path: root/gfx/layers/client/ClientLayerManager.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * 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 "ClientLayerManager.h"
#include "GeckoProfiler.h"              // for PROFILER_LABEL
#include "gfxPrefs.h"                   // for gfxPrefs::LayersTile...
#include "mozilla/Assertions.h"         // for MOZ_ASSERT, etc
#include "mozilla/Hal.h"
#include "mozilla/dom/ScreenOrientation.h"  // for ScreenOrientation
#include "mozilla/dom/TabChild.h"       // for TabChild
#include "mozilla/hal_sandbox/PHal.h"   // for ScreenConfiguration
#include "mozilla/layers/CompositableClient.h"
#include "mozilla/layers/CompositorBridgeChild.h" // for CompositorBridgeChild
#include "mozilla/layers/ContentClient.h"
#include "mozilla/layers/FrameUniformityData.h"
#include "mozilla/layers/ISurfaceAllocator.h"
#include "mozilla/layers/LayersMessages.h"  // for EditReply, etc
#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor
#include "mozilla/layers/PLayerChild.h"  // for PLayerChild
#include "mozilla/layers/LayerTransactionChild.h"
#include "mozilla/layers/ShadowLayerChild.h"
#include "mozilla/layers/PersistentBufferProvider.h"
#include "ClientReadbackLayer.h"        // for ClientReadbackLayer
#include "nsAString.h"
#include "nsDisplayList.h"
#include "nsIWidgetListener.h"
#include "nsTArray.h"                   // for AutoTArray
#include "nsXULAppAPI.h"                // for XRE_GetProcessType, etc
#include "TiledLayerBuffer.h"
#include "mozilla/dom/WindowBinding.h"  // for Overfill Callback
#include "FrameLayerBuilder.h"          // for FrameLayerbuilder
#ifdef MOZ_WIDGET_ANDROID
#include "AndroidBridge.h"
#include "LayerMetricsWrapper.h"
#endif
#ifdef XP_WIN
#include "mozilla/gfx/DeviceManagerDx.h"
#endif

namespace mozilla {
namespace layers {

using namespace mozilla::gfx;

void
ClientLayerManager::MemoryPressureObserver::Destroy()
{
  UnregisterMemoryPressureEvent();
  mClientLayerManager = nullptr;
}

NS_IMETHODIMP
ClientLayerManager::MemoryPressureObserver::Observe(nsISupports* aSubject,
                                                    const char* aTopic,
                                                    const char16_t* aSomeData)
{
  if (!mClientLayerManager || strcmp(aTopic, "memory-pressure")) {
    return NS_OK;
  }

  mClientLayerManager->HandleMemoryPressure();
  return NS_OK;
}

void
ClientLayerManager::MemoryPressureObserver::RegisterMemoryPressureEvent()
{
  nsCOMPtr<nsIObserverService> observerService =
    mozilla::services::GetObserverService();

  MOZ_ASSERT(observerService);

  if (observerService) {
    observerService->AddObserver(this, "memory-pressure", false);
  }
}

void
ClientLayerManager::MemoryPressureObserver::UnregisterMemoryPressureEvent()
{
  nsCOMPtr<nsIObserverService> observerService =
      mozilla::services::GetObserverService();

  if (observerService) {
      observerService->RemoveObserver(this, "memory-pressure");
  }
}

NS_IMPL_ISUPPORTS(ClientLayerManager::MemoryPressureObserver, nsIObserver)

ClientLayerManager::ClientLayerManager(nsIWidget* aWidget)
  : mPhase(PHASE_NONE)
  , mWidget(aWidget)
  , mLatestTransactionId(0)
  , mLastPaintTime(TimeDuration::Forever())
  , mTargetRotation(ROTATION_0)
  , mRepeatTransaction(false)
  , mIsRepeatTransaction(false)
  , mTransactionIncomplete(false)
  , mCompositorMightResample(false)
  , mNeedsComposite(false)
  , mPaintSequenceNumber(0)
  , mForwarder(new ShadowLayerForwarder(this))
  , mDeviceCounter(gfxPlatform::GetPlatform()->GetDeviceCounter())
{
  MOZ_COUNT_CTOR(ClientLayerManager);
  mMemoryPressureObserver = new MemoryPressureObserver(this);
}


ClientLayerManager::~ClientLayerManager()
{
  mMemoryPressureObserver->Destroy();
  ClearCachedResources();
  // Stop receiveing AsyncParentMessage at Forwarder.
  // After the call, the message is directly handled by LayerTransactionChild. 
  // Basically this function should be called in ShadowLayerForwarder's
  // destructor. But when the destructor is triggered by 
  // CompositorBridgeChild::Destroy(), the destructor can not handle it correctly.
  // See Bug 1000525.
  mForwarder->StopReceiveAsyncParentMessge();
  mRoot = nullptr;

  MOZ_COUNT_DTOR(ClientLayerManager);
}

void
ClientLayerManager::Destroy()
{
  // It's important to call ClearCachedResource before Destroy because the
  // former will early-return if the later has already run.
  ClearCachedResources();
  LayerManager::Destroy();

  if (mTransactionIdAllocator) {
    // Make sure to notify the refresh driver just in case it's waiting on a
    // pending transaction. Do this at the top of the event loop so we don't
    // cause a paint to occur during compositor shutdown.
    RefPtr<TransactionIdAllocator> allocator = mTransactionIdAllocator;
    uint64_t id = mLatestTransactionId;

    RefPtr<Runnable> task = NS_NewRunnableFunction([allocator, id] () -> void {
      allocator->NotifyTransactionCompleted(id);
    });
    NS_DispatchToMainThread(task.forget());
  }

  // Forget the widget pointer in case we outlive our owning widget.
  mWidget = nullptr;
}

int32_t
ClientLayerManager::GetMaxTextureSize() const
{
  return mForwarder->GetMaxTextureSize();
}

void
ClientLayerManager::SetDefaultTargetConfiguration(BufferMode aDoubleBuffering,
                                                  ScreenRotation aRotation)
{
  mTargetRotation = aRotation;
 }

void
ClientLayerManager::SetRoot(Layer* aLayer)
{
  if (mRoot != aLayer) {
    // Have to hold the old root and its children in order to
    // maintain the same view of the layer tree in this process as
    // the parent sees.  Otherwise layers can be destroyed
    // mid-transaction and bad things can happen (v. bug 612573)
    if (mRoot) {
      Hold(mRoot);
    }
    mForwarder->SetRoot(Hold(aLayer));
    NS_ASSERTION(aLayer, "Root can't be null");
    NS_ASSERTION(aLayer->Manager() == this, "Wrong manager");
    NS_ASSERTION(InConstruction(), "Only allowed in construction phase");
    mRoot = aLayer;
  }
}

void
ClientLayerManager::Mutated(Layer* aLayer)
{
  LayerManager::Mutated(aLayer);

  NS_ASSERTION(InConstruction() || InDrawing(), "wrong phase");
  mForwarder->Mutated(Hold(aLayer));
}

already_AddRefed<ReadbackLayer>
ClientLayerManager::CreateReadbackLayer()
{
  RefPtr<ReadbackLayer> layer = new ClientReadbackLayer(this);
  return layer.forget();
}

bool
ClientLayerManager::BeginTransactionWithTarget(gfxContext* aTarget)
{
  MOZ_ASSERT(mForwarder, "ClientLayerManager::BeginTransaction without forwarder");
  if (!mForwarder->IPCOpen()) {
    gfxCriticalNote << "ClientLayerManager::BeginTransaction with IPC channel down. GPU process may have died.";
    return false;
  }

  mInTransaction = true;
  mTransactionStart = TimeStamp::Now();

#ifdef MOZ_LAYERS_HAVE_LOG
  MOZ_LAYERS_LOG(("[----- BeginTransaction"));
  Log();
#endif

  NS_ASSERTION(!InTransaction(), "Nested transactions not allowed");
  mPhase = PHASE_CONSTRUCTION;

  if (DependsOnStaleDevice()) {
    FrameLayerBuilder::InvalidateAllLayers(this);
    mDeviceCounter = gfxPlatform::GetPlatform()->GetDeviceCounter();
  }

  MOZ_ASSERT(mKeepAlive.IsEmpty(), "uncommitted txn?");

  // If the last transaction was incomplete (a failed DoEmptyTransaction),
  // don't signal a new transaction to ShadowLayerForwarder. Carry on adding
  // to the previous transaction.
  dom::ScreenOrientationInternal orientation;
  if (dom::TabChild* window = mWidget->GetOwningTabChild()) {
    orientation = window->GetOrientation();
  } else {
    hal::ScreenConfiguration currentConfig;
    hal::GetCurrentScreenConfiguration(&currentConfig);
    orientation = currentConfig.orientation();
  }
  LayoutDeviceIntRect targetBounds = mWidget->GetNaturalBounds();
  targetBounds.x = targetBounds.y = 0;
  mForwarder->BeginTransaction(targetBounds.ToUnknownRect(), mTargetRotation,
                               orientation);

  // If we're drawing on behalf of a context with async pan/zoom
  // enabled, then the entire buffer of painted layers might be
  // composited (including resampling) asynchronously before we get
  // a chance to repaint, so we have to ensure that it's all valid
  // and not rotated.
  //
  // Desktop does not support async zoom yet, so we ignore this for those
  // platforms.
#if defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_UIKIT)
  if (mWidget && mWidget->GetOwningTabChild()) {
    mCompositorMightResample = AsyncPanZoomEnabled();
  }
#endif

  // If we have a non-default target, we need to let our shadow manager draw
  // to it. This will happen at the end of the transaction.
  if (aTarget && XRE_IsParentProcess()) {
    mShadowTarget = aTarget;
  } else {
    NS_ASSERTION(!aTarget,
                 "Content-process ClientLayerManager::BeginTransactionWithTarget not supported");
  }

  // If this is a new paint, increment the paint sequence number.
  if (!mIsRepeatTransaction) {
    // Increment the paint sequence number even if test logging isn't
    // enabled in this process; it may be enabled in the parent process,
    // and the parent process expects unique sequence numbers.
    ++mPaintSequenceNumber;
    if (gfxPrefs::APZTestLoggingEnabled()) {
      mApzTestData.StartNewPaint(mPaintSequenceNumber);
    }
  }
  return true;
}

bool
ClientLayerManager::BeginTransaction()
{
  return BeginTransactionWithTarget(nullptr);
}

bool
ClientLayerManager::EndTransactionInternal(DrawPaintedLayerCallback aCallback,
                                           void* aCallbackData,
                                           EndTransactionFlags)
{
  PROFILER_LABEL("ClientLayerManager", "EndTransactionInternal",
    js::ProfileEntry::Category::GRAPHICS);

#ifdef MOZ_LAYERS_HAVE_LOG
  MOZ_LAYERS_LOG(("  ----- (beginning paint)"));
  Log();
#endif
  profiler_tracing("Paint", "Rasterize", TRACING_INTERVAL_START);

  NS_ASSERTION(InConstruction(), "Should be in construction phase");
  mPhase = PHASE_DRAWING;

  ClientLayer* root = ClientLayer::ToClientLayer(GetRoot());

  mTransactionIncomplete = false;

  // Apply pending tree updates before recomputing effective
  // properties.
  GetRoot()->ApplyPendingUpdatesToSubtree();

  mPaintedLayerCallback = aCallback;
  mPaintedLayerCallbackData = aCallbackData;

  GetRoot()->ComputeEffectiveTransforms(Matrix4x4());

  // Skip the painting if the device is in device-reset status.
  if (!gfxPlatform::GetPlatform()->DidRenderingDeviceReset()) {
    if (gfxPrefs::AlwaysPaint() && XRE_IsContentProcess()) {
      TimeStamp start = TimeStamp::Now();
      root->RenderLayer();
      mLastPaintTime = TimeStamp::Now() - start;
    } else {
      root->RenderLayer();
    }
  } else {
    gfxCriticalNote << "LayerManager::EndTransaction skip RenderLayer().";
  }

  if (!mRepeatTransaction && !GetRoot()->GetInvalidRegion().IsEmpty()) {
    GetRoot()->Mutated();
  }

  if (!mIsRepeatTransaction) {
    mAnimationReadyTime = TimeStamp::Now();
    GetRoot()->StartPendingAnimations(mAnimationReadyTime);
  }

  mPaintedLayerCallback = nullptr;
  mPaintedLayerCallbackData = nullptr;

  // Go back to the construction phase if the transaction isn't complete.
  // Layout will update the layer tree and call EndTransaction().
  mPhase = mTransactionIncomplete ? PHASE_CONSTRUCTION : PHASE_NONE;

  NS_ASSERTION(!aCallback || !mTransactionIncomplete,
               "If callback is not null, transaction must be complete");

  if (gfxPlatform::GetPlatform()->DidRenderingDeviceReset()) {
    FrameLayerBuilder::InvalidateAllLayers(this);
  }

  return !mTransactionIncomplete;
}

void
ClientLayerManager::StorePluginWidgetConfigurations(const nsTArray<nsIWidget::Configuration>& aConfigurations)
{
  if (mForwarder) {
    mForwarder->StorePluginWidgetConfigurations(aConfigurations);
  }
}

void
ClientLayerManager::EndTransaction(DrawPaintedLayerCallback aCallback,
                                   void* aCallbackData,
                                   EndTransactionFlags aFlags)
{
  if (!mForwarder->IPCOpen()) {
    mInTransaction = false;
    return;
  }

  if (mWidget) {
    mWidget->PrepareWindowEffects();
  }
  EndTransactionInternal(aCallback, aCallbackData, aFlags);
  ForwardTransaction(!(aFlags & END_NO_REMOTE_COMPOSITE));

  if (mRepeatTransaction) {
    mRepeatTransaction = false;
    mIsRepeatTransaction = true;
    if (BeginTransaction()) {
      ClientLayerManager::EndTransaction(aCallback, aCallbackData, aFlags);
    }
    mIsRepeatTransaction = false;
  } else {
    MakeSnapshotIfRequired();
  }

  mInTransaction = false;
  mTransactionStart = TimeStamp();
}

bool
ClientLayerManager::EndEmptyTransaction(EndTransactionFlags aFlags)
{
  mInTransaction = false;

  if (!mRoot || !mForwarder->IPCOpen()) {
    return false;
  }

  if (!EndTransactionInternal(nullptr, nullptr, aFlags)) {
    // Return without calling ForwardTransaction. This leaves the
    // ShadowLayerForwarder transaction open; the following
    // EndTransaction will complete it.
    return false;
  }
  if (mWidget) {
    mWidget->PrepareWindowEffects();
  }
  ForwardTransaction(!(aFlags & END_NO_REMOTE_COMPOSITE));
  MakeSnapshotIfRequired();
  return true;
}

CompositorBridgeChild *
ClientLayerManager::GetRemoteRenderer()
{
  if (!mWidget) {
    return nullptr;
  }

  return mWidget->GetRemoteRenderer();
}

CompositorBridgeChild*
ClientLayerManager::GetCompositorBridgeChild()
{
  if (!XRE_IsParentProcess()) {
    return CompositorBridgeChild::Get();
  }
  return GetRemoteRenderer();
}

void
ClientLayerManager::Composite()
{
  mForwarder->Composite();
}

void
ClientLayerManager::DidComposite(uint64_t aTransactionId,
                                 const TimeStamp& aCompositeStart,
                                 const TimeStamp& aCompositeEnd)
{
  MOZ_ASSERT(mWidget);

  // |aTransactionId| will be > 0 if the compositor is acknowledging a shadow
  // layers transaction.
  if (aTransactionId) {
    nsIWidgetListener *listener = mWidget->GetWidgetListener();
    if (listener) {
      listener->DidCompositeWindow(aTransactionId, aCompositeStart, aCompositeEnd);
    }
    listener = mWidget->GetAttachedWidgetListener();
    if (listener) {
      listener->DidCompositeWindow(aTransactionId, aCompositeStart, aCompositeEnd);
    }
    mTransactionIdAllocator->NotifyTransactionCompleted(aTransactionId);
  }

  // These observers fire whether or not we were in a transaction.
  for (size_t i = 0; i < mDidCompositeObservers.Length(); i++) {
    mDidCompositeObservers[i]->DidComposite();
  }
}

void
ClientLayerManager::GetCompositorSideAPZTestData(APZTestData* aData) const
{
  if (mForwarder->HasShadowManager()) {
    if (!mForwarder->GetShadowManager()->SendGetAPZTestData(aData)) {
      NS_WARNING("Call to PLayerTransactionChild::SendGetAPZTestData() failed");
    }
  }
}

float
ClientLayerManager::RequestProperty(const nsAString& aProperty)
{
  if (mForwarder->HasShadowManager()) {
    float value;
    if (!mForwarder->GetShadowManager()->SendRequestProperty(nsString(aProperty), &value)) {
      NS_WARNING("Call to PLayerTransactionChild::SendGetAPZTestData() failed");
    }
    return value;
  }
  return -1;
}

void
ClientLayerManager::StartNewRepaintRequest(SequenceNumber aSequenceNumber)
{
  if (gfxPrefs::APZTestLoggingEnabled()) {
    mApzTestData.StartNewRepaintRequest(aSequenceNumber);
  }
}

void
ClientLayerManager::GetFrameUniformity(FrameUniformityData* aOutData)
{
  MOZ_ASSERT(XRE_IsParentProcess(), "Frame Uniformity only supported in parent process");

  if (HasShadowManager()) {
    CompositorBridgeChild* child = GetRemoteRenderer();
    child->SendGetFrameUniformity(aOutData);
    return;
  }

  return LayerManager::GetFrameUniformity(aOutData);
}

bool
ClientLayerManager::RequestOverfill(mozilla::dom::OverfillCallback* aCallback)
{
  MOZ_ASSERT(aCallback != nullptr);
  MOZ_ASSERT(HasShadowManager(), "Request Overfill only supported on b2g for now");

  if (HasShadowManager()) {
    CompositorBridgeChild* child = GetRemoteRenderer();
    NS_ASSERTION(child, "Could not get CompositorBridgeChild");

    child->AddOverfillObserver(this);
    child->SendRequestOverfill();
    mOverfillCallbacks.AppendElement(aCallback);
  }

  return true;
}

void
ClientLayerManager::RunOverfillCallback(const uint32_t aOverfill)
{
  for (size_t i = 0; i < mOverfillCallbacks.Length(); i++) {
    ErrorResult error;
    mOverfillCallbacks[i]->Call(aOverfill, error);
  }

  mOverfillCallbacks.Clear();
}

void
ClientLayerManager::MakeSnapshotIfRequired()
{
  if (!mShadowTarget) {
    return;
  }
  if (mWidget) {
    if (CompositorBridgeChild* remoteRenderer = GetRemoteRenderer()) {
      // The compositor doesn't draw to a different sized surface
      // when there's a rotation. Instead we rotate the result
      // when drawing into dt
      LayoutDeviceIntRect outerBounds = mWidget->GetBounds();

      IntRect bounds = ToOutsideIntRect(mShadowTarget->GetClipExtents());
      if (mTargetRotation) {
        bounds =
          RotateRect(bounds, outerBounds.ToUnknownRect(), mTargetRotation);
      }

      SurfaceDescriptor inSnapshot;
      if (!bounds.IsEmpty() &&
          mForwarder->AllocSurfaceDescriptor(bounds.Size(),
                                             gfxContentType::COLOR_ALPHA,
                                             &inSnapshot)) {

        // Make a copy of |inSnapshot| because the call to send it over IPC
        // will call forget() on the Shmem inside, and zero it out.
        SurfaceDescriptor outSnapshot = inSnapshot;

        if (remoteRenderer->SendMakeSnapshot(inSnapshot, bounds)) {
          RefPtr<DataSourceSurface> surf = GetSurfaceForDescriptor(outSnapshot);
          DrawTarget* dt = mShadowTarget->GetDrawTarget();

          Rect dstRect(bounds.x, bounds.y, bounds.width, bounds.height);
          Rect srcRect(0, 0, bounds.width, bounds.height);

          gfx::Matrix rotate =
            ComputeTransformForUnRotation(outerBounds.ToUnknownRect(),
                                          mTargetRotation);

          gfx::Matrix oldMatrix = dt->GetTransform();
          dt->SetTransform(rotate * oldMatrix);
          dt->DrawSurface(surf, dstRect, srcRect,
                          DrawSurfaceOptions(),
                          DrawOptions(1.0f, CompositionOp::OP_OVER));
          dt->SetTransform(oldMatrix);
        }
        mForwarder->DestroySurfaceDescriptor(&outSnapshot);
      }
    }
  }
  mShadowTarget = nullptr;
}

void
ClientLayerManager::FlushRendering()
{
  if (mWidget) {
    if (CompositorBridgeChild* remoteRenderer = mWidget->GetRemoteRenderer()) {
      remoteRenderer->SendFlushRendering();
    }
  }
}

void
ClientLayerManager::UpdateTextureFactoryIdentifier(const TextureFactoryIdentifier& aNewIdentifier)
{
  mForwarder->IdentifyTextureHost(aNewIdentifier);
}

void
ClientLayerManager::SendInvalidRegion(const nsIntRegion& aRegion)
{
  if (mWidget) {
    if (CompositorBridgeChild* remoteRenderer = mWidget->GetRemoteRenderer()) {
      remoteRenderer->SendNotifyRegionInvalidated(aRegion);
    }
  }
}

uint32_t
ClientLayerManager::StartFrameTimeRecording(int32_t aBufferSize)
{
  CompositorBridgeChild* renderer = GetRemoteRenderer();
  if (renderer) {
    uint32_t startIndex;
    renderer->SendStartFrameTimeRecording(aBufferSize, &startIndex);
    return startIndex;
  }
  return -1;
}

void
ClientLayerManager::StopFrameTimeRecording(uint32_t         aStartIndex,
                                           nsTArray<float>& aFrameIntervals)
{
  CompositorBridgeChild* renderer = GetRemoteRenderer();
  if (renderer) {
    renderer->SendStopFrameTimeRecording(aStartIndex, &aFrameIntervals);
  }
}

void
ClientLayerManager::ForwardTransaction(bool aScheduleComposite)
{
  TimeStamp start = TimeStamp::Now();

  // Skip the synchronization for buffer since we also skip the painting during
  // device-reset status.
  if (!gfxPlatform::GetPlatform()->DidRenderingDeviceReset()) {
    if (mForwarder->GetSyncObject() &&
        mForwarder->GetSyncObject()->IsSyncObjectValid()) {
      mForwarder->GetSyncObject()->FinalizeFrame();
    }
  }

  mPhase = PHASE_FORWARD;

  mLatestTransactionId = mTransactionIdAllocator->GetTransactionId();
  TimeStamp transactionStart;
  if (!mTransactionIdAllocator->GetTransactionStart().IsNull()) {
    transactionStart = mTransactionIdAllocator->GetTransactionStart();
  } else {
    transactionStart = mTransactionStart;
  }

  if (gfxPrefs::AlwaysPaint() && XRE_IsContentProcess()) {
    mForwarder->SendPaintTime(mLatestTransactionId, mLastPaintTime);
  }

  // forward this transaction's changeset to our LayerManagerComposite
  bool sent;
  AutoTArray<EditReply, 10> replies;
  if (mForwarder->EndTransaction(&replies, mRegionToClear,
        mLatestTransactionId, aScheduleComposite, mPaintSequenceNumber,
        mIsRepeatTransaction, transactionStart, &sent)) {
    for (nsTArray<EditReply>::size_type i = 0; i < replies.Length(); ++i) {
      const EditReply& reply = replies[i];

      switch (reply.type()) {
      case EditReply::TOpContentBufferSwap: {
        MOZ_LAYERS_LOG(("[LayersForwarder] DoubleBufferSwap"));

        const OpContentBufferSwap& obs = reply.get_OpContentBufferSwap();

        RefPtr<CompositableClient> compositable =
          CompositableClient::FromIPDLActor(obs.compositableChild());
        ContentClientRemote* contentClient =
          static_cast<ContentClientRemote*>(compositable.get());
        MOZ_ASSERT(contentClient);

        contentClient->SwapBuffers(obs.frontUpdatedRegion());

        break;
      }
      default:
        NS_RUNTIMEABORT("not reached");
      }
    }

    if (sent) {
      mNeedsComposite = false;
    }
  } else if (HasShadowManager()) {
    NS_WARNING("failed to forward Layers transaction");
  }

  if (!sent) {
    // Clear the transaction id so that it doesn't get returned
    // unless we forwarded to somewhere that doesn't actually
    // have a compositor.
    mTransactionIdAllocator->RevokeTransactionId(mLatestTransactionId);
  }

  mPhase = PHASE_NONE;

  // this may result in Layers being deleted, which results in
  // PLayer::Send__delete__() and DeallocShmem()
  mKeepAlive.Clear();

  TabChild* window = mWidget ? mWidget->GetOwningTabChild() : nullptr;
  if (window) {
    TimeStamp end = TimeStamp::Now();
    window->DidRequestComposite(start, end);
  }
}

ShadowableLayer*
ClientLayerManager::Hold(Layer* aLayer)
{
  MOZ_ASSERT(HasShadowManager(),
             "top-level tree, no shadow tree to remote to");

  ShadowableLayer* shadowable = ClientLayer::ToClientLayer(aLayer);
  MOZ_ASSERT(shadowable, "trying to remote an unshadowable layer");

  mKeepAlive.AppendElement(aLayer);
  return shadowable;
}

bool
ClientLayerManager::IsCompositingCheap()
{
  // Whether compositing is cheap depends on the parent backend.
  return mForwarder->mShadowManager &&
         LayerManager::IsCompositingCheap(mForwarder->GetCompositorBackendType());
}

bool
ClientLayerManager::AreComponentAlphaLayersEnabled()
{
  return GetCompositorBackendType() != LayersBackend::LAYERS_BASIC &&
         AsShadowForwarder()->SupportsComponentAlpha() &&
         LayerManager::AreComponentAlphaLayersEnabled();
}

void
ClientLayerManager::SetIsFirstPaint()
{
  mForwarder->SetIsFirstPaint();
}

void
ClientLayerManager::ClearCachedResources(Layer* aSubtree)
{
  if (mDestroyed) {
    // ClearCachedResource was already called by ClientLayerManager::Destroy
    return;
  }
  MOZ_ASSERT(!HasShadowManager() || !aSubtree);
  mForwarder->ClearCachedResources();
  if (aSubtree) {
    ClearLayer(aSubtree);
  } else if (mRoot) {
    ClearLayer(mRoot);
  }
}

void
ClientLayerManager::HandleMemoryPressure()
{
  if (mRoot) {
    HandleMemoryPressureLayer(mRoot);
  }

  if (GetCompositorBridgeChild()) {
    GetCompositorBridgeChild()->HandleMemoryPressure();
  }
}

void
ClientLayerManager::ClearLayer(Layer* aLayer)
{
  ClientLayer::ToClientLayer(aLayer)->ClearCachedResources();
  for (Layer* child = aLayer->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    ClearLayer(child);
  }
}

void
ClientLayerManager::HandleMemoryPressureLayer(Layer* aLayer)
{
  ClientLayer::ToClientLayer(aLayer)->HandleMemoryPressure();
  for (Layer* child = aLayer->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    HandleMemoryPressureLayer(child);
  }
}

void
ClientLayerManager::GetBackendName(nsAString& aName)
{
  switch (mForwarder->GetCompositorBackendType()) {
    case LayersBackend::LAYERS_NONE: aName.AssignLiteral("None"); return;
    case LayersBackend::LAYERS_BASIC: aName.AssignLiteral("Basic"); return;
    case LayersBackend::LAYERS_OPENGL: aName.AssignLiteral("OpenGL"); return;
    case LayersBackend::LAYERS_D3D9: aName.AssignLiteral("Direct3D 9"); return;
    case LayersBackend::LAYERS_D3D11: {
#ifdef XP_WIN
      if (DeviceManagerDx::Get()->IsWARP()) {
        aName.AssignLiteral("Direct3D 11 WARP");
      } else {
        aName.AssignLiteral("Direct3D 11");
      }
#endif
      return;
    }
    default: NS_RUNTIMEABORT("Invalid backend");
  }
}

bool
ClientLayerManager::AsyncPanZoomEnabled() const
{
  return mWidget && mWidget->AsyncPanZoomEnabled();
}

void
ClientLayerManager::SetNextPaintSyncId(int32_t aSyncId)
{
  mForwarder->SetPaintSyncId(aSyncId);
}

void
ClientLayerManager::SetLayerObserverEpoch(uint64_t aLayerObserverEpoch)
{
  mForwarder->SetLayerObserverEpoch(aLayerObserverEpoch);
}

void
ClientLayerManager::AddDidCompositeObserver(DidCompositeObserver* aObserver)
{
  if (!mDidCompositeObservers.Contains(aObserver)) {
    mDidCompositeObservers.AppendElement(aObserver);
  }
}

void
ClientLayerManager::RemoveDidCompositeObserver(DidCompositeObserver* aObserver)
{
  mDidCompositeObservers.RemoveElement(aObserver);
}

bool
ClientLayerManager::DependsOnStaleDevice() const
{
  return gfxPlatform::GetPlatform()->GetDeviceCounter() != mDeviceCounter;
}


already_AddRefed<PersistentBufferProvider>
ClientLayerManager::CreatePersistentBufferProvider(const gfx::IntSize& aSize,
                                                   gfx::SurfaceFormat aFormat)
{
  // Don't use a shared buffer provider if compositing is considered "not cheap"
  // because the canvas will most likely be flattened into a thebes layer instead
  // of being sent to the compositor, in which case rendering into shared memory
  // is wasteful.
  if (IsCompositingCheap() &&
      gfxPrefs::PersistentBufferProviderSharedEnabled()) {
    RefPtr<PersistentBufferProvider> provider
      = PersistentBufferProviderShared::Create(aSize, aFormat, AsShadowForwarder());
    if (provider) {
      return provider.forget();
    }
  }

  return LayerManager::CreatePersistentBufferProvider(aSize, aFormat);
}


ClientLayer::~ClientLayer()
{
  if (HasShadow()) {
    PLayerChild::Send__delete__(GetShadow());
  }
  MOZ_COUNT_DTOR(ClientLayer);
}

} // namespace layers
} // namespace mozilla