services/media/framework_mojo/mojo_producer.h

// Copyright 2016 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 SERVICES_MEDIA_FRAMEWORK_MOJO_PUSH_PRODUCER_BASE_H_
#define SERVICES_MEDIA_FRAMEWORK_MOJO_PUSH_PRODUCER_BASE_H_

#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "mojo/common/binding_set.h"
#include "mojo/services/media/common/interfaces/media_state.mojom.h"
#include "mojo/services/media/common/interfaces/media_transport.mojom.h"
#include "services/media/framework/models/active_sink.h"
#include "services/media/framework_mojo/mojo_allocator.h"

namespace mojo {
namespace media {

// Implements MediaProducer to forward a stream across mojo.
class MojoProducer : public MediaProducer, public ActiveSink {
 public:
  using StatusCallback = std::function<void(MediaState)>;
  using PrimeConnectionCallback = mojo::Callback<void()>;
  using FlushConnectionCallback = mojo::Callback<void()>;

  static std::shared_ptr<MojoProducer> Create() {
    return std::shared_ptr<MojoProducer>(new MojoProducer());
  }

  ~MojoProducer() override;

  // Adds a binding.
  void AddBinding(InterfaceRequest<MediaProducer> producer);

  // Initiates demand to provide downstream parties with enough content to
  // start without starving.
  void PrimeConnection(const PrimeConnectionCallback& callback);

  // Unprimes and tells the connected consumer to flush.
  void FlushConnection(const FlushConnectionCallback& callback);

  // Sets a callback for reporting status updates.
  void SetStatusCallback(const StatusCallback& callback);

  // Gets the first presentation time seen on any packet after the most recent
  // flush or, if there has never been a flush, the first packet supplied.
  int64_t GetFirstPtsSinceFlush();

  // ActiveSink implementation.
  PayloadAllocator* allocator() override;

  void SetDemandCallback(const DemandCallback& demand_callback) override;

  Demand SupplyPacket(PacketPtr packet) override;

  // MediaProducer implementation.
  void Connect(InterfaceHandle<MediaConsumer> consumer,
               const ConnectCallback& callback) override;

  void Disconnect() override;

 private:
  MojoProducer();

  // Sends a packet to the consumer.
  // TODO(dalesat): Don't use a raw pointer, if possible.
  void SendPacket(Packet* packet_raw_ptr, MediaPacketPtr media_packet);

  // Sets the current state and calls the registered callback, if there is one.
  void SetState(MediaState state);

  // Creates a MediaPacket from a Packet.
  MediaPacketPtr CreateMediaPacket(const PacketPtr& packet);

  // Allocates from the shared buffer.
  MojoAllocator mojo_allocator_;

  BindingSet<MediaProducer> bindings_;
  MediaConsumerPtr consumer_;
  StatusCallback status_callback_;

  mutable base::Lock lock_;
  // THE FIELDS BELOW SHOULD ONLY BE ACCESSED WITH lock_ TAKEN.
  MediaState state_ = MediaState::UNPREPARED;
  bool end_of_stream_ = false;
  DemandCallback demand_callback_;
  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  int64_t first_pts_since_flush_ = Packet::kUnknownPts;
  // TODO(dalesat): Base this logic on presentation time or duration.
  uint32_t max_pushes_outstanding_ = 0;
  uint32_t current_pushes_outstanding_ = 0;
  // THE FIELDS ABOVE SHOULD ONLY BE ACCESSED WITH lock_ TAKEN.
};

}  // namespace media
}  // namespace mojo

#endif  // SERVICES_MEDIA_FRAMEWORK_MOJO_PUSH_PRODUCER_BASE_H_