization, a precursor to other ranking.
AddRanker(std::make_unique<ScoreNormalizingRanker>(
score_normalizer_params,
ash::PersistentProto<ScoreNormalizerProto>(
state_dir.AppendASCII("score_norm.pb"), kStandardWriteDelay)));
// 3. Ranking for results.
// 3a. Most-frequently-recently-used (MRFU) ranking.
auto mrfu_ranker = std::make_unique<MrfuResultRanker>(
mrfu_result_params,
ash::PersistentProto<MrfuCacheProto>(
state_dir.AppendASCII("mrfu_results.pb"), kStandardWriteDelay));
AddRanker(std::move(mrfu_ranker));
// 3b. Ensembling between MRFU and normalized score ranking.
auto ftrl_ranker = std::make_unique<FtrlRanker>(
FtrlRanker::RankingKind::kResults, ftrl_result_params,
ash::PersistentProto<FtrlOptimizerProto>(
state_dir.AppendASCII("ftrl_results.pb"), kStandardWriteDelay));
ftrl_ranker->AddExpert(std::make_unique<ResultScoringShim>(
ResultScoringShim::ScoringMember::kNormalizedRelevance));
ftrl_ranker->AddExpert(std::make_unique<ResultScoringShim>(
ResultScoringShim::ScoringMember::kMrfuResultScore));
AddRanker(std::move(ftrl_ranker));
// 4. Ranking for categories
AddRanker(std::make_unique<MrfuCategoryRanker>(
mrfu_category_params,
ash::PersistentProto<MrfuCacheProto>(
state_dir.AppendASCII("mrfu_categories.pb"), kStandardWriteDelay)));
// TODO(b/274921356): Temporarily comment out the `KeywordRanker` construction
// to avoid any possible crashes. Re-enable it when we make sure this problem
// has been fixed.
//
// if (search_features::IsLauncherKeywordExtractionScoringEnabled()) {
// AddRanker(std::make_unique<KeywordRanker>());
// }
// 5. Result post-processing.
// Nb. the best match ranker relies on score normalization, and the answer
// ranker relies on the best match ranker.
AddRanker(std::make_unique<BestMatchRanker>());
AddRanker(std::make_unique<AnswerRanker>());
}
RankerManager::~RankerManager() {}
void RankerManager::Start(const std::u16string& query,
CategoriesList& categories) {
for (auto& ranker : rankers_) {
ranker->Start(query, categories);
}
}
void RankerManager::UpdateResultRanks(ResultsMap& results,
ProviderType provider) {
for (auto& ranker : rankers_) {
ranker->UpdateResultRanks(results, provider);
}
}
void RankerManager::UpdateCategoryRanks(const ResultsMap& results,
CategoriesList& categories,
ProviderType provider) {
for (auto& ranker : rankers_) {
ranker->UpdateCategoryRanks(results, categories, provider);
}
}
void RankerManager::Train(const LaunchData& launch) {
for (auto& ranker : rankers_) {
ranker->Train(launch);
}
}
void RankerManager::Remove(ChromeSearchResult* result) {
for (auto& ranker : rankers_) {
ranker->Remove(result);
}
}
void RankerManager::AddRanker(std::unique_ptr<Ranker> ranker) {
rankers_.emplace_back(std::move(ranker));
}
void RankerManager::OnBurnInPeriodElapsed() {
for (auto& ranker : rankers_) {
ranker->OnBurnInPeriodElapsed();
}
}
} // namespace app_list
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