/* -*- 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 "mozilla/layers/TextureClient.h"

#include <stdint.h>  // for uint8_t, uint32_t, etc

#include "BufferTexture.h"
#include "IPDLActor.h"
#include "ImageContainer.h"  // for PlanarYCbCrData, etc
#include "MainThreadUtils.h"
#include "gfx2DGlue.h"
#include "gfxPlatform.h"  // for gfxPlatform
#include "gfxUtils.h"     // for gfxUtils::GetAsLZ4Base64Str
#include "mozilla/Atomics.h"
#include "mozilla/Mutex.h"
#include "mozilla/ProfilerLabels.h"
#include "mozilla/SchedulerGroup.h"
#include "mozilla/StaticPrefs_gfx.h"
#include "mozilla/StaticPrefs_layers.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/DataSurfaceHelpers.h"  // for CreateDataSourceSurfaceByCloning
#include "mozilla/gfx/Logging.h"             // for gfxDebug
#include "mozilla/gfx/gfxVars.h"
#include "mozilla/ipc/CrossProcessSemaphore.h"
#include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
#include "mozilla/layers/CompositableForwarder.h"
#include "mozilla/layers/ISurfaceAllocator.h"
#include "mozilla/layers/ImageBridgeChild.h"
#include "mozilla/layers/ImageDataSerializer.h"
#include "mozilla/layers/PTextureChild.h"
#include "mozilla/layers/TextureClientOGL.h"
#include "mozilla/layers/TextureClientRecycleAllocator.h"
#include "mozilla/layers/TextureRecorded.h"
#include "nsDebug.h"  // for NS_ASSERTION, NS_WARNING, etc
#include "nsISerialEventTarget.h"
#include "nsISupportsImpl.h"  // for MOZ_COUNT_CTOR, etc
#include "nsPrintfCString.h"  // for nsPrintfCString

#ifdef XP_WIN
#  include "gfx2DGlue.h"
#  include "gfxWindowsPlatform.h"
#  include "mozilla/gfx/DeviceManagerDx.h"
#  include "mozilla/layers/TextureD3D11.h"
#endif
#ifdef MOZ_WAYLAND
#  include <gtk/gtkx.h>

#  include "gfxPlatformGtk.h"
#  include "mozilla/layers/DMABUFTextureClientOGL.h"
#  include "mozilla/widget/nsWaylandDisplay.h"
#endif

#ifdef XP_MACOSX
#  include "mozilla/layers/MacIOSurfaceTextureClientOGL.h"
#endif

#if 0
#  define RECYCLE_LOG(...) printf_stderr(__VA_ARGS__)
#else
#  define RECYCLE_LOG(...) \
    do {                   \
    } while (0)
#endif

namespace mozilla::layers {

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

struct TextureDeallocParams {
  TextureData* data;
  RefPtr<TextureChild> actor;
  RefPtr<LayersIPCChannel> allocator;
  bool clientDeallocation;
  bool syncDeallocation;
};

void DeallocateTextureClient(TextureDeallocParams params);

/**
 * TextureChild is the content-side incarnation of the PTexture IPDL actor.
 *
 * TextureChild is used to synchronize a texture client and its corresponding
 * TextureHost if needed (a TextureClient that is not shared with the compositor
 * does not have a TextureChild)
 *
 * During the deallocation phase, a TextureChild may hold its recently destroyed
 * TextureClient's data until the compositor side confirmed that it is safe to
 * deallocte or recycle the it.
 */
class TextureChild final : PTextureChild {
  ~TextureChild() {
    // We should have deallocated mTextureData in ActorDestroy
    MOZ_ASSERT(!mTextureData);
    MOZ_ASSERT_IF(!mOwnerCalledDestroy, !mTextureClient);
  }

 public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(TextureChild)

  TextureChild()
      : mCompositableForwarder(nullptr),
        mTextureForwarder(nullptr),
        mTextureClient(nullptr),
        mTextureData(nullptr),
        mDestroyed(false),
        mIPCOpen(false),
        mOwnsTextureData(false),
        mOwnerCalledDestroy(false),
        mUsesImageBridge(false) {}

  mozilla::ipc::IPCResult Recv__delete__() override { return IPC_OK(); }

  LayersIPCChannel* GetAllocator() { return mTextureForwarder; }

  void ActorDestroy(ActorDestroyReason why) override;

  bool IPCOpen() const { return mIPCOpen; }

  void Lock() const {
    if (mUsesImageBridge) {
      mLock.Enter();
    }
  }

  void Unlock() const {
    if (mUsesImageBridge) {
      mLock.Leave();
    }
  }

 private:
  // AddIPDLReference and ReleaseIPDLReference are only to be called by
  // CreateIPDLActor and DestroyIPDLActor, respectively. We intentionally make
  // them private to prevent misuse. The purpose of these methods is to be aware
  // of when the IPC system around this actor goes down: mIPCOpen is then set to
  // false.
  void AddIPDLReference() {
    MOZ_ASSERT(mIPCOpen == false);
    mIPCOpen = true;
    AddRef();
  }
  void ReleaseIPDLReference() {
    MOZ_ASSERT(mIPCOpen == false);
    Release();
  }

  /// The normal way to destroy the actor.
  ///
  /// This will asynchronously send a Destroy message to the parent actor, whom
  /// will send the delete message.
  void Destroy(const TextureDeallocParams& aParams);

  // This lock is used order to prevent several threads to access the
  // TextureClient's data concurrently. In particular, it prevents shutdown
  // code to destroy a texture while another thread is reading or writing into
  // it.
  // In most places, the lock is held in short and bounded scopes in which we
  // don't block on any other resource. There are few exceptions to this, which
  // are discussed below.
  //
  // The locking pattern of TextureClient may in some case upset deadlock
  // detection tools such as TSan. Typically our tile rendering code will lock
  // all of its tiles, render into them and unlock them all right after that,
  // which looks something like:
  //
  // Lock tile A
  // Lock tile B
  // Lock tile C
  // Apply drawing commands to tiles A, B and C
  // Unlock tile A
  // Unlock tile B
  // Unlock tile C
  //
  // And later, we may end up rendering a tile buffer that has the same tiles,
  // in a different order, for example:
  //
  // Lock tile B
  // Lock tile A
  // Lock tile D
  // Apply drawing commands to tiles A, B and D
  // Unlock tile B
  // Unlock tile A
  // Unlock tile D
  //
  // This is because textures being expensive to create, we recycle them as much
  // as possible and they may reappear in the tile buffer in a different order.
  //
  // Unfortunately this is not very friendly to TSan's analysis, which will see
  // that B was once locked while A was locked, and then A locked while B was
  // locked. TSan identifies this as a potential dead-lock which would be the
  // case if this kind of inconsistent and dependent locking order was happening
  // concurrently.
  // In the case of TextureClient, dependent locking only ever happens on the
  // thread that draws into the texture (let's call it the producer thread).
  // Other threads may call into a method that can lock the texture in a short
  // and bounded scope inside of which it is not allowed to do anything that
  // could cause the thread to block. A given texture can only have one producer
  // thread.
  //
  // Another example of TSan-unfriendly locking pattern is when copying a
  // texture into another, which also never happens outside of the producer
  // thread. Copying A into B looks like this:
  //
  // Lock texture B
  // Lock texture A
  // Copy A into B
  // Unlock A
  // Unlock B
  //
  // In a given frame we may need to copy A into B and in another frame copy
  // B into A. For example A and B can be the Front and Back buffers,
  // alternating roles and the copy is needed to avoid the cost of re-drawing
  // the valid region.
  //
  // The important rule is that all of the dependent locking must occur only
  // in the texture's producer thread to avoid deadlocks.
  mutable gfx::CriticalSection mLock;

  RefPtr<CompositableForwarder> mCompositableForwarder;
  RefPtr<TextureForwarder> mTextureForwarder;

  TextureClient* mTextureClient;
  TextureData* mTextureData;
  Atomic<bool> mDestroyed;
  bool mIPCOpen;
  bool mOwnsTextureData;
  bool mOwnerCalledDestroy;
  bool mUsesImageBridge;

  friend class TextureClient;
  friend void DeallocateTextureClient(TextureDeallocParams params);
};

static inline gfx::BackendType BackendTypeForBackendSelector(
    LayersBackend aLayersBackend, BackendSelector aSelector) {
  switch (aSelector) {
    case BackendSelector::Canvas:
      return gfxPlatform::GetPlatform()->GetPreferredCanvasBackend();
    case BackendSelector::Content:
      return gfxPlatform::GetPlatform()->GetContentBackendFor(aLayersBackend);
    default:
      MOZ_ASSERT_UNREACHABLE("Unknown backend selector");
      return gfx::BackendType::NONE;
  }
};

static TextureType GetTextureType(gfx::SurfaceFormat aFormat,
                                  gfx::IntSize aSize,
                                  KnowsCompositor* aKnowsCompositor,
                                  BackendSelector aSelector,
                                  TextureAllocationFlags aAllocFlags) {
  LayersBackend layersBackend = aKnowsCompositor->GetCompositorBackendType();
  gfx::BackendType moz2DBackend =
      BackendTypeForBackendSelector(layersBackend, aSelector);
  Unused << moz2DBackend;

#ifdef XP_WIN
  int32_t maxTextureSize = aKnowsCompositor->GetMaxTextureSize();
  if ((layersBackend == LayersBackend::LAYERS_WR &&
       !aKnowsCompositor->UsingSoftwareWebRender()) &&
      (moz2DBackend == gfx::BackendType::DIRECT2D ||
       moz2DBackend == gfx::BackendType::DIRECT2D1_1) &&
      aSize.width <= maxTextureSize && aSize.height <= maxTextureSize &&
      !(aAllocFlags & (ALLOC_UPDATE_FROM_SURFACE | ALLOC_DO_NOT_ACCELERATE))) {
    return TextureType::D3D11;
  }
#endif

#ifdef MOZ_WAYLAND
  if ((layersBackend == LayersBackend::LAYERS_WR &&
       !aKnowsCompositor->UsingSoftwareWebRender()) &&
      widget::DMABufDevice::IsDMABufTexturesEnabled() &&
      aFormat != SurfaceFormat::A8) {
    return TextureType::DMABUF;
  }
#endif

#ifdef XP_MACOSX
  if (StaticPrefs::gfx_use_iosurface_textures_AtStartup()) {
    return TextureType::MacIOSurface;
  }
#endif

#ifdef MOZ_WIDGET_ANDROID
  if (StaticPrefs::gfx_use_surfacetexture_textures_AtStartup()) {
    return TextureType::AndroidNativeWindow;
  }
#endif

  return TextureType::Unknown;
}

TextureType PreferredCanvasTextureType(KnowsCompositor* aKnowsCompositor) {
  return GetTextureType(gfx::SurfaceFormat::R8G8B8A8, {1, 1}, aKnowsCompositor,
                        BackendSelector::Canvas,
                        TextureAllocationFlags::ALLOC_DEFAULT);
}

static bool ShouldRemoteTextureType(TextureType aTextureType,
                                    BackendSelector aSelector) {
  if (aSelector != BackendSelector::Canvas || !gfxPlatform::UseRemoteCanvas()) {
    return false;
  }

  switch (aTextureType) {
    case TextureType::D3D11:
      return true;
    default:
      return false;
  }
}

/* static */
TextureData* TextureData::Create(TextureForwarder* aAllocator,
                                 gfx::SurfaceFormat aFormat, gfx::IntSize aSize,
                                 KnowsCompositor* aKnowsCompositor,
                                 BackendSelector aSelector,
                                 TextureFlags aTextureFlags,
                                 TextureAllocationFlags aAllocFlags) {
  TextureType textureType =
      GetTextureType(aFormat, aSize, aKnowsCompositor, aSelector, aAllocFlags);

  if (ShouldRemoteTextureType(textureType, aSelector)) {
    RefPtr<CanvasChild> canvasChild = aAllocator->GetCanvasChild();
    if (canvasChild) {
      return new RecordedTextureData(canvasChild.forget(), aSize, aFormat,
                                     textureType);
    }

    // We don't have a CanvasChild, but are supposed to be remote.
    // Fall back to software.
    textureType = TextureType::Unknown;
  }

#if defined(XP_MACOSX) || defined(MOZ_WAYLAND)
  gfx::BackendType moz2DBackend = BackendTypeForBackendSelector(
      aKnowsCompositor->GetCompositorBackendType(), aSelector);
#endif

  switch (textureType) {
#ifdef XP_WIN
    case TextureType::D3D11:
      return D3D11TextureData::Create(aSize, aFormat, aAllocFlags);
#endif

#ifdef MOZ_WAYLAND
    case TextureType::DMABUF:
      return DMABUFTextureData::Create(aSize, aFormat, moz2DBackend);
#endif

#ifdef XP_MACOSX
    case TextureType::MacIOSurface:
      return MacIOSurfaceTextureData::Create(aSize, aFormat, moz2DBackend);
#endif
#ifdef MOZ_WIDGET_ANDROID
    case TextureType::AndroidNativeWindow:
      return AndroidNativeWindowTextureData::Create(aSize, aFormat);
#endif
    default:
      return nullptr;
  }
}

/* static */
bool TextureData::IsRemote(KnowsCompositor* aKnowsCompositor,
                           BackendSelector aSelector) {
  TextureType textureType = GetTextureType(
      gfx::SurfaceFormat::UNKNOWN, gfx::IntSize(1, 1), aKnowsCompositor,
      aSelector, TextureAllocationFlags::ALLOC_DEFAULT);

  return ShouldRemoteTextureType(textureType, aSelector);
}

static void DestroyTextureData(TextureData* aTextureData,
                               LayersIPCChannel* aAllocator, bool aDeallocate) {
  if (!aTextureData) {
    return;
  }

  if (aDeallocate) {
    aTextureData->Deallocate(aAllocator);
  } else {
    aTextureData->Forget(aAllocator);
  }
  delete aTextureData;
}

void TextureChild::ActorDestroy(ActorDestroyReason why) {
  AUTO_PROFILER_LABEL("TextureChild::ActorDestroy", GRAPHICS);
  MOZ_ASSERT(mIPCOpen);
  mIPCOpen = false;

  if (mTextureData) {
    DestroyTextureData(mTextureData, GetAllocator(), mOwnsTextureData);
    mTextureData = nullptr;
  }
}

void TextureChild::Destroy(const TextureDeallocParams& aParams) {
  MOZ_ASSERT(!mOwnerCalledDestroy);
  if (mOwnerCalledDestroy) {
    return;
  }

  mOwnerCalledDestroy = true;

  if (!IPCOpen()) {
    DestroyTextureData(aParams.data, aParams.allocator,
                       aParams.clientDeallocation);
    return;
  }

  // DestroyTextureData will be called by TextureChild::ActorDestroy
  mTextureData = aParams.data;
  mOwnsTextureData = aParams.clientDeallocation;

  if (!mCompositableForwarder ||
      !mCompositableForwarder->DestroyInTransaction(this)) {
    this->SendDestroy();
  }
}

/* static */
Atomic<uint64_t> TextureClient::sSerialCounter(0);

static void DeallocateTextureClientSyncProxy(TextureDeallocParams params,
                                             ReentrantMonitor* aBarrier,
                                             bool* aDone) {
  DeallocateTextureClient(params);
  ReentrantMonitorAutoEnter autoMon(*aBarrier);
  *aDone = true;
  aBarrier->NotifyAll();
}

/// The logic for synchronizing a TextureClient's deallocation goes here.
///
/// This funciton takes care of dispatching work to the right thread using
/// a synchronous proxy if needed, and handles client/host deallocation.
void DeallocateTextureClient(TextureDeallocParams params) {
  if (!params.actor && !params.data) {
    // Nothing to do
    return;
  }

  TextureChild* actor = params.actor;
  nsCOMPtr<nsISerialEventTarget> ipdlThread;

  if (params.allocator) {
    ipdlThread = params.allocator->GetThread();
    if (!ipdlThread) {
      // An allocator with no thread means we are too late in the shutdown
      // sequence.
      gfxCriticalError() << "Texture deallocated too late during shutdown";
      return;
    }
  }

  // First make sure that the work is happening on the IPDL thread.
  if (ipdlThread && !ipdlThread->IsOnCurrentThread()) {
    if (params.syncDeallocation) {
      bool done = false;
      ReentrantMonitor barrier MOZ_UNANNOTATED("DeallocateTextureClient");
      ReentrantMonitorAutoEnter autoMon(barrier);
      ipdlThread->Dispatch(NewRunnableFunction(
          "DeallocateTextureClientSyncProxyRunnable",
          DeallocateTextureClientSyncProxy, params, &barrier, &done));
      while (!done) {
        barrier.Wait();
      }
    } else {
      ipdlThread->Dispatch(NewRunnableFunction(
          "DeallocateTextureClientRunnable", DeallocateTextureClient, params));
    }
    // The work has been forwarded to the IPDL thread, we are done.
    return;
  }

  // Below this line, we are either in the IPDL thread or ther is no IPDL
  // thread anymore.

  if (!ipdlThread) {
    // If we don't have a thread we can't know for sure that we are in
    // the IPDL thread and use the LayersIPCChannel.
    // This should ideally not happen outside of gtest, but some shutdown
    // raciness could put us in this situation.
    params.allocator = nullptr;
  }

  if (!actor) {
    // We don't have an IPDL actor, probably because we destroyed the
    // TextureClient before sharing it with the compositor. It means the data
    // cannot be owned by the TextureHost since we never created the
    // TextureHost...
    DestroyTextureData(params.data, params.allocator, /* aDeallocate */ true);
    return;
  }

  actor->Destroy(params);
}

void TextureClient::Destroy() {
  // Async paints should have been flushed by now.
  MOZ_RELEASE_ASSERT(mPaintThreadRefs == 0);

  if (mActor && !mIsLocked) {
    mActor->Lock();
  }

  mBorrowedDrawTarget = nullptr;
  mReadLock = nullptr;

  RefPtr<TextureChild> actor = mActor;
  mActor = nullptr;

  if (actor && !actor->mDestroyed.compareExchange(false, true)) {
    actor->Unlock();
    actor = nullptr;
  }

  TextureData* data = mData;
  mData = nullptr;

  if (data || actor) {
    TextureDeallocParams params;
    params.actor = actor;
    params.allocator = mAllocator;
    params.clientDeallocation = !!(mFlags & TextureFlags::DEALLOCATE_CLIENT);
    params.data = data;
    // At the moment we always deallocate synchronously when deallocating on the
    // client side, but having asynchronous deallocate in some of the cases will
    // be a worthwhile optimization.
    params.syncDeallocation = !!(mFlags & TextureFlags::DEALLOCATE_CLIENT);

    // Release the lock before calling DeallocateTextureClient because the
    // latter may wait for the main thread which could create a dead-lock.

    if (actor) {
      actor->Unlock();
    }

    DeallocateTextureClient(params);
  }
}

void TextureClient::LockActor() const {
  if (mActor) {
    mActor->Lock();
  }
}

void TextureClient::UnlockActor() const {
  if (mActor) {
    mActor->Unlock();
  }
}

bool TextureClient::IsReadLocked() const {
  if (!mReadLock) {
    return false;
  }
  MOZ_ASSERT(mReadLock->AsNonBlockingLock(),
             "Can only check locked for non-blocking locks!");
  return mReadLock->AsNonBlockingLock()->GetReadCount() > 1;
}

bool TextureClient::TryReadLock() {
  if (!mReadLock || mIsReadLocked) {
    return true;
  }

  if (mReadLock->AsNonBlockingLock()) {
    if (IsReadLocked()) {
      return false;
    }
  }

  if (!mReadLock->TryReadLock(TimeDuration::FromMilliseconds(500))) {
    return false;
  }

  mIsReadLocked = true;
  return true;
}

void TextureClient::ReadUnlock() {
  if (!mIsReadLocked) {
    return;
  }
  MOZ_ASSERT(mReadLock);
  mReadLock->ReadUnlock();
  mIsReadLocked = false;
}

bool TextureClient::Lock(OpenMode aMode) {
  MOZ_ASSERT(IsValid());
  MOZ_ASSERT(!mIsLocked);
  if (!IsValid()) {
    return false;
  }
  if (mIsLocked) {
    return mOpenMode == aMode;
  }

  if ((aMode & OpenMode::OPEN_WRITE || !mInfo.canConcurrentlyReadLock) &&
      !TryReadLock()) {
    // Only warn if attempting to write. Attempting to read is acceptable usage.
    if (aMode & OpenMode::OPEN_WRITE) {
      NS_WARNING(
          "Attempt to Lock a texture that is being read by the compositor!");
    }
    return false;
  }

  LockActor();

  mIsLocked = mData->Lock(aMode);
  mOpenMode = aMode;

  auto format = GetFormat();
  if (mIsLocked && CanExposeDrawTarget() &&
      (aMode & OpenMode::OPEN_READ_WRITE) == OpenMode::OPEN_READ_WRITE &&
      NS_IsMainThread() &&
      // the formats that we apparently expect, in the cairo backend. Any other
      // format will trigger an assertion in GfxFormatToCairoFormat.
      (format == SurfaceFormat::A8R8G8B8_UINT32 ||
       format == SurfaceFormat::X8R8G8B8_UINT32 ||
       format == SurfaceFormat::A8 || format == SurfaceFormat::R5G6B5_UINT16)) {
    if (!BorrowDrawTarget()) {
      // Failed to get a DrawTarget, means we won't be able to write into the
      // texture, might as well fail now.
      Unlock();
      return false;
    }
  }

  if (!mIsLocked) {
    UnlockActor();
    ReadUnlock();
  }

  return mIsLocked;
}

void TextureClient::Unlock() {
  MOZ_ASSERT(IsValid());
  MOZ_ASSERT(mIsLocked);
  if (!IsValid() || !mIsLocked) {
    return;
  }

  if (mBorrowedDrawTarget) {
    if (!(mOpenMode & OpenMode::OPEN_ASYNC)) {
      if (mOpenMode & OpenMode::OPEN_WRITE) {
        mBorrowedDrawTarget->Flush();
      }

      mBorrowedDrawTarget->DetachAllSnapshots();
      // If this assertion is hit, it means something is holding a strong
      // reference to our DrawTarget externally, which is not allowed.
      MOZ_ASSERT(mBorrowedDrawTarget->refCount() <= mExpectedDtRefs);
    }

    mBorrowedDrawTarget = nullptr;
  }

  if (mOpenMode & OpenMode::OPEN_WRITE) {
    mUpdated = true;
  }

  if (mData) {
    mData->Unlock();
  }
  mIsLocked = false;
  mOpenMode = OpenMode::OPEN_NONE;

  UnlockActor();
  ReadUnlock();
}

void TextureClient::EnableReadLock() {
  if (!mReadLock) {
    if (mAllocator->GetTileLockAllocator()) {
      mReadLock = NonBlockingTextureReadLock::Create(mAllocator);
    } else {
      // IPC is down
      gfxCriticalError() << "TextureClient::EnableReadLock IPC is down";
    }
  }
}

bool TextureClient::OnForwardedToHost() {
  if (mData) {
    mData->OnForwardedToHost();
  }

  if (mReadLock && mUpdated) {
    // Take a read lock on behalf of the TextureHost. The latter will unlock
    // after the shared data is available again for drawing.
    mReadLock->ReadLock();
    mUpdated = false;
    return true;
  }

  return false;
}

TextureClient::~TextureClient() {
  // TextureClients should be kept alive while there are references on the
  // paint thread.
  MOZ_ASSERT(mPaintThreadRefs == 0);
  mReadLock = nullptr;
  Destroy();
}

void TextureClient::UpdateFromSurface(gfx::SourceSurface* aSurface) {
  MOZ_ASSERT(IsValid());
  MOZ_ASSERT(mIsLocked);
  MOZ_ASSERT(aSurface);
  // If you run into this assertion, make sure the texture was locked write-only
  // rather than read-write.
  MOZ_ASSERT(!mBorrowedDrawTarget);

  // XXX - It would be better to first try the DrawTarget approach and fallback
  // to the backend-specific implementation because the latter will usually do
  // an expensive read-back + cpu-side copy if the texture is on the gpu.
  // There is a bug with the DrawTarget approach, though specific to reading
  // back from WebGL (where R and B channel end up inverted) to figure out
  // first.
  if (mData->UpdateFromSurface(aSurface)) {
    return;
  }
  if (CanExposeDrawTarget() && NS_IsMainThread()) {
    RefPtr<DrawTarget> dt = BorrowDrawTarget();

    MOZ_ASSERT(dt);
    if (dt) {
      dt->CopySurface(aSurface,
                      gfx::IntRect(gfx::IntPoint(0, 0), aSurface->GetSize()),
                      gfx::IntPoint(0, 0));
      return;
    }
  }
  NS_WARNING("TextureClient::UpdateFromSurface failed");
}

already_AddRefed<TextureClient> TextureClient::CreateSimilar(
    LayersBackend aLayersBackend, TextureFlags aFlags,
    TextureAllocationFlags aAllocFlags) const {
  MOZ_ASSERT(IsValid());

  MOZ_ASSERT(!mIsLocked);
  if (mIsLocked) {
    return nullptr;
  }

  LockActor();
  TextureData* data =
      mData->CreateSimilar(mAllocator, aLayersBackend, aFlags, aAllocFlags);
  UnlockActor();

  if (!data) {
    return nullptr;
  }

  return MakeAndAddRef<TextureClient>(data, aFlags, mAllocator);
}

gfx::DrawTarget* TextureClient::BorrowDrawTarget() {
  MOZ_ASSERT(IsValid());
  MOZ_ASSERT(mIsLocked);
  // TODO- We can't really assert that at the moment because there is code that
  // Borrows the DrawTarget, just to get a snapshot, which is legit in term of
  // OpenMode but we should have a way to get a SourceSurface directly instead.
  // MOZ_ASSERT(mOpenMode & OpenMode::OPEN_WRITE);

  if (!IsValid() || !mIsLocked) {
    return nullptr;
  }

  if (!mBorrowedDrawTarget) {
    mBorrowedDrawTarget = mData->BorrowDrawTarget();
#ifdef DEBUG
    mExpectedDtRefs = mBorrowedDrawTarget ? mBorrowedDrawTarget->refCount() : 0;
#endif
  }

  return mBorrowedDrawTarget;
}

void TextureClient::EndDraw() {
  MOZ_ASSERT(mOpenMode & OpenMode::OPEN_READ_WRITE);

  // Because EndDraw is used when we are not unlocking this TextureClient at the
  // end of a transaction, we need to Flush and DetachAllSnapshots to ensure any
  // dependents are updated.
  mBorrowedDrawTarget->Flush();
  mBorrowedDrawTarget->DetachAllSnapshots();
  MOZ_ASSERT(mBorrowedDrawTarget->refCount() <= mExpectedDtRefs);

  mBorrowedDrawTarget = nullptr;
  mData->EndDraw();
}

already_AddRefed<gfx::SourceSurface> TextureClient::BorrowSnapshot() {
  MOZ_ASSERT(mIsLocked);

  RefPtr<gfx::SourceSurface> surface = mData->BorrowSnapshot();
  if (!surface) {
    surface = BorrowDrawTarget()->Snapshot();
  }

  return surface.forget();
}

bool TextureClient::BorrowMappedData(MappedTextureData& aMap) {
  MOZ_ASSERT(IsValid());

  // TODO - SharedRGBImage just accesses the buffer without properly locking
  // the texture. It's bad.
  // MOZ_ASSERT(mIsLocked);
  // if (!mIsLocked) {
  //  return nullptr;
  //}

  return mData ? mData->BorrowMappedData(aMap) : false;
}

bool TextureClient::BorrowMappedYCbCrData(MappedYCbCrTextureData& aMap) {
  MOZ_ASSERT(IsValid());

  return mData ? mData->BorrowMappedYCbCrData(aMap) : false;
}

bool TextureClient::ToSurfaceDescriptor(SurfaceDescriptor& aOutDescriptor) {
  MOZ_ASSERT(IsValid());

  return mData ? mData->Serialize(aOutDescriptor) : false;
}

// static
PTextureChild* TextureClient::CreateIPDLActor() {
  TextureChild* c = new TextureChild();
  c->AddIPDLReference();
  return c;
}

// static
bool TextureClient::DestroyIPDLActor(PTextureChild* actor) {
  static_cast<TextureChild*>(actor)->ReleaseIPDLReference();
  return true;
}

// static
already_AddRefed<TextureClient> TextureClient::AsTextureClient(
    PTextureChild* actor) {
  if (!actor) {
    return nullptr;
  }

  TextureChild* tc = static_cast<TextureChild*>(actor);

  tc->Lock();

  // Since TextureClient may be destroyed asynchronously with respect to its
  // IPDL actor, we must acquire a reference within a lock. The mDestroyed bit
  // tells us whether or not the main thread has disconnected the TextureClient
  // from its actor.
  if (tc->mDestroyed) {
    tc->Unlock();
    return nullptr;
  }

  RefPtr<TextureClient> texture = tc->mTextureClient;
  tc->Unlock();

  return texture.forget();
}

bool TextureClient::IsSharedWithCompositor() const {
  return mActor && mActor->IPCOpen();
}

void TextureClient::AddFlags(TextureFlags aFlags) {
  MOZ_ASSERT(
      !IsSharedWithCompositor() ||
      ((GetFlags() & TextureFlags::RECYCLE) && !IsAddedToCompositableClient()));
  mFlags |= aFlags;
}

void TextureClient::RemoveFlags(TextureFlags aFlags) {
  MOZ_ASSERT(
      !IsSharedWithCompositor() ||
      ((GetFlags() & TextureFlags::RECYCLE) && !IsAddedToCompositableClient()));
  mFlags &= ~aFlags;
}

void TextureClient::RecycleTexture(TextureFlags aFlags) {
  MOZ_ASSERT(GetFlags() & TextureFlags::RECYCLE);
  MOZ_ASSERT(!mIsLocked);

  mAddedToCompositableClient = false;
  if (mFlags != aFlags) {
    mFlags = aFlags;
  }
}

void TextureClient::SetAddedToCompositableClient() {
  if (!mAddedToCompositableClient) {
    mAddedToCompositableClient = true;
    if (!(GetFlags() & TextureFlags::RECYCLE)) {
      return;
    }
    MOZ_ASSERT(!mIsLocked);
    LockActor();
    if (IsValid() && mActor && !mActor->mDestroyed && mActor->IPCOpen()) {
      mActor->SendRecycleTexture(mFlags);
    }
    UnlockActor();
  }
}

static void CancelTextureClientNotifyNotUsed(uint64_t aTextureId,
                                             LayersIPCChannel* aAllocator) {
  if (!aAllocator) {
    return;
  }
  nsCOMPtr<nsISerialEventTarget> thread = aAllocator->GetThread();
  if (!thread) {
    return;
  }
  if (thread->IsOnCurrentThread()) {
    aAllocator->CancelWaitForNotifyNotUsed(aTextureId);
  } else {
    thread->Dispatch(NewRunnableFunction(
        "CancelTextureClientNotifyNotUsedRunnable",
        CancelTextureClientNotifyNotUsed, aTextureId, aAllocator));
  }
}

void TextureClient::CancelWaitForNotifyNotUsed() {
  if (GetFlags() & TextureFlags::RECYCLE) {
    CancelTextureClientNotifyNotUsed(mSerial, GetAllocator());
    return;
  }
}

/* static */
void TextureClient::TextureClientRecycleCallback(TextureClient* aClient,
                                                 void* aClosure) {
  MOZ_ASSERT(aClient->GetRecycleAllocator());
  aClient->GetRecycleAllocator()->RecycleTextureClient(aClient);
}

void TextureClient::SetRecycleAllocator(
    ITextureClientRecycleAllocator* aAllocator) {
  mRecycleAllocator = aAllocator;
  if (aAllocator) {
    SetRecycleCallback(TextureClientRecycleCallback, nullptr);
  } else {
    ClearRecycleCallback();
  }
}

bool TextureClient::InitIPDLActor(CompositableForwarder* aForwarder) {
  MOZ_ASSERT(aForwarder && aForwarder->GetTextureForwarder()->GetThread() ==
                               mAllocator->GetThread());

  if (mActor && !mActor->IPCOpen()) {
    return false;
  }

  if (mActor && !mActor->mDestroyed) {
    CompositableForwarder* currentFwd = mActor->mCompositableForwarder;
    TextureForwarder* currentTexFwd = mActor->mTextureForwarder;
    if (currentFwd != aForwarder) {
      // It's a bit iffy but right now ShadowLayerForwarder inherits
      // TextureForwarder even though it should not.
      // ShadowLayerForwarder::GetTextureForwarder actually returns a pointer to
      // the CompositorBridgeChild. It's Ok for a texture to move from a
      // ShadowLayerForwarder to another, but not form a CompositorBridgeChild
      // to another (they use different channels).
      if (currentTexFwd && currentTexFwd != aForwarder->GetTextureForwarder()) {
        gfxCriticalError()
            << "Attempt to move a texture to a different channel CF.";
        MOZ_ASSERT_UNREACHABLE("unexpected to be called");
        return false;
      }
      if (currentFwd && currentFwd->GetCompositorBackendType() !=
                            aForwarder->GetCompositorBackendType()) {
        gfxCriticalError()
            << "Attempt to move a texture to different compositor backend.";
        MOZ_ASSERT_UNREACHABLE("unexpected to be called");
        return false;
      }
      mActor->mCompositableForwarder = aForwarder;
      mActor->mUsesImageBridge =
          aForwarder->GetTextureForwarder()->UsesImageBridge();
    }
    return true;
  }
  MOZ_ASSERT(!mActor || mActor->mDestroyed,
             "Cannot use a texture on several IPC channels.");

  SurfaceDescriptor desc;
  if (!ToSurfaceDescriptor(desc)) {
    return false;
  }

  // Try external image id allocation.
  mExternalImageId =
      aForwarder->GetTextureForwarder()->GetNextExternalImageId();

  ReadLockDescriptor readLockDescriptor = null_t();
  if (mReadLock) {
    mReadLock->Serialize(readLockDescriptor, GetAllocator()->GetParentPid());
  }

  PTextureChild* actor = aForwarder->GetTextureForwarder()->CreateTexture(
      desc, std::move(readLockDescriptor),
      aForwarder->GetCompositorBackendType(), GetFlags(),
      dom::ContentParentId(), mSerial, mExternalImageId);

  if (!actor) {
    gfxCriticalNote << static_cast<int32_t>(desc.type()) << ", "
                    << static_cast<int32_t>(
                           aForwarder->GetCompositorBackendType())
                    << ", " << static_cast<uint32_t>(GetFlags()) << ", "
                    << mSerial;
    return false;
  }

  mActor = static_cast<TextureChild*>(actor);
  mActor->mCompositableForwarder = aForwarder;
  mActor->mTextureForwarder = aForwarder->GetTextureForwarder();
  mActor->mTextureClient = this;

  // If the TextureClient is already locked, we have to lock TextureChild's
  // mutex since it will be unlocked in TextureClient::Unlock.
  if (mIsLocked) {
    LockActor();
  }

  return mActor->IPCOpen();
}

bool TextureClient::InitIPDLActor(KnowsCompositor* aKnowsCompositor,
                                  const dom::ContentParentId& aContentId) {
  MOZ_ASSERT(aKnowsCompositor &&
             aKnowsCompositor->GetTextureForwarder()->GetThread() ==
                 mAllocator->GetThread());
  TextureForwarder* fwd = aKnowsCompositor->GetTextureForwarder();
  if (mActor && !mActor->mDestroyed) {
    CompositableForwarder* currentFwd = mActor->mCompositableForwarder;
    TextureForwarder* currentTexFwd = mActor->mTextureForwarder;

    if (currentFwd) {
      gfxCriticalError()
          << "Attempt to remove a texture from a CompositableForwarder.";
      return false;
    }

    if (currentTexFwd && currentTexFwd != fwd) {
      gfxCriticalError()
          << "Attempt to move a texture to a different channel TF.";
      return false;
    }
    mActor->mTextureForwarder = fwd;
    return true;
  }
  MOZ_ASSERT(!mActor || mActor->mDestroyed,
             "Cannot use a texture on several IPC channels.");

  SurfaceDescriptor desc;
  if (!ToSurfaceDescriptor(desc)) {
    return false;
  }

  // Try external image id allocation.
  mExternalImageId =
      aKnowsCompositor->GetTextureForwarder()->GetNextExternalImageId();

  ReadLockDescriptor readLockDescriptor = null_t();
  if (mReadLock) {
    mReadLock->Serialize(readLockDescriptor, GetAllocator()->GetParentPid());
  }

  PTextureChild* actor =
      fwd->CreateTexture(desc, std::move(readLockDescriptor),
                         aKnowsCompositor->GetCompositorBackendType(),
                         GetFlags(), aContentId, mSerial, mExternalImageId);
  if (!actor) {
    gfxCriticalNote << static_cast<int32_t>(desc.type()) << ", "
                    << static_cast<int32_t>(
                           aKnowsCompositor->GetCompositorBackendType())
                    << ", " << static_cast<uint32_t>(GetFlags()) << ", "
                    << mSerial;
    return false;
  }

  mActor = static_cast<TextureChild*>(actor);
  mActor->mTextureForwarder = fwd;
  mActor->mTextureClient = this;

  // If the TextureClient is already locked, we have to lock TextureChild's
  // mutex since it will be unlocked in TextureClient::Unlock.
  if (mIsLocked) {
    LockActor();
  }

  return mActor->IPCOpen();
}

PTextureChild* TextureClient::GetIPDLActor() { return mActor; }

// static
already_AddRefed<TextureClient> TextureClient::CreateForDrawing(
    KnowsCompositor* aAllocator, gfx::SurfaceFormat aFormat, gfx::IntSize aSize,
    BackendSelector aSelector, TextureFlags aTextureFlags,
    TextureAllocationFlags aAllocFlags) {
  return TextureClient::CreateForDrawing(aAllocator->GetTextureForwarder(),
                                         aFormat, aSize, aAllocator, aSelector,
                                         aTextureFlags, aAllocFlags);
}

// static
already_AddRefed<TextureClient> TextureClient::CreateForDrawing(
    TextureForwarder* aAllocator, gfx::SurfaceFormat aFormat,
    gfx::IntSize aSize, KnowsCompositor* aKnowsCompositor,
    BackendSelector aSelector, TextureFlags aTextureFlags,
    TextureAllocationFlags aAllocFlags) {
  LayersBackend layersBackend = aKnowsCompositor->GetCompositorBackendType();
  gfx::BackendType moz2DBackend =
      BackendTypeForBackendSelector(layersBackend, aSelector);

  // also test the validity of aAllocator
  if (!aAllocator || !aAllocator->IPCOpen()) {
    return nullptr;
  }

  if (!gfx::Factory::AllowedSurfaceSize(aSize)) {
    return nullptr;
  }

  TextureData* data =
      TextureData::Create(aAllocator, aFormat, aSize, aKnowsCompositor,
                          aSelector, aTextureFlags, aAllocFlags);

  if (data) {
    return MakeAndAddRef<TextureClient>(data, aTextureFlags, aAllocator);
  }

  // Can't do any better than a buffer texture client.
  return TextureClient::CreateForRawBufferAccess(aAllocator, aFormat, aSize,
                                                 moz2DBackend, layersBackend,
                                                 aTextureFlags, aAllocFlags);
}

// static
already_AddRefed<TextureClient> TextureClient::CreateFromSurface(
    KnowsCompositor* aAllocator, gfx::SourceSurface* aSurface,
    BackendSelector aSelector, TextureFlags aTextureFlags,
    TextureAllocationFlags aAllocFlags) {
  // also test the validity of aAllocator
  if (!aAllocator || !aAllocator->GetTextureForwarder()->IPCOpen()) {
    return nullptr;
  }

  gfx::IntSize size = aSurface->GetSize();

  if (!gfx::Factory::AllowedSurfaceSize(size)) {
    return nullptr;
  }

  TextureData* data = nullptr;
#if defined(XP_WIN)
  LayersBackend layersBackend = aAllocator->GetCompositorBackendType();
  gfx::BackendType moz2DBackend =
      BackendTypeForBackendSelector(layersBackend, aSelector);

  int32_t maxTextureSize = aAllocator->GetMaxTextureSize();

  if (layersBackend == LayersBackend::LAYERS_WR &&
      (moz2DBackend == gfx::BackendType::DIRECT2D ||
       moz2DBackend == gfx::BackendType::DIRECT2D1_1) &&
      size.width <= maxTextureSize && size.height <= maxTextureSize) {
    data = D3D11TextureData::Create(aSurface, aAllocFlags);
  }
#endif

  if (data) {
    return MakeAndAddRef<TextureClient>(data, aTextureFlags,
                                        aAllocator->GetTextureForwarder());
  }

  // Fall back to using UpdateFromSurface

  TextureAllocationFlags allocFlags =
      TextureAllocationFlags(aAllocFlags | ALLOC_UPDATE_FROM_SURFACE);
  RefPtr<TextureClient> client =
      CreateForDrawing(aAllocator, aSurface->GetFormat(), size, aSelector,
                       aTextureFlags, allocFlags);
  if (!client) {
    return nullptr;
  }

  TextureClientAutoLock autoLock(client, OpenMode::OPEN_WRITE_ONLY);
  if (!autoLock.Succeeded()) {
    return nullptr;
  }

  client->UpdateFromSurface(aSurface);
  return client.forget();
}

// static
already_AddRefed<TextureClient> TextureClient::CreateForRawBufferAccess(
    KnowsCompositor* aAllocator, gfx::SurfaceFormat aFormat, gfx::IntSize aSize,
    gfx::BackendType aMoz2DBackend, TextureFlags aTextureFlags,
    TextureAllocationFlags aAllocFlags) {
  return CreateForRawBufferAccess(
      aAllocator->GetTextureForwarder(), aFormat, aSize, aMoz2DBackend,
      aAllocator->GetCompositorBackendType(), aTextureFlags, aAllocFlags);
}

// static
already_AddRefed<TextureClient> TextureClient::CreateForRawBufferAccess(
    LayersIPCChannel* aAllocator, gfx::SurfaceFormat aFormat,
    gfx::IntSize aSize, gfx::BackendType aMoz2DBackend,
    LayersBackend aLayersBackend, TextureFlags aTextureFlags,
    TextureAllocationFlags aAllocFlags) {
  // also test the validity of aAllocator
  if (!aAllocator || !aAllocator->IPCOpen()) {
    return nullptr;
  }

  if (!gfx::Factory::AllowedSurfaceSize(aSize)) {
    return nullptr;
  }

  if (aFormat == SurfaceFormat::B8G8R8X8) {
    // Skia doesn't support RGBX, so ensure we clear the buffer for the proper
    // alpha values.
    aAllocFlags = TextureAllocationFlags(aAllocFlags | ALLOC_CLEAR_BUFFER);
  }

  // Note that we ignore the backend type if we get here. It should only be D2D
  // or Skia, and D2D does not support data surfaces. Therefore it is safe to
  // force the buffer to be Skia.
  NS_WARNING_ASSERTION(aMoz2DBackend == gfx::BackendType::SKIA ||
                           aMoz2DBackend == gfx::BackendType::DIRECT2D ||
                           aMoz2DBackend == gfx::BackendType::DIRECT2D1_1,
                       "Unsupported TextureClient backend type");

  TextureData* texData = BufferTextureData::Create(
      aSize, aFormat, gfx::BackendType::SKIA, aLayersBackend, aTextureFlags,
      aAllocFlags, aAllocator);
  if (!texData) {
    return nullptr;
  }

  return MakeAndAddRef<TextureClient>(texData, aTextureFlags, aAllocator);
}

// static
already_AddRefed<TextureClient> TextureClient::CreateForYCbCr(
    KnowsCompositor* aAllocator, const gfx::IntRect& aDisplay,
    const gfx::IntSize& aYSize, uint32_t aYStride,
    const gfx::IntSize& aCbCrSize, uint32_t aCbCrStride, StereoMode aStereoMode,
    gfx::ColorDepth aColorDepth, gfx::YUVColorSpace aYUVColorSpace,
    gfx::ColorRange aColorRange, gfx::ChromaSubsampling aSubsampling,
    TextureFlags aTextureFlags) {
  if (!aAllocator || !aAllocator->GetLayersIPCActor()->IPCOpen()) {
    return nullptr;
  }

  if (!gfx::Factory::AllowedSurfaceSize(aYSize)) {
    return nullptr;
  }

  TextureData* data = BufferTextureData::CreateForYCbCr(
      aAllocator, aDisplay, aYSize, aYStride, aCbCrSize, aCbCrStride,
      aStereoMode, aColorDepth, aYUVColorSpace, aColorRange, aSubsampling,
      aTextureFlags);
  if (!data) {
    return nullptr;
  }

  return MakeAndAddRef<TextureClient>(data, aTextureFlags,
                                      aAllocator->GetTextureForwarder());
}

TextureClient::TextureClient(TextureData* aData, TextureFlags aFlags,
                             LayersIPCChannel* aAllocator)
    : AtomicRefCountedWithFinalize("TextureClient"),
      mAllocator(aAllocator),
      mActor(nullptr),
      mData(aData),
      mFlags(aFlags),
      mOpenMode(OpenMode::OPEN_NONE)
#ifdef DEBUG
      ,
      mExpectedDtRefs(0)
#endif
      ,
      mIsLocked(false),
      mIsReadLocked(false),
      mUpdated(false),
      mAddedToCompositableClient(false),
      mFwdTransactionId(0),
      mSerial(++sSerialCounter)
#ifdef GFX_DEBUG_TRACK_CLIENTS_IN_POOL
      ,
      mPoolTracker(nullptr)
#endif
{
  mData->FillInfo(mInfo);
  mFlags |= mData->GetTextureFlags();

  if (mFlags & TextureFlags::NON_BLOCKING_READ_LOCK) {
    MOZ_ASSERT(!(mFlags & TextureFlags::BLOCKING_READ_LOCK));
    EnableReadLock();
  } else if (mFlags & TextureFlags::BLOCKING_READ_LOCK) {
    MOZ_ASSERT(!(mFlags & TextureFlags::NON_BLOCKING_READ_LOCK));
    EnableBlockingReadLock();
  }
}

bool TextureClient::CopyToTextureClient(TextureClient* aTarget,
                                        const gfx::IntRect* aRect,
                                        const gfx::IntPoint* aPoint) {
  MOZ_ASSERT(IsLocked());
  MOZ_ASSERT(aTarget->IsLocked());

  if (!aTarget->CanExposeDrawTarget() || !CanExposeDrawTarget()) {
    return false;
  }

  RefPtr<DrawTarget> destinationTarget = aTarget->BorrowDrawTarget();
  if (!destinationTarget) {
    gfxWarning() << "TextureClient::CopyToTextureClient (dest) failed in "
                    "BorrowDrawTarget";
    return false;
  }

  RefPtr<DrawTarget> sourceTarget = BorrowDrawTarget();
  if (!sourceTarget) {
    gfxWarning() << "TextureClient::CopyToTextureClient (src) failed in "
                    "BorrowDrawTarget";
    return false;
  }

  RefPtr<gfx::SourceSurface> source = sourceTarget->Snapshot();
  destinationTarget->CopySurface(
      source, aRect ? *aRect : gfx::IntRect(gfx::IntPoint(0, 0), GetSize()),
      aPoint ? *aPoint : gfx::IntPoint(0, 0));
  return true;
}

already_AddRefed<gfx::DataSourceSurface> TextureClient::GetAsSurface() {
  if (!Lock(OpenMode::OPEN_READ)) {
    return nullptr;
  }
  RefPtr<gfx::DataSourceSurface> data;
  {  // scope so that the DrawTarget is destroyed before Unlock()
    RefPtr<gfx::DrawTarget> dt = BorrowDrawTarget();
    if (dt) {
      RefPtr<gfx::SourceSurface> surf = dt->Snapshot();
      if (surf) {
        data = surf->GetDataSurface();
      }
    }
  }
  Unlock();
  return data.forget();
}

void TextureClient::GetSurfaceDescriptorRemoteDecoder(
    SurfaceDescriptorRemoteDecoder* const aOutDesc) {
  const auto handle = GetSerial();

  RemoteDecoderVideoSubDescriptor subDesc = null_t();
  MOZ_RELEASE_ASSERT(mData);
  mData->GetSubDescriptor(&subDesc);

  *aOutDesc =
      SurfaceDescriptorRemoteDecoder(handle, std::move(subDesc), Nothing());
}

class MemoryTextureReadLock : public NonBlockingTextureReadLock {
 public:
  MemoryTextureReadLock();

  virtual ~MemoryTextureReadLock();

  bool ReadLock() override;

  int32_t ReadUnlock() override;

  int32_t GetReadCount() override;

  LockType GetType() override { return TYPE_NONBLOCKING_MEMORY; }

  bool IsValid() const override { return true; };

  bool Serialize(ReadLockDescriptor& aOutput, base::ProcessId aOther) override;

  Atomic<int32_t> mReadCount;
};

// The cross-prcess implementation of TextureReadLock.
//
// Since we don't use cross-process reference counting for the ReadLock objects,
// we use the lock's internal counter as a way to know when to deallocate the
// underlying shmem section: when the counter is equal to 1, it means that the
// lock is not "held" (the texture is writable), when the counter is equal to 0
// it means that we can safely deallocate the shmem section without causing a
// race condition with the other process.
class ShmemTextureReadLock : public NonBlockingTextureReadLock {
 public:
  struct ShmReadLockInfo {
    int32_t readCount;
  };

  explicit ShmemTextureReadLock(LayersIPCChannel* aAllocator);

  virtual ~ShmemTextureReadLock();

  bool ReadLock() override;

  int32_t ReadUnlock() override;

  int32_t GetReadCount() override;

  bool IsValid() const override { return mAllocSuccess; };

  LockType GetType() override { return TYPE_NONBLOCKING_SHMEM; }

  bool Serialize(ReadLockDescriptor& aOutput, base::ProcessId aOther) override;

  mozilla::layers::ShmemSection& GetShmemSection() { return mShmemSection; }

  explicit ShmemTextureReadLock(
      const mozilla::layers::ShmemSection& aShmemSection)
      : mShmemSection(aShmemSection), mAllocSuccess(true) {
    MOZ_COUNT_CTOR(ShmemTextureReadLock);
  }

  ShmReadLockInfo* GetShmReadLockInfoPtr() {
    return reinterpret_cast<ShmReadLockInfo*>(
        mShmemSection.shmem().get<char>() + mShmemSection.offset());
  }

  RefPtr<LayersIPCChannel> mClientAllocator;
  mozilla::layers::ShmemSection mShmemSection;
  bool mAllocSuccess;
};

class CrossProcessSemaphoreReadLock : public TextureReadLock {
 public:
  CrossProcessSemaphoreReadLock()
      : mSemaphore(CrossProcessSemaphore::Create("TextureReadLock", 1)),
        mShared(false) {}
  explicit CrossProcessSemaphoreReadLock(CrossProcessSemaphoreHandle aHandle)
      : mSemaphore(CrossProcessSemaphore::Create(std::move(aHandle))),
        mShared(false) {}

  bool ReadLock() override {
    if (!IsValid()) {
      return false;
    }
    return mSemaphore->Wait();
  }
  bool TryReadLock(TimeDuration aTimeout) override {
    if (!IsValid()) {
      return false;
    }
    return mSemaphore->Wait(Some(aTimeout));
  }
  int32_t ReadUnlock() override {
    if (!IsValid()) {
      return 1;
    }
    mSemaphore->Signal();
    return 1;
  }
  bool IsValid() const override { return !!mSemaphore; }

  bool Serialize(ReadLockDescriptor& aOutput, base::ProcessId aOther) override;

  LockType GetType() override { return TYPE_CROSS_PROCESS_SEMAPHORE; }

  UniquePtr<CrossProcessSemaphore> mSemaphore;
  bool mShared;
};

// static
already_AddRefed<TextureReadLock> TextureReadLock::Deserialize(
    ReadLockDescriptor&& aDescriptor, ISurfaceAllocator* aAllocator) {
  switch (aDescriptor.type()) {
    case ReadLockDescriptor::TShmemSection: {
      const ShmemSection& section = aDescriptor.get_ShmemSection();
      MOZ_RELEASE_ASSERT(section.shmem().IsReadable());
      return MakeAndAddRef<ShmemTextureReadLock>(section);
    }
    case ReadLockDescriptor::Tuintptr_t: {
      if (!aAllocator->IsSameProcess()) {
        // Trying to use a memory based lock instead of a shmem based one in
        // the cross-process case is a bad security violation.
        NS_ERROR(
            "A client process may be trying to peek at the host's address "
            "space!");
        return nullptr;
      }
      RefPtr<TextureReadLock> lock =
          reinterpret_cast<MemoryTextureReadLock*>(aDescriptor.get_uintptr_t());

      MOZ_ASSERT(lock);
      if (lock) {
        // The corresponding AddRef is in MemoryTextureReadLock::Serialize
        lock.get()->Release();
      }

      return lock.forget();
    }
    case ReadLockDescriptor::TCrossProcessSemaphoreDescriptor: {
      return MakeAndAddRef<CrossProcessSemaphoreReadLock>(
          std::move(aDescriptor.get_CrossProcessSemaphoreDescriptor().sem()));
    }
    case ReadLockDescriptor::Tnull_t: {
      return nullptr;
    }
    default: {
      // Invalid descriptor.
      MOZ_DIAGNOSTIC_ASSERT(false);
    }
  }
  return nullptr;
}
// static
already_AddRefed<TextureReadLock> NonBlockingTextureReadLock::Create(
    LayersIPCChannel* aAllocator) {
  if (aAllocator->IsSameProcess()) {
    // If our compositor is in the same process, we can save some cycles by not
    // using shared memory.
    return MakeAndAddRef<MemoryTextureReadLock>();
  }

  return MakeAndAddRef<ShmemTextureReadLock>(aAllocator);
}

MemoryTextureReadLock::MemoryTextureReadLock() : mReadCount(1) {
  MOZ_COUNT_CTOR(MemoryTextureReadLock);
}

MemoryTextureReadLock::~MemoryTextureReadLock() {
  // One read count that is added in constructor.
  MOZ_ASSERT(mReadCount == 1);
  MOZ_COUNT_DTOR(MemoryTextureReadLock);
}

bool MemoryTextureReadLock::Serialize(ReadLockDescriptor& aOutput,
                                      base::ProcessId aOther) {
  // AddRef here and Release when receiving on the host side to make sure the
  // reference count doesn't go to zero before the host receives the message.
  // see TextureReadLock::Deserialize
  this->AddRef();
  aOutput = ReadLockDescriptor(uintptr_t(this));
  return true;
}

bool MemoryTextureReadLock::ReadLock() {
  NS_ASSERT_OWNINGTHREAD(MemoryTextureReadLock);

  ++mReadCount;
  return true;
}

int32_t MemoryTextureReadLock::ReadUnlock() {
  int32_t readCount = --mReadCount;
  MOZ_ASSERT(readCount >= 0);

  return readCount;
}

int32_t MemoryTextureReadLock::GetReadCount() {
  NS_ASSERT_OWNINGTHREAD(MemoryTextureReadLock);
  return mReadCount;
}

ShmemTextureReadLock::ShmemTextureReadLock(LayersIPCChannel* aAllocator)
    : mClientAllocator(aAllocator), mAllocSuccess(false) {
  MOZ_COUNT_CTOR(ShmemTextureReadLock);
  MOZ_ASSERT(mClientAllocator);
  MOZ_ASSERT(mClientAllocator->GetTileLockAllocator());
#define MOZ_ALIGN_WORD(x) (((x) + 3) & ~3)
  if (mClientAllocator->GetTileLockAllocator()->AllocShmemSection(
          MOZ_ALIGN_WORD(sizeof(ShmReadLockInfo)), &mShmemSection)) {
    ShmReadLockInfo* info = GetShmReadLockInfoPtr();
    info->readCount = 1;
    mAllocSuccess = true;
  }
}

ShmemTextureReadLock::~ShmemTextureReadLock() {
  if (mClientAllocator) {
    // Release one read count that is added in constructor.
    // The count is kept for calling GetReadCount() by TextureClientPool.
    ReadUnlock();
  }
  MOZ_COUNT_DTOR(ShmemTextureReadLock);
}

bool ShmemTextureReadLock::Serialize(ReadLockDescriptor& aOutput,
                                     base::ProcessId aOther) {
  aOutput = ReadLockDescriptor(GetShmemSection());
  return true;
}

bool ShmemTextureReadLock::ReadLock() {
  NS_ASSERT_OWNINGTHREAD(ShmemTextureReadLock);
  if (!mAllocSuccess) {
    return false;
  }
  ShmReadLockInfo* info = GetShmReadLockInfoPtr();
  PR_ATOMIC_INCREMENT(&info->readCount);
  return true;
}

int32_t ShmemTextureReadLock::ReadUnlock() {
  if (!mAllocSuccess) {
    return 0;
  }
  ShmReadLockInfo* info = GetShmReadLockInfoPtr();
  int32_t readCount = PR_ATOMIC_DECREMENT(&info->readCount);
  MOZ_ASSERT(readCount >= 0);
  if (readCount <= 0) {
    if (mClientAllocator && mClientAllocator->GetTileLockAllocator()) {
      mClientAllocator->GetTileLockAllocator()->DeallocShmemSection(
          mShmemSection);
    } else {
      // we are on the compositor process, or IPC is down.
      FixedSizeSmallShmemSectionAllocator::FreeShmemSection(mShmemSection);
    }
  }
  return readCount;
}

int32_t ShmemTextureReadLock::GetReadCount() {
  NS_ASSERT_OWNINGTHREAD(ShmemTextureReadLock);
  if (!mAllocSuccess) {
    return 0;
  }
  ShmReadLockInfo* info = GetShmReadLockInfoPtr();
  return info->readCount;
}

bool CrossProcessSemaphoreReadLock::Serialize(ReadLockDescriptor& aOutput,
                                              base::ProcessId aOther) {
  if (!mShared && IsValid()) {
    aOutput = ReadLockDescriptor(
        CrossProcessSemaphoreDescriptor(mSemaphore->CloneHandle()));
    mSemaphore->CloseHandle();
    mShared = true;
    return true;
  } else {
    return mShared;
  }
}

void TextureClient::EnableBlockingReadLock() {
  if (!mReadLock) {
    mReadLock = new CrossProcessSemaphoreReadLock();
  }
}

bool UpdateYCbCrTextureClient(TextureClient* aTexture,
                              const PlanarYCbCrData& aData) {
  MOZ_ASSERT(aTexture);
  MOZ_ASSERT(aTexture->IsLocked());
  MOZ_ASSERT(aTexture->GetFormat() == gfx::SurfaceFormat::YUV,
             "This textureClient can only use YCbCr data");
  MOZ_ASSERT(!aTexture->IsImmutable());
  MOZ_ASSERT(aTexture->IsValid());
  MOZ_ASSERT(aData.mCbSkip == aData.mCrSkip);

  MappedYCbCrTextureData mapped;
  if (!aTexture->BorrowMappedYCbCrData(mapped)) {
    NS_WARNING("Failed to extract YCbCr info!");
    return false;
  }

  uint32_t bytesPerPixel =
      BytesPerPixel(SurfaceFormatForColorDepth(aData.mColorDepth));
  MappedYCbCrTextureData srcData;
  srcData.y.data = aData.mYChannel;
  srcData.y.size = aData.YDataSize();
  srcData.y.stride = aData.mYStride;
  srcData.y.skip = aData.mYSkip;
  srcData.y.bytesPerPixel = bytesPerPixel;
  srcData.cb.data = aData.mCbChannel;
  srcData.cb.size = aData.CbCrDataSize();
  srcData.cb.stride = aData.mCbCrStride;
  srcData.cb.skip = aData.mCbSkip;
  srcData.cb.bytesPerPixel = bytesPerPixel;
  srcData.cr.data = aData.mCrChannel;
  srcData.cr.size = aData.CbCrDataSize();
  srcData.cr.stride = aData.mCbCrStride;
  srcData.cr.skip = aData.mCrSkip;
  srcData.cr.bytesPerPixel = bytesPerPixel;
  srcData.metadata = nullptr;

  if (!srcData.CopyInto(mapped)) {
    NS_WARNING("Failed to copy image data!");
    return false;
  }

  if (TextureRequiresLocking(aTexture->GetFlags())) {
    // We don't have support for proper locking yet, so we'll
    // have to be immutable instead.
    aTexture->MarkImmutable();
  }
  return true;
}

already_AddRefed<TextureClient> TextureClient::CreateWithData(
    TextureData* aData, TextureFlags aFlags, LayersIPCChannel* aAllocator) {
  if (!aData) {
    return nullptr;
  }
  return MakeAndAddRef<TextureClient>(aData, aFlags, aAllocator);
}

template <class PixelDataType>
static void copyData(PixelDataType* aDst,
                     const MappedYCbCrChannelData& aChannelDst,
                     PixelDataType* aSrc,
                     const MappedYCbCrChannelData& aChannelSrc) {
  uint8_t* srcByte = reinterpret_cast<uint8_t*>(aSrc);
  const int32_t srcSkip = aChannelSrc.skip + 1;
  uint8_t* dstByte = reinterpret_cast<uint8_t*>(aDst);
  const int32_t dstSkip = aChannelDst.skip + 1;
  for (int32_t i = 0; i < aChannelSrc.size.height; ++i) {
    for (int32_t j = 0; j < aChannelSrc.size.width; ++j) {
      *aDst = *aSrc;
      aSrc += srcSkip;
      aDst += dstSkip;
    }
    srcByte += aChannelSrc.stride;
    aSrc = reinterpret_cast<PixelDataType*>(srcByte);
    dstByte += aChannelDst.stride;
    aDst = reinterpret_cast<PixelDataType*>(dstByte);
  }
}

bool MappedYCbCrChannelData::CopyInto(MappedYCbCrChannelData& aDst) {
  if (!data || !aDst.data || size != aDst.size) {
    return false;
  }

  if (stride == aDst.stride && skip == aDst.skip) {
    // fast path!
    // We assume that the padding in the destination is there for alignment
    // purposes and doesn't contain useful data.
    memcpy(aDst.data, data, stride * size.height);
    return true;
  }

  if (aDst.skip == 0 && skip == 0) {
    // fast-ish path
    for (int32_t i = 0; i < size.height; ++i) {
      memcpy(aDst.data + i * aDst.stride, data + i * stride,
             size.width * bytesPerPixel);
    }
    return true;
  }

  MOZ_ASSERT(bytesPerPixel == 1 || bytesPerPixel == 2);
  // slow path
  if (bytesPerPixel == 1) {
    copyData(aDst.data, aDst, data, *this);
  } else if (bytesPerPixel == 2) {
    copyData(reinterpret_cast<uint16_t*>(aDst.data), aDst,
             reinterpret_cast<uint16_t*>(data), *this);
  }
  return true;
}

}  // namespace mozilla::layers