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// Copyright 2024 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_ACCESSIBILITY_PHRASE_SEGMENTATION_DEPENDENCY_PARSER_MODEL_LOADER_H_
#define CHROME_BROWSER_ACCESSIBILITY_PHRASE_SEGMENTATION_DEPENDENCY_PARSER_MODEL_LOADER_H_
#include "base/files/file.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "components/keyed_service/core/keyed_service.h"
#include "components/optimization_guide/core/delivery/optimization_target_model_observer.h"
namespace optimization_guide {
class OptimizationGuideModelProvider;
} // namespace optimization_guide
// Service that manages models required to support dependency parsing in the
// browser. Currently, the service should only be used in the browser as it
// relies on the Optimization Guide.
class DependencyParserModelLoader
: public KeyedService,
public optimization_guide::OptimizationTargetModelObserver {
public:
using GetModelCallback = base::OnceCallback<void(base::File)>;
using NotifyModelAvailableCallback = base::OnceCallback<void(bool)>;
DependencyParserModelLoader(
optimization_guide::OptimizationGuideModelProvider* opt_guide,
const scoped_refptr<base::SequencedTaskRunner>& background_task_runner);
DependencyParserModelLoader(const DependencyParserModelLoader&) = delete;
~DependencyParserModelLoader() override;
// KeyedService implementation:
void Shutdown() override;
// optimization_guide::OptimizationTargetModelObserver implementation:
void OnModelUpdated(
optimization_guide::proto::OptimizationTarget optimization_target,
base::optional_ref<const optimization_guide::ModelInfo> model_info)
override;
// Returns the dependency parser model file, should only be called when the
// model file is already available. See the |NotifyOnModelFileAvailable|
// for an asynchronous notification of the model being available.
base::File GetDependencyParserModelFile();
// Returns whether the dependency parser model is loaded and available to be
// requested.
bool IsModelAvailable() { return dependency_parser_model_file_.has_value(); }
// If the model file is not available, requestors can ask to be notified, via
// |callback|. This enables a two-step approach to relabily get the model file
// when it becomes available if the requestor needs the file right when it
// becomes available. This is to ensure that if the callback becomes empty,
// only the notification gets dropped, rather than the model file which has to
// be closed on a background thread.
void NotifyOnModelFileAvailable(NotifyModelAvailableCallback callback);
private:
// Unloads the model in background task.
void UnloadModelFile();
// Notifies the model update to observers, and clears the observer list.
void NotifyModelUpdatesAndClear(bool is_model_available);
void OnModelFileLoaded(base::File model_file);
// Optimization Guide Service that provides model files for this service.
// Optimization Guide Service is a BrowserContextKeyedServiceFactory and
// should not be used after Shutdown.
raw_ptr<optimization_guide::OptimizationGuideModelProvider> opt_guide_;
// The file that contains the dependency parser model. Available when the
// file path has been provided by the Optimization Guide and has been
// successfully loaded.
std::optional<base::File> dependency_parser_model_file_;
// The set of callbacks associated with requests for the dependency parser
// model. The callback notifies requesters than the model file is
// now available and can be safely requested.
std::vector<NotifyModelAvailableCallback> pending_model_requests_;
scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
SEQUENCE_CHECKER(sequence_checker_);
base::WeakPtrFactory<DependencyParserModelLoader> weak_ptr_factory_{this};
};
#endif // CHROME_BROWSER_ACCESSIBILITY_PHRASE_SEGMENTATION_DEPENDENCY_PARSER_MODEL_LOADER_H_
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