src/dawn_native/null/DeviceNull.cpp - dawn - Git at Google

 // Copyright 2017 The Dawn Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "dawn_native/null/DeviceNull.h"

 #include "dawn_native/BackendConnection.h"
 #include "dawn_native/Commands.h"
 #include "dawn_native/ErrorData.h"
 #include "dawn_native/Instance.h"
 #include "dawn_native/Surface.h"

 #include <spirv_cross.hpp>

 namespace dawn_native { namespace null {

     // Implementation of pre-Device objects: the null adapter, null backend connection and Connect()

     Adapter::Adapter(InstanceBase* instance) : AdapterBase(instance, wgpu::BackendType::Null) {
         mPCIInfo.name = "Null backend";
         mAdapterType = wgpu::AdapterType::CPU;

         // Enable all extensions by default for the convenience of tests.
         mSupportedExtensions.extensionsBitSet.flip();
     }

     Adapter::~Adapter() = default;

     // Used for the tests that intend to use an adapter without all extensions enabled.
     void Adapter::SetSupportedExtensions(const std::vector<const char*>& requiredExtensions) {
         mSupportedExtensions = GetInstance()->ExtensionNamesToExtensionsSet(requiredExtensions);
     }

     ResultOrError<DeviceBase*> Adapter::CreateDeviceImpl(const DeviceDescriptor* descriptor) {
         return Device::Create(this, descriptor);
     }

     class Backend : public BackendConnection {
       public:
         Backend(InstanceBase* instance) : BackendConnection(instance, wgpu::BackendType::Null) {
         }

         std::vector<std::unique_ptr<AdapterBase>> DiscoverDefaultAdapters() override {
             // There is always a single Null adapter because it is purely CPU based and doesn't
             // depend on the system.
             std::vector<std::unique_ptr<AdapterBase>> adapters;
             adapters.push_back(std::make_unique<Adapter>(GetInstance()));
             return adapters;
         }
     };

     BackendConnection* Connect(InstanceBase* instance) {
         return new Backend(instance);
     }

     struct CopyFromStagingToBufferOperation : PendingOperation {
         virtual void Execute() {
             destination->CopyFromStaging(staging, sourceOffset, destinationOffset, size);
         }

         StagingBufferBase* staging;
         Ref<Buffer> destination;
         uint64_t sourceOffset;
         uint64_t destinationOffset;
         uint64_t size;
     };

     // Device

     // static
     ResultOrError<Device*> Device::Create(Adapter* adapter, const DeviceDescriptor* descriptor) {
         Ref<Device> device = AcquireRef(new Device(adapter, descriptor));
         DAWN_TRY(device->Initialize());
         return device.Detach();
     }

     Device::~Device() {
         ShutDownBase();
     }

     MaybeError Device::Initialize() {
         return DeviceBase::Initialize(new Queue(this));
     }

     ResultOrError<Ref<BindGroupBase>> Device::CreateBindGroupImpl(
         const BindGroupDescriptor* descriptor) {
         return AcquireRef(new BindGroup(this, descriptor));
     }
     ResultOrError<Ref<BindGroupLayoutBase>> Device::CreateBindGroupLayoutImpl(
         const BindGroupLayoutDescriptor* descriptor) {
         return AcquireRef(new BindGroupLayout(this, descriptor));
     }
     ResultOrError<Ref<BufferBase>> Device::CreateBufferImpl(const BufferDescriptor* descriptor) {
         DAWN_TRY(IncrementMemoryUsage(descriptor->size));
         return AcquireRef(new Buffer(this, descriptor));
     }
     ResultOrError<Ref<CommandBufferBase>> Device::CreateCommandBuffer(
         CommandEncoder* encoder,
         const CommandBufferDescriptor* descriptor) {
         return AcquireRef(new CommandBuffer(encoder, descriptor));
     }
     ResultOrError<Ref<ComputePipelineBase>> Device::CreateComputePipelineImpl(
         const ComputePipelineDescriptor* descriptor) {
         return AcquireRef(new ComputePipeline(this, descriptor));
     }
     ResultOrError<Ref<PipelineLayoutBase>> Device::CreatePipelineLayoutImpl(
         const PipelineLayoutDescriptor* descriptor) {
         return AcquireRef(new PipelineLayout(this, descriptor));
     }
     ResultOrError<Ref<QuerySetBase>> Device::CreateQuerySetImpl(
         const QuerySetDescriptor* descriptor) {
         return AcquireRef(new QuerySet(this, descriptor));
     }
     ResultOrError<Ref<RenderPipelineBase>> Device::CreateRenderPipelineImpl(
         const RenderPipelineDescriptor* descriptor) {
         return AcquireRef(new RenderPipeline(this, descriptor));
     }
     ResultOrError<Ref<SamplerBase>> Device::CreateSamplerImpl(const SamplerDescriptor* descriptor) {
         return AcquireRef(new Sampler(this, descriptor));
     }
     ResultOrError<Ref<ShaderModuleBase>> Device::CreateShaderModuleImpl(
         const ShaderModuleDescriptor* descriptor,
         ShaderModuleParseResult* parseResult) {
         Ref<ShaderModule> module = AcquireRef(new ShaderModule(this, descriptor));
         DAWN_TRY(module->Initialize(parseResult));
         return module;
     }
     ResultOrError<Ref<SwapChainBase>> Device::CreateSwapChainImpl(
         const SwapChainDescriptor* descriptor) {
         return AcquireRef(new OldSwapChain(this, descriptor));
     }
     ResultOrError<Ref<NewSwapChainBase>> Device::CreateSwapChainImpl(
         Surface* surface,
         NewSwapChainBase* previousSwapChain,
         const SwapChainDescriptor* descriptor) {
         return SwapChain::Create(this, surface, previousSwapChain, descriptor);
     }
     ResultOrError<Ref<TextureBase>> Device::CreateTextureImpl(const TextureDescriptor* descriptor) {
         return AcquireRef(new Texture(this, descriptor, TextureBase::TextureState::OwnedInternal));
     }
     ResultOrError<Ref<TextureViewBase>> Device::CreateTextureViewImpl(
         TextureBase* texture,
         const TextureViewDescriptor* descriptor) {
         return AcquireRef(new TextureView(texture, descriptor));
     }

     ResultOrError<std::unique_ptr<StagingBufferBase>> Device::CreateStagingBuffer(size_t size) {
         std::unique_ptr<StagingBufferBase> stagingBuffer =
             std::make_unique<StagingBuffer>(size, this);
         DAWN_TRY(stagingBuffer->Initialize());
         return std::move(stagingBuffer);
     }

     void Device::ShutDownImpl() {
         ASSERT(GetState() == State::Disconnected);

         // Clear pending operations before checking mMemoryUsage because some operations keep a
         // reference to Buffers.
         mPendingOperations.clear();
         ASSERT(mMemoryUsage == 0);
     }

     MaybeError Device::WaitForIdleForDestruction() {
         mPendingOperations.clear();
         return {};
     }

     MaybeError Device::CopyFromStagingToBuffer(StagingBufferBase* source,
                                                uint64_t sourceOffset,
                                                BufferBase* destination,
                                                uint64_t destinationOffset,
                                                uint64_t size) {
         if (IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse)) {
             destination->SetIsDataInitialized();
         }

         auto operation = std::make_unique<CopyFromStagingToBufferOperation>();
         operation->staging = source;
         operation->destination = ToBackend(destination);
         operation->sourceOffset = sourceOffset;
         operation->destinationOffset = destinationOffset;
         operation->size = size;

         AddPendingOperation(std::move(operation));

         return {};
     }

     MaybeError Device::CopyFromStagingToTexture(const StagingBufferBase* source,
                                                 const TextureDataLayout& src,
                                                 TextureCopy* dst,
                                                 const Extent3D& copySizePixels) {
         return {};
     }

     MaybeError Device::IncrementMemoryUsage(uint64_t bytes) {
         static_assert(kMaxMemoryUsage <= std::numeric_limits<size_t>::max(), "");
         if (bytes > kMaxMemoryUsage || mMemoryUsage + bytes > kMaxMemoryUsage) {
             return DAWN_OUT_OF_MEMORY_ERROR("Out of memory.");
         }
         mMemoryUsage += bytes;
         return {};
     }

     void Device::DecrementMemoryUsage(uint64_t bytes) {
         ASSERT(mMemoryUsage >= bytes);
         mMemoryUsage -= bytes;
     }

     MaybeError Device::TickImpl() {
         return SubmitPendingOperations();
     }

     ResultOrError<ExecutionSerial> Device::CheckAndUpdateCompletedSerials() {
         return GetLastSubmittedCommandSerial();
     }

     void Device::AddPendingOperation(std::unique_ptr<PendingOperation> operation) {
         mPendingOperations.emplace_back(std::move(operation));
     }

     MaybeError Device::SubmitPendingOperations() {
         for (auto& operation : mPendingOperations) {
             operation->Execute();
         }
         mPendingOperations.clear();

         DAWN_TRY(CheckPassedSerials());
         IncrementLastSubmittedCommandSerial();

         return {};
     }

     // BindGroupDataHolder

     BindGroupDataHolder::BindGroupDataHolder(size_t size)
         : mBindingDataAllocation(malloc(size))  // malloc is guaranteed to return a
                                                 // pointer aligned enough for the allocation
     {
     }

     BindGroupDataHolder::~BindGroupDataHolder() {
         free(mBindingDataAllocation);
     }

     // BindGroup

     BindGroup::BindGroup(DeviceBase* device, const BindGroupDescriptor* descriptor)
         : BindGroupDataHolder(descriptor->layout->GetBindingDataSize()),
           BindGroupBase(device, descriptor, mBindingDataAllocation) {
     }

     // Buffer

     Buffer::Buffer(Device* device, const BufferDescriptor* descriptor)
         : BufferBase(device, descriptor) {
         mBackingData = std::unique_ptr<uint8_t[]>(new uint8_t[GetSize()]);
     }

     Buffer::~Buffer() {
         DestroyInternal();
         ToBackend(GetDevice())->DecrementMemoryUsage(GetSize());
     }

     bool Buffer::IsCPUWritableAtCreation() const {
         // Only return true for mappable buffers so we can test cases that need / don't need a
         // staging buffer.
         return (GetUsage() & (wgpu::BufferUsage::MapRead | wgpu::BufferUsage::MapWrite)) != 0;
     }

     MaybeError Buffer::MapAtCreationImpl() {
         return {};
     }

     void Buffer::CopyFromStaging(StagingBufferBase* staging,
                                  uint64_t sourceOffset,
                                  uint64_t destinationOffset,
                                  uint64_t size) {
         uint8_t* ptr = reinterpret_cast<uint8_t*>(staging->GetMappedPointer());
         memcpy(mBackingData.get() + destinationOffset, ptr + sourceOffset, size);
     }

     void Buffer::DoWriteBuffer(uint64_t bufferOffset, const void* data, size_t size) {
         ASSERT(bufferOffset + size <= GetSize());
         ASSERT(mBackingData);
         memcpy(mBackingData.get() + bufferOffset, data, size);
     }

     MaybeError Buffer::MapAsyncImpl(wgpu::MapMode mode, size_t offset, size_t size) {
         return {};
     }

     void* Buffer::GetMappedPointerImpl() {
         return mBackingData.get();
     }

     void Buffer::UnmapImpl() {
     }

     void Buffer::DestroyImpl() {
     }

     // CommandBuffer

     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
         : CommandBufferBase(encoder, descriptor) {
     }

     // QuerySet

     QuerySet::QuerySet(Device* device, const QuerySetDescriptor* descriptor)
         : QuerySetBase(device, descriptor) {
     }

     QuerySet::~QuerySet() {
         DestroyInternal();
     }

     void QuerySet::DestroyImpl() {
     }

     // Queue

     Queue::Queue(Device* device) : QueueBase(device) {
     }

     Queue::~Queue() {
     }

     MaybeError Queue::SubmitImpl(uint32_t, CommandBufferBase* const*) {
         Device* device = ToBackend(GetDevice());

         // The Vulkan, D3D12 and Metal implementation all tick the device here,
         // for testing purposes we should also tick in the null implementation.
         DAWN_TRY(device->Tick());

         return device->SubmitPendingOperations();
     }

     MaybeError Queue::WriteBufferImpl(BufferBase* buffer,
                                       uint64_t bufferOffset,
                                       const void* data,
                                       size_t size) {
         ToBackend(buffer)->DoWriteBuffer(bufferOffset, data, size);
         return {};
     }

     // SwapChain

     // static
     ResultOrError<Ref<SwapChain>> SwapChain::Create(Device* device,
                                                     Surface* surface,
                                                     NewSwapChainBase* previousSwapChain,
                                                     const SwapChainDescriptor* descriptor) {
         Ref<SwapChain> swapchain = AcquireRef(new SwapChain(device, surface, descriptor));
         DAWN_TRY(swapchain->Initialize(previousSwapChain));
         return swapchain;
     }

     MaybeError SwapChain::Initialize(NewSwapChainBase* previousSwapChain) {
         if (previousSwapChain != nullptr) {
             // TODO(crbug.com/dawn/269): figure out what should happen when surfaces are used by
             // multiple backends one after the other. It probably needs to block until the backend
             // and GPU are completely finished with the previous swapchain.
             if (previousSwapChain->GetBackendType() != wgpu::BackendType::Null) {
                 return DAWN_VALIDATION_ERROR("null::SwapChain cannot switch between APIs");
             }
         }

         return {};
     }

     SwapChain::~SwapChain() = default;

     MaybeError SwapChain::PresentImpl() {
         mTexture->APIDestroy();
         mTexture = nullptr;
         return {};
     }

     ResultOrError<TextureViewBase*> SwapChain::GetCurrentTextureViewImpl() {
         TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
         // TODO(dawn:723): change to not use AcquireRef for reentrant object creation.
         mTexture = AcquireRef(
             new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
         // TODO(dawn:723): change to not use AcquireRef for reentrant object creation.
         return mTexture->APICreateView();
     }

     void SwapChain::DetachFromSurfaceImpl() {
         if (mTexture != nullptr) {
             mTexture->APIDestroy();
             mTexture = nullptr;
         }
     }

     // ShaderModule

     MaybeError ShaderModule::Initialize(ShaderModuleParseResult* parseResult) {
         return InitializeBase(parseResult);
     }

     // OldSwapChain

     OldSwapChain::OldSwapChain(Device* device, const SwapChainDescriptor* descriptor)
         : OldSwapChainBase(device, descriptor) {
         const auto& im = GetImplementation();
         im.Init(im.userData, nullptr);
     }

     OldSwapChain::~OldSwapChain() {
     }

     TextureBase* OldSwapChain::GetNextTextureImpl(const TextureDescriptor* descriptor) {
         return GetDevice()->APICreateTexture(descriptor);
     }

     MaybeError OldSwapChain::OnBeforePresent(TextureViewBase*) {
         return {};
     }

     // NativeSwapChainImpl

     void NativeSwapChainImpl::Init(WSIContext* context) {
     }

     DawnSwapChainError NativeSwapChainImpl::Configure(WGPUTextureFormat format,
                                                       WGPUTextureUsage,
                                                       uint32_t width,
                                                       uint32_t height) {
         return DAWN_SWAP_CHAIN_NO_ERROR;
     }

     DawnSwapChainError NativeSwapChainImpl::GetNextTexture(DawnSwapChainNextTexture* nextTexture) {
         return DAWN_SWAP_CHAIN_NO_ERROR;
     }

     DawnSwapChainError NativeSwapChainImpl::Present() {
         return DAWN_SWAP_CHAIN_NO_ERROR;
     }

     wgpu::TextureFormat NativeSwapChainImpl::GetPreferredFormat() const {
         return wgpu::TextureFormat::RGBA8Unorm;
     }

     // StagingBuffer

     StagingBuffer::StagingBuffer(size_t size, Device* device)
         : StagingBufferBase(size), mDevice(device) {
     }

     StagingBuffer::~StagingBuffer() {
         if (mBuffer) {
             mDevice->DecrementMemoryUsage(GetSize());
         }
     }

     MaybeError StagingBuffer::Initialize() {
         DAWN_TRY(mDevice->IncrementMemoryUsage(GetSize()));
         mBuffer = std::make_unique<uint8_t[]>(GetSize());
         mMappedPointer = mBuffer.get();
         return {};
     }

     uint32_t Device::GetOptimalBytesPerRowAlignment() const {
         return 1;
     }

     uint64_t Device::GetOptimalBufferToTextureCopyOffsetAlignment() const {
         return 1;
     }

     float Device::GetTimestampPeriodInNS() const {
         return 1.0f;
     }

 }}  // namespace dawn_native::null
	// Copyright 2017 The Dawn Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "dawn_native/null/DeviceNull.h"

	#include "dawn_native/BackendConnection.h"
	#include "dawn_native/Commands.h"
	#include "dawn_native/ErrorData.h"
	#include "dawn_native/Instance.h"
	#include "dawn_native/Surface.h"

	#include <spirv_cross.hpp>

	namespace dawn_native { namespace null {

	// Implementation of pre-Device objects: the null adapter, null backend connection and Connect()

	Adapter::Adapter(InstanceBase* instance) : AdapterBase(instance, wgpu::BackendType::Null) {
	mPCIInfo.name = "Null backend";
	mAdapterType = wgpu::AdapterType::CPU;

	// Enable all extensions by default for the convenience of tests.
	mSupportedExtensions.extensionsBitSet.flip();
	}

	Adapter::~Adapter() = default;

	// Used for the tests that intend to use an adapter without all extensions enabled.
	void Adapter::SetSupportedExtensions(const std::vector<const char*>& requiredExtensions) {
	mSupportedExtensions = GetInstance()->ExtensionNamesToExtensionsSet(requiredExtensions);
	}

	ResultOrError<DeviceBase> Adapter::CreateDeviceImpl(const DeviceDescriptor descriptor) {
	return Device::Create(this, descriptor);
	}

	class Backend : public BackendConnection {
	public:
	Backend(InstanceBase* instance) : BackendConnection(instance, wgpu::BackendType::Null) {
	}

	std::vector<std::unique_ptr<AdapterBase>> DiscoverDefaultAdapters() override {
	// There is always a single Null adapter because it is purely CPU based and doesn't
	// depend on the system.
	std::vector<std::unique_ptr<AdapterBase>> adapters;
	adapters.push_back(std::make_unique<Adapter>(GetInstance()));
	return adapters;
	}
	};

	BackendConnection* Connect(InstanceBase* instance) {
	return new Backend(instance);
	}

	struct CopyFromStagingToBufferOperation : PendingOperation {
	virtual void Execute() {
	destination->CopyFromStaging(staging, sourceOffset, destinationOffset, size);
	}

	StagingBufferBase* staging;
	Ref<Buffer> destination;
	uint64_t sourceOffset;
	uint64_t destinationOffset;
	uint64_t size;
	};

	// Device

	// static
	ResultOrError<Device> Device::Create(Adapter adapter, const DeviceDescriptor* descriptor) {
	Ref<Device> device = AcquireRef(new Device(adapter, descriptor));
	DAWN_TRY(device->Initialize());
	return device.Detach();
	}

	Device::~Device() {
	ShutDownBase();
	}

	MaybeError Device::Initialize() {
	return DeviceBase::Initialize(new Queue(this));
	}

	ResultOrError<Ref<BindGroupBase>> Device::CreateBindGroupImpl(
	const BindGroupDescriptor* descriptor) {
	return AcquireRef(new BindGroup(this, descriptor));
	}
	ResultOrError<Ref<BindGroupLayoutBase>> Device::CreateBindGroupLayoutImpl(
	const BindGroupLayoutDescriptor* descriptor) {
	return AcquireRef(new BindGroupLayout(this, descriptor));
	}
	ResultOrError<Ref<BufferBase>> Device::CreateBufferImpl(const BufferDescriptor* descriptor) {
	DAWN_TRY(IncrementMemoryUsage(descriptor->size));
	return AcquireRef(new Buffer(this, descriptor));
	}
	ResultOrError<Ref<CommandBufferBase>> Device::CreateCommandBuffer(
	CommandEncoder* encoder,
	const CommandBufferDescriptor* descriptor) {
	return AcquireRef(new CommandBuffer(encoder, descriptor));
	}
	ResultOrError<Ref<ComputePipelineBase>> Device::CreateComputePipelineImpl(
	const ComputePipelineDescriptor* descriptor) {
	return AcquireRef(new ComputePipeline(this, descriptor));
	}
	ResultOrError<Ref<PipelineLayoutBase>> Device::CreatePipelineLayoutImpl(
	const PipelineLayoutDescriptor* descriptor) {
	return AcquireRef(new PipelineLayout(this, descriptor));
	}
	ResultOrError<Ref<QuerySetBase>> Device::CreateQuerySetImpl(
	const QuerySetDescriptor* descriptor) {
	return AcquireRef(new QuerySet(this, descriptor));
	}
	ResultOrError<Ref<RenderPipelineBase>> Device::CreateRenderPipelineImpl(
	const RenderPipelineDescriptor* descriptor) {
	return AcquireRef(new RenderPipeline(this, descriptor));
	}
	ResultOrError<Ref<SamplerBase>> Device::CreateSamplerImpl(const SamplerDescriptor* descriptor) {
	return AcquireRef(new Sampler(this, descriptor));
	}
	ResultOrError<Ref<ShaderModuleBase>> Device::CreateShaderModuleImpl(
	const ShaderModuleDescriptor* descriptor,
	ShaderModuleParseResult* parseResult) {
	Ref<ShaderModule> module = AcquireRef(new ShaderModule(this, descriptor));
	DAWN_TRY(module->Initialize(parseResult));
	return module;
	}
	ResultOrError<Ref<SwapChainBase>> Device::CreateSwapChainImpl(
	const SwapChainDescriptor* descriptor) {
	return AcquireRef(new OldSwapChain(this, descriptor));
	}
	ResultOrError<Ref<NewSwapChainBase>> Device::CreateSwapChainImpl(
	Surface* surface,
	NewSwapChainBase* previousSwapChain,
	const SwapChainDescriptor* descriptor) {
	return SwapChain::Create(this, surface, previousSwapChain, descriptor);
	}
	ResultOrError<Ref<TextureBase>> Device::CreateTextureImpl(const TextureDescriptor* descriptor) {
	return AcquireRef(new Texture(this, descriptor, TextureBase::TextureState::OwnedInternal));
	}
	ResultOrError<Ref<TextureViewBase>> Device::CreateTextureViewImpl(
	TextureBase* texture,
	const TextureViewDescriptor* descriptor) {
	return AcquireRef(new TextureView(texture, descriptor));
	}

	ResultOrError<std::unique_ptr<StagingBufferBase>> Device::CreateStagingBuffer(size_t size) {
	std::unique_ptr<StagingBufferBase> stagingBuffer =
	std::make_unique<StagingBuffer>(size, this);
	DAWN_TRY(stagingBuffer->Initialize());
	return std::move(stagingBuffer);
	}

	void Device::ShutDownImpl() {
	ASSERT(GetState() == State::Disconnected);

	// Clear pending operations before checking mMemoryUsage because some operations keep a
	// reference to Buffers.
	mPendingOperations.clear();
	ASSERT(mMemoryUsage == 0);
	}

	MaybeError Device::WaitForIdleForDestruction() {
	mPendingOperations.clear();
	return {};
	}

	MaybeError Device::CopyFromStagingToBuffer(StagingBufferBase* source,
	uint64_t sourceOffset,
	BufferBase* destination,
	uint64_t destinationOffset,
	uint64_t size) {
	if (IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse)) {
	destination->SetIsDataInitialized();
	}

	auto operation = std::make_unique<CopyFromStagingToBufferOperation>();
	operation->staging = source;
	operation->destination = ToBackend(destination);
	operation->sourceOffset = sourceOffset;
	operation->destinationOffset = destinationOffset;
	operation->size = size;

	AddPendingOperation(std::move(operation));

	return {};
	}

	MaybeError Device::CopyFromStagingToTexture(const StagingBufferBase* source,
	const TextureDataLayout& src,
	TextureCopy* dst,
	const Extent3D& copySizePixels) {
	return {};
	}

	MaybeError Device::IncrementMemoryUsage(uint64_t bytes) {
	static_assert(kMaxMemoryUsage <= std::numeric_limits<size_t>::max(), "");
	if (bytes > kMaxMemoryUsage \|\| mMemoryUsage + bytes > kMaxMemoryUsage) {
	return DAWN_OUT_OF_MEMORY_ERROR("Out of memory.");
	}
	mMemoryUsage += bytes;
	return {};
	}

	void Device::DecrementMemoryUsage(uint64_t bytes) {
	ASSERT(mMemoryUsage >= bytes);
	mMemoryUsage -= bytes;
	}

	MaybeError Device::TickImpl() {
	return SubmitPendingOperations();
	}

	ResultOrError<ExecutionSerial> Device::CheckAndUpdateCompletedSerials() {
	return GetLastSubmittedCommandSerial();
	}

	void Device::AddPendingOperation(std::unique_ptr<PendingOperation> operation) {
	mPendingOperations.emplace_back(std::move(operation));
	}

	MaybeError Device::SubmitPendingOperations() {
	for (auto& operation : mPendingOperations) {
	operation->Execute();
	}
	mPendingOperations.clear();

	DAWN_TRY(CheckPassedSerials());
	IncrementLastSubmittedCommandSerial();

	return {};
	}

	// BindGroupDataHolder

	BindGroupDataHolder::BindGroupDataHolder(size_t size)
	: mBindingDataAllocation(malloc(size)) // malloc is guaranteed to return a
	// pointer aligned enough for the allocation
	{
	}

	BindGroupDataHolder::~BindGroupDataHolder() {
	free(mBindingDataAllocation);
	}

	// BindGroup

	BindGroup::BindGroup(DeviceBase* device, const BindGroupDescriptor* descriptor)
	: BindGroupDataHolder(descriptor->layout->GetBindingDataSize()),
	BindGroupBase(device, descriptor, mBindingDataAllocation) {
	}

	// Buffer

	Buffer::Buffer(Device* device, const BufferDescriptor* descriptor)
	: BufferBase(device, descriptor) {
	mBackingData = std::unique_ptr<uint8_t[]>(new uint8_t[GetSize()]);
	}

	Buffer::~Buffer() {
	DestroyInternal();
	ToBackend(GetDevice())->DecrementMemoryUsage(GetSize());
	}

	bool Buffer::IsCPUWritableAtCreation() const {
	// Only return true for mappable buffers so we can test cases that need / don't need a
	// staging buffer.
	return (GetUsage() & (wgpu::BufferUsage::MapRead \| wgpu::BufferUsage::MapWrite)) != 0;
	}

	MaybeError Buffer::MapAtCreationImpl() {
	return {};
	}

	void Buffer::CopyFromStaging(StagingBufferBase* staging,
	uint64_t sourceOffset,
	uint64_t destinationOffset,
	uint64_t size) {
	uint8_t* ptr = reinterpret_cast<uint8_t*>(staging->GetMappedPointer());
	memcpy(mBackingData.get() + destinationOffset, ptr + sourceOffset, size);
	}

	void Buffer::DoWriteBuffer(uint64_t bufferOffset, const void* data, size_t size) {
	ASSERT(bufferOffset + size <= GetSize());
	ASSERT(mBackingData);
	memcpy(mBackingData.get() + bufferOffset, data, size);
	}

	MaybeError Buffer::MapAsyncImpl(wgpu::MapMode mode, size_t offset, size_t size) {
	return {};
	}

	void* Buffer::GetMappedPointerImpl() {
	return mBackingData.get();
	}

	void Buffer::UnmapImpl() {
	}

	void Buffer::DestroyImpl() {
	}

	// CommandBuffer

	CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
	: CommandBufferBase(encoder, descriptor) {
	}

	// QuerySet

	QuerySet::QuerySet(Device* device, const QuerySetDescriptor* descriptor)
	: QuerySetBase(device, descriptor) {
	}

	QuerySet::~QuerySet() {
	DestroyInternal();
	}

	void QuerySet::DestroyImpl() {
	}

	// Queue

	Queue::Queue(Device* device) : QueueBase(device) {
	}

	Queue::~Queue() {
	}

	MaybeError Queue::SubmitImpl(uint32_t, CommandBufferBase* const*) {
	Device* device = ToBackend(GetDevice());

	// The Vulkan, D3D12 and Metal implementation all tick the device here,
	// for testing purposes we should also tick in the null implementation.
	DAWN_TRY(device->Tick());

	return device->SubmitPendingOperations();
	}

	MaybeError Queue::WriteBufferImpl(BufferBase* buffer,
	uint64_t bufferOffset,
	const void* data,
	size_t size) {
	ToBackend(buffer)->DoWriteBuffer(bufferOffset, data, size);
	return {};
	}

	// SwapChain

	// static
	ResultOrError<Ref<SwapChain>> SwapChain::Create(Device* device,
	Surface* surface,
	NewSwapChainBase* previousSwapChain,
	const SwapChainDescriptor* descriptor) {
	Ref<SwapChain> swapchain = AcquireRef(new SwapChain(device, surface, descriptor));
	DAWN_TRY(swapchain->Initialize(previousSwapChain));
	return swapchain;
	}

	MaybeError SwapChain::Initialize(NewSwapChainBase* previousSwapChain) {
	if (previousSwapChain != nullptr) {
	// TODO(crbug.com/dawn/269): figure out what should happen when surfaces are used by
	// multiple backends one after the other. It probably needs to block until the backend
	// and GPU are completely finished with the previous swapchain.
	if (previousSwapChain->GetBackendType() != wgpu::BackendType::Null) {
	return DAWN_VALIDATION_ERROR("null::SwapChain cannot switch between APIs");
	}
	}

	return {};
	}

	SwapChain::~SwapChain() = default;

	MaybeError SwapChain::PresentImpl() {
	mTexture->APIDestroy();
	mTexture = nullptr;
	return {};
	}

	ResultOrError<TextureViewBase*> SwapChain::GetCurrentTextureViewImpl() {
	TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
	// TODO(dawn:723): change to not use AcquireRef for reentrant object creation.
	mTexture = AcquireRef(
	new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
	// TODO(dawn:723): change to not use AcquireRef for reentrant object creation.
	return mTexture->APICreateView();
	}

	void SwapChain::DetachFromSurfaceImpl() {
	if (mTexture != nullptr) {
	mTexture->APIDestroy();
	mTexture = nullptr;
	}
	}

	// ShaderModule

	MaybeError ShaderModule::Initialize(ShaderModuleParseResult* parseResult) {
	return InitializeBase(parseResult);
	}

	// OldSwapChain

	OldSwapChain::OldSwapChain(Device* device, const SwapChainDescriptor* descriptor)
	: OldSwapChainBase(device, descriptor) {
	const auto& im = GetImplementation();
	im.Init(im.userData, nullptr);
	}

	OldSwapChain::~OldSwapChain() {
	}

	TextureBase* OldSwapChain::GetNextTextureImpl(const TextureDescriptor* descriptor) {
	return GetDevice()->APICreateTexture(descriptor);
	}

	MaybeError OldSwapChain::OnBeforePresent(TextureViewBase*) {
	return {};
	}

	// NativeSwapChainImpl

	void NativeSwapChainImpl::Init(WSIContext* context) {
	}

	DawnSwapChainError NativeSwapChainImpl::Configure(WGPUTextureFormat format,
	WGPUTextureUsage,
	uint32_t width,
	uint32_t height) {
	return DAWN_SWAP_CHAIN_NO_ERROR;
	}

	DawnSwapChainError NativeSwapChainImpl::GetNextTexture(DawnSwapChainNextTexture* nextTexture) {
	return DAWN_SWAP_CHAIN_NO_ERROR;
	}

	DawnSwapChainError NativeSwapChainImpl::Present() {
	return DAWN_SWAP_CHAIN_NO_ERROR;
	}

	wgpu::TextureFormat NativeSwapChainImpl::GetPreferredFormat() const {
	return wgpu::TextureFormat::RGBA8Unorm;
	}

	// StagingBuffer

	StagingBuffer::StagingBuffer(size_t size, Device* device)
	: StagingBufferBase(size), mDevice(device) {
	}

	StagingBuffer::~StagingBuffer() {
	if (mBuffer) {
	mDevice->DecrementMemoryUsage(GetSize());
	}
	}

	MaybeError StagingBuffer::Initialize() {
	DAWN_TRY(mDevice->IncrementMemoryUsage(GetSize()));
	mBuffer = std::make_unique<uint8_t[]>(GetSize());
	mMappedPointer = mBuffer.get();
	return {};
	}

	uint32_t Device::GetOptimalBytesPerRowAlignment() const {
	return 1;
	}

	uint64_t Device::GetOptimalBufferToTextureCopyOffsetAlignment() const {
	return 1;
	}

	float Device::GetTimestampPeriodInNS() const {
	return 1.0f;
	}

	}} // namespace dawn_native::null