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/*
* Copyright (C) 2018-2022 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 "IsoSubspace.h"
#include <wtf/Function.h>
#include <wtf/HashMap.h>
#include <wtf/Lock.h>
namespace JSC {
class Heap;
class VM;
// This is an appropriate way to stash IsoSubspaces for rarely-used classes or classes that are mostly
// sure to be main-thread-only. But if a class typically gets instantiated from multiple threads at
// once, then this is not great, because concurrent allocations will probably contend on this thing's
// lock.
//
// Usage: A IsoSubspacePerVM instance is instantiated using NeverDestroyed i.e. each IsoSubspacePerVM
// instance is immortal for the life of the process. There is one IsoSubspace type per IsoSubspacePerVM.
// IsoSubspacePerVM itself is a factory for those IsoSubspaces per VM and per Heap. IsoSubspacePerVM
// also serves as the manager of the IsoSubspaces. Client VMs are responsible for calling
// releaseClientIsoSubspace() to release the IsoSubspace when the VM shuts down. Similarly, if the
// Heap is not an immortal singleton heap (when global GC is enabled), the per Heap IsoSubspace also
// needs to be released when the Heap is destructed.
class IsoSubspacePerVM final {
public:
struct SubspaceParameters {
SubspaceParameters() { }
SubspaceParameters(CString name, const HeapCellType& heapCellType, size_t size)
: name(WTFMove(name))
, heapCellType(&heapCellType)
, size(size)
{
}
CString name;
const HeapCellType* heapCellType { nullptr };
size_t size { 0 };
};
JS_EXPORT_PRIVATE IsoSubspacePerVM(Function<SubspaceParameters(Heap&)>);
JS_EXPORT_PRIVATE ~IsoSubspacePerVM();
JS_EXPORT_PRIVATE GCClient::IsoSubspace& clientIsoSubspaceforVM(VM&);
// FIXME: GlobalGC: this is only needed until we have a immortal singleton heap with GlobalGC.
void releaseIsoSubspace(Heap&);
void releaseClientIsoSubspace(VM&);
private:
IsoSubspace& isoSubspaceforHeap(LockHolder&, Heap&);
Lock m_lock;
HashMap<Heap*, IsoSubspace*> m_subspacePerHeap;
HashMap<VM*, GCClient::IsoSubspace*> m_clientSubspacePerVM WTF_GUARDED_BY_LOCK(m_lock);
Function<SubspaceParameters(Heap&)> m_subspaceParameters;
};
#define ISO_SUBSPACE_PARAMETERS(heapCellType, type) ::JSC::IsoSubspacePerVM::SubspaceParameters("IsoSpace " #type, (heapCellType), sizeof(type))
} // namespace JSC
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