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8ded4ad88c
This patch moves everything from KBufferImpl into KBuffer instead. One layer of indirection is removed, and the whole thing is massively simplified. :^)
67 lines
2.4 KiB
C++
67 lines
2.4 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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// KBuffer: Memory buffer backed by a kernel region.
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//
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// The memory is allocated via the global kernel-only page allocator, rather than via
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// kmalloc() which is what ByteBuffer/Vector/etc will use.
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//
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// This makes KBuffer a little heavier to allocate, but much better for large and/or
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// long-lived allocations, since they don't put all that weight and pressure on the
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// severely limited kmalloc heap.
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#include <AK/Assertions.h>
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#include <AK/Memory.h>
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#include <AK/StringView.h>
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#include <Kernel/Memory/MemoryManager.h>
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namespace Kernel {
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class [[nodiscard]] KBuffer {
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public:
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static KResultOr<NonnullOwnPtr<KBuffer>> try_create_with_size(size_t size, Memory::Region::Access access = Memory::Region::Access::ReadWrite, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto region = TRY(MM.allocate_kernel_region(Memory::page_round_up(size), name, access, strategy));
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return TRY(adopt_nonnull_own_or_enomem(new (nothrow) KBuffer { size, move(region) }));
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}
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static KResultOr<NonnullOwnPtr<KBuffer>> try_create_with_bytes(ReadonlyBytes bytes, Memory::Region::Access access = Memory::Region::Access::ReadWrite, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto buffer = TRY(try_create_with_size(bytes.size(), access, name, strategy));
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memcpy(buffer->data(), bytes.data(), bytes.size());
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return buffer;
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}
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static KResultOr<NonnullOwnPtr<KBuffer>> try_copy(const void* data, size_t size, Memory::Region::Access access = Memory::Region::Access::ReadWrite, StringView name = "KBuffer")
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{
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return try_create_with_bytes(ReadonlyBytes { data, size }, access, name);
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}
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[[nodiscard]] u8* data() { return m_region->vaddr().as_ptr(); }
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[[nodiscard]] u8 const* data() const { return m_region->vaddr().as_ptr(); }
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[[nodiscard]] size_t size() const { return m_size; }
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[[nodiscard]] size_t capacity() const { return m_region->size(); }
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void set_size(size_t size)
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{
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VERIFY(size <= capacity());
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m_size = size;
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}
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private:
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explicit KBuffer(size_t size, NonnullOwnPtr<Memory::Region> region)
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: m_size(size)
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, m_region(move(region))
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{
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}
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size_t m_size { 0 };
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NonnullOwnPtr<Memory::Region> m_region;
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};
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}
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