bin/media/audio_server/audio_link.h

// Copyright 2017 The Fuchsia 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 GARNET_BIN_MEDIA_AUDIO_SERVER_AUDIO_LINK_H_
#define GARNET_BIN_MEDIA_AUDIO_SERVER_AUDIO_LINK_H_

#include <fbl/ref_ptr.h>

#include "garnet/bin/media/audio_server/gain.h"
#include "lib/fxl/logging.h"
#include "lib/fxl/synchronization/thread_annotations.h"

namespace media {
namespace audio {

class AudioDevice;
class AudioObject;

// AudioLink is the base class of two different versions of AudioLinks which
// join sources of audio (renderers, inputs, and loop-backed outputs) to
// destinations (outputs and capturers).
//
// TODO(johngro): Finish docs.
// TODO(johngro): Manage link tracking using instrusive pointers.  Intrusive
// storage goes at this level.
//
class AudioLink {
 public:
  enum class SourceType {
    Packet,
    RingBuffer,
  };
  struct Bookkeeping {
    virtual ~Bookkeeping() {}
  };

  virtual ~AudioLink();

  const fbl::RefPtr<AudioObject>& GetSource() { return source_; }
  const fbl::RefPtr<AudioObject>& GetDest() { return dest_; }

  SourceType source_type() const { return source_type_; }

  // Accessor for the link's gain state tracking class.  Used by both the main
  // message loop thread and the mixer threads.
  Gain& gain() { return gain_; }

  // Current validity.  Sources invalidate links when they either go away, or
  // change formats.
  void Invalidate() { valid_.store(false); }
  bool valid() const { return valid_.load(); }

  // Bookkeeping access.
  const std::unique_ptr<Bookkeeping>& bookkeeping() { return bookkeeping_; }
  void set_bookkeeping(std::unique_ptr<Bookkeeping> bookkeeping) {
    FXL_DCHECK(bookkeeping_ == nullptr);
    bookkeeping_ = std::move(bookkeeping);
  }

 protected:
  AudioLink(SourceType source_type, fbl::RefPtr<AudioObject> source,
            fbl::RefPtr<AudioObject> dest);

 private:
  const SourceType source_type_;
  fbl::RefPtr<AudioObject> source_;
  fbl::RefPtr<AudioObject> dest_;
  std::unique_ptr<Bookkeeping> bookkeeping_;
  Gain gain_;
  std::atomic_bool valid_;
};

}  // namespace audio
}  // namespace media

#endif  // GARNET_BIN_MEDIA_AUDIO_SERVER_AUDIO_LINK_H_