如何在C++中跟踪内存分配(尤其是新建/删除)

如何跟踪C++中的内存分配,尤其是new/ delete.对于一个对象,我可以轻松覆盖operator new,但我不确定如何全局覆盖所有分配,以便它们通过我的自定义new/ delete.这应该不是一个大问题,但我不确定应该怎么做(#define new MY_NEW？).

一旦这个工作,我会认为它足以在分配的指针/位置的某处有一个映射,所以我可以跟踪当前"活动"的所有分配,并且 - 在应用程序结束时 - 检查分配没有被释放的.

好吧,这似乎再次像肯定已经多次完成了几次,所以任何好的库(最好是便携式的)？

我建议你使用valgrindlinux.它会捕获未释放的内存,以及写入未分配内存等其他错误.另一种选择是mudflap,它告诉你没有释放内存.使用-fmudflap -lmudflapgcc选项,然后启动你的程序MUDFLAP_OPTIONS=-print-leaks ./my_program.

这是一些非常简单的代码.它不适合复杂的跟踪,但是如果你自己实现它,它的目的是向你展示你原则上如何做.像这样的东西(省略了调用注册的new_handler和其他细节的东西).

template
struct track_alloc : std::allocator {
    typedef typename std::allocator::pointer pointer;
    typedef typename std::allocator::size_type size_type;

    template
    struct rebind {
        typedef track_alloc other;
    };

    track_alloc() {}

    template
    track_alloc(track_alloc const& u)
        :std::allocator(u) {}

    pointer allocate(size_type size, 
                     std::allocator::const_pointer = 0) {
        void * p = std::malloc(size * sizeof(T));
        if(p == 0) {
            throw std::bad_alloc();
        }
        return static_cast(p);
    }

    void deallocate(pointer p, size_type) {
        std::free(p);
    }
};

typedef std::map< void*, std::size_t, std::less, 
                  track_alloc< std::pair > > track_type;

struct track_printer {
    track_type * track;
    track_printer(track_type * track):track(track) {}
    ~track_printer() {
        track_type::const_iterator it = track->begin();
        while(it != track->end()) {
            std::cerr << "TRACK: leaked at " << it->first << ", "
                      << it->second << " bytes\n";
            ++it;
        }
    }
};

track_type * get_map() {
    // don't use normal new to avoid infinite recursion.
    static track_type * track = new (std::malloc(sizeof *track)) 
        track_type;
    static track_printer printer(track);
    return track;
}

void * operator new(std::size_t size) throw(std::bad_alloc) {
    // we are required to return non-null
    void * mem = std::malloc(size == 0 ? 1 : size);
    if(mem == 0) {
        throw std::bad_alloc();
    }
    (*get_map())[mem] = size;
    return mem;
}

void operator delete(void * mem) throw() {
    if(get_map()->erase(mem) == 0) {
        // this indicates a serious bug
        std::cerr << "bug: memory at " 
                  << mem << " wasn't allocated by us\n";
    }
    std::free(mem);
}

int main() {
    std::string *s = new std::string;
        // will print something like: TRACK: leaked at 0x9564008, 4 bytes
}

valgrind --tool=massif  
ms_print massif.out. | less

inline void * __cdecl operator new(unsigned int size,
    const char *file, int line);

extern AllocList *allocList;