716e5f72f2
Before this change, we'd use the system page size as the HeapBlock size. This caused it to vary on different platforms, going as low as 4 KiB on most Linux systems. To make this work, we now use posix_memalign() to ensure we get size-aligned allocations on every platform. Also nice: HeapBlock::BLOCK_SIZE is now a constant.
121 lines
3.3 KiB
C++
121 lines
3.3 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <andreas@ladybird.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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#include <AK/IntrusiveList.h>
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#include <AK/Platform.h>
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#include <AK/StringView.h>
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#include <AK/Types.h>
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#include <LibGC/Cell.h>
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#include <LibGC/Forward.h>
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#include <LibGC/Internals.h>
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#ifdef HAS_ADDRESS_SANITIZER
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# include <sanitizer/asan_interface.h>
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#endif
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namespace GC {
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class GC_API HeapBlock : public HeapBlockBase {
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AK_MAKE_NONCOPYABLE(HeapBlock);
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AK_MAKE_NONMOVABLE(HeapBlock);
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public:
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using HeapBlockBase::BLOCK_SIZE;
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static NonnullOwnPtr<HeapBlock> create_with_cell_size(Heap&, CellAllocator&, size_t cell_size, char const* class_name);
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size_t cell_size() const { return m_cell_size; }
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size_t cell_count() const { return (HeapBlock::BLOCK_SIZE - sizeof(HeapBlock)) / m_cell_size; }
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bool is_full() const { return !has_lazy_freelist() && !m_freelist; }
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ALWAYS_INLINE Cell* allocate()
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{
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Cell* allocated_cell = nullptr;
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if (m_freelist) {
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VERIFY(is_valid_cell_pointer(m_freelist));
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allocated_cell = exchange(m_freelist, m_freelist->next);
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} else if (has_lazy_freelist()) {
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allocated_cell = cell(m_next_lazy_freelist_index++);
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}
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if (allocated_cell) {
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ASAN_UNPOISON_MEMORY_REGION(allocated_cell, m_cell_size);
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}
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return allocated_cell;
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}
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void deallocate(Cell*);
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template<typename Callback>
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void for_each_cell(Callback callback)
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{
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auto end = has_lazy_freelist() ? m_next_lazy_freelist_index : cell_count();
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for (size_t i = 0; i < end; ++i)
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callback(cell(i));
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}
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template<Cell::State state, typename Callback>
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void for_each_cell_in_state(Callback callback)
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{
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for_each_cell([&](auto* cell) {
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if (cell->state() == state)
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callback(cell);
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});
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}
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static HeapBlock* from_cell(Cell const* cell)
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{
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return static_cast<HeapBlock*>(HeapBlockBase::from_cell(cell));
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}
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Cell* cell_from_possible_pointer(FlatPtr pointer)
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{
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if (pointer < reinterpret_cast<FlatPtr>(m_storage))
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return nullptr;
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size_t cell_index = (pointer - reinterpret_cast<FlatPtr>(m_storage)) / m_cell_size;
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auto end = has_lazy_freelist() ? m_next_lazy_freelist_index : cell_count();
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if (cell_index >= end)
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return nullptr;
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return cell(cell_index);
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}
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bool is_valid_cell_pointer(Cell const* cell)
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{
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return cell_from_possible_pointer((FlatPtr)cell);
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}
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IntrusiveListNode<HeapBlock> m_list_node;
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CellAllocator& cell_allocator() { return m_cell_allocator; }
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private:
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HeapBlock(Heap&, CellAllocator&, size_t cell_size);
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bool has_lazy_freelist() const { return m_next_lazy_freelist_index < cell_count(); }
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struct FreelistEntry final : public Cell {
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GC_CELL(FreelistEntry, Cell);
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RawPtr<FreelistEntry> next;
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};
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Cell* cell(size_t index)
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{
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return reinterpret_cast<Cell*>(&m_storage[index * cell_size()]);
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}
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CellAllocator& m_cell_allocator;
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size_t m_cell_size { 0 };
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size_t m_next_lazy_freelist_index { 0 };
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Ptr<FreelistEntry> m_freelist;
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alignas(__BIGGEST_ALIGNMENT__) u8 m_storage[];
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public:
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static constexpr size_t min_possible_cell_size = sizeof(FreelistEntry);
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};
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}
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