// Copyright 2024 The Dawn & Tint Authors
//
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#include "src/dawn/native/SharedBufferMemory.h"

#include <memory>
#include <utility>

#include "src/dawn/native/Buffer.h"
#include "src/dawn/native/ChainUtils.h"
#include "src/dawn/native/Device.h"
#include "src/dawn/native/Queue.h"
#include "src/utils/compiler.h"
#include "src/utils/heap_array.h"

namespace dawn::native {

namespace {

class ErrorSharedBufferMemory : public SharedBufferMemoryBase {
  public:
    ErrorSharedBufferMemory(DeviceBase* device, const SharedBufferMemoryDescriptor* descriptor)
        : SharedBufferMemoryBase(device, descriptor, ObjectBase::kError) {}

    Ref<SharedResourceMemoryContents> CreateContents() override { DAWN_UNREACHABLE(); }
    ResultOrError<Ref<BufferBase>> CreateBufferImpl(
        const UnpackedPtr<BufferDescriptor>& descriptor) override {
        DAWN_UNREACHABLE();
    }
    MaybeValError BeginAccessImpl(BufferBase* buffer,
                                  const UnpackedPtr<BeginAccessDescriptor>& descriptor) override {
        DAWN_UNREACHABLE();
    }
    ResultOrUnknownError<FenceAndSignalValue> EndAccessImpl(
        BufferBase* buffer,
        ExecutionSerial lastUsageSerial,
        UnpackedPtr<EndAccessState>& state) override {
        DAWN_UNREACHABLE();
    }
    void DestroyImpl(DestroyReason reason) override {}
};

}  // namespace

// static
SharedBufferMemoryBase* SharedBufferMemoryBase::MakeError(
    DeviceBase* device,
    const SharedBufferMemoryDescriptor* descriptor) {
    return new ErrorSharedBufferMemory(device, descriptor);
}

SharedBufferMemoryBase::SharedBufferMemoryBase(DeviceBase* device,
                                               const SharedBufferMemoryDescriptor* descriptor,
                                               ObjectBase::ErrorTag tag)
    : SharedResourceMemory(device, tag, descriptor->label),
      mProperties{nullptr, wgpu::BufferUsage::None, 0} {}

SharedBufferMemoryBase::SharedBufferMemoryBase(DeviceBase* device,
                                               StringView label,
                                               const SharedBufferMemoryProperties& properties)
    : SharedResourceMemory(device, label), mProperties(properties) {
    GetObjectTrackingList()->Track(this);
}

ObjectType SharedBufferMemoryBase::GetType() const {
    return ObjectType::SharedBufferMemory;
}

bool SharedBufferMemoryBase::CanBeWrittenByCPU() const {
    return (mProperties.usage & wgpu::BufferUsage::MapWrite) != 0;
}

wgpu::Status SharedBufferMemoryBase::APIGetProperties(
    SharedBufferMemoryProperties* properties) const {
    properties->usage = mProperties.usage;
    properties->size = mProperties.size;

    UnpackedPtr<SharedBufferMemoryProperties> unpacked;
    if (GetDevice()->ConsumedError(ValidateAndUnpack(properties), &unpacked,
                                   "calling %s.GetProperties", this)) {
        return wgpu::Status::Error;
    }
    return wgpu::Status::Success;
}

BufferBase* SharedBufferMemoryBase::APICreateBuffer(const BufferDescriptor* rawDescriptor) {
    // Provide the defaults if no descriptor is provided.
    BufferDescriptor defaultDescriptor;
    if (rawDescriptor == nullptr) {
        defaultDescriptor = {};
        defaultDescriptor.size = mProperties.size;

        // The buffers created with default descriptor won't contain buffer mapping usages.
        defaultDescriptor.usage = mProperties.usage & ~kMappableBufferUsages;
        rawDescriptor = &defaultDescriptor;
    }

    // 1. Validate the descriptor and create the buffer (without mapping).
    bool fakeOOMAtNativeMap = false;
    ResultOrUnknownError<Ref<BufferBase>> resultOrError =
        ([&]() -> ResultOrUnknownError<Ref<BufferBase>> {
            DAWN_TRY(GetDevice()->ValidateIsAlive());
            DAWN_TRY(GetDevice()->ValidateObject(this));
            // Validate the buffer descriptor.
            UnpackedPtr<BufferDescriptor> descriptor;
            DAWN_TRY_ASSIGN(descriptor, ValidateBufferDescriptor(GetDevice(), rawDescriptor));

            // Ensure the buffer descriptor usage is a subset of the shared buffer memory's usage.
            DAWN_INVALID_IF(
                !IsSubset(descriptor->usage, mProperties.usage),
                "The buffer usage (%s) is incompatible with the SharedBufferMemory usage (%s).",
                descriptor->usage, mProperties.usage);

            // Require MapWrite usage on the shared buffer memory when mappedAtCreation is true.
            DAWN_INVALID_IF(
                descriptor->mappedAtCreation && !CanBeWrittenByCPU(),
                "Buffer created from SharedBufferMemory with mappedAtCreation=true requires "
                "the SharedBufferMemory to have MapWrite usage.");

            // Validate that the buffer size does not exceed the shared buffer memory's size.
            DAWN_INVALID_IF(descriptor->size > mProperties.size,
                            "The buffer size (%u) is larger than SharedBufferMemory size (%u).",
                            descriptor->size, mProperties.size);

            if (auto* ext = descriptor.Get<DawnFakeBufferOOMForTesting>()) {
                fakeOOMAtNativeMap = ext->fakeOOMAtNativeMap;
                if (ext->fakeOOMAtDevice) {
                    return DAWN_OUT_OF_MEMORY_ERROR("DawnFakeBufferOOMForTesting fakeOOMAtDevice");
                }
            }
            return CreateBufferImpl(descriptor);
        })();

    // 2. Error handling. Defer descriptor / allocation errors until after we've tried to map, so
    // that errors from mapping take priority. This mirrors DeviceBase::APICreateBuffer.
    Ref<BufferBase> buffer;
    std::unique_ptr<UnknownError> deferredError;
    const bool createSucceeded = resultOrError.IsSuccess();
    if (createSucceeded) [[likely]] {
        buffer = resultOrError.AcquireSuccess();
    } else {
        deferredError = resultOrError.AcquireError();
        buffer = BufferBase::MakeError(GetDevice(), rawDescriptor);
    }

    // 3. Mapping at creation. The buffer may be either valid or an ErrorBuffer.
    if (rawDescriptor->mappedAtCreation) {
        if (!buffer->TryMapAtCreation(fakeOOMAtNativeMap)) {
            // The deferredError is silenced because we drop it here.
            return nullptr;
        }
    }

    // If there was a deferredError saved from earlier, surface it now.
    if (deferredError) {
        GetDevice()->ConsumeError(std::move(deferredError), InternalErrorType::OutOfMemory,
                                  "calling %s.CreateBuffer(%s).", this, rawDescriptor);
    }

    // Access is not allowed until BeginAccess has been called.
    if (createSucceeded) {
        buffer->OnEndAccess();
    }
    return ReturnToAPI(std::move(buffer));
}

void APISharedBufferMemoryEndAccessStateFreeMembers(WGPUSharedBufferMemoryEndAccessState cState) {
    auto* state = reinterpret_cast<SharedBufferMemoryBase::EndAccessState*>(&cState);
    for (SharedFenceBase* fence : state->fences) {
        fence->APIRelease();
    }
    DeleteAllocationFromHeapArray(state->fences.data());
    DeleteAllocationFromHeapArray(state->signaledValues.data());
}

}  // namespace dawn::native