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// 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 CONTENT_BROWSER_PRELOADING_PRELOADING_CONFIG_H_
#define CONTENT_BROWSER_PRELOADING_PRELOADING_CONFIG_H_
#include <string_view>
#include "base/containers/flat_map.h"
#include "base/feature_list.h"
#include "base/no_destructor.h"
#include "base/values.h"
#include "content/public/browser/preloading.h"
namespace content {
namespace test {
class PreloadingConfigOverride;
} // namespace test
class CONTENT_EXPORT PreloadingConfig {
public:
PreloadingConfig();
~PreloadingConfig();
static PreloadingConfig& GetInstance();
// Whether the given (|preloading_type|, |predictor|) combination should be
// held back in order to evaluate how well this type of preloading is
// performing. This is controlled via field trial configuration.
bool ShouldHoldback(PreloadingType preloading_type,
PreloadingPredictor predictor);
// Whether the given (|preloading_type|, |predictor|) combination logging
// should be sampled. Some types of preloading trigger more than others so
// we randomly drop logging for a fraction of page loads of the more noisy
// preloading. The sampling rate is configured via field trial.
double SamplingLikelihood(PreloadingType preloading_type,
PreloadingPredictor predictor);
// Initializes the PreloadingConfig from the FeatureParams. Exported
// publicly only for tests.
void ParseConfig();
private:
friend class content::test::PreloadingConfigOverride;
struct Key {
Key(std::string_view preloading_type, std::string_view predictdor);
static Key FromEnums(PreloadingType preloading_type,
PreloadingPredictor predictor);
std::string preloading_type_;
std::string predictor_;
};
struct Entry {
static Entry FromDict(const base::Value::Dict* dict);
bool holdback_ = false;
float sampling_likelihood_ = 1.0;
};
struct KeyCompare {
bool operator()(const Key& lhs, const Key& rhs) const;
};
// Overrides the PreloadingConfig for testing. Returns the previous override,
// if any. The caller is responsible for calling OverrideForTesting with the
// previous value once they're done.
static PreloadingConfig* OverrideForTesting(
PreloadingConfig* config_override);
// Sets whether the given feature should be held back (disabled) and prevents
// sampling UKM logs for that feature.
void SetHoldbackForTesting(PreloadingType preloading_type,
PreloadingPredictor predictor,
bool holdback);
void SetHoldbackForTesting(std::string_view preloading_type,
std::string_view predictdor,
bool holdback);
base::flat_map<Key, Entry, KeyCompare> entries_;
};
} // namespace content
#endif // CONTENT_BROWSER_PRELOADING_PRELOADING_CONFIG_H_
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