FrameTransformerProxy.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#ifndef MOZILLA_DOM_MEDIA_WEBRTC_LIBWEBRTCGLUE_FRAMETRANSFORMERPROXY_H_

#define MOZILLA_DOM_MEDIA_WEBRTC_LIBWEBRTCGLUE_FRAMETRANSFORMERPROXY_H_

#include "nsISupportsImpl.h"

#include "mozilla/Mutex.h"

#include "mozilla/Maybe.h"

#include <list>

#include <memory>

class nsIEventTarget;

namespace webrtc {

class TransformableFrameInterface;

class VideoReceiveStreamInterface;

}  // namespace webrtc

namespace mozilla {

class FrameTransformer;

class WebrtcVideoConduit;

class CopyableErrorResult;

namespace dom {

class RTCRtpScriptTransformer;

class RTCRtpSender;

class RTCRtpReceiver;

}  // namespace dom

// This corresponds to a single RTCRtpScriptTransform (and its

// RTCRtpScriptTransformer, once that is created on the worker thread). This

// is intended to decouple threading/lifecycle/include-dependencies between

// FrameTransformer (on the libwebrtc side of things), RTCRtpScriptTransformer

// (on the worker side of things), RTCRtpScriptTransform and

// RTCRtpSender/Receiver (on the main thread), and prevents frames from being

// lost while we're setting things up on the worker. In other words, this

// handles the inconvenient stuff.

class FrameTransformerProxy {

 public:

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FrameTransformerProxy);

  FrameTransformerProxy();

  FrameTransformerProxy(const FrameTransformerProxy& aRhs) = delete;

  FrameTransformerProxy(FrameTransformerProxy&& aRhs) = delete;

  FrameTransformerProxy& operator=(const FrameTransformerProxy& aRhs) = delete;

  FrameTransformerProxy& operator=(FrameTransformerProxy&& aRhs) = delete;

  // Called at most once (might not be called if the worker is shutting down),

  // on the worker thread.

  void SetScriptTransformer(dom::RTCRtpScriptTransformer& aTransformer);

  // Can be called from the worker thread (if the worker is shutting down), or

  // main (if RTCRtpSender/RTCRtpReceiver is done with us).

  void ReleaseScriptTransformer();

  // RTCRtpScriptTransformer calls this when it is done transforming a frame.

  void OnTransformedFrame(

      std::unique_ptr<webrtc::TransformableFrameInterface> aFrame);

  Maybe<bool> IsVideo() const;

  // Called by FrameTransformer, on main. Only one FrameTransformer will ever

  // be registered over the lifetime of this object. This is where we route

  // transformed frames. If this is set, we can also expect to receive calls to

  // Transform.

  void SetLibwebrtcTransformer(FrameTransformer* aLibwebrtcTransformer);

  // FrameTransformer calls this while we're registered with it (by

  // SetLibwebrtcTransformer)

  void Transform(std::unique_ptr<webrtc::TransformableFrameInterface> aFrame);

  void SetSender(dom::RTCRtpSender* aSender);

  void SetReceiver(dom::RTCRtpReceiver* aReceiver);

  // Called on worker thread

  bool RequestKeyFrame();

  // Called on call thread

  void KeyFrameRequestDone(bool aSuccess);

  bool GenerateKeyFrame(const Maybe<std::string>& aRid);

  void GenerateKeyFrameError(const Maybe<std::string>& aRid,

                             const CopyableErrorResult& aResult);

 private:

  virtual ~FrameTransformerProxy();

  // Worker thread only. Set at most once.

  // Does not need any mutex protection.

  RefPtr<dom::RTCRtpScriptTransformer> mScriptTransformer;

  mutable Mutex mMutex;

  // Written on the worker thread. Read on libwebrtc threads, mainthread, and

  // the worker thread.

  RefPtr<nsIEventTarget> mWorkerThread MOZ_GUARDED_BY(mMutex);

  // We need a flag for this in case the ReleaseScriptTransformer call comes

  // _before_ the script transformer is set, to disable SetScriptTransformer.

  // Could be written on main or the worker thread. Read on main, worker, and

  // libwebrtc threads.

  bool mReleaseScriptTransformerCalled MOZ_GUARDED_BY(mMutex) = false;

  // Used when frames arrive before the script transformer is created, which

  // should be pretty rare. Accessed on worker and libwebrtc threads.

  std::list<std::unique_ptr<webrtc::TransformableFrameInterface>> mQueue

      MOZ_GUARDED_BY(mMutex);

  // Written on main, read on the worker thread.

  FrameTransformer* mLibwebrtcTransformer MOZ_GUARDED_BY(mMutex) = nullptr;

  // TODO: Will be used to route GenerateKeyFrame. Details TBD.

  RefPtr<dom::RTCRtpSender> mSender MOZ_GUARDED_BY(mMutex);

  // Set on mainthread. This is where we route RequestKeyFrame calls from the

  // worker thread. Mutex protected because spec wants sync errors if the

  // receiver is not set (or the right type). If spec drops this requirement,

  // this could be mainthread only and non-mutex-protected.

  RefPtr<dom::RTCRtpReceiver> mReceiver MOZ_GUARDED_BY(mMutex);

  Maybe<bool> mVideo MOZ_GUARDED_BY(mMutex);

};

}  // namespace mozilla

#endif  // MOZILLA_DOM_MEDIA_WEBRTC_LIBWEBRTCGLUE_FRAMETRANSFORMERPROXY_H_