src/dawn/wire/WireDeserializeAllocator.cpp

// Copyright 2019 The Dawn & Tint Authors
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#include "src/dawn/wire/WireDeserializeAllocator.h"

#include <algorithm>
#include <utility>

#include "src/utils/compiler.h"

namespace dawn::wire {
WireDeserializeAllocator::WireDeserializeAllocator() {
    Reset();
}

WireDeserializeAllocator::~WireDeserializeAllocator() {
    Reset();
}

std::optional<Span<std::byte>> WireDeserializeAllocator::TryGetSpace(size_t size) {
    // Return space in the current buffer if possible first.
    if (mCurrentBuffer.size() >= size) {
        return mCurrentBuffer.TakeFirst(size);
    }

    // Otherwise allocate a new buffer and try again.
    size_t allocationSize = std::max(size, kDefaultBufferSize);
    auto allocation =
        // SAFETY: This is a pool allocation that will be initialized when it's suballocated.
        DAWN_UNSAFE_BUFFERS(HeapArray<std::byte>::Uninit(allocationSize, std::nothrow));
    if (!allocation) {
        return std::nullopt;
    }

    mCurrentBuffer = allocation;
    mAllocations.push_back(std::move(allocation));
    return TryGetSpace(size);
}

void WireDeserializeAllocator::Reset() {
    // The initial buffer is the inline buffer so that some allocations can be skipped
    mCurrentBuffer = mStaticBuffer;
    mAllocations.clear();
}
}  // namespace dawn::wire