my_memory_pool.h

#ifndef MY_MEMORY_POOL_H
#define MY_MEMORY_POOL_H

#define TBB_PREVIEW_MEMORY_POOL 1

#include "tbb/memory_pool.h"
#include "tbb/enumerable_thread_specific.h"

#include <list>

using namespace tbb;
template <class T>
class MyMemoryPool
{

#ifdef __EMSCRIPTEN__
    std::allocator<T> my_pool; // memory pool
    std::list<T> data_list;    // list of all nodes allocated
#else
    tbb::memory_pool<std::allocator<T>> my_pool;            // memory pool
    typedef tbb::memory_pool_allocator<T> pool_allocator_t; // memory allocator
    std::list<T, pool_allocator_t> data_list;               // list of all nodes allocated
#endif
    std::list<T *> free_list; // list of all free nodes

public:
    // constructor
#ifdef __EMSCRIPTEN__
    MyMemoryPool() : data_list(my_pool){};
#else
    MyMemoryPool() : data_list(pool_allocator_t(my_pool)){};
#endif
    // deconstructor
    ~MyMemoryPool(){
        // my_pool.recycle();
    };
    // prepare an available node
    T *malloc()
    {
        if (free_list.empty())
        {
            data_list.emplace_back(T());
            return (&data_list.back());
        }
        else
        {
            T *result = free_list.front();
            free_list.pop_front();
            return result;
        }
    };
    // relinquish an unused node
    void free(T *ptr)
    {
        free_list.push_back(ptr);
    };
    // return the total number of nodes allocated
    int capacity()
    {
        return data_list.size();
    };
    // return the number of current available nodes
    int available_node()
    {
        return free_list.size();
    };
};

#endif // MY_MEMORY_POOL_H