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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include <utility>
#include <vector>
#include "base/files/file.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/sequence_checker.h"
#include "base/task/task_traits.h"
#include "base/task/thread_pool.h"
#include "build/build_config.h"
#include "services/audio/ml_model_manager.h"
#include "third_party/tflite/src/tensorflow/lite/model_builder.h"
namespace audio {
// Holds the TFLite model and the buffer that backs it.
// The buffer must outlive the model.
struct ModelWithBuffer {
explicit ModelWithBuffer(size_t buffer_size) : buffer(buffer_size) {}
~ModelWithBuffer() = default;
std::vector<uint8_t> buffer;
std::unique_ptr<tflite::FlatBufferModel> model;
int num_active_clients = 0;
};
namespace {
// Reads the model contents from the given base::File.
// This function is intended to run on a background thread.
// Returns a struct containing the model and its backing buffer.
std::unique_ptr<ModelWithBuffer> ReadModelContents(base::File model_file) {
if (!model_file.IsValid()) {
LOG(ERROR) << "Invalid model file.";
return nullptr;
}
int64_t length = model_file.GetLength();
if (length <= 0) {
LOG(ERROR) << "Invalid model file length.";
return nullptr;
}
auto model_with_buffer = std::make_unique<ModelWithBuffer>(length);
if (!model_file.ReadAndCheck(0, model_with_buffer->buffer)) {
LOG(ERROR) << "Failed to read model file contents.";
return nullptr;
}
model_with_buffer->model = tflite::FlatBufferModel::BuildFromBuffer(
reinterpret_cast<const char*>(model_with_buffer->buffer.data()),
model_with_buffer->buffer.size());
if (!model_with_buffer->model) {
LOG(ERROR) << "Failed to build FlatBufferModel from buffer.";
return nullptr;
}
return model_with_buffer;
}
class MlModelHandleImpl : public MlModelHandle {
public:
MlModelHandleImpl(tflite::FlatBufferModel* model,
base::OnceClosure on_destruction_closure)
: model_(model),
on_destruction_closure_(std::move(on_destruction_closure)) {
CHECK(model);
}
~MlModelHandleImpl() override {
// Explicitly reset the model pointer as the pointed-to memory may be
// affected by the destruction closure.
model_ = nullptr;
std::move(on_destruction_closure_).Run();
}
const tflite::FlatBufferModel* Get() override { return model_; }
private:
raw_ptr<tflite::FlatBufferModel> model_;
base::OnceClosure on_destruction_closure_;
};
} // namespace
MlModelManagerImpl::MlModelManagerImpl() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
MlModelManagerImpl::~MlModelManagerImpl() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CHECK(!used_serving_model_ && retired_models_.size() == 0)
<< "MlModelManagerImpl has existing clients at destruction time";
}
void MlModelManagerImpl::BindReceiver(
mojo::PendingReceiver<mojom::MlModelManager> receiver) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CHECK(!receiver_.has_value());
receiver_.emplace(this, std::move(receiver));
}
void MlModelManagerImpl::OnResidualEchoEstimationModelRead(
std::unique_ptr<ModelWithBuffer> model_with_buffer) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (!model_with_buffer) {
// Model load failed, ignore.
return;
}
if (used_serving_model_) {
retired_models_.emplace(used_serving_model_.get(),
std::move(used_serving_model_));
}
unused_serving_model_ = std::move(model_with_buffer);
}
void MlModelManagerImpl::StopServingResidualEchoEstimationModel() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Stop any ongoing model loading: This stop signal makes it obsolete.
CancelModelLoadingTasks();
if (used_serving_model_) {
retired_models_.emplace(used_serving_model_.get(),
std::move(used_serving_model_));
}
unused_serving_model_.reset();
used_serving_model_.reset();
}
void MlModelManagerImpl::SetResidualEchoEstimationModel(
base::File tflite_file) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Stop loading any older models:
// - They are soon replaced with this new file, and
// - we don't want races due to different file operation durations.
CancelModelLoadingTasks();
base::ThreadPool::PostTaskAndReplyWithResult(
FROM_HERE, {base::MayBlock(), base::TaskPriority::BEST_EFFORT},
base::BindOnce(&ReadModelContents, std::move(tflite_file)),
base::BindOnce(&MlModelManagerImpl::OnResidualEchoEstimationModelRead,
weak_factory_.GetWeakPtr()));
}
void MlModelManagerImpl::OnModelHandleDestruction(ModelWithBuffer* model) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CHECK(model);
// Find the model, and update the client count.
if (model == used_serving_model_.get()) {
// The model is actively serving.
CHECK_GT(used_serving_model_->num_active_clients, 0);
--used_serving_model_->num_active_clients;
if (used_serving_model_->num_active_clients == 0) {
unused_serving_model_ = std::move(used_serving_model_);
}
return;
}
// If we get here, the model is one of the retired models.
auto iter = retired_models_.find(model);
CHECK(iter != retired_models_.end());
ModelWithBuffer& retired_model = *(*iter).second;
CHECK_GT(retired_model.num_active_clients, 0);
--(retired_model.num_active_clients);
if (retired_model.num_active_clients == 0) {
// All clients are gone, the model can be deleted.
retired_models_.erase(iter);
}
}
std::unique_ptr<MlModelHandle>
MlModelManagerImpl::GetResidualEchoEstimationModel() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (!unused_serving_model_ && !used_serving_model_) {
return nullptr;
}
if (unused_serving_model_) {
used_serving_model_ = std::move(unused_serving_model_);
}
++(used_serving_model_->num_active_clients);
return std::make_unique<MlModelHandleImpl>(
used_serving_model_->model.get(),
base::BindOnce(&MlModelManagerImpl::OnModelHandleDestruction,
// Safe because the MlModelManager API requires clients to
// destroy their model handles within the manager lifetime.
base::Unretained(this), used_serving_model_.get()));
}
void MlModelManagerImpl::CancelModelLoadingTasks() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
weak_factory_.InvalidateWeakPtrs();
}
bool MlModelManagerImpl::HasPendingTasksForTesting() const {
return weak_factory_.HasWeakPtrs();
}
} // namespace audio
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