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https://github.com/LadybirdBrowser/ladybird
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babfd70ca7
This ensures that we are explicitly declaring the allocator to use when allocating a cell(-inheriting) type, instead of silently falling back to size-based allocation. Since this is done in allocate_cell, this will only be detected for types that are actively being allocated. However, since that means they're _not_ being allocated, that means it's safe to not declare an allocator to use for those. For example, the base TypedArray<T>, which is never directly allocated and only the defined specializations are ever allocated.
96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
/*
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* Copyright (c) 2020-2023, 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/NeverDestroyed.h>
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#include <AK/NonnullOwnPtr.h>
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#include <LibGC/BlockAllocator.h>
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#include <LibGC/Forward.h>
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#include <LibGC/HeapBlock.h>
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// The default allocator, which isolates different Cell types from being allocated in the same blocks.
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#define GC_DECLARE_ALLOCATOR(ClassName) \
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using gc_allocator_marker = ClassName; \
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static GC::TypeIsolatingCellAllocator<ClassName> cell_allocator
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#define GC_DEFINE_ALLOCATOR(ClassName) \
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GC::TypeIsolatingCellAllocator<ClassName> ClassName::cell_allocator { #ClassName##sv, ClassName::OVERRIDES_MUST_SURVIVE_GARBAGE_COLLECTION, ClassName::OVERRIDES_FINALIZE }
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// The size-based allocator, which isolates different Cell types based on their size instead of their concrete type.
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// This should only be used if it's not possible or undesirable to use a type-isolated cell allocator.
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// Different Cell types can use the same blocks if they happen to have the same size, which allows type confusion
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// to occur if a Cell is used after it's freed.
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#define GC_DECLARE_SIZE_BASED_ALLOCATOR(ClassName) \
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using gc_allocator_marker = ClassName
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namespace GC {
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class GC_API CellAllocator {
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public:
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CellAllocator(size_t cell_size, StringView = {}, bool overrides_must_survive_garbage_collection = false, bool overrides_finalize = false);
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~CellAllocator() = default;
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StringView class_name() const { return m_class_name; }
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size_t cell_size() const { return m_cell_size; }
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Cell* allocate_cell(Heap&);
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template<typename Callback>
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IterationDecision for_each_block(Callback callback)
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{
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for (auto& block : m_full_blocks) {
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if (callback(block) == IterationDecision::Break)
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return IterationDecision::Break;
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}
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for (auto& block : m_usable_blocks) {
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if (callback(block) == IterationDecision::Break)
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return IterationDecision::Break;
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}
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return IterationDecision::Continue;
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}
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void block_did_become_empty(Badge<Heap>, HeapBlock&);
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void block_did_become_usable(Badge<Heap>, HeapBlock&);
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IntrusiveListNode<CellAllocator> m_list_node;
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using List = IntrusiveList<&CellAllocator::m_list_node>;
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BlockAllocator& block_allocator() { return m_block_allocator; }
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FlatPtr min_block_address() const { return m_min_block_address; }
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FlatPtr max_block_address() const { return m_max_block_address; }
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private:
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StringView m_class_name;
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size_t const m_cell_size;
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BlockAllocator m_block_allocator;
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using BlockList = IntrusiveList<&HeapBlock::m_list_node>;
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BlockList m_full_blocks;
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BlockList m_usable_blocks;
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FlatPtr m_min_block_address { explode_byte(0xff) };
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FlatPtr m_max_block_address { 0 };
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bool m_overrides_must_survive_garbage_collection { false };
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bool m_overrides_finalize { false };
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};
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template<typename T>
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class GC_API TypeIsolatingCellAllocator {
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public:
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using CellType = T;
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TypeIsolatingCellAllocator(StringView class_name, bool overrides_must_survive_garbage_collection, bool overrides_finalize)
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: allocator(sizeof(T), class_name, overrides_must_survive_garbage_collection, overrides_finalize)
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{
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}
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NeverDestroyed<CellAllocator> allocator;
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};
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}
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