Source/bmalloc/bmalloc/IsoMallocFallback.h

/*
 * Copyright (C) 2017-2020 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 "BExport.h"
#include "BInline.h"
#include "BPlatform.h"
#include <cstddef>
#include <cstdint>

#if BENABLE_MALLOC_HEAP_BREAKDOWN
#include <malloc/malloc.h>
#endif

namespace bmalloc { namespace IsoMallocFallback {

enum class MallocFallbackState : uint8_t {
    Undecided,
    FallBackToMalloc,
    DoNotFallBack
};

extern MallocFallbackState mallocFallbackState;

BINLINE bool shouldTryToFallBack()
{
    if ((true))
        return false;
    
    return mallocFallbackState != MallocFallbackState::DoNotFallBack;
}
    
struct MallocResult {
    MallocResult() = default;
    
    MallocResult(void* ptr)
        : ptr(ptr)
        , didFallBack(true)
    {
    }
    
    void* ptr { nullptr } ;
    bool didFallBack { false };
};

BEXPORT MallocResult tryMalloc(
    size_t size
#if BENABLE_MALLOC_HEAP_BREAKDOWN
    , malloc_zone_t* zone = nullptr
#endif
    );

// Returns true if it did fall back.
BEXPORT bool tryFree(
    void* ptr
#if BENABLE_MALLOC_HEAP_BREAKDOWN
    , malloc_zone_t* zone = nullptr
#endif
    );
    
} } // namespace bmalloc::IsoMallocFallback