mirror of
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159 lines
6.3 KiB
C++
159 lines
6.3 KiB
C++
/*
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* Copyright (c) 2018-2020, 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: Statically sized kernel-only memory buffer.
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//
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// A KBuffer is a value-type convenience class that wraps a NonnullRefPtr<KBufferImpl>.
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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/ByteBuffer.h>
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#include <AK/Memory.h>
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#include <AK/StringView.h>
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#include <Kernel/VM/MemoryManager.h>
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#include <Kernel/VM/Region.h>
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namespace Kernel {
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class KBufferImpl : public RefCounted<KBufferImpl> {
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public:
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static RefPtr<KBufferImpl> try_create_with_size(size_t size, Region::Access access, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto region = MM.allocate_kernel_region(page_round_up(size), name, access, strategy);
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if (!region)
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return nullptr;
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return adopt_ref_if_nonnull(new (nothrow) KBufferImpl(region.release_nonnull(), size, strategy));
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}
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static RefPtr<KBufferImpl> try_create_with_bytes(ReadonlyBytes bytes, Region::Access access, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto region = MM.allocate_kernel_region(page_round_up(bytes.size()), name, access, strategy);
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if (!region)
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return nullptr;
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memcpy(region->vaddr().as_ptr(), bytes.data(), bytes.size());
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return adopt_ref_if_nonnull(new (nothrow) KBufferImpl(region.release_nonnull(), bytes.size(), strategy));
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}
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static RefPtr<KBufferImpl> create_with_size(size_t size, Region::Access access, StringView name, AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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return try_create_with_size(size, access, name, strategy);
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}
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static RefPtr<KBufferImpl> copy(const void* data, size_t size, Region::Access access, StringView name)
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{
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auto buffer = create_with_size(size, access, name, AllocationStrategy::AllocateNow);
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if (!buffer)
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return {};
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memcpy(buffer->data(), data, size);
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return buffer;
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}
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[[nodiscard]] bool expand(size_t new_capacity)
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{
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auto new_region = MM.allocate_kernel_region(page_round_up(new_capacity), m_region->name(), m_region->access(), m_allocation_strategy);
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if (!new_region)
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return false;
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if (m_size > 0)
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memcpy(new_region->vaddr().as_ptr(), data(), min(m_region->size(), m_size));
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m_region = new_region.release_nonnull();
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return true;
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}
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[[nodiscard]] u8* data() { return m_region->vaddr().as_ptr(); }
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[[nodiscard]] const u8* 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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[[nodiscard]] const Region& region() const { return *m_region; }
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[[nodiscard]] Region& region() { return *m_region; }
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private:
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explicit KBufferImpl(NonnullOwnPtr<Region>&& region, size_t size, AllocationStrategy strategy)
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: m_size(size)
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, m_allocation_strategy(strategy)
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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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AllocationStrategy m_allocation_strategy { AllocationStrategy::Reserve };
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NonnullOwnPtr<Region> m_region;
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};
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class [[nodiscard]] KBuffer {
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public:
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explicit KBuffer(RefPtr<KBufferImpl>&& impl)
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: m_impl(move(impl))
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{
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}
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[[nodiscard]] static OwnPtr<KBuffer> try_create_with_size(size_t size, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto impl = KBufferImpl::try_create_with_size(size, access, name, strategy);
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if (!impl)
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return {};
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return adopt_own_if_nonnull(new (nothrow) KBuffer(impl.release_nonnull()));
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}
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[[nodiscard]] static OwnPtr<KBuffer> try_create_with_bytes(ReadonlyBytes bytes, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto impl = KBufferImpl::try_create_with_bytes(bytes, access, name, strategy);
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if (!impl)
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return {};
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return adopt_own_if_nonnull(new (nothrow) KBuffer(impl.release_nonnull()));
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}
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[[nodiscard]] static KBuffer create_with_size(size_t size, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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return KBuffer(KBufferImpl::create_with_size(size, access, name, strategy));
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}
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[[nodiscard]] static KBuffer copy(const void* data, size_t size, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer")
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{
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return KBuffer(KBufferImpl::copy(data, size, access, name));
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}
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[[nodiscard]] bool is_null() const { return !m_impl; }
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[[nodiscard]] u8* data() { return m_impl ? m_impl->data() : nullptr; }
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[[nodiscard]] const u8* data() const { return m_impl ? m_impl->data() : nullptr; }
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[[nodiscard]] size_t size() const { return m_impl ? m_impl->size() : 0; }
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[[nodiscard]] size_t capacity() const { return m_impl ? m_impl->capacity() : 0; }
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[[nodiscard]] void* end_pointer() { return data() + size(); }
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[[nodiscard]] const void* end_pointer() const { return data() + size(); }
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void set_size(size_t size) { m_impl->set_size(size); }
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[[nodiscard]] KBufferImpl& impl() { return *m_impl; }
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[[nodiscard]] const KBufferImpl& impl() const { return *m_impl; }
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[[nodiscard]] RefPtr<KBufferImpl> take_impl() { return move(m_impl); }
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KBuffer(const ByteBuffer& buffer, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer")
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: m_impl(KBufferImpl::copy(buffer.data(), buffer.size(), access, name))
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{
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}
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private:
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RefPtr<KBufferImpl> m_impl;
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};
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}
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