c++ - epoll struct epoll_data 已设置但稍后返回未初始化

Question

我正在创建 Epoll 事件，在用户数据 epoll 结构中设置索引epoll_data并将它们添加到 Epoll。但是，当收到来自 Epoll 的调用时，该用户数据索引未初始化。

代码：

class Epoll
{
    Epoll()
    {
        _epollFd = epoll_create1(0);
        assert(_epollFd >= 0);
    }

    void addEvent()
    {
        struct epoll_event event;
        event.events = EPOLLIN;

        event.data.u32 = getIndexFromSomwhere();   // This is set with/prints 0

        int sock = getSockFromSomewhere();
        assert(epoll_ctl(_epollFd, EPOLL_CTL_ADD, sock, &event));
    }

    void receiveEvents()
    {
        while(true)
        {
            struct epoll_event events[MAX_SOCKETS];
            const size_t count = epoll_wait(_epollFd, &events[0], sizeof(events), -1);

            for(size_t j = 0; j < count; ++j)
            {
                const uint32_t callbackIndex = events[j].data.u32;
                // This returns 32735, not 0 as expected
            }
        }
    }

    int _epollFd;
};