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/*
* Copyright (C) 2011-2021 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. AND ITS CONTRIBUTORS ``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 ITS 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 "Handle.h"
#include "HandleBlock.h"
#include "HeapCell.h"
#include <wtf/DoublyLinkedList.h>
#include <wtf/HashCountedSet.h>
#include <wtf/SentinelLinkedList.h>
#include <wtf/SinglyLinkedList.h>
namespace JSC {
class HandleSet;
class VM;
class JSValue;
class HandleNode final : public BasicRawSentinelNode<HandleNode> {
public:
HandleNode() = default;
HandleSlot slot();
HandleSet* handleSet();
static HandleNode* toHandleNode(HandleSlot slot)
{
return bitwise_cast<HandleNode*>(bitwise_cast<uintptr_t>(slot) - OBJECT_OFFSETOF(HandleNode, m_value));
}
private:
JSValue m_value { };
};
class HandleSet {
friend class HandleBlock;
public:
static HandleSet* heapFor(HandleSlot);
HandleSet(VM&);
~HandleSet();
VM& vm();
HandleSlot allocate();
void deallocate(HandleSlot);
template<typename Visitor> void visitStrongHandles(Visitor&);
template<bool isCellOnly>
void writeBarrier(HandleSlot, JSValue);
unsigned protectedGlobalObjectCount();
template<typename Functor> void forEachStrongHandle(const Functor&, const HashCountedSet<JSCell*>& skipSet);
private:
typedef HandleNode Node;
JS_EXPORT_PRIVATE void grow();
#if ENABLE(GC_VALIDATION) || ASSERT_ENABLED
JS_EXPORT_PRIVATE bool isLiveNode(Node*);
#endif
VM& m_vm;
DoublyLinkedList<HandleBlock> m_blockList;
using NodeList = SentinelLinkedList<Node, BasicRawSentinelNode<Node>>;
NodeList m_strongList;
SinglyLinkedList<Node> m_freeList;
};
inline HandleSet* HandleSet::heapFor(HandleSlot handle)
{
return HandleNode::toHandleNode(handle)->handleSet();
}
inline VM& HandleSet::vm()
{
return m_vm;
}
inline HandleSlot HandleSet::allocate()
{
if (m_freeList.isEmpty())
grow();
HandleSet::Node* node = m_freeList.pop();
new (NotNull, node) HandleSet::Node();
return node->slot();
}
inline void HandleSet::deallocate(HandleSlot handle)
{
HandleSet::Node* node = HandleNode::toHandleNode(handle);
if (node->isOnList())
NodeList::remove(node);
m_freeList.push(node);
}
inline HandleSlot HandleNode::slot()
{
return &m_value;
}
inline HandleSet* HandleNode::handleSet()
{
return HandleBlock::blockFor(this)->handleSet();
}
template<typename Functor> void HandleSet::forEachStrongHandle(const Functor& functor, const HashCountedSet<JSCell*>& skipSet)
{
for (Node& node : m_strongList) {
JSValue value = *node.slot();
if (!value || !value.isCell())
continue;
if (skipSet.contains(value.asCell()))
continue;
functor(value.asCell());
}
}
template<bool isCellOnly>
inline void HandleSet::writeBarrier(HandleSlot slot, JSValue value)
{
bool valueIsNonEmptyCell = value && (isCellOnly || value.isCell());
bool slotIsNonEmptyCell = *slot && (isCellOnly || slot->isCell());
if (valueIsNonEmptyCell == slotIsNonEmptyCell)
return;
Node* node = HandleNode::toHandleNode(slot);
#if ENABLE(GC_VALIDATION)
if (node->isOnList())
RELEASE_ASSERT(isLiveNode(node));
#endif
if (!valueIsNonEmptyCell) {
ASSERT(slotIsNonEmptyCell);
ASSERT(node->isOnList());
NodeList::remove(node);
return;
}
ASSERT(!slotIsNonEmptyCell);
ASSERT(!node->isOnList());
m_strongList.push(node);
#if ENABLE(GC_VALIDATION)
RELEASE_ASSERT(isLiveNode(node));
#endif
}
} // namespace JSC
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