integration/luprex/core/cpp/two-mallocs.hpp

#ifndef TWO_MALLOCS_HPP
#define TWO_MALLOCS_HPP

#include <cstddef>

// dlmalloc is only used on linux.
extern "C" {
#ifdef __linux__
void* dlmalloc(size_t x);
void  dlfree(void *p);
void* dlrealloc(void*, size_t);
#else
void* dlmalloc(size_t x) { return malloc(x); }
void  dlfree(void *p) { free(p); }
void* dlrealloc(void *p, size_t x) { return realloc(p,x); }
#endif
}

// Return the current state of the dlmalloc allocator as a 30-bit hash.
extern int dlmalloc_hash();

// EngAllocator: a class meant to be used as an STL Allocator.
// Causes objects to be allocated using dlmalloc and dlfree.
template <class T>
class EngAllocator
{
public:
    using value_type    = T;
    EngAllocator() noexcept {}
    template <class U> EngAllocator(EngAllocator<U> const&) noexcept {}

    value_type* allocate(std::size_t n)
    {
        return static_cast<value_type*>(dlmalloc(n*sizeof(value_type)));
    }

    void deallocate(value_type* p, std::size_t) noexcept
    {
        dlfree(p);
    }
};

template <class T, class U>
bool operator==(EngAllocator<T> const&, EngAllocator<U> const&) noexcept
{
    return true;
}

template <class T, class U>
bool operator!=(EngAllocator<T> const&, EngAllocator<U> const&) noexcept
{
    return false;
}

// DrvAllocator: a class meant to be used as an STL Allocator.
// Causes objects to be allocated using malloc and free.
template <class T>
class DrvAllocator
{
public:
    using value_type    = T;
    DrvAllocator() noexcept {}
    template <class U> DrvAllocator(DrvAllocator<U> const&) noexcept {}

    value_type* allocate(std::size_t n)
    {
        return static_cast<value_type*>(dlmalloc(n*sizeof(value_type)));
    }

    void deallocate(value_type* p, std::size_t) noexcept
    {
        dlfree(p);
    }
};

template <class T, class U>
bool operator==(DrvAllocator<T> const&, DrvAllocator<U> const&) noexcept
{
    return true;
}

template <class T, class U>
bool operator!=(DrvAllocator<T> const&, DrvAllocator<U> const&) noexcept
{
    return false;
}

#endif // TWO_MALLOCS_HPP