Source/JavaScriptCore/heap/IsoMemoryAllocatorBase.h

/*
 * Copyright (C) 2017-2021 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. ``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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include "AlignedMemoryAllocator.h"
#include <wtf/BitVector.h>
#include <wtf/DebugHeap.h>
#include <wtf/HashMap.h>
#include <wtf/Vector.h>


namespace JSC {

class IsoMemoryAllocatorBase : public AlignedMemoryAllocator {
public:
    IsoMemoryAllocatorBase(CString);
    ~IsoMemoryAllocatorBase() override;

    void* tryAllocateAlignedMemory(size_t alignment, size_t size) final;
    void freeAlignedMemory(void*) final;

protected:
    void releaseMemoryFromSubclassDestructor();
    virtual void* tryMallocBlock() = 0;
    virtual void freeBlock(void* block) = 0;
    virtual void commitBlock(void* block) = 0;
    virtual void decommitBlock(void* block) = 0;

#if ENABLE(MALLOC_HEAP_BREAKDOWN)
protected:
    // If breakdown is enabled, we do not ensure Iso-feature. This is totally OK since breakdown is memory bloat debugging feature.
    WTF::DebugHeap m_debugHeap;
#else
private:
    Vector<void*> m_blocks;
    HashMap<void*, unsigned> m_blockIndices;
    BitVector m_committed;
    unsigned m_firstUncommitted { 0 };
    Lock m_lock;
#endif
};

} // namespace JSC