path: root/gfx/layers/ipc/ShadowLayers.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 "ShadowLayers.h"

#include <set>     // for _Rb_tree_const_iterator, etc
#include <vector>  // for vector

#include "ClientLayerManager.h"  // for ClientLayerManager
#include "GeckoProfiler.h"       // for AUTO_PROFILER_LABEL
#include "IPDLActor.h"
#include "ISurfaceAllocator.h"    // for IsSurfaceDescriptorValid
#include "Layers.h"               // for Layer
#include "RenderTrace.h"          // for RenderTraceScope
#include "gfx2DGlue.h"            // for Moz2D transition helpers
#include "gfxPlatform.h"          // for gfxImageFormat, gfxPlatform
#include "ipc/IPCMessageUtils.h"  // for gfxContentType, null_t
#include "mozilla/Assertions.h"   // for MOZ_ASSERT, etc
#include "mozilla/gfx/Point.h"    // for IntSize
#include "mozilla/layers/CompositableClient.h"  // for CompositableClient, etc
#include "mozilla/layers/CompositorBridgeChild.h"
#include "mozilla/layers/ContentClient.h"
#include "mozilla/layers/ImageBridgeChild.h"
#include "mozilla/layers/ImageDataSerializer.h"
#include "mozilla/layers/LayerTransactionChild.h"
#include "mozilla/layers/LayersMessages.h"  // for Edit, etc
#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor, etc
#include "mozilla/layers/LayersTypes.h"     // for MOZ_LAYERS_LOG
#include "mozilla/layers/PTextureChild.h"
#include "mozilla/layers/SyncObject.h"
#ifdef XP_DARWIN
#  include "mozilla/layers/TextureSync.h"
#endif
#include "ShadowLayerUtils.h"
#include "mozilla/ReentrantMonitor.h"
#include "mozilla/StaticPrefs_layers.h"
#include "mozilla/layers/TextureClient.h"  // for TextureClient
#include "mozilla/mozalloc.h"              // for operator new, etc
#include "nsIXULRuntime.h"                 // for BrowserTabsRemoteAutostart
#include "nsTArray.h"                      // for AutoTArray, nsTArray, etc
#include "nsXULAppAPI.h"                   // for XRE_GetProcessType, etc

namespace mozilla {
namespace ipc {
class Shmem;
}  // namespace ipc

namespace layers {

using namespace mozilla::gfx;
using namespace mozilla::gl;
using namespace mozilla::ipc;

class ClientTiledLayerBuffer;

typedef nsTArray<SurfaceDescriptor> BufferArray;
typedef nsTArray<Edit> EditVector;
typedef nsTHashtable<nsPtrHashKey<ShadowableLayer>> ShadowableLayerSet;
typedef nsTArray<OpDestroy> OpDestroyVector;

class Transaction {
 public:
  Transaction()
      : mTargetRotation(ROTATION_0),
        mTargetOrientation(hal::eScreenOrientation_None),
        mOpen(false),
        mRotationChanged(false) {}

  void Begin(const gfx::IntRect& aTargetBounds, ScreenRotation aRotation,
             hal::ScreenOrientation aOrientation) {
    mOpen = true;
    mTargetBounds = aTargetBounds;
    if (aRotation != mTargetRotation) {
      // the first time this is called, mRotationChanged will be false if
      // aRotation is 0, but we should be OK because for the first transaction
      // we should only compose if it is non-empty. See the caller(s) of
      // RotationChanged.
      mRotationChanged = true;
    }
    mTargetRotation = aRotation;
    mTargetOrientation = aOrientation;
  }
  void AddEdit(const Edit& aEdit) {
    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
    mCset.AppendElement(aEdit);
  }
  void AddEdit(const CompositableOperation& aEdit) { AddEdit(Edit(aEdit)); }

  void AddNoSwapPaint(const CompositableOperation& aPaint) {
    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
    mPaints.AppendElement(Edit(aPaint));
  }
  void AddMutant(ShadowableLayer* aLayer) {
    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
    mMutants.PutEntry(aLayer);
  }
  void AddSimpleMutant(ShadowableLayer* aLayer) {
    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
    mSimpleMutants.PutEntry(aLayer);
  }
  void End() {
    mCset.Clear();
    mPaints.Clear();
    mMutants.Clear();
    mSimpleMutants.Clear();
    mDestroyedActors.Clear();
    mOpen = false;
    mRotationChanged = false;
  }

  bool Empty() const {
    return mCset.IsEmpty() && mPaints.IsEmpty() && mMutants.IsEmpty() &&
           mSimpleMutants.IsEmpty() && mDestroyedActors.IsEmpty();
  }
  bool RotationChanged() const { return mRotationChanged; }
  bool Finished() const { return !mOpen && Empty(); }

  bool Opened() const { return mOpen; }

  EditVector mCset;
  nsTArray<CompositableOperation> mPaints;
  OpDestroyVector mDestroyedActors;
  ShadowableLayerSet mMutants;
  ShadowableLayerSet mSimpleMutants;
  gfx::IntRect mTargetBounds;
  ScreenRotation mTargetRotation;
  hal::ScreenOrientation mTargetOrientation;

 private:
  bool mOpen;
  bool mRotationChanged;

  // disabled
  Transaction(const Transaction&);
  Transaction& operator=(const Transaction&);
};
struct AutoTxnEnd final {
  explicit AutoTxnEnd(Transaction* aTxn) : mTxn(aTxn) {}
  ~AutoTxnEnd() { mTxn->End(); }
  Transaction* mTxn;
};

void KnowsCompositor::IdentifyTextureHost(
    const TextureFactoryIdentifier& aIdentifier) {
  auto lock = mData.Lock();
  lock.ref().mTextureFactoryIdentifier = aIdentifier;

  lock.ref().mSyncObject =
      SyncObjectClient::CreateSyncObjectClientForContentDevice(
          aIdentifier.mSyncHandle);
}

KnowsCompositor::KnowsCompositor()
    : mData("KnowsCompositorMutex"), mSerial(++sSerialCounter) {}

KnowsCompositor::~KnowsCompositor() = default;

KnowsCompositorMediaProxy::KnowsCompositorMediaProxy(
    const TextureFactoryIdentifier& aIdentifier) {
  auto lock = mData.Lock();
  lock.ref().mTextureFactoryIdentifier = aIdentifier;
  // overwrite mSerial's value set by the parent class because we use the same
  // serial as the KnowsCompositor we are proxying.
  mThreadSafeAllocator = ImageBridgeChild::GetSingleton();
  lock.ref().mSyncObject = mThreadSafeAllocator->GetSyncObject();
}

KnowsCompositorMediaProxy::~KnowsCompositorMediaProxy() = default;

TextureForwarder* KnowsCompositorMediaProxy::GetTextureForwarder() {
  return mThreadSafeAllocator->GetTextureForwarder();
}

LayersIPCActor* KnowsCompositorMediaProxy::GetLayersIPCActor() {
  return mThreadSafeAllocator->GetLayersIPCActor();
}

ActiveResourceTracker* KnowsCompositorMediaProxy::GetActiveResourceTracker() {
  return mThreadSafeAllocator->GetActiveResourceTracker();
}

void KnowsCompositorMediaProxy::SyncWithCompositor() {
  mThreadSafeAllocator->SyncWithCompositor();
}

RefPtr<KnowsCompositor> ShadowLayerForwarder::GetForMedia() {
  return MakeAndAddRef<KnowsCompositorMediaProxy>(
      GetTextureFactoryIdentifier());
}

ShadowLayerForwarder::ShadowLayerForwarder(
    ClientLayerManager* aClientLayerManager)
    : mClientLayerManager(aClientLayerManager),
      mThread(NS_GetCurrentThread()),
      mDiagnosticTypes(DiagnosticTypes::NO_DIAGNOSTIC),
      mIsFirstPaint(false),
      mNextLayerHandle(1) {
  mTxn = new Transaction();
  mEventTarget = GetMainThreadSerialEventTarget();

  MOZ_ASSERT(mEventTarget || !XRE_IsContentProcess());
  mActiveResourceTracker = MakeUnique<ActiveResourceTracker>(
      1000, "CompositableForwarder", mEventTarget);
}

template <typename T>
struct ReleaseOnMainThreadTask : public Runnable {
  UniquePtr<T> mObj;

  explicit ReleaseOnMainThreadTask(UniquePtr<T>& aObj)
      : Runnable("layers::ReleaseOnMainThreadTask"), mObj(std::move(aObj)) {}

  NS_IMETHOD Run() override {
    mObj = nullptr;
    return NS_OK;
  }
};

ShadowLayerForwarder::~ShadowLayerForwarder() {
  MOZ_ASSERT(mTxn->Finished(), "unfinished transaction?");
  delete mTxn;
  if (mShadowManager) {
    mShadowManager->SetForwarder(nullptr);
    if (NS_IsMainThread()) {
      mShadowManager->Destroy();
    } else {
      if (mEventTarget) {
        mEventTarget->Dispatch(
            NewRunnableMethod("LayerTransactionChild::Destroy", mShadowManager,
                              &LayerTransactionChild::Destroy),
            nsIEventTarget::DISPATCH_NORMAL);
      } else {
        NS_DispatchToMainThread(
            NewRunnableMethod("layers::LayerTransactionChild::Destroy",
                              mShadowManager, &LayerTransactionChild::Destroy));
      }
    }
  }

  if (!NS_IsMainThread()) {
    RefPtr<ReleaseOnMainThreadTask<ActiveResourceTracker>> event =
        new ReleaseOnMainThreadTask<ActiveResourceTracker>(
            mActiveResourceTracker);
    if (mEventTarget) {
      mEventTarget->Dispatch(event.forget(), nsIEventTarget::DISPATCH_NORMAL);
    } else {
      NS_DispatchToMainThread(event);
    }
  }
}

void ShadowLayerForwarder::BeginTransaction(
    const gfx::IntRect& aTargetBounds, ScreenRotation aRotation,
    hal::ScreenOrientation aOrientation) {
  MOZ_ASSERT(IPCOpen(), "no manager to forward to");
  MOZ_ASSERT(mTxn->Finished(), "uncommitted txn?");
  UpdateFwdTransactionId();
  mTxn->Begin(aTargetBounds, aRotation, aOrientation);
}

static const LayerHandle& Shadow(ShadowableLayer* aLayer) {
  return aLayer->GetShadow();
}

template <typename OpCreateT>
static void CreatedLayer(Transaction* aTxn, ShadowableLayer* aLayer) {
  aTxn->AddEdit(OpCreateT(Shadow(aLayer)));
}

void ShadowLayerForwarder::CreatedPaintedLayer(ShadowableLayer* aThebes) {
  CreatedLayer<OpCreatePaintedLayer>(mTxn, aThebes);
}
void ShadowLayerForwarder::CreatedContainerLayer(ShadowableLayer* aContainer) {
  CreatedLayer<OpCreateContainerLayer>(mTxn, aContainer);
}
void ShadowLayerForwarder::CreatedImageLayer(ShadowableLayer* aImage) {
  CreatedLayer<OpCreateImageLayer>(mTxn, aImage);
}
void ShadowLayerForwarder::CreatedColorLayer(ShadowableLayer* aColor) {
  CreatedLayer<OpCreateColorLayer>(mTxn, aColor);
}
void ShadowLayerForwarder::CreatedCanvasLayer(ShadowableLayer* aCanvas) {
  CreatedLayer<OpCreateCanvasLayer>(mTxn, aCanvas);
}
void ShadowLayerForwarder::CreatedRefLayer(ShadowableLayer* aRef) {
  CreatedLayer<OpCreateRefLayer>(mTxn, aRef);
}

void ShadowLayerForwarder::Mutated(ShadowableLayer* aMutant) {
  mTxn->AddMutant(aMutant);
}

void ShadowLayerForwarder::MutatedSimple(ShadowableLayer* aMutant) {
  mTxn->AddSimpleMutant(aMutant);
}

void ShadowLayerForwarder::SetRoot(ShadowableLayer* aRoot) {
  mTxn->AddEdit(OpSetRoot(Shadow(aRoot)));
}
void ShadowLayerForwarder::InsertAfter(ShadowableLayer* aContainer,
                                       ShadowableLayer* aChild,
                                       ShadowableLayer* aAfter) {
  if (!aChild->HasShadow()) {
    return;
  }

  while (aAfter && !aAfter->HasShadow()) {
    aAfter = aAfter->AsLayer()->GetPrevSibling()
                 ? aAfter->AsLayer()->GetPrevSibling()->AsShadowableLayer()
                 : nullptr;
  }

  if (aAfter) {
    mTxn->AddEdit(
        OpInsertAfter(Shadow(aContainer), Shadow(aChild), Shadow(aAfter)));
  } else {
    mTxn->AddEdit(OpPrependChild(Shadow(aContainer), Shadow(aChild)));
  }
}
void ShadowLayerForwarder::RemoveChild(ShadowableLayer* aContainer,
                                       ShadowableLayer* aChild) {
  MOZ_LAYERS_LOG(("[LayersForwarder] OpRemoveChild container=%p child=%p\n",
                  aContainer->AsLayer(), aChild->AsLayer()));

  if (!aChild->HasShadow()) {
    return;
  }

  mTxn->AddEdit(OpRemoveChild(Shadow(aContainer), Shadow(aChild)));
}
void ShadowLayerForwarder::RepositionChild(ShadowableLayer* aContainer,
                                           ShadowableLayer* aChild,
                                           ShadowableLayer* aAfter) {
  if (!aChild->HasShadow()) {
    return;
  }

  while (aAfter && !aAfter->HasShadow()) {
    aAfter = aAfter->AsLayer()->GetPrevSibling()
                 ? aAfter->AsLayer()->GetPrevSibling()->AsShadowableLayer()
                 : nullptr;
  }

  if (aAfter) {
    MOZ_LAYERS_LOG(
        ("[LayersForwarder] OpRepositionChild container=%p child=%p after=%p",
         aContainer->AsLayer(), aChild->AsLayer(), aAfter->AsLayer()));
    mTxn->AddEdit(
        OpRepositionChild(Shadow(aContainer), Shadow(aChild), Shadow(aAfter)));
  } else {
    MOZ_LAYERS_LOG(("[LayersForwarder] OpRaiseToTopChild container=%p child=%p",
                    aContainer->AsLayer(), aChild->AsLayer()));
    mTxn->AddEdit(OpRaiseToTopChild(Shadow(aContainer), Shadow(aChild)));
  }
}

#ifdef DEBUG
void ShadowLayerForwarder::CheckSurfaceDescriptor(
    const SurfaceDescriptor* aDescriptor) const {
  if (!aDescriptor) {
    return;
  }

  if (aDescriptor->type() == SurfaceDescriptor::TSurfaceDescriptorBuffer &&
      aDescriptor->get_SurfaceDescriptorBuffer().data().type() ==
          MemoryOrShmem::TShmem) {
    const Shmem& shmem =
        aDescriptor->get_SurfaceDescriptorBuffer().data().get_Shmem();
    shmem.AssertInvariants();
    MOZ_ASSERT(mShadowManager &&
               mShadowManager->IsTrackingSharedMemory(shmem.mSegment));
  }
}
#endif

void ShadowLayerForwarder::UseTiledLayerBuffer(
    CompositableClient* aCompositable,
    const SurfaceDescriptorTiles& aTileLayerDescriptor) {
  MOZ_ASSERT(aCompositable);

  if (!aCompositable->IsConnected()) {
    return;
  }

  mTxn->AddNoSwapPaint(
      CompositableOperation(aCompositable->GetIPCHandle(),
                            OpUseTiledLayerBuffer(aTileLayerDescriptor)));
}

void ShadowLayerForwarder::UpdateTextureRegion(
    CompositableClient* aCompositable,
    const ThebesBufferData& aThebesBufferData,
    const nsIntRegion& aUpdatedRegion) {
  MOZ_ASSERT(aCompositable);

  if (!aCompositable->IsConnected()) {
    return;
  }

  mTxn->AddNoSwapPaint(CompositableOperation(
      aCompositable->GetIPCHandle(),
      OpPaintTextureRegion(aThebesBufferData, aUpdatedRegion)));
}

void ShadowLayerForwarder::UseTextures(
    CompositableClient* aCompositable,
    const nsTArray<TimedTextureClient>& aTextures) {
  MOZ_ASSERT(aCompositable);

  if (!aCompositable->IsConnected()) {
    return;
  }

  AutoTArray<TimedTexture, 4> textures;

  for (auto& t : aTextures) {
    MOZ_ASSERT(t.mTextureClient);
    MOZ_ASSERT(t.mTextureClient->GetIPDLActor());
    MOZ_RELEASE_ASSERT(t.mTextureClient->GetIPDLActor()->GetIPCChannel() ==
                       mShadowManager->GetIPCChannel());
    bool readLocked = t.mTextureClient->OnForwardedToHost();
    textures.AppendElement(
        TimedTexture(nullptr, t.mTextureClient->GetIPDLActor(), t.mTimeStamp,
                     t.mPictureRect, t.mFrameID, t.mProducerID, readLocked));
    mClientLayerManager->GetCompositorBridgeChild()
        ->HoldUntilCompositableRefReleasedIfNecessary(t.mTextureClient);

    auto fenceFd = t.mTextureClient->GetInternalData()->GetAcquireFence();
    if (fenceFd.IsValid()) {
      mTxn->AddEdit(CompositableOperation(
          aCompositable->GetIPCHandle(),
          OpDeliverAcquireFence(nullptr, t.mTextureClient->GetIPDLActor(),
                                fenceFd)));
    }
  }
  mTxn->AddEdit(CompositableOperation(aCompositable->GetIPCHandle(),
                                      OpUseTexture(textures)));
}

void ShadowLayerForwarder::UseComponentAlphaTextures(
    CompositableClient* aCompositable, TextureClient* aTextureOnBlack,
    TextureClient* aTextureOnWhite) {
  MOZ_ASSERT(aCompositable);

  if (!aCompositable->IsConnected()) {
    return;
  }

  MOZ_ASSERT(aTextureOnWhite);
  MOZ_ASSERT(aTextureOnBlack);
  MOZ_ASSERT(aCompositable->GetIPCHandle());
  MOZ_ASSERT(aTextureOnBlack->GetIPDLActor());
  MOZ_ASSERT(aTextureOnWhite->GetIPDLActor());
  MOZ_ASSERT(aTextureOnBlack->GetSize() == aTextureOnWhite->GetSize());
  MOZ_RELEASE_ASSERT(aTextureOnWhite->GetIPDLActor()->GetIPCChannel() ==
                     mShadowManager->GetIPCChannel());
  MOZ_RELEASE_ASSERT(aTextureOnBlack->GetIPDLActor()->GetIPCChannel() ==
                     mShadowManager->GetIPCChannel());

  bool readLockedB = aTextureOnBlack->OnForwardedToHost();
  bool readLockedW = aTextureOnWhite->OnForwardedToHost();

  mClientLayerManager->GetCompositorBridgeChild()
      ->HoldUntilCompositableRefReleasedIfNecessary(aTextureOnBlack);
  mClientLayerManager->GetCompositorBridgeChild()
      ->HoldUntilCompositableRefReleasedIfNecessary(aTextureOnWhite);

  auto fenceFdB = aTextureOnBlack->GetInternalData()->GetAcquireFence();
  if (fenceFdB.IsValid()) {
    mTxn->AddEdit(CompositableOperation(
        aCompositable->GetIPCHandle(),
        OpDeliverAcquireFence(nullptr, aTextureOnBlack->GetIPDLActor(),
                              fenceFdB)));
  }

  auto fenceFdW = aTextureOnWhite->GetInternalData()->GetAcquireFence();
  if (fenceFdW.IsValid()) {
    mTxn->AddEdit(CompositableOperation(
        aCompositable->GetIPCHandle(),
        OpDeliverAcquireFence(nullptr, aTextureOnWhite->GetIPDLActor(),
                              fenceFdW)));
  }

  mTxn->AddEdit(CompositableOperation(
      aCompositable->GetIPCHandle(),
      OpUseComponentAlphaTextures(nullptr, aTextureOnBlack->GetIPDLActor(),
                                  nullptr, aTextureOnWhite->GetIPDLActor(),
                                  readLockedB, readLockedW)));
}

static bool AddOpDestroy(Transaction* aTxn, const OpDestroy& op) {
  if (!aTxn->Opened()) {
    return false;
  }

  aTxn->mDestroyedActors.AppendElement(op);
  return true;
}

bool ShadowLayerForwarder::DestroyInTransaction(PTextureChild* aTexture) {
  return AddOpDestroy(mTxn, OpDestroy(aTexture));
}

bool ShadowLayerForwarder::DestroyInTransaction(
    const CompositableHandle& aHandle) {
  return AddOpDestroy(mTxn, OpDestroy(aHandle));
}

void ShadowLayerForwarder::RemoveTextureFromCompositable(
    CompositableClient* aCompositable, TextureClient* aTexture) {
  MOZ_ASSERT(aCompositable);
  MOZ_ASSERT(aTexture);
  MOZ_ASSERT(aTexture->GetIPDLActor());
  MOZ_RELEASE_ASSERT(aTexture->GetIPDLActor()->GetIPCChannel() ==
                     mShadowManager->GetIPCChannel());
  if (!aCompositable->IsConnected() || !aTexture->GetIPDLActor()) {
    // We don't have an actor anymore, don't try to use it!
    return;
  }

  mTxn->AddEdit(CompositableOperation(
      aCompositable->GetIPCHandle(),
      OpRemoveTexture(nullptr, aTexture->GetIPDLActor())));
}

bool ShadowLayerForwarder::InWorkerThread() {
  return GetTextureForwarder()->GetThread()->IsOnCurrentThread();
}

void ShadowLayerForwarder::StorePluginWidgetConfigurations(
    const nsTArray<nsIWidget::Configuration>& aConfigurations) {
  // Cache new plugin widget configs here until we call update, at which
  // point this data will get shipped over to chrome.
  mPluginWindowData.Clear();
  for (uint32_t idx = 0; idx < aConfigurations.Length(); idx++) {
    const nsIWidget::Configuration& configuration = aConfigurations[idx];
    mPluginWindowData.AppendElement(
        PluginWindowData(configuration.mWindowID, configuration.mClipRegion,
                         configuration.mBounds, configuration.mVisible));
  }
}

void ShadowLayerForwarder::SendPaintTime(TransactionId aId,
                                         TimeDuration aPaintTime) {
  if (!IPCOpen() || !mShadowManager->SendPaintTime(aId, aPaintTime)) {
    NS_WARNING("Could not send paint times over IPC");
  }
}

bool ShadowLayerForwarder::EndTransaction(
    const nsIntRegion& aRegionToClear, TransactionId aId,
    bool aScheduleComposite, uint32_t aPaintSequenceNumber,
    bool aIsRepeatTransaction, const mozilla::VsyncId& aVsyncId,
    const mozilla::TimeStamp& aVsyncStart,
    const mozilla::TimeStamp& aRefreshStart,
    const mozilla::TimeStamp& aTransactionStart, bool aContainsSVG,
    const nsCString& aURL, bool* aSent,
    const nsTArray<CompositionPayload>& aPayload) {
  *aSent = false;

  TransactionInfo info;

  MOZ_ASSERT(IPCOpen(), "no manager to forward to");
  if (!IPCOpen()) {
    return false;
  }

  Maybe<TimeStamp> startTime;
  if (StaticPrefs::layers_acceleration_draw_fps()) {
    startTime = Some(TimeStamp::Now());
  }

  GetCompositorBridgeChild()->WillEndTransaction();

  MOZ_ASSERT(aId.IsValid());

  AUTO_PROFILER_LABEL("ShadowLayerForwarder::EndTransaction", GRAPHICS);

  RenderTraceScope rendertrace("Foward Transaction", "000091");
  MOZ_ASSERT(!mTxn->Finished(), "forgot BeginTransaction?");

  DiagnosticTypes diagnostics =
      gfxPlatform::GetPlatform()->GetLayerDiagnosticTypes();
  if (mDiagnosticTypes != diagnostics) {
    mDiagnosticTypes = diagnostics;
    mTxn->AddEdit(OpSetDiagnosticTypes(diagnostics));
  }

  AutoTxnEnd _(mTxn);

  if (mTxn->Empty() && !mTxn->RotationChanged()) {
    MOZ_LAYERS_LOG(
        ("[LayersForwarder] 0-length cset (?) and no rotation event, skipping "
         "Update()"));
    return true;
  }

  if (!mTxn->mPaints.IsEmpty()) {
    // With some platforms, telling the drawing backend that there will be no
    // more drawing for this frame helps with preventing command queues from
    // spanning across multiple frames.
    gfxPlatform::GetPlatform()->FlushContentDrawing();
  }

  MOZ_LAYERS_LOG(("[LayersForwarder] destroying buffers..."));

  MOZ_LAYERS_LOG(("[LayersForwarder] building transaction..."));

  nsTArray<OpSetSimpleLayerAttributes> setSimpleAttrs;
  for (ShadowableLayerSet::Iterator it(&mTxn->mSimpleMutants); !it.Done();
       it.Next()) {
    ShadowableLayer* shadow = it.Get()->GetKey();
    if (!shadow->HasShadow()) {
      continue;
    }

    Layer* mutant = shadow->AsLayer();
    setSimpleAttrs.AppendElement(OpSetSimpleLayerAttributes(
        Shadow(shadow), mutant->GetSimpleAttributes()));
  }

  nsTArray<OpSetLayerAttributes> setAttrs;

  // We purposely add attribute-change ops to the final changeset
  // before we add paint ops.  This allows layers to record the
  // attribute changes before new pixels arrive, which can be useful
  // for setting up back/front buffers.
  RenderTraceScope rendertrace2("Foward Transaction", "000092");
  for (ShadowableLayerSet::Iterator it(&mTxn->mMutants); !it.Done();
       it.Next()) {
    ShadowableLayer* shadow = it.Get()->GetKey();

    if (!shadow->HasShadow()) {
      continue;
    }
    Layer* mutant = shadow->AsLayer();
    MOZ_ASSERT(!!mutant, "unshadowable layer?");

    OpSetLayerAttributes op;
    op.layer() = Shadow(shadow);

    LayerAttributes& attrs = op.attrs();
    CommonLayerAttributes& common = attrs.common();
    common.visibleRegion() = mutant->GetVisibleRegion();
    common.eventRegions() = mutant->GetEventRegions();
    common.useClipRect() = !!mutant->GetClipRect();
    common.clipRect() =
        (common.useClipRect() ? *mutant->GetClipRect() : ParentLayerIntRect());
    if (Layer* maskLayer = mutant->GetMaskLayer()) {
      common.maskLayer() = Shadow(maskLayer->AsShadowableLayer());
    } else {
      common.maskLayer() = LayerHandle();
    }
    common.compositorAnimations().id() = mutant->GetCompositorAnimationsId();
    common.compositorAnimations().animations() =
        mutant->GetAnimations().Clone();
    common.invalidRegion() = mutant->GetInvalidRegion().GetRegion();
    common.scrollMetadata() = mutant->GetAllScrollMetadata().Clone();
    for (size_t i = 0; i < mutant->GetAncestorMaskLayerCount(); i++) {
      auto layer =
          Shadow(mutant->GetAncestorMaskLayerAt(i)->AsShadowableLayer());
      common.ancestorMaskLayers().AppendElement(layer);
    }
    nsCString log;
    mutant->GetDisplayListLog(log);
    common.displayListLog() = log;

    attrs.specific() = null_t();
    mutant->FillSpecificAttributes(attrs.specific());

    MOZ_LAYERS_LOG(("[LayersForwarder] OpSetLayerAttributes(%p)\n", mutant));

    setAttrs.AppendElement(op);
  }

  if (mTxn->mCset.IsEmpty() && mTxn->mPaints.IsEmpty() && setAttrs.IsEmpty() &&
      !mTxn->RotationChanged()) {
    return true;
  }

  info.cset() = std::move(mTxn->mCset);
  info.setSimpleAttrs() = std::move(setSimpleAttrs);
  info.setAttrs() = std::move(setAttrs);
  info.paints() = std::move(mTxn->mPaints);
  info.toDestroy() = mTxn->mDestroyedActors.Clone();
  info.fwdTransactionId() = GetFwdTransactionId();
  info.id() = aId;
  info.plugins() = mPluginWindowData.Clone();
  info.isFirstPaint() = mIsFirstPaint;
  info.focusTarget() = mFocusTarget;
  info.scheduleComposite() = aScheduleComposite;
  info.paintSequenceNumber() = aPaintSequenceNumber;
  info.isRepeatTransaction() = aIsRepeatTransaction;
  info.vsyncId() = aVsyncId;
  info.vsyncStart() = aVsyncStart;
  info.refreshStart() = aRefreshStart;
  info.transactionStart() = aTransactionStart;
  info.url() = aURL;
  info.containsSVG() = aContainsSVG;
#if defined(ENABLE_FRAME_LATENCY_LOG)
  info.fwdTime() = TimeStamp::Now();
#endif
  info.payload() = aPayload.Clone();

  TargetConfig targetConfig(mTxn->mTargetBounds, mTxn->mTargetRotation,
                            mTxn->mTargetOrientation, aRegionToClear);
  info.targetConfig() = targetConfig;

  if (!GetTextureForwarder()->IsSameProcess()) {
    MOZ_LAYERS_LOG(("[LayersForwarder] syncing before send..."));
    PlatformSyncBeforeUpdate();
  }

  if (startTime) {
    mPaintTiming.serializeMs() =
        (TimeStamp::Now() - startTime.value()).ToMilliseconds();
    startTime = Some(TimeStamp::Now());
  }

  // We delay at the last possible minute, to give the paint thread a chance to
  // finish. If it does we don't have to delay messages at all.
  GetCompositorBridgeChild()->PostponeMessagesIfAsyncPainting();

  MOZ_LAYERS_LOG(("[LayersForwarder] sending transaction..."));
  RenderTraceScope rendertrace3("Forward Transaction", "000093");
  if (!mShadowManager->SendUpdate(info)) {
    MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
    return false;
  }

  if (startTime) {
    mPaintTiming.sendMs() =
        (TimeStamp::Now() - startTime.value()).ToMilliseconds();
    mShadowManager->SendRecordPaintTimes(mPaintTiming);
  }

  *aSent = true;
  mIsFirstPaint = false;
  mFocusTarget = FocusTarget();
  MOZ_LAYERS_LOG(("[LayersForwarder] ... done"));
  return true;
}

RefPtr<CompositableClient> ShadowLayerForwarder::FindCompositable(
    const CompositableHandle& aHandle) {
  CompositableClient* client = nullptr;
  if (!mCompositables.Get(aHandle.Value(), &client)) {
    return nullptr;
  }
  return client;
}

void ShadowLayerForwarder::SetLayersObserverEpoch(LayersObserverEpoch aEpoch) {
  if (!IPCOpen()) {
    return;
  }
  Unused << mShadowManager->SendSetLayersObserverEpoch(aEpoch);
}

void ShadowLayerForwarder::UpdateTextureLocks() {
#ifdef XP_DARWIN
  if (!IPCOpen()) {
    return;
  }

  auto compositorBridge = GetCompositorBridgeChild();
  if (compositorBridge) {
    auto pid = compositorBridge->OtherPid();
    TextureSync::UpdateTextureLocks(pid);
  }
#endif
}

void ShadowLayerForwarder::SyncTextures(const nsTArray<uint64_t>& aSerials) {
#ifdef XP_DARWIN
  if (!IPCOpen()) {
    return;
  }

  auto compositorBridge = GetCompositorBridgeChild();
  if (compositorBridge) {
    auto pid = compositorBridge->OtherPid();
    TextureSync::WaitForTextures(pid, aSerials);
  }
#endif
}

void ShadowLayerForwarder::ReleaseLayer(const LayerHandle& aHandle) {
  if (!IPCOpen()) {
    return;
  }
  Unused << mShadowManager->SendReleaseLayer(aHandle);
}

bool ShadowLayerForwarder::IPCOpen() const {
  return HasShadowManager() && mShadowManager->IPCOpen();
}

/**
 * We bail out when we have no shadow manager. That can happen when the
 * layer manager is created by the preallocated process.
 * See bug 914843 for details.
 */
LayerHandle ShadowLayerForwarder::ConstructShadowFor(ShadowableLayer* aLayer) {
  return LayerHandle(mNextLayerHandle++);
}

#if !defined(MOZ_HAVE_PLATFORM_SPECIFIC_LAYER_BUFFERS)

/*static*/
void ShadowLayerForwarder::PlatformSyncBeforeUpdate() {}

#endif  // !defined(MOZ_HAVE_PLATFORM_SPECIFIC_LAYER_BUFFERS)

void ShadowLayerForwarder::Connect(CompositableClient* aCompositable,
                                   ImageContainer* aImageContainer) {
#ifdef GFX_COMPOSITOR_LOGGING
  printf("ShadowLayerForwarder::Connect(Compositable)\n");
#endif
  MOZ_ASSERT(aCompositable);
  MOZ_ASSERT(mShadowManager);
  if (!IPCOpen()) {
    return;
  }

  static uint64_t sNextID = 1;
  uint64_t id = sNextID++;

  mCompositables.Put(id, aCompositable);

  CompositableHandle handle(id);
  aCompositable->InitIPDL(handle);
  mShadowManager->SendNewCompositable(handle, aCompositable->GetTextureInfo());
}

void ShadowLayerForwarder::Attach(CompositableClient* aCompositable,
                                  ShadowableLayer* aLayer) {
  MOZ_ASSERT(aLayer);
  MOZ_ASSERT(aCompositable);
  mTxn->AddEdit(
      OpAttachCompositable(Shadow(aLayer), aCompositable->GetIPCHandle()));
}

void ShadowLayerForwarder::AttachAsyncCompositable(
    const CompositableHandle& aHandle, ShadowableLayer* aLayer) {
  MOZ_ASSERT(aLayer);
  MOZ_ASSERT(aHandle);
  mTxn->AddEdit(OpAttachAsyncCompositable(Shadow(aLayer), aHandle));
}

void ShadowLayerForwarder::SetShadowManager(
    PLayerTransactionChild* aShadowManager) {
  mShadowManager = static_cast<LayerTransactionChild*>(aShadowManager);
  mShadowManager->SetForwarder(this);
}

void ShadowLayerForwarder::StopReceiveAsyncParentMessge() {
  if (!IPCOpen()) {
    return;
  }
  mShadowManager->SetForwarder(nullptr);
}

void ShadowLayerForwarder::ClearCachedResources() {
  if (!IPCOpen()) {
    return;
  }
  mShadowManager->SendClearCachedResources();
}

void ShadowLayerForwarder::ScheduleComposite() {
  if (!IPCOpen()) {
    return;
  }
  mShadowManager->SendScheduleComposite();
}

bool IsSurfaceDescriptorValid(const SurfaceDescriptor& aSurface) {
  return aSurface.type() != SurfaceDescriptor::T__None &&
         aSurface.type() != SurfaceDescriptor::Tnull_t;
}

uint8_t* GetAddressFromDescriptor(const SurfaceDescriptor& aDescriptor) {
  MOZ_ASSERT(IsSurfaceDescriptorValid(aDescriptor));
  MOZ_RELEASE_ASSERT(
      aDescriptor.type() == SurfaceDescriptor::TSurfaceDescriptorBuffer,
      "GFX: surface descriptor is not the right type.");

  auto memOrShmem = aDescriptor.get_SurfaceDescriptorBuffer().data();
  if (memOrShmem.type() == MemoryOrShmem::TShmem) {
    return memOrShmem.get_Shmem().get<uint8_t>();
  } else {
    return reinterpret_cast<uint8_t*>(memOrShmem.get_uintptr_t());
  }
}

already_AddRefed<gfx::DataSourceSurface> GetSurfaceForDescriptor(
    const SurfaceDescriptor& aDescriptor) {
  if (aDescriptor.type() != SurfaceDescriptor::TSurfaceDescriptorBuffer) {
    return nullptr;
  }
  uint8_t* data = GetAddressFromDescriptor(aDescriptor);
  auto rgb =
      aDescriptor.get_SurfaceDescriptorBuffer().desc().get_RGBDescriptor();
  uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
  return gfx::Factory::CreateWrappingDataSourceSurface(data, stride, rgb.size(),
                                                       rgb.format());
}

already_AddRefed<gfx::DrawTarget> GetDrawTargetForDescriptor(
    const SurfaceDescriptor& aDescriptor, gfx::BackendType aBackend) {
  uint8_t* data = GetAddressFromDescriptor(aDescriptor);
  auto rgb =
      aDescriptor.get_SurfaceDescriptorBuffer().desc().get_RGBDescriptor();
  uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
  return gfx::Factory::CreateDrawTargetForData(
      gfx::BackendType::CAIRO, data, rgb.size(), stride, rgb.format());
}

void DestroySurfaceDescriptor(IShmemAllocator* aAllocator,
                              SurfaceDescriptor* aSurface) {
  MOZ_ASSERT(aSurface);

  SurfaceDescriptorBuffer& desc = aSurface->get_SurfaceDescriptorBuffer();
  switch (desc.data().type()) {
    case MemoryOrShmem::TShmem: {
      aAllocator->DeallocShmem(desc.data().get_Shmem());
      break;
    }
    case MemoryOrShmem::Tuintptr_t: {
      uint8_t* ptr = (uint8_t*)desc.data().get_uintptr_t();
      GfxMemoryImageReporter::WillFree(ptr);
      delete[] ptr;
      break;
    }
    default:
      MOZ_CRASH("surface type not implemented!");
  }
  *aSurface = SurfaceDescriptor();
}

bool ShadowLayerForwarder::AllocSurfaceDescriptor(const gfx::IntSize& aSize,
                                                  gfxContentType aContent,
                                                  SurfaceDescriptor* aBuffer) {
  if (!IPCOpen()) {
    return false;
  }
  return AllocSurfaceDescriptorWithCaps(aSize, aContent, DEFAULT_BUFFER_CAPS,
                                        aBuffer);
}

bool ShadowLayerForwarder::AllocSurfaceDescriptorWithCaps(
    const gfx::IntSize& aSize, gfxContentType aContent, uint32_t aCaps,
    SurfaceDescriptor* aBuffer) {
  if (!IPCOpen()) {
    return false;
  }
  gfx::SurfaceFormat format =
      gfxPlatform::GetPlatform()->Optimal2DFormatForContent(aContent);
  size_t size = ImageDataSerializer::ComputeRGBBufferSize(aSize, format);
  if (!size) {
    return false;
  }

  MemoryOrShmem bufferDesc;
  if (GetTextureForwarder()->IsSameProcess()) {
    uint8_t* data = new (std::nothrow) uint8_t[size];
    if (!data) {
      return false;
    }
    GfxMemoryImageReporter::DidAlloc(data);
    memset(data, 0, size);
    bufferDesc = reinterpret_cast<uintptr_t>(data);
  } else {
    mozilla::ipc::Shmem shmem;
    if (!GetTextureForwarder()->AllocUnsafeShmem(size, OptimalShmemType(),
                                                 &shmem)) {
      return false;
    }

    bufferDesc = std::move(shmem);
  }

  // Use an intermediate buffer by default. Skipping the intermediate buffer is
  // only possible in certain configurations so let's keep it simple here for
  // now.
  const bool hasIntermediateBuffer = true;
  *aBuffer = SurfaceDescriptorBuffer(
      RGBDescriptor(aSize, format, hasIntermediateBuffer), bufferDesc);

  return true;
}

/* static */
bool ShadowLayerForwarder::IsShmem(SurfaceDescriptor* aSurface) {
  return aSurface &&
         (aSurface->type() == SurfaceDescriptor::TSurfaceDescriptorBuffer) &&
         (aSurface->get_SurfaceDescriptorBuffer().data().type() ==
          MemoryOrShmem::TShmem);
}

void ShadowLayerForwarder::DestroySurfaceDescriptor(
    SurfaceDescriptor* aSurface) {
  MOZ_ASSERT(aSurface);
  MOZ_ASSERT(IPCOpen());
  if (!IPCOpen() || !aSurface) {
    return;
  }

  ::mozilla::layers::DestroySurfaceDescriptor(GetTextureForwarder(), aSurface);
}

void ShadowLayerForwarder::UpdateFwdTransactionId() {
  auto compositorBridge = GetCompositorBridgeChild();
  if (compositorBridge) {
    compositorBridge->UpdateFwdTransactionId();
  }
}

uint64_t ShadowLayerForwarder::GetFwdTransactionId() {
  auto compositorBridge = GetCompositorBridgeChild();
  MOZ_DIAGNOSTIC_ASSERT(compositorBridge);
  return compositorBridge ? compositorBridge->GetFwdTransactionId() : 0;
}

CompositorBridgeChild* ShadowLayerForwarder::GetCompositorBridgeChild() {
  if (mCompositorBridgeChild) {
    return mCompositorBridgeChild;
  }
  if (!mShadowManager) {
    return nullptr;
  }
  mCompositorBridgeChild =
      static_cast<CompositorBridgeChild*>(mShadowManager->Manager());
  return mCompositorBridgeChild;
}

void ShadowLayerForwarder::SyncWithCompositor() {
  auto compositorBridge = GetCompositorBridgeChild();
  if (compositorBridge && compositorBridge->IPCOpen()) {
    compositorBridge->SendSyncWithCompositor();
  }
}

void ShadowLayerForwarder::ReleaseCompositable(
    const CompositableHandle& aHandle) {
  AssertInForwarderThread();
  if (!DestroyInTransaction(aHandle)) {
    if (!IPCOpen()) {
      return;
    }
    mShadowManager->SendReleaseCompositable(aHandle);
  }
  mCompositables.Remove(aHandle.Value());
}

void ShadowLayerForwarder::SynchronouslyShutdown() {
  if (IPCOpen()) {
    mShadowManager->SendShutdownSync();
    mShadowManager->MarkDestroyed();
  }
}

ShadowableLayer::~ShadowableLayer() {
  if (mShadow) {
    mForwarder->ReleaseLayer(GetShadow());
  }
}

}  // namespace layers
}  // namespace mozilla