layers/ipc/CanvasChild.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=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 http://mozilla.org/MPL/2.0/. */

#include "CanvasChild.h"

#include "MainThreadUtils.h"
#include "mozilla/gfx/DrawTargetRecording.h"
#include "mozilla/gfx/Tools.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/gfx/Point.h"
#include "mozilla/ipc/Endpoint.h"
#include "mozilla/ipc/ProcessChild.h"
#include "mozilla/layers/CanvasDrawEventRecorder.h"
#include "nsIObserverService.h"
#include "RecordedCanvasEventImpl.h"

namespace mozilla {
namespace layers {

class RingBufferWriterServices final
    : public CanvasEventRingBuffer::WriterServices {
 public:
  explicit RingBufferWriterServices(RefPtr<CanvasChild> aCanvasChild)
      : mCanvasChild(std::move(aCanvasChild)) {}

  ~RingBufferWriterServices() final = default;

  bool ReaderClosed() final {
    return !mCanvasChild->GetIPCChannel()->CanSend() ||
           ipc::ProcessChild::ExpectingShutdown();
  }

  void ResumeReader() final { mCanvasChild->ResumeTranslation(); }

 private:
  RefPtr<CanvasChild> mCanvasChild;
};

class SourceSurfaceCanvasRecording final : public gfx::SourceSurface {
 public:
  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(SourceSurfaceCanvasRecording, final)

  SourceSurfaceCanvasRecording(
      const RefPtr<gfx::SourceSurface>& aRecordedSuface,
      CanvasChild* aCanvasChild,
      const RefPtr<CanvasDrawEventRecorder>& aRecorder)
      : mRecordedSurface(aRecordedSuface),
        mCanvasChild(aCanvasChild),
        mRecorder(aRecorder) {
    mRecorder->RecordEvent(RecordedAddSurfaceAlias(this, aRecordedSuface));
    mRecorder->AddStoredObject(this);
  }

  ~SourceSurfaceCanvasRecording() {
    ReleaseOnMainThread(std::move(mRecorder), this, std::move(mRecordedSurface),
                        std::move(mCanvasChild));
  }

  gfx::SurfaceType GetType() const final { return mRecordedSurface->GetType(); }

  gfx::IntSize GetSize() const final { return mRecordedSurface->GetSize(); }

  gfx::SurfaceFormat GetFormat() const final {
    return mRecordedSurface->GetFormat();
  }

  already_AddRefed<gfx::DataSourceSurface> GetDataSurface() final {
    EnsureDataSurfaceOnMainThread();
    return do_AddRef(mDataSourceSurface);
  }

 private:
  void EnsureDataSurfaceOnMainThread() {
    // The data can only be retrieved on the main thread.
    if (!mDataSourceSurface && NS_IsMainThread()) {
      mDataSourceSurface = mCanvasChild->GetDataSurface(mRecordedSurface);
    }
  }

  // Used to ensure that clean-up that requires it is done on the main thread.
  static void ReleaseOnMainThread(RefPtr<CanvasDrawEventRecorder> aRecorder,
                                  ReferencePtr aSurfaceAlias,
                                  RefPtr<gfx::SourceSurface> aAliasedSurface,
                                  RefPtr<CanvasChild> aCanvasChild) {
    if (!NS_IsMainThread()) {
      NS_DispatchToMainThread(NewRunnableFunction(
          "SourceSurfaceCanvasRecording::ReleaseOnMainThread",
          SourceSurfaceCanvasRecording::ReleaseOnMainThread,
          std::move(aRecorder), aSurfaceAlias, std::move(aAliasedSurface),
          std::move(aCanvasChild)));
      return;
    }

    aRecorder->RemoveStoredObject(aSurfaceAlias);
    aRecorder->RecordEvent(RecordedRemoveSurfaceAlias(aSurfaceAlias));
    aAliasedSurface = nullptr;
    aCanvasChild = nullptr;
    aRecorder = nullptr;
  }

  RefPtr<gfx::SourceSurface> mRecordedSurface;
  RefPtr<CanvasChild> mCanvasChild;
  RefPtr<CanvasDrawEventRecorder> mRecorder;
  RefPtr<gfx::DataSourceSurface> mDataSourceSurface;
};

CanvasChild::CanvasChild(Endpoint<PCanvasChild>&& aEndpoint) {
  aEndpoint.Bind(this);
}

CanvasChild::~CanvasChild() = default;

static void NotifyCanvasDeviceReset() {
  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  if (obs) {
    obs->NotifyObservers(nullptr, "canvas-device-reset", nullptr);
  }
}

ipc::IPCResult CanvasChild::RecvNotifyDeviceChanged() {
  NotifyCanvasDeviceReset();
  mRecorder->RecordEvent(RecordedDeviceChangeAcknowledged());
  return IPC_OK();
}

/* static */ bool CanvasChild::mDeactivated = false;

ipc::IPCResult CanvasChild::RecvDeactivate() {
  mDeactivated = true;
  NotifyCanvasDeviceReset();
  return IPC_OK();
}

void CanvasChild::EnsureRecorder(TextureType aTextureType) {
  if (!mRecorder) {
    MOZ_ASSERT(mTextureType == TextureType::Unknown);
    mTextureType = aTextureType;
    mRecorder = MakeAndAddRef<CanvasDrawEventRecorder>();
    SharedMemoryBasic::Handle handle;
    CrossProcessSemaphoreHandle readerSem;
    CrossProcessSemaphoreHandle writerSem;
    if (!mRecorder->Init(OtherPid(), &handle, &readerSem, &writerSem,
                         MakeUnique<RingBufferWriterServices>(this))) {
      mRecorder = nullptr;
      return;
    }

    if (CanSend()) {
      Unused << SendInitTranslator(mTextureType, std::move(handle),
                                   std::move(readerSem), std::move(writerSem));
    }
  }

  MOZ_RELEASE_ASSERT(mTextureType == aTextureType,
                     "We only support one remote TextureType currently.");
}

void CanvasChild::ActorDestroy(ActorDestroyReason aWhy) {
  // Explicitly drop our reference to the recorder, because it holds a reference
  // to us via the ResumeTranslation callback.
  mRecorder = nullptr;
}

void CanvasChild::ResumeTranslation() {
  if (CanSend()) {
    SendResumeTranslation();
  }
}

void CanvasChild::Destroy() {
  if (CanSend()) {
    Close();
  }
}

void CanvasChild::OnTextureWriteLock() {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return;
  }

  mHasOutstandingWriteLock = true;
  mLastWriteLockCheckpoint = mRecorder->CreateCheckpoint();
}

void CanvasChild::OnTextureForwarded() {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return;
  }

  if (mHasOutstandingWriteLock) {
    mRecorder->RecordEvent(RecordedCanvasFlush());
    if (!mRecorder->WaitForCheckpoint(mLastWriteLockCheckpoint)) {
      gfxWarning() << "Timed out waiting for last write lock to be processed.";
    }

    mHasOutstandingWriteLock = false;
  }

  // We hold onto the last transaction's external surfaces until we have waited
  // for the write locks in this transaction. This means we know that the
  // surfaces have been picked up in the canvas threads and there is no race
  // with them being removed from SharedSurfacesParent. Note this releases the
  // current contents of mLastTransactionExternalSurfaces.
  mRecorder->TakeExternalSurfaces(mLastTransactionExternalSurfaces);
}

void CanvasChild::EnsureBeginTransaction() {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return;
  }

  if (!mIsInTransaction) {
    mRecorder->RecordEvent(RecordedCanvasBeginTransaction());
    mIsInTransaction = true;
  }
}

void CanvasChild::EndTransaction() {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return;
  }

  if (mIsInTransaction) {
    mRecorder->RecordEvent(RecordedCanvasEndTransaction());
    mIsInTransaction = false;
    mLastNonEmptyTransaction = TimeStamp::NowLoRes();
  }

  ++mTransactionsSinceGetDataSurface;
}

bool CanvasChild::ShouldBeCleanedUp() const {
  // Always return true if we've been deactivated.
  if (Deactivated()) {
    return true;
  }

  // We can only be cleaned up if nothing else references our recorder.
  if (mRecorder && !mRecorder->hasOneRef()) {
    return false;
  }

  static const TimeDuration kCleanUpCanvasThreshold =
      TimeDuration::FromSeconds(10);
  return TimeStamp::NowLoRes() - mLastNonEmptyTransaction >
         kCleanUpCanvasThreshold;
}

already_AddRefed<gfx::DrawTarget> CanvasChild::CreateDrawTarget(
    gfx::IntSize aSize, gfx::SurfaceFormat aFormat) {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return nullptr;
  }

  RefPtr<gfx::DrawTarget> dummyDt = gfx::Factory::CreateDrawTarget(
      gfx::BackendType::SKIA, gfx::IntSize(1, 1), aFormat);
  RefPtr<gfx::DrawTarget> dt = MakeAndAddRef<gfx::DrawTargetRecording>(
      mRecorder, dummyDt, gfx::IntRect(gfx::IntPoint(0, 0), aSize));
  return dt.forget();
}

void CanvasChild::RecordEvent(const gfx::RecordedEvent& aEvent) {
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return;
  }

  mRecorder->RecordEvent(aEvent);
}

already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
    const gfx::SourceSurface* aSurface) {
  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aSurface);

  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return nullptr;
  }

  mTransactionsSinceGetDataSurface = 0;
  EnsureBeginTransaction();
  mRecorder->RecordEvent(RecordedPrepareDataForSurface(aSurface));
  uint32_t checkpoint = mRecorder->CreateCheckpoint();

  gfx::IntSize ssSize = aSurface->GetSize();
  gfx::SurfaceFormat ssFormat = aSurface->GetFormat();
  size_t dataFormatWidth = ssSize.width * BytesPerPixel(ssFormat);
  RefPtr<gfx::DataSourceSurface> dataSurface =
      gfx::Factory::CreateDataSourceSurfaceWithStride(ssSize, ssFormat,
                                                      dataFormatWidth);
  if (!dataSurface) {
    gfxWarning() << "Failed to create DataSourceSurface.";
    return nullptr;
  }
  gfx::DataSourceSurface::ScopedMap map(dataSurface,
                                        gfx::DataSourceSurface::READ_WRITE);
  char* dest = reinterpret_cast<char*>(map.GetData());
  if (!mRecorder->WaitForCheckpoint(checkpoint)) {
    gfxWarning() << "Timed out preparing data for DataSourceSurface.";
    return dataSurface.forget();
  }

  mRecorder->RecordEvent(RecordedGetDataForSurface(aSurface));
  mRecorder->ReturnRead(dest, ssSize.height * dataFormatWidth);

  return dataSurface.forget();
}

already_AddRefed<gfx::SourceSurface> CanvasChild::WrapSurface(
    const RefPtr<gfx::SourceSurface>& aSurface) {
  MOZ_ASSERT(aSurface);
  // We drop mRecorder in ActorDestroy to break the reference cycle.
  if (!mRecorder) {
    return nullptr;
  }

  return MakeAndAddRef<SourceSurfaceCanvasRecording>(aSurface, this, mRecorder);
}

}  // namespace layers
}  // namespace mozilla