blob: 1a94ac3f4ea3a2c3f53d12db0492cef901e7dd5b [file] [log] [blame]
// Copyright 2017 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 "components/assist_ranker/ranker_model_loader.h"
#include <memory>
#include <string>
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
#include "url/gurl.h"
namespace base {
class SequencedTaskRunner;
} // namespace base
namespace network {
class SharedURLLoaderFactory;
namespace assist_ranker {
class RankerURLFetcher;
// Loads a ranker model. Will attempt to load the model from disk cache. If it
// fails, will attempt to download from the given URL.
class RankerModelLoaderImpl : public RankerModelLoader {
// |validate_model_callback| may be called on any sequence; it must be thread
// safe.
// |on_model_available_callback| will be called on the sequence on which the
// ranker model loader is constructed.
// |model_path| denotes the file path at which the model is cached. The loader
// will attempt to load the model from this path first, falling back to the
// |model_url| if the model cannot be loaded or has expired. Upon downloading
// a fresh model from |model_url| the model will be persisted to |model_path|
// for subsequent caching.
// |model_url| denotes the URL from which the model should be loaded, if it
// has not already been cached at |model_path|.
// |uma_prefix| will be used as a prefix for the names of all UMA metrics
// generated by this loader.
ValidateModelCallback validate_model_callback,
OnModelAvailableCallback on_model_available_callback,
scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory,
base::FilePath model_path,
GURL model_url,
std::string uma_prefix);
~RankerModelLoaderImpl() override;
// Call this method periodically to notify the model loader the ranker is
// actively in use. The user's engagement with the ranked feature is used
// as a proxy for network availability and activity. If a model download
// is pending, this will trigger (subject to retry and frequency limits) a
// model download attempt.
void NotifyOfRankerActivity() override;
// A enum to track the current loader state.
enum class LoaderState {
// The loader is newly created and has not started trying to load the model.
// This state can transition to LOADING_FROM_FILE or, if |model_path_| is
// empty, to LOADING_FROM_URL. If both |model_path_| and |model_url_| are
// empty/invalid then it can transition to FINISHED.
// The loader is busy loading the model from |model_path_| in the
// background. This state can transition to FINISHED if the loaded model is
// compatible and up to date; otherwise, this state can transition to IDLE.
// The loader is not currently busy. The loader can transition to the
// LOADING_FROM_URL_ state if |model_url_| is valid; the loader can also
// transition to FINISHED if it the maximum number of download attempts
// has been reached.
// The loader is busy loading the model from |model_url_| in the background.
// This state can transition to FINISHED if the loaded model is valid;
// otherwise, this state can re-transition to IDLE.
// The loader has finished. This is the terminal state.
// Asynchronously initiates loading the model from model_path_;
void StartLoadFromFile();
// Called when the background worker has finished loading |data| from
// |model_path_|. If |data| is empty, the load from |model_path_| failed.
void OnFileLoaded(const std::string& data);
// Asynchronously initiates loading the model from |model_url_|.
void StartLoadFromURL();
// Called when |url_fetcher_| has finished loading |data| from |model_url_|.
// This call signature is mandated by RankerURLFetcher.
// success - true of the download was successful
// data - the body of the downloads response
void OnURLFetched(bool success, const std::string& data);
// Parse |data| and return a validated model. Returns nullptr on failure.
std::unique_ptr<assist_ranker::RankerModel> CreateAndValidateModel(
const std::string& data);
// Helper function to log |model_status| to UMA and return it.
RankerModelStatus ReportModelStatus(RankerModelStatus model_status);
// Validates that ranker model loader tasks are all performed on the same
// sequence.
// The task runner on which background tasks are performed.
const scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
// Validates a ranker model on behalf of the model loader client. This will be
// called on the sequence on which the model leader was constructed.
const ValidateModelCallback validate_model_cb_;
// Transfers ownership of a loaded model back to the model loader client.
// This will be called on the sequence on which the model loader was
// constructed.
const OnModelAvailableCallback on_model_available_cb_;
// URL loader factory used for RankerURLFetcher.
scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory_;
// The path at which the model is (or should be) cached.
const base::FilePath model_path_;
// The URL from which to download the model if the model is not in the cache
// or the cached model is invalid/expired.
const GURL model_url_;
// This will prefix all UMA metrics generated by the model loader.
const std::string uma_prefix_;
// Used to download model data from |model_url_|.
std::unique_ptr<RankerURLFetcher> url_fetcher_;
// The next time before which no new attempts to download the model should be
// attempted.
base::TimeTicks next_earliest_download_time_;
// Tracks the last time of the last attempt to load a model, either from file
// of from URL. Used for UMA reporting of load durations.
base::TimeTicks load_start_time_;
// The current state of the loader.
LoaderState state_ = LoaderState::NOT_STARTED;
// Creates weak pointer references to the loader.
base::WeakPtrFactory<RankerModelLoaderImpl> weak_ptr_factory_;
} // namespace assist_ranker