c++ - C++ 池分配器程序仅在控制台关闭时崩溃

问题描述

我正在查看这个池分配器实现。我实际上已经对其进行了一些修改，我的完整代码是：

template <class T, size_t T_per_page = 200>
class PoolAllocator
{
    private:
        const size_t pool_size = T_per_page * sizeof(T);
        std::vector<T *> pools;
        size_t count;
        size_t next_pos;

        void alloc_pool() {
            next_pos = 0;
            void *temp = operator new(pool_size);
            pools.push_back(static_cast<T *>(temp));
        }
    public:
        PoolAllocator() {
            count = 0;
            alloc_pool();
        }

        void* allocate() {
            if (next_pos == T_per_page)
                alloc_pool();

            void* ret = pools.back() + next_pos;
            ++next_pos;
            ++count;
            return ret;
        }

        size_t getSize() const
        {
            return T_per_page * (pools.size() - 1) + next_pos;
        }

        size_t getCount() const
        {
            return count;
        }

        size_t getCapacity() const
        {
            return T_per_page * pools.size();
        }

        T* get(size_t index) const
        {
            if (index >= getCount()) { return NULL; }

            size_t poolIndex = index / T_per_page;
            return pools[poolIndex] + (index % T_per_page);
        }

        ~PoolAllocator() {
            std::cout << "POOL ALLOCATOR DESTRUCTOR CALLED" << std::endl;
            while (!pools.empty()) {
                T *p = pools.back();
                size_t start = T_per_page;
                if (pools.size() == 1){
                    start = next_pos;
                }

                std::cout << "start: " << start << std::endl;
                for (size_t pos = start; pos > 0; --pos)
                {
                    std::cout << "pos: " << pos << std::endl;
                    p[pos - 1].~T();
                }
                operator delete(static_cast<void *>(p));
                pools.pop_back();
            }
        }
};

template<class T>
PoolAllocator<T>& getAllocator()
{
    static PoolAllocator<T> allocator;
    return allocator;
}

class Node
{
    private:
        int id;
        std::vector<float> vertices;

    public:
        Node() : id(42)
        { 
            std::cout << "Node constructor called" << std::endl;
        }
        ~Node(){ std::cout << "Node destructor called" << std::endl; }

        void* operator new(size_t size)
        {
            std::cout << "Node operator new called" << std::endl;
            return getAllocator<Node>().allocate();
        }

        void operator delete(void*)
        {
            std::cout << "Node operator delete called" << std::endl;
        }
    };

int _tmain(int argc, _TCHAR* argv[])
{
    Node* n1 = new Node();
    Node* n2 = new Node();  
    Node* n3 = new Node();
    Node* n4 = new Node();

    std::cout << "Count: " << getAllocator<Node>().getCount() << " size: " << getAllocator<Node>().getSize() << " capacity: " << getAllocator<Node>().getCapacity() << std::endl;

    while (true){}

    return 0;
}

当我在 Visual Studio 中运行此代码时，它似乎可以正常工作，直到我关闭控制台时出现访问冲突错误。我尝试在分配器上手动调用析构函数，它似乎工作正常，但我一定在某处犯了错误。我得到的错误是：

谁能发现我在哪里犯错？

编辑1：

经过进一步调查，即使 main 中没有新的 Node 行，它仍然会崩溃。似乎与 getAllocator() 方法以及如何调用析构函数有关？或者分配器是静态的事实？

编辑2：

我实际上根本不认为它与我的分配器有任何关系！如果我尝试代码：

class Node2
{
    private:
        int x;
    public:
        Node2():x(42){std::cout << "Node2 constructor called" << std::endl;};
        Node2(const Node2& other){ std::cout << "Node2 copy constructor called" << std::endl; };
        ~Node2(){ std::cout << "Node2 destructor called" << std::endl; };
};

Node2& Test(){
    static Node2 myIndex;

    return myIndex;
}

int _tmain(int argc, _TCHAR* argv[])
{
    Test();

    while (true){}

    return 0;
}

它导致同样的错误！情节变厚了。我假设是编写自定义分配器的新手，分配器代码是问题所在。仍然不确定为什么我的较小代码会发生此错误...

标签： c++memory-managementvisual-studio-2012

c++ - C++ 池分配器程序仅在控制台关闭时崩溃

问题描述

解决方案

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