mirror of
https://github.com/RGBCube/serenity
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07a36c8f80
Doing things in the destructor of a GC-allocated object isn't always safe, in case it involves accessing other GC-allocated objects. If they were already swept by GC, we'd be poking into freed memory. This patch adds a separate finalization pass where GC calls finalize() on every unmarked cell that's about to be deleted. It's safe to access other GC objects in finalize(), even if they're also unmarked.
124 lines
3.4 KiB
C++
124 lines
3.4 KiB
C++
/*
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* Copyright (c) 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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#include <AK/Badge.h>
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#include <AK/HashTable.h>
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#include <AK/IntrusiveList.h>
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#include <AK/Noncopyable.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/Types.h>
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#include <AK/Vector.h>
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#include <LibCore/Forward.h>
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#include <LibJS/Forward.h>
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#include <LibJS/Heap/BlockAllocator.h>
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#include <LibJS/Heap/Cell.h>
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#include <LibJS/Heap/CellAllocator.h>
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#include <LibJS/Heap/Handle.h>
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#include <LibJS/Heap/MarkedVector.h>
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#include <LibJS/Runtime/WeakContainer.h>
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namespace JS {
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class Heap {
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AK_MAKE_NONCOPYABLE(Heap);
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AK_MAKE_NONMOVABLE(Heap);
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public:
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explicit Heap(VM&);
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~Heap();
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template<typename T, typename... Args>
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T* allocate_without_realm(Args&&... args)
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{
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auto* memory = allocate_cell(sizeof(T));
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new (memory) T(forward<Args>(args)...);
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return static_cast<T*>(memory);
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}
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template<typename T, typename... Args>
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T* allocate(Realm& realm, Args&&... args)
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{
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auto* memory = allocate_cell(sizeof(T));
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new (memory) T(forward<Args>(args)...);
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auto* cell = static_cast<T*>(memory);
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memory->initialize(realm);
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return cell;
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}
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enum class CollectionType {
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CollectGarbage,
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CollectEverything,
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};
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void collect_garbage(CollectionType = CollectionType::CollectGarbage, bool print_report = false);
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VM& vm() { return m_vm; }
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bool should_collect_on_every_allocation() const { return m_should_collect_on_every_allocation; }
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void set_should_collect_on_every_allocation(bool b) { m_should_collect_on_every_allocation = b; }
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void did_create_handle(Badge<HandleImpl>, HandleImpl&);
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void did_destroy_handle(Badge<HandleImpl>, HandleImpl&);
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void did_create_marked_vector(Badge<MarkedVectorBase>, MarkedVectorBase&);
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void did_destroy_marked_vector(Badge<MarkedVectorBase>, MarkedVectorBase&);
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void did_create_weak_container(Badge<WeakContainer>, WeakContainer&);
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void did_destroy_weak_container(Badge<WeakContainer>, WeakContainer&);
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void defer_gc(Badge<DeferGC>);
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void undefer_gc(Badge<DeferGC>);
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BlockAllocator& block_allocator() { return m_block_allocator; }
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void uproot_cell(Cell* cell);
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private:
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Cell* allocate_cell(size_t);
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void gather_roots(HashTable<Cell*>&);
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void gather_conservative_roots(HashTable<Cell*>&);
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void mark_live_cells(HashTable<Cell*> const& live_cells);
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void finalize_unmarked_cells();
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void sweep_dead_cells(bool print_report, Core::ElapsedTimer const&);
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CellAllocator& allocator_for_size(size_t);
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template<typename Callback>
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void for_each_block(Callback callback)
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{
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for (auto& allocator : m_allocators) {
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if (allocator->for_each_block(callback) == IterationDecision::Break)
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return;
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}
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}
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size_t m_max_allocations_between_gc { 100000 };
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size_t m_allocations_since_last_gc { 0 };
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bool m_should_collect_on_every_allocation { false };
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VM& m_vm;
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Vector<NonnullOwnPtr<CellAllocator>> m_allocators;
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HandleImpl::List m_handles;
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MarkedVectorBase::List m_marked_vectors;
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WeakContainer::List m_weak_containers;
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Vector<Cell*> m_uprooted_cells;
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BlockAllocator m_block_allocator;
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size_t m_gc_deferrals { 0 };
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bool m_should_gc_when_deferral_ends { false };
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bool m_collecting_garbage { false };
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};
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}
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