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/*
* Copyright (C) 2017-2023 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "AllocationFailureMode.h"
#include "AllocatorForMode.h"
#include "Allocator.h"
#include "MarkedBlock.h"
#include "MarkedSpace.h"
#include <wtf/TZoneMalloc.h>
#include <wtf/text/CString.h>
namespace JSC {
class AlignedMemoryAllocator;
class HeapCellType;
enum class SubspaceKind {
CompleteSubspace,
IsoSubspace,
PreciseSubspace,
};
// The idea of subspaces is that you can provide some custom behavior for your objects if you
// allocate them from a custom Subspace in which you override some of the virtual methods. This
// class is the baseclass of all subspaces e.g. CompleteSubspace, IsoSubspace.
class Subspace {
WTF_MAKE_NONCOPYABLE(Subspace);
WTF_MAKE_TZONE_ALLOCATED(Subspace);
public:
JS_EXPORT_PRIVATE virtual ~Subspace();
const char* name() const { return m_name.data(); }
unsigned nameHash() const { return m_name.hash(); } // FIXME: rdar://139998916
MarkedSpace& space() const { return m_space; }
CellAttributes attributes() const;
const HeapCellType* heapCellType() const { return m_heapCellType; }
AlignedMemoryAllocator* alignedMemoryAllocator() const { return m_alignedMemoryAllocator; }
void finishSweep(MarkedBlock::Handle&, FreeList*);
void destroy(VM&, JSCell*);
void prepareForAllocation();
void didCreateFirstDirectory(BlockDirectory* directory) { m_directoryForEmptyAllocation = directory; }
// Finds an empty block from any Subspace that agrees to trade blocks with us.
MarkedBlock::Handle* findEmptyBlockToSteal();
template<typename Func>
void forEachDirectory(const Func&);
Ref<SharedTask<BlockDirectory*()>> parallelDirectorySource();
template<typename Func>
void forEachMarkedBlock(const Func&);
template<typename Func>
void forEachNotEmptyMarkedBlock(const Func&);
JS_EXPORT_PRIVATE Ref<SharedTask<MarkedBlock::Handle*()>> parallelNotEmptyMarkedBlockSource();
template<typename Func>
void forEachPreciseAllocation(const Func&);
template<typename Func>
void forEachMarkedCell(const Func&);
template<typename Visitor, typename Func>
Ref<SharedTask<void(Visitor&)>> forEachMarkedCellInParallel(const Func&);
template<typename Func>
void forEachLiveCell(const Func&);
void sweepBlocks();
Subspace* nextSubspaceInAlignedMemoryAllocator() const { return m_nextSubspaceInAlignedMemoryAllocator; }
void setNextSubspaceInAlignedMemoryAllocator(Subspace* subspace) { m_nextSubspaceInAlignedMemoryAllocator = subspace; }
virtual void didResizeBits(unsigned newSize);
virtual void didRemoveBlock(unsigned blockIndex);
virtual void didBeginSweepingToFreeList(MarkedBlock::Handle*);
SubspaceKind kind() const { return m_kind; }
bool isIsoSubspace() const { return kind() == SubspaceKind::IsoSubspace; }
bool isPreciseOnly() const { return kind() == SubspaceKind::PreciseSubspace; }
protected:
Subspace(SubspaceKind, CString name, Heap&);
void initialize(const HeapCellType&, AlignedMemoryAllocator*);
MarkedSpace& m_space;
const HeapCellType* m_heapCellType { nullptr };
AlignedMemoryAllocator* m_alignedMemoryAllocator { nullptr };
BlockDirectory* m_firstDirectory { nullptr };
BlockDirectory* m_directoryForEmptyAllocation { nullptr }; // Uses the MarkedSpace linked list of blocks.
SentinelLinkedList<PreciseAllocation, BasicRawSentinelNode<PreciseAllocation>> m_preciseAllocations;
SubspaceKind m_kind;
uint8_t m_remainingLowerTierPreciseCount { 0 }; // Lower tier is a precise allocation but we use the term lower to avoid confusion with precise-only.
Subspace* m_nextSubspaceInAlignedMemoryAllocator { nullptr };
CString m_name;
};
} // namespace JSC
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