四：深入Nginx之事件與連結 （之一）

<code><span>typedef</span><span>struct</span> {
<span>//位于文件 ngx_event.h</span><span>//事件模块 的名字</span>
    ngx_str_t              *name;
    <span>//在解析 配置前，这个回调 方法用于创建存储配置选项参数的结构体</span><span>void</span>                 *(*create_conf)(ngx_cycle_t *cycle);
    <span>// 在解析配置项完成 之后,init_conf方法会被调用，用以综合处理当前事件模块感兴趣的全部配置项</span><span>char</span>                 *(*init_conf)(ngx_cycle_t *cycle, <span>void</span> *conf);
    <span>// 对于事件驱动机制，每个事件模块需要实现10个抽象方法 </span>
    ngx_event_actions_t     actions;
} ngx_event_module_t;</code>

<code><span>typedef</span><span>struct</span> {
    <span>/* 添加事件方法，它将负责把1个感兴趣 事件添加到操作 系统提供的事件驱动机制 */</span>
    ngx_int_t  (*add)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags);
    <span>/*删除事件方法，它将1个已经存在于事件驱动机制中的事件移除 */</span>
    ngx_int_t  (*del)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags);
    <span>/*启用 1个 事件，目前事件框架不会调用 这个 方法，大部分事件驱动模块对于该方法的实现都是与上面的add方法完全一致的*/</span>
    ngx_int_t  (*enable)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags);
    <span>/*禁用1个事件，目前事件框架不会 调用这个方法 ，大部分事件驱动器对于这个方法的实现与上面的del方法完全一致*/</span>
    ngx_int_t  (*disable)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags);
    <span>/*向事件驱动机制中添加一个新的连接，这意味着连接上的读写事件都添加到事件驱动机制中*/</span>
    ngx_int_t  (*add_conn)(ngx_connection_t *c);
    <span>/*从事件驱动机制中移除一个连接的读写事件*/</span>
    ngx_int_t  (*del_conn)(ngx_connection_t *c, ngx_uint_t flags);
    <span>/*仅在多线程环境下会被调用，目前Nginx在产品环境下还不会以多线程方式运行*/</span>
    ngx_int_t  (*notify)(ngx_event_handler_pt handler);
    <span>/*在正常的工作循环中，将调用process_events方法来 处理事件*/</span>
    ngx_int_t  (*process_events)(ngx_cycle_t *cycle, ngx_msec_t timer,
                                 ngx_uint_t flags);
   <span>/*初始化事件驱动模块的方法*/</span>
    ngx_int_t  (*init)(ngx_cycle_t *cycle, ngx_msec_t timer);
    <span>// 退出事件驱动模块前调用的方法</span><span>void</span>       (*done)(ngx_cycle_t *cycle);
} ngx_event_actions_t;</code>

<code><span>struct</span> ngx_event_s {
    <span>/*事件相关的对象，通常data指向ngx_connection_t连接对象。开启文件异步I/O 时，它可能会指向*/</span><span>void</span>            *data;
     <span>/* 标志位，标识事件可写，意味着对应的TCP连接可写，也即连接处于发送网络包状态 */</span><span>unsigned</span>         write:<span>1</span>;
     <span>/* 标志位，标识可建立新的连接，一般是在ngx_listening_t对应的读事件中标记 */</span><span>unsigned</span>         accept:<span>1</span>;
     <span>/*检测当前事件是否是过期的，它仅仅是给驱动模块使用的，而事件消费模块可以不用关心 */</span><span>/* used to detect the stale events in kqueue and epoll */</span><span>unsigned</span>         instance:<span>1</span>;

    <span>/*
     * the event was passed or would be passed to a kernel;
     * in aio mode - operation was posted.
     */</span><span>unsigned</span>         active:<span>1</span>;

    <span>unsigned</span>         disabled:<span>1</span>;

    <span>/* the ready event; in aio mode 0 means that no operation can be posted */</span><span>unsigned</span>         ready:<span>1</span>;

    <span>unsigned</span>         oneshot:<span>1</span>;

    <span>/* aio operation is complete */</span><span>unsigned</span>         complete:<span>1</span>;

    <span>unsigned</span>         eof:<span>1</span>;
    <span>unsigned</span>         error:<span>1</span>;

    <span>unsigned</span>         timedout:<span>1</span>;
    <span>unsigned</span>         timer_set:<span>1</span>;

    <span>unsigned</span>         delayed:<span>1</span>;

    <span>unsigned</span>         deferred_accept:<span>1</span>;

    <span>/* the pending eof reported by kqueue, epoll or in aio chain operation */</span><span>unsigned</span>         pending_eof:<span>1</span>;

    <span>unsigned</span>         posted:<span>1</span>;

    <span>unsigned</span>         closed:<span>1</span>;

    <span>/* to test on worker exit */</span><span>unsigned</span>         channel:<span>1</span>;
    <span>unsigned</span>         resolver:<span>1</span>;

    <span>unsigned</span>         cancelable:<span>1</span>;

<span>#if (NGX_WIN32)</span><span>/* setsockopt(SO_UPDATE_ACCEPT_CONTEXT) was successful */</span><span>unsigned</span>         accept_context_updated:<span>1</span>;
<span>#endif</span><span>#if (NGX_HAVE_KQUEUE)</span><span>unsigned</span>         kq_vnode:<span>1</span>;

    <span>/* the pending errno reported by kqueue */</span><span>int</span>              kq_errno;
<span>#endif</span><span>/*
     * kqueue only:
     *   accept:     number of sockets that wait to be accepted
     *   read:       bytes to read when event is ready
     *               or lowat when event is set with NGX_LOWAT_EVENT flag
     *   write:      available space in buffer when event is ready
     *               or lowat when event is set with NGX_LOWAT_EVENT flag
     *
     * epoll with EPOLLRDHUP:
     *   accept:     1 if accept many, 0 otherwise
     *   read:       1 if there can be data to read, 0 otherwise
     *
     * iocp: TODO
     *
     * otherwise:
     *   accept:     1 if accept many, 0 otherwise
     */</span><span>#if (NGX_HAVE_KQUEUE) || (NGX_HAVE_IOCP)</span><span>int</span>              available;
<span>#else</span><span>unsigned</span>         available:<span>1</span>;
<span>#endif</span>    ngx_event_handler_pt  handler;


<span>#if (NGX_HAVE_IOCP)</span>
    ngx_event_ovlp_t ovlp;
<span>#endif</span>    ngx_uint_t       index;

    ngx_log_t       *<span>log</span>;

    ngx_rbtree_node_t   timer;

    <span>/* the posted queue */</span>
    ngx_queue_t      <span>queue</span>;

<span>#if 0</span><span>/* the threads support */</span><span>/*
     * the event thread context, we store it here
     * if $(CC) does not understand __thread declaration
     * and pthread_getspecific() is too costly
     */</span><span>void</span>            *thr_ctx;

<span>#if (NGX_EVENT_T_PADDING)</span><span>/* event should not cross cache line in SMP */</span>    uint32_t         padding[NGX_EVENT_T_PADDING];
<span>#endif</span><span>#endif</span>
};


<span>#if (NGX_HAVE_FILE_AIO)</span><span>struct</span> ngx_event_aio_s {
    <span>void</span>                      *data;
    ngx_event_handler_pt       handler;
    ngx_file_t                *file;

<span>#if (NGX_HAVE_AIO_SENDFILE)</span>
    ssize_t                  (*preload_handler)(ngx_buf_t *file);
<span>#endif</span>    ngx_fd_t                   fd;

<span>#if (NGX_HAVE_EVENTFD)</span>
    int64_t                    res;
<span>#endif</span><span>#if !(NGX_HAVE_EVENTFD) || (NGX_TEST_BUILD_EPOLL)</span>
    ngx_err_t                  err;
    size_t                     nbytes;
<span>#endif</span>    ngx_aiocb_t                aiocb;
    ngx_event_t                event;
};

<span>#endif</span></code>