DecoderAgent.h - mozsearch

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

/* vim:set ts=2 sw=2 sts=2 et cindent: */

/* 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 http://mozilla.org/MPL/2.0/. */

#ifndef DOM_MEDIA_WEBCODECS_DECODERAGENT_H

#define DOM_MEDIA_WEBCODECS_DECODERAGENT_H

#include "MediaResult.h"

#include "PlatformDecoderModule.h"

#include "mozilla/RefPtr.h"

#include "mozilla/TaskQueue.h"

#include "mozilla/UniquePtr.h"

class nsISerialEventTarget;

namespace mozilla {

class PDMFactory;

class TrackInfo;

namespace layers {

class ImageContainer;

}  // namespace layers

// DecoderAgent is a wrapper that contains a MediaDataDecoder. It adapts the

// MediaDataDecoder APIs for use in WebCodecs.

//

// If Configure() is called, Shutdown() must be called to release the resources

// gracefully. Except Shutdown(), all the methods can't be called concurrently,

// meaning a method can only be called when the previous API call has completed.

// The responsability of arranging the method calls is on the caller.

//

// When Shutdown() is called, all the operations in flight are canceled and the

// MediaDataDecoder is shut down. On the other hand, errors are final. A new

// DecoderAgent must be created when an error is encountered.

//

// All the methods need to be called on the DecoderAgent's owner thread. In

// WebCodecs, it's either on the main thread or worker thread.

class DecoderAgent final {

 public:

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DecoderAgent);

  using Id = uint32_t;

  DecoderAgent(Id aId, UniquePtr<TrackInfo>&& aInfo);

  // The following APIs are owner thread only.

  using ConfigurePromise = MozPromise<bool, MediaResult, true /* exclusive */>;

  RefPtr<ConfigurePromise> Configure(bool aPreferSoftwareDecoder,

                                     bool aLowLatency);

  RefPtr<ShutdownPromise> Shutdown();

  using DecodePromise = MediaDataDecoder::DecodePromise;

  RefPtr<DecodePromise> Decode(MediaRawData* aSample);

  // WebCodecs's flush() flushes out all the pending decoded data in the

  // MediaDataDecoder so it is a combination of Drain and Flush. To distinguish

  // the term from MediaDataDecoder's one, we call it DrainAndFlush() here.

  RefPtr<DecodePromise> DrainAndFlush();

  const Id mId;  // A unique id.

  const UniquePtr<TrackInfo> mInfo;

 private:

  ~DecoderAgent();

  // Push out all the data in the MediaDataDecoder's pipeline.

  // TODO: MediaDataDecoder should implement this, instead of asking call site

  // to run `Drain` multiple times.

  RefPtr<DecodePromise> Dry();

  void DrainUntilDry();

  enum class State {

    Unconfigured,

    Configuring,

    Configured,

    Decoding,

    Flushing,

    ShuttingDown,

    Error,

};

  void SetState(State aState);

  const RefPtr<nsISerialEventTarget> mOwnerThread;

  const RefPtr<PDMFactory> mPDMFactory;

  const RefPtr<layers::ImageContainer> mImageContainer;

  RefPtr<MediaDataDecoder> mDecoder;

  State mState;

  // Configure

  MozPromiseHolder<ConfigurePromise> mConfigurePromise;

  using CreateDecoderPromise = PlatformDecoderModule::CreateDecoderPromise;

  MozPromiseRequestHolder<CreateDecoderPromise> mCreateRequest;

  using InitPromise = MediaDataDecoder::InitPromise;

  MozPromiseRequestHolder<InitPromise> mInitRequest;

  // Shutdown

  MozPromiseHolder<ShutdownPromise> mShutdownWhileCreationPromise;

  // Decode

  MozPromiseHolder<DecodePromise> mDecodePromise;

  MozPromiseRequestHolder<DecodePromise> mDecodeRequest;

  // DrainAndFlush

  MozPromiseHolder<DecodePromise> mDrainAndFlushPromise;

  MediaDataDecoder::DecodedData mDrainAndFlushData;

  MozPromiseRequestHolder<DecodePromise> mDryRequest;

  MozPromiseHolder<DecodePromise> mDryPromise;

  MediaDataDecoder::DecodedData mDryData;

  MozPromiseRequestHolder<DecodePromise> mDrainRequest;

  using FlushPromise = MediaDataDecoder::FlushPromise;

  MozPromiseRequestHolder<FlushPromise> mFlushRequest;

};

}  // namespace mozilla

#endif  // DOM_MEDIA_WEBCODECS_DECODERAGENT_H