chromium/chrome/browser/predictors/lcp_critical_path_predictor/lcp_critical_path_predictor_util.h

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_PREDICTORS_LCP_CRITICAL_PATH_PREDICTOR_LCP_CRITICAL_PATH_PREDICTOR_UTIL_H_
#define CHROME_BROWSER_PREDICTORS_LCP_CRITICAL_PATH_PREDICTOR_LCP_CRITICAL_PATH_PREDICTOR_UTIL_H_

#include <optional>

#include "chrome/browser/predictors/lcp_critical_path_predictor/lcp_critical_path_predictor.pb.h"
#include "chrome/browser/predictors/loading_predictor_config.h"
#include "components/sqlite_proto/key_value_data.h"
#include "components/sqlite_proto/key_value_table.h"
#include "third_party/blink/public/mojom/lcp_critical_path_predictor/lcp_critical_path_predictor.mojom.h"

namespace url {
class Origin;
}  // namespace url

namespace predictors {
namespace lcpp {
struct LastVisitTimeCompare { … };

}  // namespace lcpp

// Converts LcppStat to LCPCriticalPathPredictorNavigationTimeHint
// so that it can be passed to the renderer via the navigation handle.
std::optional<blink::mojom::LCPCriticalPathPredictorNavigationTimeHint>
ConvertLcppStatToLCPCriticalPathPredictorNavigationTimeHint(
    const LcppStat& data);

// Returns possible fonts from past loads for a given `stat`.
// The returned urls are ordered by descending frequency (the most
// frequent one comes first). If there is no data, it returns an empty
// vector.
std::vector<GURL> PredictFetchedFontUrls(const LcppStat& stat);

// Returns possible preconnects based on past loads for a given `stat`.
// The returned origins are ordered by descending frequency (the most
// frequent one comes first). If there is no data, it returns an empty
// vector.
std::vector<GURL> PredictPreconnectableOrigins(const LcppStat& stat);

// Returns possible subresource URLs from past loads for a given `stat`.
// The returned URLs are ordered by descending frequency (the most
// frequent one comes first). If there is no data, it returns an empty
// vector.
std::vector<GURL> PredictFetchedSubresourceUrls(const LcppStat& stat);

// Returns possible unused preload URLs from past loads for a given `stat`.
// The returned URLs are ordered by descending frequency (the most
// frequent one comes first). If there is no data, it returns an empty
// vector.
std::vector<GURL> PredictUnusedPreloads(const LcppStat& stat);

// An input to update LcppData.
struct LcppDataInputs { … };

bool UpdateLcppStatWithLcppDataInputs(const LoadingPredictorConfig& config,
                                      const LcppDataInputs& inputs,
                                      LcppStat& stat);

// Update `lcpp_stat_data` adding `new_entry` with `sliding_window_size` and
// `max_histogram_buckets` parameters by the top-k algorithm.
// See lcp_critical_path_predictor_util.cc for detail.
// `dropped_entry` is assigned if this updating dropped an existing entry.
void UpdateLcppStringFrequencyStatData(
    size_t sliding_window_size,
    size_t max_histogram_buckets,
    const std::string& new_entry,
    LcppStringFrequencyStatData& lcpp_stat_data,
    std::optional<std::string>& dropped_entry);

// Update `lcpp_stat_data` adding `new_entry` with `sliding_window_size` and
// `max_histogram_buckets` parameters by the top-k algorithm while
// keeping `map` have same keys in `lcpp_stat_data`.
// See lcp_critical_path_predictor_util.cc for detail.
template <typename T>
T* UpdateFrequencyStatAndTryGetEntry(
    size_t sliding_window_size,
    size_t max_histogram_buckets,
    const std::string& new_entry,
    LcppStringFrequencyStatData& frequency_stat,
    google::protobuf::Map<std::string, T>& map) { … }

// Aligns `frequency_stat` elements and `map` elements.
// Clears both if `frequency_stat` has invalid parameters too.
template <typename T>
bool CanonicalizeFrequencyData(size_t max_histogram_buckets,
                               LcppStringFrequencyStatData& frequency_stat,
                               google::protobuf::Map<std::string, T>& map) { … }

// Returns true if the LcppData is valid. i.e. looks not corrupted.
// Otherwise, data might be corrupted.
bool IsValidLcppStat(const LcppStat& lcpp_stat);

// Returns true if the url is valid for learning.
bool IsURLValidForLcpp(const GURL& url);

// Returns the first level path of the url. The url should be true for
// the above IsURLValidForLcpp(url).
// This function can return empty string if the URL doesn't have
// the first level path or it length exceeds kLCPPMultipleKeyMaxPathLength.
std::string GetFirstLevelPath(const GURL& url);

class LcppDataMap { … };

}  // namespace predictors

#endif  // CHROME_BROWSER_PREDICTORS_LCP_CRITICAL_PATH_PREDICTOR_LCP_CRITICAL_PATH_PREDICTOR_UTIL_H_