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// Copyright 2019 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.
#ifndef MEDIA_LEARNING_IMPL_LEARNING_TASK_CONTROLLER_HELPER_H_
#define MEDIA_LEARNING_IMPL_LEARNING_TASK_CONTROLLER_HELPER_H_
#include <map>
#include <memory>
#include "base/callback.h"
#include "base/component_export.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequenced_task_runner.h"
#include "base/threading/sequence_bound.h"
#include "media/learning/common/learning_task_controller.h"
#include "media/learning/impl/feature_provider.h"
#include "services/metrics/public/cpp/ukm_source_id.h"
namespace media {
namespace learning {
class LearningTaskControllerHelperTest;
// Helper class for managing LabelledExamples that are constructed
// incrementally. Keeps track of in-flight examples as they're added via
// BeginObservation, updated with features from a FeatureProvider, or given a
// TargetValue. When examples are complete, it provides them to a callback for
// further processing.
//
// Since both the mojo LearningTaskController and LearningTaskControllerImpl
// will need to do almost exactly the same thing, this class handles the common
// logic for them.
class COMPONENT_EXPORT(LEARNING_IMPL) LearningTaskControllerHelper
: public base::SupportsWeakPtr<LearningTaskControllerHelper> {
public:
// Callback to add labelled examples as training data.
using AddExampleCB =
base::RepeatingCallback<void(LabelledExample, ukm::SourceId)>;
// TODO(liberato): Consider making the FP not optional.
LearningTaskControllerHelper(const LearningTask& task,
AddExampleCB add_example_cb,
SequenceBoundFeatureProvider feature_provider =
SequenceBoundFeatureProvider());
virtual ~LearningTaskControllerHelper();
// See LearningTaskController::BeginObservation.
void BeginObservation(base::UnguessableToken id, FeatureVector features);
void CompleteObservation(base::UnguessableToken id,
const ObservationCompletion& completion);
void CancelObservation(base::UnguessableToken id);
private:
// Record of an example that has been started by RecordObservedFeatures, but
// not finished yet.
struct PendingExample {
// The example we're constructing.
LabelledExample example;
// Has the FeatureProvider added features?
bool features_done = false;
// Has the client added a TargetValue?
// TODO(liberato): Should it provide a weight with the target value?
bool target_done = false;
ukm::SourceId source_id = ukm::kInvalidSourceId;
};
// [non-repeating int] = example
using PendingExampleMap = std::map<base::UnguessableToken, PendingExample>;
// Called on any sequence when features are ready. Will call OnFeatureReady
// if called on |task_runner|, or will post to |task_runner|.
static void OnFeaturesReadyTrampoline(
scoped_refptr<base::SequencedTaskRunner> task_runner,
base::WeakPtr<LearningTaskControllerHelper> weak_this,
base::UnguessableToken id,
FeatureVector features);
// Called when a new feature vector has been finished by |feature_provider_|,
// if needed, to actually add the example.
void OnFeaturesReady(base::UnguessableToken example_id,
FeatureVector features);
// If |example| is finished, then send it to the LearningSession and remove it
// from the map. Otherwise, do nothing.
void ProcessExampleIfFinished(PendingExampleMap::iterator example);
// The task we'll add examples to.
LearningTask task_;
// Optional feature provider.
SequenceBoundFeatureProvider feature_provider_;
// All outstanding PendingExamples.
PendingExampleMap pending_examples_;
// While the handling of |pending_examples_| is an implementation detail, we
// still let tests verify the map size, to help catch cases where we forget to
// remove things from the map and slowly leak memory.
size_t pending_example_count_for_testing() const {
return pending_examples_.size();
}
scoped_refptr<base::SequencedTaskRunner> task_runner_;
// Callback to which we'll send finished examples.
AddExampleCB add_example_cb_;
friend class LearningTaskControllerHelperTest;
};
} // namespace learning
} // namespace media
#endif // MEDIA_LEARNING_IMPL_LEARNING_TASK_CONTROLLER_HELPER_H_
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