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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_CAST_STREAMING_RENDERER_WEB_CODECS_DELEGATING_DECODER_BUFFER_PROVIDER_H_
#define COMPONENTS_CAST_STREAMING_RENDERER_WEB_CODECS_DELEGATING_DECODER_BUFFER_PROVIDER_H_
#include <memory>
#include "base/functional/bind.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task/sequenced_task_runner.h"
#include "components/cast_streaming/renderer/public/decoder_buffer_provider.h"
namespace cast_streaming::webcodecs {
// This class provides a thread-safe wrapper around a DecoderBufferProvider's
// weak_ptr, to avoid the limitation that a weak_ptr may only be called from
// the thread where it is created. All calls are delegated to the underlying
// instance.
//
// In practice, an instance of this class will be provided to a javascript
// instance, which will then use it to pull frame data from the
// |delegated_provider_| on a javascript-specific task runner.
template <typename TConfigType>
class DelegatingDecoderBufferProvider
: public DecoderBufferProvider<TConfigType> {
public:
using GetConfigCb = typename DecoderBufferProvider<TConfigType>::GetConfigCb;
using NewBufferCb = typename DecoderBufferProvider<TConfigType>::NewBufferCb;
using DeletionCb = typename DecoderBufferProvider<TConfigType>::DeletionCb;
DelegatingDecoderBufferProvider(
base::WeakPtr<DecoderBufferProvider<TConfigType>> delegated_provider,
scoped_refptr<base::SequencedTaskRunner> task_runner)
: delegated_provider_(std::move(delegated_provider)),
task_runner_(std::move(task_runner)),
weak_factory_(this) {}
~DelegatingDecoderBufferProvider() override = default;
// DecoderBufferProvider overrides.
bool IsValid() const override { return existed_at_last_check_.load(); }
void GetConfigAsync(GetConfigCb callback) const override {
if (!existed_at_last_check_) {
return;
}
if (!task_runner_->RunsTasksInCurrentSequence()) {
task_runner_->PostTask(
FROM_HERE,
base::BindOnce(&DelegatingDecoderBufferProvider::GetConfigAsync,
weak_factory_.GetWeakPtr(), std::move(callback)));
return;
}
if (!delegated_provider_) {
existed_at_last_check_.store(false);
return;
}
delegated_provider_->GetConfigAsync(std::move(callback));
}
void ReadBufferAsync(NewBufferCb callback) override {
if (!existed_at_last_check_) {
return;
}
if (!task_runner_->RunsTasksInCurrentSequence()) {
task_runner_->PostTask(
FROM_HERE,
base::BindOnce(&DelegatingDecoderBufferProvider::ReadBufferAsync,
weak_factory_.GetWeakPtr(), std::move(callback)));
return;
}
if (!delegated_provider_) {
existed_at_last_check_.store(false);
return;
}
delegated_provider_->ReadBufferAsync(std::move(callback));
}
void SetInvalidationCallback(DeletionCb callback) override {
if (!existed_at_last_check_) {
std::move(callback).Run();
return;
}
if (!task_runner_->RunsTasksInCurrentSequence()) {
task_runner_->PostTask(
FROM_HERE,
base::BindOnce(
&DelegatingDecoderBufferProvider::SetInvalidationCallback,
weak_factory_.GetWeakPtr(), std::move(callback)));
return;
}
if (!delegated_provider_) {
existed_at_last_check_.store(false);
std::move(callback).Run();
return;
}
delegated_provider_->SetInvalidationCallback(std::move(callback));
}
private:
mutable std::atomic_bool existed_at_last_check_{true};
base::WeakPtr<DecoderBufferProvider<TConfigType>> delegated_provider_;
scoped_refptr<base::SequencedTaskRunner> task_runner_;
base::WeakPtrFactory<DelegatingDecoderBufferProvider> weak_factory_;
};
} // namespace cast_streaming::webcodecs
#endif // COMPONENTS_CAST_STREAMING_RENDERER_WEB_CODECS_DELEGATING_DECODER_BUFFER_PROVIDER_H_
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