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<BindGroupBase*> Device::CreateBindGroupImpl(
         const BindGroupDescriptor* descriptor) {
         return new BindGroup(this, descriptor);
     }
     ResultOrError<BindGroupLayoutBase*> Device::CreateBindGroupLayoutImpl(
         const BindGroupLayoutDescriptor* descriptor) {
         return new BindGroupLayout(this, descriptor);
     }
     ResultOrError<BufferBase*> Device::CreateBufferImpl(const BufferDescriptor* descriptor) {
         DAWN_TRY(IncrementMemoryUsage(descriptor->size));
         return new Buffer(this, descriptor);
     }
     CommandBufferBase* Device::CreateCommandBuffer(CommandEncoder* encoder,
                                                    const CommandBufferDescriptor* descriptor) {
         return new CommandBuffer(encoder, descriptor);
     }
     ResultOrError<ComputePipelineBase*> Device::CreateComputePipelineImpl(
         const ComputePipelineDescriptor* descriptor) {
         return new ComputePipeline(this, descriptor);
     }
     ResultOrError<PipelineLayoutBase*> Device::CreatePipelineLayoutImpl(
         const PipelineLayoutDescriptor* descriptor) {
         return new PipelineLayout(this, descriptor);
     }
     ResultOrError<QuerySetBase*> Device::CreateQuerySetImpl(const QuerySetDescriptor* descriptor) {
         return new QuerySet(this, descriptor);
     }
     ResultOrError<RenderPipelineBase*> Device::CreateRenderPipelineImpl(
         const RenderPipelineDescriptor* descriptor) {
         return new RenderPipeline(this, descriptor);
     }
     ResultOrError<SamplerBase*> Device::CreateSamplerImpl(const SamplerDescriptor* descriptor) {
         return new Sampler(this, descriptor);
     }
     ResultOrError<ShaderModuleBase*> Device::CreateShaderModuleImpl(
         const ShaderModuleDescriptor* descriptor) {
         Ref<ShaderModule> module = AcquireRef(new ShaderModule(this, descriptor));

         if (IsToggleEnabled(Toggle::UseSpvc)) {
             shaderc_spvc::CompileOptions options;
             options.SetValidate(IsValidationEnabled());
             shaderc_spvc::Context* context = module->GetContext();
             shaderc_spvc_status status = context->InitializeForGlsl(
                 module->GetSpirv().data(), module->GetSpirv().size(), options);
             if (status != shaderc_spvc_status_success) {
                 return DAWN_VALIDATION_ERROR("Unable to initialize instance of spvc");
             }

             spirv_cross::Compiler* compiler;
             status = context->GetCompiler(reinterpret_cast<void**>(&compiler));
             if (status != shaderc_spvc_status_success) {
                 return DAWN_VALIDATION_ERROR("Unable to get cross compiler");
             }
             DAWN_TRY(module->ExtractSpirvInfo(*compiler));
         } else {
             spirv_cross::Compiler compiler(module->GetSpirv());
             DAWN_TRY(module->ExtractSpirvInfo(compiler));
         }
         return module.Detach();
     }
     ResultOrError<SwapChainBase*> Device::CreateSwapChainImpl(
         const SwapChainDescriptor* descriptor) {
         return new OldSwapChain(this, descriptor);
     }
     ResultOrError<NewSwapChainBase*> Device::CreateSwapChainImpl(
         Surface* surface,
         NewSwapChainBase* previousSwapChain,
         const SwapChainDescriptor* descriptor) {
         return new SwapChain(this, surface, previousSwapChain, descriptor);
     }
     ResultOrError<Ref<TextureBase>> Device::CreateTextureImpl(const TextureDescriptor* descriptor) {
         return AcquireRef(new Texture(this, descriptor, TextureBase::TextureState::OwnedInternal));
     }
     ResultOrError<TextureViewBase*> Device::CreateTextureViewImpl(
         TextureBase* texture,
         const TextureViewDescriptor* descriptor) {
         return 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) {
         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::IncrementMemoryUsage(size_t bytes) {
         static_assert(kMaxMemoryUsage <= std::numeric_limits<size_t>::max() / 2, "");
         if (bytes > kMaxMemoryUsage || mMemoryUsage + bytes > kMaxMemoryUsage) {
             return DAWN_OUT_OF_MEMORY_ERROR("Out of memory.");
         }
         mMemoryUsage += bytes;
         return {};
     }

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

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

     Serial Device::CheckAndUpdateCompletedSerials() {
         return GetLastSubmittedCommandSerial();
     }

     void Device::AddPendingOperation(std::unique_ptr<PendingOperation> operation) {
         mPendingOperations.emplace_back(std::move(operation));
     }
     void Device::SubmitPendingOperations() {
         for (auto& operation : mPendingOperations) {
             operation->Execute();
         }
         mPendingOperations.clear();

         CheckPassedSerials();
         IncrementLastSubmittedCommandSerial();
     }

     // 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

     struct BufferMapOperation : PendingOperation {
         virtual void Execute() {
             buffer->OnMapCommandSerialFinished(serial, isWrite);
         }

         Ref<Buffer> buffer;
         void* ptr;
         uint32_t serial;
         bool isWrite;
     };

     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::IsMapWritable() 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(uint8_t** mappedPointer) {
         *mappedPointer = mBackingData.get();
         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::MapReadAsyncImpl(uint32_t serial) {
         MapAsyncImplCommon(serial, false);
         return {};
     }

     MaybeError Buffer::MapWriteAsyncImpl(uint32_t serial) {
         MapAsyncImplCommon(serial, true);
         return {};
     }

     void Buffer::MapAsyncImplCommon(uint32_t serial, bool isWrite) {
         ASSERT(mBackingData);

         auto operation = std::make_unique<BufferMapOperation>();
         operation->buffer = this;
         operation->ptr = mBackingData.get();
         operation->serial = serial;
         operation->isWrite = isWrite;

         ToBackend(GetDevice())->AddPendingOperation(std::move(operation));
     }

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

     void Buffer::UnmapImpl() {
     }

     void Buffer::DestroyImpl() {
     }

     // CommandBuffer

     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
         : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
     }

     CommandBuffer::~CommandBuffer() {
         FreeCommands(&mCommands);
     }

     // 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*) {
         ToBackend(GetDevice())->SubmitPendingOperations();
         return {};
     }

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

     // SwapChain

     SwapChain::SwapChain(Device* device,
                          Surface* surface,
                          NewSwapChainBase* previousSwapChain,
                          const SwapChainDescriptor* descriptor)
         : NewSwapChainBase(device, surface, descriptor) {
         if (previousSwapChain != nullptr) {
             // TODO(cwallez@chromium.org): 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.
             ASSERT(previousSwapChain->GetBackendType() == wgpu::BackendType::Null);
             previousSwapChain->DetachFromSurface();
         }
     }

     SwapChain::~SwapChain() {
         DetachFromSurface();
     }

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

     ResultOrError<TextureViewBase*> SwapChain::GetCurrentTextureViewImpl() {
         TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
         mTexture = AcquireRef(
             new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
         return mTexture->CreateView(nullptr);
     }

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

     // 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()->CreateTexture(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 {};
     }

 }}  // 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<BindGroupBase*> Device::CreateBindGroupImpl(
	const BindGroupDescriptor* descriptor) {
	return new BindGroup(this, descriptor);
	}
	ResultOrError<BindGroupLayoutBase*> Device::CreateBindGroupLayoutImpl(
	const BindGroupLayoutDescriptor* descriptor) {
	return new BindGroupLayout(this, descriptor);
	}
	ResultOrError<BufferBase> Device::CreateBufferImpl(const BufferDescriptor descriptor) {
	DAWN_TRY(IncrementMemoryUsage(descriptor->size));
	return new Buffer(this, descriptor);
	}
	CommandBufferBase* Device::CreateCommandBuffer(CommandEncoder* encoder,
	const CommandBufferDescriptor* descriptor) {
	return new CommandBuffer(encoder, descriptor);
	}
	ResultOrError<ComputePipelineBase*> Device::CreateComputePipelineImpl(
	const ComputePipelineDescriptor* descriptor) {
	return new ComputePipeline(this, descriptor);
	}
	ResultOrError<PipelineLayoutBase*> Device::CreatePipelineLayoutImpl(
	const PipelineLayoutDescriptor* descriptor) {
	return new PipelineLayout(this, descriptor);
	}
	ResultOrError<QuerySetBase> Device::CreateQuerySetImpl(const QuerySetDescriptor descriptor) {
	return new QuerySet(this, descriptor);
	}
	ResultOrError<RenderPipelineBase*> Device::CreateRenderPipelineImpl(
	const RenderPipelineDescriptor* descriptor) {
	return new RenderPipeline(this, descriptor);
	}
	ResultOrError<SamplerBase> Device::CreateSamplerImpl(const SamplerDescriptor descriptor) {
	return new Sampler(this, descriptor);
	}
	ResultOrError<ShaderModuleBase*> Device::CreateShaderModuleImpl(
	const ShaderModuleDescriptor* descriptor) {
	Ref<ShaderModule> module = AcquireRef(new ShaderModule(this, descriptor));

	if (IsToggleEnabled(Toggle::UseSpvc)) {
	shaderc_spvc::CompileOptions options;
	options.SetValidate(IsValidationEnabled());
	shaderc_spvc::Context* context = module->GetContext();
	shaderc_spvc_status status = context->InitializeForGlsl(
	module->GetSpirv().data(), module->GetSpirv().size(), options);
	if (status != shaderc_spvc_status_success) {
	return DAWN_VALIDATION_ERROR("Unable to initialize instance of spvc");
	}

	spirv_cross::Compiler* compiler;
	status = context->GetCompiler(reinterpret_cast<void**>(&compiler));
	if (status != shaderc_spvc_status_success) {
	return DAWN_VALIDATION_ERROR("Unable to get cross compiler");
	}
	DAWN_TRY(module->ExtractSpirvInfo(*compiler));
	} else {
	spirv_cross::Compiler compiler(module->GetSpirv());
	DAWN_TRY(module->ExtractSpirvInfo(compiler));
	}
	return module.Detach();
	}
	ResultOrError<SwapChainBase*> Device::CreateSwapChainImpl(
	const SwapChainDescriptor* descriptor) {
	return new OldSwapChain(this, descriptor);
	}
	ResultOrError<NewSwapChainBase*> Device::CreateSwapChainImpl(
	Surface* surface,
	NewSwapChainBase* previousSwapChain,
	const SwapChainDescriptor* descriptor) {
	return new SwapChain(this, surface, previousSwapChain, descriptor);
	}
	ResultOrError<Ref<TextureBase>> Device::CreateTextureImpl(const TextureDescriptor* descriptor) {
	return AcquireRef(new Texture(this, descriptor, TextureBase::TextureState::OwnedInternal));
	}
	ResultOrError<TextureViewBase*> Device::CreateTextureViewImpl(
	TextureBase* texture,
	const TextureViewDescriptor* descriptor) {
	return 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) {
	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::IncrementMemoryUsage(size_t bytes) {
	static_assert(kMaxMemoryUsage <= std::numeric_limits<size_t>::max() / 2, "");
	if (bytes > kMaxMemoryUsage \|\| mMemoryUsage + bytes > kMaxMemoryUsage) {
	return DAWN_OUT_OF_MEMORY_ERROR("Out of memory.");
	}
	mMemoryUsage += bytes;
	return {};
	}

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

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

	Serial Device::CheckAndUpdateCompletedSerials() {
	return GetLastSubmittedCommandSerial();
	}

	void Device::AddPendingOperation(std::unique_ptr<PendingOperation> operation) {
	mPendingOperations.emplace_back(std::move(operation));
	}
	void Device::SubmitPendingOperations() {
	for (auto& operation : mPendingOperations) {
	operation->Execute();
	}
	mPendingOperations.clear();

	CheckPassedSerials();
	IncrementLastSubmittedCommandSerial();
	}

	// 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

	struct BufferMapOperation : PendingOperation {
	virtual void Execute() {
	buffer->OnMapCommandSerialFinished(serial, isWrite);
	}

	Ref<Buffer> buffer;
	void* ptr;
	uint32_t serial;
	bool isWrite;
	};

	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::IsMapWritable() 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(uint8_t** mappedPointer) {
	*mappedPointer = mBackingData.get();
	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::MapReadAsyncImpl(uint32_t serial) {
	MapAsyncImplCommon(serial, false);
	return {};
	}

	MaybeError Buffer::MapWriteAsyncImpl(uint32_t serial) {
	MapAsyncImplCommon(serial, true);
	return {};
	}

	void Buffer::MapAsyncImplCommon(uint32_t serial, bool isWrite) {
	ASSERT(mBackingData);

	auto operation = std::make_unique<BufferMapOperation>();
	operation->buffer = this;
	operation->ptr = mBackingData.get();
	operation->serial = serial;
	operation->isWrite = isWrite;

	ToBackend(GetDevice())->AddPendingOperation(std::move(operation));
	}

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

	void Buffer::UnmapImpl() {
	}

	void Buffer::DestroyImpl() {
	}

	// CommandBuffer

	CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
	: CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
	}

	CommandBuffer::~CommandBuffer() {
	FreeCommands(&mCommands);
	}

	// 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*) {
	ToBackend(GetDevice())->SubmitPendingOperations();
	return {};
	}

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

	// SwapChain

	SwapChain::SwapChain(Device* device,
	Surface* surface,
	NewSwapChainBase* previousSwapChain,
	const SwapChainDescriptor* descriptor)
	: NewSwapChainBase(device, surface, descriptor) {
	if (previousSwapChain != nullptr) {
	// TODO(cwallez@chromium.org): 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.
	ASSERT(previousSwapChain->GetBackendType() == wgpu::BackendType::Null);
	previousSwapChain->DetachFromSurface();
	}
	}

	SwapChain::~SwapChain() {
	DetachFromSurface();
	}

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

	ResultOrError<TextureViewBase*> SwapChain::GetCurrentTextureViewImpl() {
	TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
	mTexture = AcquireRef(
	new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
	return mTexture->CreateView(nullptr);
	}

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

	// 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()->CreateTexture(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 {};
	}

	}} // namespace dawn_native::null